WorldWideScience

Sample records for barite

  1. Surface modification of barite nanoparticles using stearate

    Institute of Scientific and Technical Information of China (English)

    LI Lin-lin; HANG Jian-zhong; SHI Li-yi

    2009-01-01

    In this study,the barite nanoparticles were successfully modified with stearate and the influence of stearate addition on the performance of barite nanoparticles was systematically investigated.The products were characterized by activating factor analysis,contact angle test,surface energy calculation,sedimentation rate calculation,rheological measurement,and FT-IR analysis,etc.As the quantity of added stearate increased,both the activating factor and contact angle of barite nanoparticles increased first then decreased.When the stearate content was 5% of the mass of barite nanoparticles,the activating factor and water contact angle of modified particles reached maximum value,97% and 126~ respectively.At this time,the sedimentation rate reached minimum,and so did the surface energy.The rheological test reveals that the viscosity of modified barite nanoparticles/ petronol system decreases greatly,indicating the surface performance of barite nanoparticles has changed from hydrophilicity to lipophilicity after modification.C=O and COO stretching vibration peaks were found in the FT-IR spectra,which proves that the stearate has combined onto the surface of barite nanoparticles.Finally,according to the zeta potential result of unmodified barite,the possible modification mechanism was provided.

  2. Durability of heavyweight concrete containing barite

    International Nuclear Information System (INIS)

    The supplementary waste barite aggregates deposit in Osmaniye, southern Turkey, has been estimated at around 500 000 000 tons based on 2007 records. The aim of the present study is to investigate the durability of concrete incorporating waste barite as coarse and river sand (RS), granule blast furnace slag (GBFS), granule basaltic pumice (GBP) and ≤ 4 mm granule barite (B) as fine aggregates. The properties of the fresh concrete determined included the air content, slump, slump loss and setting time. They also included the compressive strength, flexural and splitting tensile strengths and Young's modulus of elasticity, resistance to abrasion and sulphate resistance of hardened concrete. Besides these, control mortars were prepared with crushed limestone aggregates. The influence of waste barite as coarse aggregates and RS, GBFS, GBP and B as fine aggregates on the durability of the concretes was evaluated. The mass attenuation coefficients were calculated at photon energies of 1 keV to 100 GeV using XCOM and the obtained results were compared with the measurements at 0.66 and 1.25 MeV. The results showed the possibility of using these waste barite aggregates in the production of heavy concretes. In several cases, some of these properties have been improved. Durability of the concrete made with these waste aggregates was improved. Thus, these materials should be preferably used as aggregates in heavyweight concrete production. (orig.)

  3. Rare earths in barites: distribution and effects on aqueous partitioning

    International Nuclear Information System (INIS)

    A large variety of barites collected from marine and continental environments was analyzed by neutron activation for the rare-earth elements (REE) La, Ce, Sm, Eu and Dy. Relative to chondrites all barites show a decrease of the lighter REE from La toward Eu. The abundance and distribution of rare earths in barites show a distinction of barite types. Deep-sea barites have large REE concentrations as do other authigenic deep-sea minerals and display the chondrite normalized Eu minimum, but not the negative Ce anomaly, of sea water. Other barites, mostly on land, some hydrothermal, and others of shallow marine origin, display lower total Ree concentrations. Chondrite normalized positive Eu anomalies are displayed by those varieties of reducing sedimentary and metamorphic origin. Distribution of REE in barite can be attributed both to crystallographic constraints of substitution and to solution complexing of REE in the precipitating medium. Plots of rare earth partitioning versus effective ion size suggest that the decreasing enrichment toward Eu for all barite types is caused by crystallographic constraints due to contraction of the substituting REE ion sizes relative to the size of the host Ba ion. Solution effects on REE substitution in barite can be evaluated. Under normal sea water conditions, solution complexing plays a minor role. However, increased alkalinities of reducing sediments and increased brine chlorinities could cause significant complexing and deplete REE heavier than Eu. Besides Dy in barites, this could be true for aqueous precipitation of REE in general. (author)

  4. Estimation of bioavailability of metals from drilling mud barite.

    Science.gov (United States)

    Neff, Jerry M

    2008-04-01

    Drilling mud and associated drill cuttings are the largest volume wastes associated with drilling of oil and gas wells and often are discharged to the ocean from offshore drilling platforms. Barite (BaSO4) often is added as a weighting agent to drilling muds to counteract pressure in the geologic formations being drilled, preventing a blowout. Some commercial drilling mud barites contain elevated (compared to marine sediments) concentrations of several metals. The metals, if bioavailable, may harm the local marine ecosystem. The bioavailable fraction of metals is the fraction that dissolves from the nearly insoluble, solid barite into seawater or sediment porewater. Barite-seawater and barite-porewater distribution coefficients (Kd) were calculated for determining the predicted environmental concentration (PEC; the bioavailable fraction) of metals from drilling mud barite in the water column and sediments, respectively. Values for Kdbarite-seawater and Kdbarite-porewater were calculated for barium, cadmium, chromium, copper, mercury, lead, and zinc in different grades of barite. Log Kdbarite-seawater values were higher (solubility was lower) for metals in the produced water plume than log Kdbarite-porewater values for metals in sediments. The most soluble metals were cadmium and zinc and the least soluble were mercury and copper. Log Kd values can be used with data on concentrations of metals in barite and of barite in the drilling mud-cuttings plume and in bottom sediments to calculate PECseawater and PECsediment. PMID:17994916

  5. Reaction mechanisms for barite dissolution and growth

    Energy Technology Data Exchange (ETDEWEB)

    Stack, Andrew G.

    2010-07-26

    In Stack and Rustad (2007), the reactive flux method (Rey and Hynes, 1996) and molecular dynamics (MD) were used to simulate the {001} barite-water interface structure and water exchange rate of aqueous barium ions and barium surface species. Atomic-level mineralwater interfacial structure and kinetics are being studied with increasing precision due to advances in spectroscopic methods at synchrotron x-ray sources as well as improved computational capacity. Better characterization of these interfaces in turn is leading to advances in the understanding of many macroscopic geochemical properties. Overall the barite-water interfacial structure was found to compare well to that estimated using X-ray reflectivity (XRR) measurements (Fenter et al., 2001), but there was an important difference: the MD predicted an intricate water structure present at the interface with one major peak and several minor peaks whereas the XRR found only a single layer of water. This discrepancy is thought to result from a limited resolution in the Fenter et al. (2001) study as well as over-coordination of surface sulfates by the MD model.

  6. Study on radioactive compounds in barites

    International Nuclear Information System (INIS)

    Radioactive nuclides present in samples of two different types of barite, and showing a great difference in gamma activity, were identified and quantitatively determined. Gamma spectrometry techniques were used for measuring both the natural activity and that induced by neutron activation. The samples, coming from a mine in Araxa, State of Minas Gerais, Brazil, were obtained from the solid residue of a process of niobium separation from a mineral association containing also thorium and uranium. After a period of 25 days, to allow for the reestablishment of the radium-radon equilibrium in the samples, natural activity was measured with a Ge (Li) detector coupled to a multi-channel analyzer. The results were obtained by means of a computer programme applying Covell's method. For activation analysis the samples and standards were irradiated during two hours in the Argentine RA-3 reactor under a flux of approx. 2x10/sup 13/neutrons cm/sup -2/sec/sup -1/ and measured three days thereafter by a method similar to that used for measuring natural activity. It was concluded that the main reason for the difference in radiactivity existing between the two varieties of barites is the different rate of Ra-Th separation, which is also extensive to the Ra-U. (M.E.L.)

  7. Properties of heavyweight concrete produced with barite

    International Nuclear Information System (INIS)

    Heavyweight concrete has been used for the prevention of seepage from radioactive structures due to the harmful effect of radioactive rays to living bodies (i.e., carcinogenic, etc.). The most important point about heavyweight concrete is the determination of w/c ratio. Selected cement dosage should be both high enough to allow for radioactive impermeability and low enough to prevent splits originating from shrinkage. In this study, heavyweight concrete mixtures at different w/c ratios were prepared in order to determine the most favorable w/c ratio of heavyweight concrete produced with barite. Physical and mechanical experiments were first carried out, and then by comparison with the results of other related studies the findings of this study were obtained. At the end of the study, it was found that the most favorable w/c ratio for heavyweight concrete is 0.40 and the cement dosage should not be lower than 350 kg/m3

  8. Gamma and neutron attenuation properties of barite-cement mixture

    Science.gov (United States)

    Picha, R.; Channuie, J.; Khaweerat, S.; Liamsuwan, T.; Promping, J.; Ratanatongchai, W.; Silva, K.; Wonglee, S.

    2015-05-01

    For the neutron radiography facility renovation plan at Thai Research Reactor, mixed barite-concrete blocks of different compositions were tested for their photon and neutron radiation attenuation properties. 60Co and 137Cs isotopes were used as the gamma sources; 241Am-Be was used as the neutron source. For detection, a scintillation counter and a BF3 tube were used. The intensities at various energies were measured and attenuation coefficients were calculated. Samples of barite mixture were analyzed with X-ray. The results involving the effects of barite are reported and discussed.

  9. Radiation shielding properties of barite coated fabric by computer programme

    Energy Technology Data Exchange (ETDEWEB)

    Akarslan, F.; Molla, T. [Suleyman Demirel University, Engineering Fac. Textile Dep., Isparta (Turkey); Üncü, I. S. [Suleyman Demirel University, Technological Fac. Electrical-Electronic Eng. Dep., Isparta (Turkey); Kılıncarslan, S., E-mail: seref@tef.sdu.edu.tr [Suleyman Demirel University, Engineering Fac. Civil Eng. Dep., Isparta (Turkey); Akkurt, I. [Suleyman Demirel University, Art and Science Fac., Physics Dep., Isparta (Turkey)

    2015-03-30

    With the development of technology radiation started to be used in variety of different fields. As the radiation is hazardous for human health, it is important to keep radiation dose as low as possible. This is done mainly using shielding materials. Barite is one of the important materials in this purpose. As the barite is not used directly it can be used in some other materials such as fabric. For this purposes barite has been coated on fabric in order to improve radiation shielding properties of fabric. Determination of radiation shielding properties of coated fabric has been done by using computer program written C# language. With this program the images obtained from digital Rontgen films is used to determine radiation shielding properties in terms of image processing numerical values. Those values define radiation shielding and in this way the coated barite effect on radiation shielding properties of fabric has been obtained.

  10. The origin and control of the Camamu barite deposit (BA)

    International Nuclear Information System (INIS)

    Geological and geochemical mechanisms responsible for the origin of the camamu barite deposit (Bahia State) was studied. The marine origin of sulfate is confirmed by the isotopic studies of oxygen delta and sulphur delta. (Author)

  11. Radiation shielding properties of barite coated fabric by computer programme

    International Nuclear Information System (INIS)

    With the development of technology radiation started to be used in variety of different fields. As the radiation is hazardous for human health, it is important to keep radiation dose as low as possible. This is done mainly using shielding materials. Barite is one of the important materials in this purpose. As the barite is not used directly it can be used in some other materials such as fabric. For this purposes barite has been coated on fabric in order to improve radiation shielding properties of fabric. Determination of radiation shielding properties of coated fabric has been done by using computer program written C# language. With this program the images obtained from digital Rontgen films is used to determine radiation shielding properties in terms of image processing numerical values. Those values define radiation shielding and in this way the coated barite effect on radiation shielding properties of fabric has been obtained

  12. Evaluation of redox condition by selenium speciation coprecipitated with barite

    Science.gov (United States)

    Tokunaga, K.; Takahashi, Y.; Yokoyama, Y.; Omori, E.; Kawagucci, S.

    2012-12-01

    Redox potential (Eh) is an important factor controlling chemical processes in hydrosphere on the earth, because redox reactions are related to the behaviors of many major and minor species in natural waters. The Eh may be estimated by the information of the oxidation states of redox couples (e.g., Fe(II)/Fe(III) ratio) since the Eh value tends to be controlled by the major elements. In this study, we suggest to use selenium (Se) in barite (BaSO4) as a redox indicator for hydrothermal system where barite is precipitated. Barite is stable under a high P-T condition, and this mineral contains various trace elements that may reflect the physicochemical condition of the seawater and hydrothermal water where they were formed. Selenium can occur in the environment in several oxidation states (-2, 0, +4 and +6), but Se in natural waters is mostly found in inorganic forms as oxyanions of selenite [Se(IV)] or selenate [Se(VI)]. The valence ratio of Se depends on the redox condition. Selenium is often found in minerals by substituting a site of sulfur (S) since they are homologous element. Both Se(IV) and Se(VI) may be incorporated into barite because barite is stable under a wide range of the Eh-pH condition which includes Se(IV)-Se(VI) boundary in the Eh-pH diagram. Therefore, the oxidation state of Se in barite can provide more precise information on the redox condition of the depositional environment. The purpose of this study is to establish a method to estimate the redox condition where barite is precipitated. Coprecipitation experiments of Se with barite were conducted to clarify the relationships between Se(VI)/Se(VI) ratio in artificial seawater (ASW) and that in barite at pH 8.0 and pH 4.0. These experiments were employed to evaluate the relationship between aqueous Se(VI) fraction (RwVI) and that incorporated into barite (RbVI). The initial pH of ASW was adjusted to 4.0 and 8.0 before the barite precipitation. These two pH conditions were adopted considering

  13. Insulating epoxy/barite and polyester/barite composites for radiation attenuation.

    Science.gov (United States)

    El-Sarraf, M A; El-Sayed Abdo, A

    2013-09-01

    A trial has been made to create insulating Epoxy/Barite (EP/Brt) (ρ=2.85 g cm(-3)) and Crosslinked Unsaturated Polyester/Barite (CUP/Brt) (ρ=3.25 g cm(-3)) composites with radiation attenuation and shielding capabilities. Experimental work regarding mechanical and physical properties was performed to study the composites integrity for practical applications. The properties were found to be reasonable. Radiation attenuation properties have been carried out using emitted collimated beam from a fission (252)Cf (100 µg) neutron source, and the neutron-gamma spectrometer with stilbene scintillator. The pulse shape discriminating (P.S.D) technique based on the zero cross-over method was used to discriminate between neutron and gamma-ray pulses. Thermal neutron fluxes, measured using the BF3 detector and thermal neutron detection system, were used to plot the attenuation relations. The fast neutron macroscopic effective removal cross-section ΣR, gamma ray total attenuation coefficient µ and thermal neutron macroscopic cross-section Σ have been evaluated. Theoretical calculations have been achieved using MCNP-4C2 code to calculate ΣR, µ and Σ. Also, MERCSF-N program was used to calculate macroscopic effective removal cross-section ΣR. Measured and calculated results have been compared and were found to be in reasonable agreement. PMID:23722071

  14. Radon loss from barite in submarine hydrothermal sulfide deposits

    Science.gov (United States)

    Uchida, A.; Toyoda, S.; Ishibashi, J.

    2012-12-01

    Determining the ages of the hydrothermal deposit will greatly contribute the studies of temporal change of submarine hydrothermal activities, as they are essential factors for ore formation and for the biological systems sustained by the chemical species arising from hydrothermal activities. The dating methods available for this purpose includes disequilibrium among 238U, 234U, and 230Th in sufide minerals, between 226Ra and 210Pb, and 228Ra and 228Th in barite (BaSO4) contained in the deposits, and ESR (electron spin resonance) using SO3- radical in barite. In applying these dating methods, a closed system is assumed, where radioactive nuclei decay following the law of physics but are not mobile out of the mineral. However, White and Rood (2001) reported that 3 to 20% of 222Rn is lost from barite crystal, which are used for casing of mining on the land. As 222Rn loss in barite greatly affects the dating results of 226}Ra-{210Pb method and ESR dating method in which radioactive equilibrium is assumed to calculate the dose rate, in the present paper, we investigated {222}Rn loss from the barite crystals contained in hydrothermal sulfide deposits. The radioactive nuclei, 210Pb and 214Bi were measured by the low background pure germanium gamma ray spectrometer at Okayama University of Science. A Pitchblend Uraninite (UO2) mixed with NaCl was used as the equilibrated standard. The barite crystals extracted from hydrothermal sulfide deposits taken in South Mariana Trough are also crused and mixed with NaCl. The mixed powder was packed in a thin stainless container which prevent from Rn loss, before the measurements. The measurements for 24 hours were repeated every day for 20 days. As results, it was found that the peak intensities of 210Pb and 214Bi did not change with time, meaning no Rn loss.

  15. Thermal stability of ESR signals in hydrothermal barites

    International Nuclear Information System (INIS)

    Thermal stability of the ESR signals from barites in chimneys deposited from hydrothermal vents is investigated using isothermal and isochronal annealing experiments. A combination of first and second order kinetics is required to explain the results. The Arrhenius plots of the decay rate constants give the activation energies of 1.0-1.3 eV. From the estimated decay rate constants at the sea bottom (3 oC), the decay rate of the signal was calculated to be less than 2% for the period of 20 ka, suggesting the applicability of the ESR method for dating barites up to about twenty thousand years.

  16. Thermal stability of ESR signals in hydrothermal barites

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Fumihiro [Department of Applied Physics, Okayama University of Science, 1-1 Ridai-cho, Kita-ku, Okayama 700-0005 (Japan); Toyoda, Shin, E-mail: toyoda@dap.ous.ac.jp [Department of Applied Physics, Okayama University of Science, 1-1 Ridai-cho, Kita-ku, Okayama 700-0005 (Japan); Banerjee, Debabrata [Department of Applied Physics, Okayama University of Science, 1-1 Ridai-cho, Kita-ku, Okayama 700-0005 (Japan); Planetary Sciences Division, Physical Research Laboratory, Ahmedabad 380009 (India); Ishibashi, Jun-Ichiro [Department of Earth and Planetary Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581 (Japan)

    2011-09-15

    Thermal stability of the ESR signals from barites in chimneys deposited from hydrothermal vents is investigated using isothermal and isochronal annealing experiments. A combination of first and second order kinetics is required to explain the results. The Arrhenius plots of the decay rate constants give the activation energies of 1.0-1.3 eV. From the estimated decay rate constants at the sea bottom (3 {sup o}C), the decay rate of the signal was calculated to be less than 2% for the period of 20 ka, suggesting the applicability of the ESR method for dating barites up to about twenty thousand years.

  17. The alpha effectiveness for formation of SO3- in barite: an essential factor for ESR dating of submarine hydrothermal barite

    Science.gov (United States)

    Isono, Y.; Toyoda, S.; Nishido, H.; Kayama, M.

    2013-12-01

    While Kasuya et al. (1991) first pointed out that ESR (electron spin resonance) dating of barite (BaSO4) is possible, the method was first practically applied by Okumura et al. (2010) to a sample formed by the submarine hydrothermal activity. A subsequent study by Sato et al. (2011) studied the thermal stability of the signal and concluded that the dating signal due to SO3- is stable so that dating method is applicable up to at least several thousand years. Barite crystals formed by submarine hydrothermal activities contains large amount of Ra which replaces Ba in the crystal lattice where all dose rate is due to radiation from Ra. Okumura et al. (2010) reported a concentration of 7.7 Bq/g of Ra in a hydrothermal sulfide including barite where the internal alpha dose rate in barite contributes 40 to 60 % of total dose rate. Determination of alpha effectiveness is thus the one of the essential factors for improving the precision of dating of barite by ESR. Toyoda et al. (2012) investigated the alpha effectiveness for the ESR signal due to SO3- in barite by comparing the dose responses of the signal for gamma irradiation and for He ion implantation with an energy of 4 MeV. A value 0.043 ×0.018 was obtained for a sample from Morocco. However, the dose response was far from 'good', where the number of points is not sufficient. The experiments of He ion implantation was repeated in the present study for several samples to determine the precise alpha effectiveness. A value of 0.019 ×0.0096 and 0.0062 ×0.0036 were obtained for the samples from Morocco and from Funaoka Mine, Japan, respectively. The results of further repeated analysis will be presented.

  18. Barite encrustation of benthic sulfur-oxidizing bacteria at a marine cold seep.

    Science.gov (United States)

    Stevens, E W N; Bailey, J V; Flood, B E; Jones, D S; Gilhooly, W P; Joye, S B; Teske, A; Mason, O U

    2015-11-01

    Crusts and chimneys composed of authigenic barite are found at methane seeps and hydrothermal vents that expel fluids rich in barium. Microbial processes have not previously been associated with barite precipitation in marine cold seep settings. Here, we report on the precipitation of barite on filaments of sulfide-oxidizing bacteria at a brine seep in the Gulf of Mexico. Barite-mineralized bacterial filaments in the interiors of authigenic barite crusts resemble filamentous sulfide-oxidizing bacteria of the genus Beggiatoa. Clone library and iTag amplicon sequencing of the 16S rRNA gene show that the barite crusts that host these filaments also preserve DNA of Candidatus Maribeggiatoa, as well as sulfate-reducing bacteria. Isotopic analyses show that the sulfur and oxygen isotope compositions of barite have lower δ(34)S and δ(18)O values than many other marine barite crusts, which is consistent with barite precipitation in an environment in which sulfide oxidation was occurring. Laboratory experiments employing isolates of sulfide-oxidizing bacteria from Gulf of Mexico seep sediments showed that under low sulfate conditions, such as those encountered in brine fluids, sulfate generated by sulfide-oxidizing bacteria fosters rapid barite precipitation localized on cell biomass, leading to the encrustation of bacteria in a manner reminiscent of our observations of barite-mineralized Beggiatoa in the Gulf of Mexico. The precipitation of barite directly on filaments of sulfide-oxidizing bacteria, and not on other benthic substrates, suggests that sulfide oxidation plays a role in barite formation at certain marine brine seeps where sulfide is oxidized to sulfate in contact with barium-rich fluids, either prior to, or during, the mixing of those fluids with sulfate-containing seawater in the vicinity of the sediment/water interface. As with many other geochemical interfaces that foster mineral precipitation, both biological and abiological processes likely contribute

  19. Characterization of barite and crystal glass as attenuators in X-ray and gamma radiation shieldings

    International Nuclear Information System (INIS)

    Aiming to determine the barium sulphate (BaSO4) ore and crystal glass attenuation features, both utilized as shieldings against ionizing X and gamma radiations in radiographic installations, a study of attenuation using barite plaster and barite concrete was carried out, which are used, respectively, on wall coverings and in block buildings. The crystal glass is utilized in screens and in windows. To do so, ten plates of barite plaster and three of barite concrete with 900 cm2 and with an average thickness ranging from 1 to 5 cm, and three plates of crystal glass with 323 cm2 and with thicknesses of 1, 2 and 4 cm were analyzed. The samples were irradiated with X-rays with potentials of 60, 80, 110 and 150 kilovolts, and also with 60Co gamma rays. Curves of attenuation were obtained for barite plaster and barite concrete (mGy/mA.min) and (mGy/h), both at 1 meter, as a function of thickness and curve of transmission through barite plaster and barite concrete as a function of the thickness. The equivalent thicknesses of half and tenth value layers for barite plaster, barite concrete and crystal glass for all X-Ray energies were also determined. (author)

  20. The photon attenuation coefficients of barite, marble and limra

    International Nuclear Information System (INIS)

    The linear attenuation coefficients μ (cm-1) and total mass attenuation coefficients ((μ)/(ρ)) (cm2 g-1) of γ-rays for barite, marble and limra have been calculated using the XCOM program (Version 3.1) at energies from 1 keV to 300 MeV. The calculated results were compared with the estimation coefficients ((μ)/(ρ)) based on the measured total linear attenuation coefficients (μ)

  1. The alpha effectiveness of the dating ESR signal in barite

    International Nuclear Information System (INIS)

    The alpha effectiveness was investigated for an ESR signal due to SO3− in barite by comparing the dose responses of the signal for gamma irradiation and for He ion implantation with an energy of 4 MeV. The value was obtained to be 0.043 ± 0.018 for samples from Morocco and to be 0.0089 ± 0.0006 for Kanehira Mine. The dose response for He ion implantation for the latter sample better fits to a correlation line but the signal shape changes with gamma ray dose, indicating contribution from an unknown radiation sensitive signal, while the former sample shows the same signal shapes. A value of 0.043 ± 0.018 is adopted as the alpha effectiveness of SO3− signal in barite, which is used for ESR dating of submarine hydrothermal activity. - Highlights: ► The alpha effectiveness is one of the essential factors in ESR dating. ► The alpha effectiveness value was determined for barite. ► The dose responses for gamma and for He ion implantation were compared. ► A sample shows signal shape change by gamma ray irradiation.

  2. Investigation of radiation keeping property of barite coated cloth via image processing method

    International Nuclear Information System (INIS)

    Preservative clothes which are able to absorb radiation beam are needed not only for saving people working at radioactive environment but also for saving others from natural and man-made radiation sources we are exposed in daily life. Barite is a mineral which can be used for armour plating because of high atomic numbered element barium constituent of barite. In this study, armour plating property of barite was applied to fabrics. Barite coated fabric having characteristic of keeping radiation was obtained by penetrating barite on cloth via coating method. Radiation keeping property of fabrics obtained was determined via image processing. The results of experiments showed that barite coated fabrics have blocked radiation more than normal fabrics have done.

  3. Investigation of radiation keeping property of barite coated cloth via image processing method

    Energy Technology Data Exchange (ETDEWEB)

    Kilincarslan, S.; Akkurt, I.; Molla, T.; Akarslan, F. [Department of Construction Education, Suleyman Demirel University, Isparta (Turkey); Department of Physics, Science Faculty, Suleyman Demirel University, Isparta (Turkey); Department of Construction Education, Suleyman Demirel University, Isparta (Turkey); Textil Engineering, Engineering Faculty, Suleyman Demirel University, Isparta (Turkey)

    2012-09-06

    Preservative clothes which are able to absorb radiation beam are needed not only for saving people working at radioactive environment but also for saving others from natural and man-made radiation sources we are exposed in daily life. Barite is a mineral which can be used for armour plating because of high atomic numbered element barium constituent of barite. In this study, armour plating property of barite was applied to fabrics. Barite coated fabric having characteristic of keeping radiation was obtained by penetrating barite on cloth via coating method. Radiation keeping property of fabrics obtained was determined via image processing. The results of experiments showed that barite coated fabrics have blocked radiation more than normal fabrics have done.

  4. Effect of Nature of Coal on Carbothermal Reduction of Barites

    Directory of Open Access Journals (Sweden)

    Jyotsna Agarwal

    2014-09-01

    Full Text Available The paper reports the effect of nature of coal on the carbothermal reduction of barite by using different types of coal. Usually in industrial practices, the reductive operations are carried out by using any type of cheap and easily available coal, but the extent of reduction rarely exceeds 35-40%. After admixing the steam coal in matrix, yields have been found to increase to the order of 51 to 53%. The obtained results prove to be quite economical in industrial practices.

  5. Origin of sulfate in barite and calcite cements in the Jebel Madar salt dome (Oman)

    Science.gov (United States)

    Vandeginste, V.; John, C. M.; Gilhooly, W. P.

    2012-12-01

    Jebel Madar is a 500-m high mountain rising in the desert at the Oman Foothills. The Jebel consists of Triassic to Cretaceous carbonate host rocks forming the carapace of a salt dome. Halokinesis caused major fracturing and faulting at Jebel Madar, and the resulting structures acted as the main pathways for fluids that generated diagenetic cements composed of both barite and calcite. The spatial distribution of calcite and barite occurrences shows that calcite is formed in large abundance along the three main faults, whereas barite is more concentrated along faults further away from the three main ones. The stable carbon and oxygen isotope composition of calcite and fluid inclusion data from both calcite and barite show a distinct evolution of the fluid with a highly saline component towards more mixing with meteoric water. This is in agreement with clumped isotopes data on calcite cements indicating an evolution towards lower temperatures, consistent with doming of the Jebel and greater input of lower-temperature descending meteoric fluids. Here, we present sulphur and oxygen isotopic data on barite that suggest a link between the barite formation and the Precambrian salt underlying Jebel Madar. The average δ34S measured in barite is 33‰ CDT (1σ = 5‰; n = 33), which falls at the lower end of the δ34S range reported for the Ara Group anhydrite. The average δ18O in the same barite samples is 23‰ VSMOW (1σ = 2‰; n = 33). Data from the barite will be compared with sulphur isotopes from the carbonate-associate sulfate in the calcite cements. The overall goal of our research is to gain a better insight in the formation process of barite and calcite in Jebel Madar and its link with salt tectonics. We would like to acknowledge the financial support of QCCSRC (funded jointly by Qatar Petroleum, Shell and the Qatar Science & Technology Park) and the GSA Laubach fund for this study.

  6. An investigation of X-ray and radio isotope energy absorption of heavyweight concretes containing barite

    Indian Academy of Sciences (India)

    Yüksel Esen; Berivan Yilmazer

    2011-02-01

    This study investigated the X-ray and radioisotope energy absorption capacity of heavyweight concrete containing barite aggregate. Concrete plates were prepared using differing amounts of barite aggregate instead of normal aggregate. Density–thickness–energy variations of these concretes for 85 keV, 118 keV, 164 keV, 662 keV and 1250 keV ray energies were recorded. It was observed that the concretes with greater barite content had a higher density and energy absorption capacity.

  7. ESR signals in natural barite: an application to ESR dosimetry and dating

    International Nuclear Information System (INIS)

    Barite is the natural BaSo4. A large crystal of barite was collected from El-Gedida sedimentary Iron-ore Mine, Al-Bahariya Oasis, where it is one of the most common gangue minerals in the ore. Another barite sample was collected from Gabal El-Hudi, east of Aswan, from a barite vein associated with metamorphic rocks where barite is colorless and produced economically. The two samples were subjected to ESR studies. The (ESR) spectrum of Al-Bahariya barite is characterized by ESR signals due to the electron center SO3- [g=2.0028, 2.0001 and 2.0036] and the hole-center O23- [g=2.0191, 2.0127 and 2.0103]. On the other hand, the ESR spectrum of El-Hudi barite shows the existence of both electron centers SO3- and SO2- [g=2.010, 2.007 and 2.030] and the hole center O23-, as well as the electron center CO2- (g=1.9973). The presence of the CO2- center in El-Hudi barite was not previously reported and can be attributed to the presence of carbonate impurities. The barite ESR signals SO3-(g=2.0028) were optimized, tested for linear response to artificial γ-irradiation in the dose range (6-320 Gy) and found to be stable up to 400 oC. Significant differences are observed in the ESR characteristics of the studied ba rites where the total doses (TD) are 911.4 Gy and 60 Gy for Al-Bahariya and El-Hudi barite respectively, but the saturation doses (SD) are 6.6 kGy and 26 kGy respectively. Using the annual dose (D) of 0.3 mGy due to cosmic rays; the Al-Bahariya barite yielded an age of 3.00 Ma (g=2.0028) while El-Hudi barite age is 200 ka (g=2.0028). The ESR age of Al-Bahariya barite (3.00 Ma) suggested that the last recrystallization event causing the formation of the large barite crystals occurred during the Pliocene. El-Hudi barite ESR age (200 ka) suggests its correlation and formation of barite during the humid climatic O2- isotopes stage 7, documented in the Eastern Desert of Egypt. Furthermore, Al-Bahariya barite meets the criteria suggested for new ESR dosimetric materials in

  8. Geochemistry and Fuid-Inclusion Microthermometry of the Farsesh Barite Deposit, Iran

    Directory of Open Access Journals (Sweden)

    Zarasvandi Alireza

    2014-10-01

    Full Text Available The Permian carbonate-hosted Farsesh barite deposit is located southeast of the City of Aligudarz in the province of Lorestan, Iran. Structurally, this deposit lies in the Zagros metallogenic belt and the Sanandaj-Sirjan Zone. Barite mineralisations occur as open-space flling veins, and as massive and replacement ores along fractures, faults and shear zones of the Permian carbonate host rocks. In order to determine the structure, in addition to pe-trographic and fuid-inclusions studies, an ICP-MS analysis was carried out in order to measure the major as well as the trace and rare earth elements. The Farsesh barite deposit has a simple mineralogy, of which barite is the main mineral, followed by calcite, dolomite, quartz, and opaque minerals such as Fe-oxides. Replacement of bar-ite by calcite is common and is more frequent than space-flling mineralisation. Sulphide minerals are minor and mainly consist of chalcopyrite and pyrite, which are altered by weathering to covellite, malachite and azurite. Petrographic analysis and micro-thermometry were carried out on the two-phase liquid/vapour inclusions in ellipsoidal or irregularly shaped minerals ranging in size from 5–10 µm. The measurements were conducted on fuid inclusions during the heating and subsequent homogenisation in the liquid phase. The low homogenisation temperatures (200–125°C and low to moderate salinity (4.2–20 eq wt% NaCl indicate that the barite had precipitated from hydrothermal basinal water with low to moderate salinity. It appears from the major and trace elements that geochemical features such as Ba and Sr enrichment in the barite samples was accompanied by depletion of Pb, Zn, Hg, Cu and Sb. The geochemistry of the rare earth elements, such as low σREE concentrations, LREE-enrichment chondrite-normalised REE patterns, the negative Ce and positive Eu anomalies, the low Ce/La ratio and the positive La and Gd anomalies, suggest that the Farsesh barite was deposited

  9. Palaeoarchean Barite Deposits in the Barberton Greenstone Belt: Origin and Links to Early Microbial Life

    Science.gov (United States)

    Mason, P. R.; Peters, A.; Nijman, W.; Reimer, T. O.; Whitehouse, M. J.

    2008-12-01

    Barite deposits are considered important for identifying microbial S cycling in Archean rocks since they can provide information about S isotopes in coexisting sulfate and sulfide minerals. However the degree to which barite and pyrite in metasedimentary rocks are related remains unclear. In this study we have investigated the origin of barite and pyrite in four main horizons seen in both outcrop and fresh drill core material from the Lower Mapepe formation (3.26 to 3.23 Ga), Barberton Greenstone Belt, South Africa. Host rocks include shales, cherts, tuffs and conglomerates that are variably silicified and/or affected by carbonate alteration. The high-energy depositional environment of the host rocks, mineralogical textures, barite chemistry and the occurrence of feldspars from the rarely-found celsian-hyalophane-orthoclase series suggest a seafloor exhalative origin for the barite. In contrast pyrite is closely associated with cherts and dolomitic units where rare earth element and Y data support a marine influence. Pyrite chemistry (Co/Ni= 0.1-1, Se/S <5 x 10- 5) also indicates a low temperature sedimentary origin. Multiple S isotope data (32S, 33S, 34S, determined by SIMS) for pyrite indicates a number of arrays with limited δ34S fractionation at constant Δ33S associated with individual syn-sedimentary microcrystalline pyrite layers. Isolated euhedral pyrites in massive chert and barite rich units show much more scatter and larger degrees of Δ33S variation (-1 to +4 ). Our results are consistent with models invoking microbial mass dependent fractionation of a heterogeneous elemental sulfur source derived from atmospheric photolysis. The sulfate reservoir can also be linked to photolysis but there is no clear relationship between the barite and pyrite S isotope data, suggesting that microbial (or abiotic) sulfate reduction was absent at this time or that the basinal sulfate concentration must have remained significantly lower than the mM level prior to barite

  10. EXPERIMENTAL INVESTIGATION OF COMPRESSYVE STRENGTH AND PHYSICAL PROPERTIES OF CONCRETE PRODUCED WITH GROUND BARITE

    OpenAIRE

    ESEN, Yüksel; ORHAN, Eyyüp; Kurt, Alper

    2011-01-01

    ABSTRACT In this study, compressive strength test and physical tests were made on concrete which was produced by using ground barite provided from Foreign Trade Inc. in Mu? province. Two different procedures were used in the experiments. In the first, concrete samples were prepared by decreasing the amount of aggregate in concrete mix at the rates of 20%, 40%, 60%, 80% and 100%, respectively, and by adding ground barite at the same proportions. In the second, the samples were prepared by sub...

  11. Petrology And Geochemistry Of Barite Mineralisation Around Azara North Central Nigeria

    Directory of Open Access Journals (Sweden)

    Tanko

    2015-05-01

    Full Text Available ABSTRACT The Azara barite deposits formed parts of Middle Benue Trough which is located in an elongated rift or faulted-bounded mega structural depression trending NE-SW to a length of over 1000 km and a width of 100 km.Petrological and geochemical investigations of Azrara barite deposits were carried out. Eight 8 selected samples of barites were collected from the veins four from known veins V1V3V17 and V 18 and four from new veins VAVBVCand VD werecarried out with the aim of determining their mineralisation potentials using petrographic studies and gravimetric method of analyses. The Petrographic studies of some of the thin section of the samples conducted using a polarizing microscope to determine the contents distributions and textures of the various veins Table 1. The weight percentage composition of barite in the samples are V1 86.39 VC82.61 V1881.48 V3 81.17 V17 79.82 VA78.94 VB76.82 and VD 70.55 respectively. It is deduced from this work that the chemical weathering of the carbonates resulted in two distinct types of barites Barite associated with mainly quartz SiO2 and limonite FeOOH.nH2O as major gangue and barite with siderite Ferrous Carbonate with high amount of Mg ankerite Ca Fe Mg CO3 and Calcite CaCO3. The outcomes were compared with the barite specification of Weigal1937 of 95.00 and were found to be good for making drilling mud for use in the oil industry paints and other chemicals

  12. Strontium isotopic signature of hydrothermal sedimentation from Early Cambrian barite deposits in east Guizhou, China

    Institute of Scientific and Technical Information of China (English)

    XIA Fei; MA Dongsheng; PAN Jiayong; SUN Zhanxue; CAO Shuanglin; NIE Wenming; WU Kai

    2004-01-01

    The ore genesis model for barite deposits in east Guizhou Province has been in dispute and the major debate focuses on whether they are product of the submarine hydrothermal sedimentation. This note presents new strontium isotope data from 19 samples of Dahebian and Yuping barite deposits, and their 87Sr/86Sr ratios are significantly lower than that of the coeval seawater. The 87Sr/86Sr ratios of 17 samples out of 19 samples rang from 0.708310 to 0.708967, indicating that they might be related to the mantel admixture. Two isotopic ratios in this study are higher than those of coeval seawater (0.7090), collected from late-stage barite mineral vein of interpenetrative strata and a barite nodule bearing hypidiomorphic granular pyrite, which indicates that they might be related to the continental admixture. The study provides Sr isotopic evidence not only for the submarine hydrothermal exhalative genesis of Dahebian and Yuping barite deposits, but also for distinguishing the barite mineralization of late stage.

  13. Barite-forming environments along a rifted continental margin, Southern California Borderland

    Science.gov (United States)

    Hein, James R.; Zierenberg, Robert A.; Maynard, J. Barry; Hannington, Mark D.

    2007-06-01

    The Southern California Continental Borderland (SCCB) is part of the broad San Andreas transform-fault plate boundary that consists of a series of fault-bounded, petroleum-generating basins. The SCCB has high heat flow and geothermal gradients produced by thinned continental crust and Neogene volcanism. Barite deposits in the SCCB occur along faults. Barite samples from two sea-cliff sites and four offshore sites in the SCCB were analyzed for mineralogy, chemical (54 elements) and isotopic (S, Sr) compositions, and petrography. Barite from Palos Verdes (PV) Peninsula sea-cliff outcrops is hosted by the Miocene Monterey Formation and underlying basalt; carbonate rocks from those outcrops were analyzed for C, O, and Sr isotopes and the basalt for S isotopes. Cold-seep barite from Monterey Bay, California was analyzed for comparison. SCCB offshore samples occur at water depths from about 500 to 1800 m. Those barites vary significantly in texture and occurrence, from friable, highly porous actively growing seafloor mounds to dense, brecciated, vein barite. This latter type of barite contrasts with cold-seep barite in being much more coarse grained, forms thick veins in places, and completely replaced rock clasts in breccia. The barite samples range from 94 to 99 wt% BaSO 4, with low trace-element contents, except for high Sr, Zr, Br, U, and Hg concentrations compared to their crustal abundances. δ34S for SCCB offshore barites range from 21.6‰ to 67.4‰, and for PV barite from 62‰ to 70‰. Pyrite from PV sea-cliff basalt and sedimentary rocks that host the barites averages 7.8‰ and 2.2‰, respectively. Two offshore barite samples have δ34S values (21.6‰, 22.1‰) close to that of modern seawater sulfate, whereas all other samples are enriched to strongly enriched in 34S. 87Sr/ 86Sr ratios for the barites vary over a narrow range of 0.70830-0.70856 and are much lower than that of modern seawater and also lower than the middle Miocene seawater ratio, the time

  14. Barite Crusts From A Brine Pool In The Gulf Of Mexico Entomb Filamentous Sulfur Bacteria

    Science.gov (United States)

    Stevens, E. W.; Bailey, J. V.; Flood, B. E.; Jones, D. S.; Joye, S. B.; Teske, A. P.

    2012-12-01

    Hypersaline environments offer the opportunity to study the preservation of cell material and the role of biology in catalyzing mineral precipitation under conditions where authigenic minerals are forming in the presence of microbial biomass. Mineral crusts collected from a brine pool in the Gulf of Mexico contain filamentous mineral structures of grossly similar morphology to extant Beggiatoa mats that can be found on and around the brine pool crusts. Mineralogical and molecular analyses were preformed in order to characterize the microbial and mineral assemblage associated with the crusts. Initial mineralogical analyses show the bulk composition of the crust to be barite (BaSO4). 16S rRNA gene sequencing was used to provide insight into the overall microbial community composition. Sequencing results indicate the presence of phylotypes potentially involved in methane oxidation. Sequence-data produced with Beggiatoa specific primers also indicate Beggiatoa-derived DNA within the barite crusts. Barite precipitation has been linked with sulfide oxidation in non-marine settings, and we hypothesize that it may also be important in brine pool settings where low sulfate brine waters interface with sulfide produced via AOM. Ongoing experiments using several types of bacteria are being used to determine if the metabolic oxidation of sulfide to sulfate can induce the precipitation of barite, thus providing insight into the question of whether Beggiatoa can induce the precipitation of barite within a hypersaline setting.

  15. Application of a semi-empirical model for the evaluation of transmission properties of barite mortar

    International Nuclear Information System (INIS)

    The aim of this study was to estimate barite mortar attenuation curves using X-ray spectra weighted by a workload distribution. A semi-empirical model was used for the evaluation of transmission properties of this material. Since ambient dose equivalent, H⁎(10), is the radiation quantity adopted by IAEA for dose assessment, the variation of the H⁎(10) as a function of barite mortar thickness was calculated using primary experimental spectra. A CdTe detector was used for the measurement of these spectra. The resulting spectra were adopted for estimating the optimized thickness of protective barrier needed for shielding an area in an X-ray imaging facility. - Highlights: • Barite mortar attenuation curves using X-ray spectra were calculated. • Optimized thickness of protective barrier was estimated. • An optimized model considers the energy spectra for protective barrier calculation

  16. ESR dating of barite in sulphide deposits formed by the sea-floor hydrothermal activities

    International Nuclear Information System (INIS)

    Barite is a mineral newly found to be practically useful for electron spin resonance (ESR) dating of sulphide deposits formed by the sea-floor hydrothermal activities. The recent studies for the properties of the ESR dating signal in barite are summarised in the present paper as well as the formulas for corrections for accurate dose-rate estimation are developed including the dose-rate conversion factors, shape correction for gamma-ray dose and decay of 226Ra. Although development of the techniques for ESR dating of barite has been completed, further comparative studies with other dating techniques such as U-Th and 226Ra-210Pb dating are necessary for the technique to be widely used. (authors)

  17. Precipitation and growth of barite within hydrothermal vent deposits from the Endeavour Segment, Juan de Fuca Ridge

    Science.gov (United States)

    Jamieson, John William; Hannington, Mark D.; Tivey, Margaret K.; Hansteen, Thor; Williamson, Nicole M.-B.; Stewart, Margaret; Fietzke, Jan; Butterfield, David; Frische, Matthias; Allen, Leigh; Cousens, Brian; Langer, Julia

    2016-01-01

    Hydrothermal vent deposits form on the seafloor as a result of cooling and mixing of hot hydrothermal fluids with cold seawater. Amongst the major sulfide and sulfate minerals that are preserved at vent sites, barite (BaSO4) is unique because it requires the direct mixing of Ba-rich hydrothermal fluid with sulfate-rich seawater in order for precipitation to occur. Because of its extremely low solubility, barite crystals preserve geochemical fingerprints associated with conditions of formation. Here, we present data from petrographic and geochemical analyses of hydrothermal barite from the Endeavour Segment of the Juan de Fuca Ridge, northeast Pacific Ocean, in order to determine the physical and chemical conditions under which barite precipitates within seafloor hydrothermal vent systems. Petrographic analyses of 22 barite-rich samples show a range of barite crystal morphologies: dendritic and acicular barite forms near the exterior vent walls, whereas larger bladed and tabular crystals occur within the interior of chimneys. A two component mixing model based on Sr concentrations and 87Sr/86Sr of both seawater and hydrothermal fluid, combined with 87Sr/86Sr data from whole rock and laser-ablation ICP-MS analyses of barite crystals indicate that barite precipitates from mixtures containing as low as 17% and as high as 88% hydrothermal fluid component, relative to seawater. Geochemical modelling of the relationship between aqueous species concentrations and degree of fluid mixing indicates that Ba2+ availability is the dominant control on mineral saturation. Observations combined with model results support that dendritic barite forms from fluids of less than 40% hydrothermal component and with a saturation index greater than ∼0.6, whereas more euhedral crystals form at lower levels of supersaturation associated with greater contributions of hydrothermal fluid. Fluid inclusions within barite indicate formation temperatures of between ∼120 °C and 240 °C during

  18. Exploring stable thermoluminescence signal in natural Barite (BaSO4) for retrospective dosimetry.

    Science.gov (United States)

    Sharma, Suchinder K; Thomas, Jugina; Pandian, M S; Rao, P S; Gartia, R K; Singhvi, Ashok K

    2015-11-01

    We explore the possible use of Barite (BaSO4) for radiation dosimetry and geochronology using thermoluminescence technique. Natural Barite with Mn as an impurity has a glow peak at 608K with a minimum detectable dose of 1.45±0.12mGy. This peak shows ~35% fading on 30 days of storage time and is photo-bleachable with excellent reproducibility on repeated read-out. The sensitivity changes with dose and evidence of athermal fading is also seen. We infer that the signal can be used for both retrospective dosimetry and geochronology of young deposits extending to 20ka. PMID:26325582

  19. Effect of paste humidity on kinetics of carbothermal reduction of extruded barite and coke mixture

    Science.gov (United States)

    Salem, A.; Jamshidi, S.

    2012-08-01

    The effect of the moisture content of barite-coke paste on the kinetics of carbothermal reduction was investigated to understand the role of extrusion technique on this type of solid-gas reaction. The pastes were formulated using the typical natural barite and coke powders normally used in the industrial scale. 0.65 wt.% carboxyl methyl cellulose and different amounts of distilled water, ranging 24.3-34.4% were added to the mixed powders. The obtained pastes were then shaped by a laboratory extruder. The extrusion process was assessed by determining the total porosity of dry samples. The samples in the form of disc were isothermally heated at different temperatures in the range of 800-950 °C and the conversion of barite into barium sulfide was measured by the iodometry. The reduction data were analyzed by a modified kinetic model and the frequency factor and activation energy were calculated to evaluate the reduction mechanism. It was found that the moisture content of the paste significantly affects the active site density due to increasing contact surface area between coke and barite particles.

  20. 40 CFR 436.100 - Applicability; description of the barite subcategory.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Applicability; description of the barite subcategory. 436.100 Section 436.100 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS MINERAL MINING AND PROCESSING POINT SOURCE CATEGORY...

  1. Sulfur- and oxygen-isotopes in sediment-hosted stratiform barite deposits

    Science.gov (United States)

    Johnson, Craig A.; Emsbo, Poul; Poole, Forrest G.; Rye, Robert O.

    2009-01-01

    Sulfur- and oxygen-isotope analyses have been obtained for sediment-hosted stratiform barite deposits in Alaska, Nevada, Mexico, and China to examine the environment of formation of this deposit type. The barite is contained in sedimentary sequences as old as Late Neoproterozoic and as young as Mississippian. If previously published data for other localities are considered, sulfur- and oxygen-isotope data are now available for deposits spanning a host-rock age range of Late Neoproterozoic to Triassic. On a δ 34S versus δ 18O diagram, many deposits show linear or concave-upward trends that project down toward the isotopic composition of seawater sulfate. The trends suggest that barite formed from seawater sulfate that had been isotopically modified to varying degrees. The δ 34S versus δ 18O patterns resemble patterns that have been observed in the modern oceans in pore water sulfate and water column sulfate in some anoxic basins. However, the closest isotopic analog is barite mineralization that occurs at fluid seeps on modern continental margins. Thus the data favor genetic models for the deposits in which barium was delivered by seafloor seeps over models in which barium was delivered by sedimentation of pelagic organisms. The isotopic variations within the deposits appear to reflect bacterial sulfate reduction operating at different rates and possibly with different electron donors, oxygen isotope exchange between reduction intermediates and H 2O, and sulfate availability. Because they are isotopically heterogeneous, sediment-hosted stratiform barite deposits are of limited value in reconstructing the isotopic composition of ancient seawater sulfate.

  2. Deciphering fluid sources of hydrothermal systems: A combined Sr- and S-isotope study on barite (Schwarzwald, SW Germany)

    Science.gov (United States)

    Staude, S.; Gob, S.; Pfaff, K.; Strobele, F.; Premo, W.R.; Markl, G.

    2011-01-01

    Primary and secondary barites from hydrothermal mineralizations in SW Germany were investigated, for the first time, by a combination of strontium (Sr) isotope systematics (87Sr/86Sr), Sr contents and δ34S values to distinguish fluid sources and precipitation mechanisms responsible for their formation. Barite of Permian age derived its Sr solely from crystalline basement rocks, whereas all younger barite also incorporate Sr from formation waters of the overlying sediments. In fact, most of the Sr in younger barite is leached from Lower and Middle Triassic sediments. In contrast, most of the sulfur (S) of Permian, Jurassic and northern Schwarzwald Miocene barite originated from basement rocks. The S source of Upper Rhinegraben (URG)-related Paleogene barite differs depending on geographic position: for veins of the southern URG, it is the Oligocene evaporitic sequence, while central URG mineralizations derived its S from Middle Triassic evaporites. Using Sr isotopes of barite of known age combined with estimates on the Sr contents and Sr isotopic ratios of the fluids' source rocks, we were able to quantify mixing ratios of basement-derived fluids and sedimentary formation waters for the first time. These calculations show that Jurassic barite formed by mixing of 75–95% ascending basement-derived fluids with 5–25% sedimentary formation water, but that only 20–55% of the Sr was brought by the basement-derived fluid to the depositional site. Miocene barite formed by mixing of an ascending basement-derived brine (60–70%) with 30–40% sedimentary formation waters. In this case, only 8–15% of the Sr was derived from the deep brine. This fluid-mixing calculation is an example for deposits in which the fluid source is known. This method applied to a greater number of deposits formed at different times and in various geological settings may shed light on more general causes of fluid movement in the Earth's crust and on the formation of hydrothermal ore deposits.

  3. A Combined Thermodynamic and Kinetic Model for Barite Prediction at Oil Reservoir Conditions

    DEFF Research Database (Denmark)

    Zhen Wu, Bi Yun

    research was to develop a model, based on thermodynamics and kinetics, for predicting barite precipitation rates in saline waters at the pressures and temperatures of oil bearing reservoirs, using the geochemical modelling code PHREEQC. This task is complicated by the conditions where traditional methods...... to calculate ion activity fail and for which barite reaction rates have not been determined. The model development consisted of three subprojects: first, to identify a consistent set of parameters to describe the thermodynamics of the Ba2+-SO42--H2O system at standard state conditions, based on...... detailed review of the literature (PhD Study 1). The reviewed dataset was used as starting point for geochemical speciation modelling and applied to predict the stability of sulphate minerals in North Sea oil field brines. Second, for modelling of high salinity solutions using the Pitzer ion interaction...

  4. Hydrogeochemistry of Waters of Mangampeta Barite Mining Area, Cuddapah Basin, Andhra Pradesh, India

    OpenAIRE

    NAGARAJU, Arveti

    2006-01-01

    The study is undertaken in the barite mining area of Mangampeta (Lat. 14° 01' N; Long. 79° 19' E), which is located in the Kodur Mandal of Cuddapah District, Andhra Pradesh, India. The important geological formations in this area are quartzites (quartz veins), carbonaceous tuff and dolomites. The paper presents the assessment of water quality for its suitability for agricultural and domestic purposes. The results of chemical analyses for the major ions of 50 water sample...

  5. Hydrogeochemistry of waters of Mangampeta barite mining area, Cuddapah Basin, Andhra Pradesh, India

    OpenAIRE

    A. Nagaraju; S. Suresh; Killham, K; Hudson-Edwards, K.

    2006-01-01

    The study is undertaken in the barite mining area of Mangampeta. (Lat. 14° 01′ N; Long. 79° 19′ E), which is located in the Kodur Mandal of Cuddapah District, Andhra Pradesh, India. The important geological formations in this area are quartzites (quartz veins), carbonaceous tuff and dolomites. The paper presents the assessment of water quality for its suitability for agricultural and domestic purposes. The results of chemical analyses for the major ions of 50 water samples collected from the ...

  6. Dynamics of barite growth in porous media quantified by in situ synchrotron X-ray tomography

    Science.gov (United States)

    Godinho, jose; Gerke, kirill

    2016-04-01

    Current models used to formulate mineral sequestration strategies of dissolved contaminants in the bedrock often neglect the effect of confinement and the variation of reactive surface area with time. In this work, in situ synchrotron X-ray micro-tomography is used to quantify barite growth rates in a micro-porous structure as a function of time during 13.5 hours with a resolution of 1 μm. Additionally, the 3D porous network at different time frames are used to simulate the flow velocities and calculate the permeability evolution during the experiment. The kinetics of barite growth under porous confinement is compared with the kinetics of barite growth on free surfaces in the same fluid composition. Results are discussed in terms of surface area normalization and the evolution of flow velocities as crystals fill the porous structure. During the initial hours the growth rate measured in porous media is similar to the growth rate on free surfaces. However, as the thinner flow paths clog the growth rate progressively decreases, which is correlated to a decrease of local flow velocity. The largest pores remain open, enabling growth to continue throughout the structure. Quantifying the dynamics of mineral precipitation kinetics in situ in 4D, has revealed the importance of using a time dependent reactive surface area and accounting for the local properties of the porous network, when formulating predictive models of mineral precipitation in porous media.

  7. Extensive barite deposits on a seepage site along the offshore San Clemente Fault, Mexican Borderland

    Science.gov (United States)

    Gwiazda, R.; Paull, C. K.; Maier, K. L.; McGann, M.; Caress, D. W.; Herguera, J. C.; Lundsten, E. M.; Anderson, K.

    2015-12-01

    A 6 km-long section of San Clemente Fault Zone was recently mapped with an Autonomous Underwater Vehicle, 53 km south of the U.S.-Mexican border in ~1850 m water depth. The surface expression of the fault zone as well as patches of especially rough seafloor texture on both flanks of the fault are distinctively recognized in 1-m resolution bathymetry. On the SW side of the fault, apparently accreted ovoid mounds 10 to 30 meters in diameter and up to 11 m high cover up to 50% of the seafloor within a restricted 0.43 km2 area. In contrast, on the NE side similar mounds are identified along outcropping bedding planes, suggesting that on the NE side mound formation and distribution is stratigraphically controlled. On a dive with the Remotely Operated Vehicle (ROV) Doc Ricketts we observed variably colored ~1 m-sized material clusters accreted onto the sides and top of the mounds. Some clusters consist of white, fragile, vertical spires, suggesting active upward growth of chemical precipitates. The lightly colored clusters are partially covered with gelatinous and filamentous bacterial mats on their uppermost surfaces. The mounds broke easily when prodded with the ROV arm. X-ray powder diffraction analyses show the mounds are composed of barite. Black varnish variably covers the mounds and may be related to time since the last episode of barite precipitation in a particular area. Except for thickets of tubeworms, mounds are notably devoid of attached fauna. Concentration of methane in sediment pore fluids extracted from push cores collected at the base of a tubeworm thicket was low, in the order of micromolar to undetectable Sulfur isotopic compositions of seven rock samples range between δ34S +20.1‰ to +27.5‰, indicating the sulfate in barite is mainly seawater-derived (δ34S +21) which has undergone a small degree of sulfur reduction. Overall, barite deposits covered 14% of the area within a 500 m wide band along the SW side of the fault, and 22% within a 650 m

  8. Barite precipitation following celestite dissolution in a porous medium: A SEM/BSE and μ-XRD/XRF study

    Science.gov (United States)

    Poonoosamy, J.; Curti, E.; Kosakowski, G.; Grolimund, D.; Van Loon, L. R.; Mäder, U.

    2016-06-01

    A reaction cell experiment was designed to examine mineral dissolution/precipitation processes both at the macroscopic and pore scale. A rectangular flow cell was filled with a reactive porous layer lying between two porous layers composed of quartz sand (SiO2). The reactive layer consisted of celestite (or celestine, SrSO4) with a bimodal grain size distribution (<63 μm and 125-400 μm). A barium chloride solution was then injected into the flow cell, leading to fast dissolution and replacement of celestite by barite (or baryte, BaSO4). Due to the higher molar volume of barite compared to celestite, the porosity decreased in the reactive layer. We concentrated on the refinement of post-mortem analysis and the investigation of the dissolution/precipitation mechanisms at the pore scale (10-100 μm). The sequential evolution of mineral transformations occurring in the reactive layer was determined. Our analytical techniques, combining scanning electron microscopy and synchrotron X-ray microdiffraction/microfluorescence, showed that the small celestite grain fraction dissolved rapidly to form nano-crystalline barite filling the pore space, while large celestite grains were covered with a thin rim of epitaxial micro-crystalline barite. Two distinct nucleation mechanisms for barite precipitation were involved: homogeneous nucleation (nucleation of barite in the pore space) and heterogeneous nucleation (nucleation on the surface of a solid substrate). Classical nucleation theory, using well-established and estimated parameters (e.g. effective interfacial tension) describing barite nucleation, was applied to explain the mineralogical changes occurring in our system.

  9. Massive barite deposits and carbonate mineralization in the Derugin Basin, Sea of Okhotsk: precipitation processes at cold seep sites

    Science.gov (United States)

    Greinert, Jens; Bollwerk, Sandra M.; Derkachev, Alexander; Bohrmann, Gerhard; Suess, Erwin

    2002-10-01

    An area of massive barite precipitations was studied at a tectonic horst in 1500 m water depth in the Derugin Basin, Sea of Okhotsk. Seafloor observations and dredge samples showed irregular, block- to column-shaped barite build-ups up to 10 m high which were scattered over the seafloor along an observation track 3.5 km long. High methane concentrations in the water column show that methane expulsion and probably carbonate precipitation is a recently active process. Small fields of chemoautotrophic clams ( Calyptogena sp., Acharax sp.) at the seafloor provide additional evidence for active fluid venting. The white to yellow barites show a very porous and often layered internal fabric, and are typically covered by dark-brown Mn-rich sediment; electron microprobe spectroscopy measurements of barite sub-samples show a Ba substitution of up to 10.5 mol% of Sr. Rare idiomorphic pyrite crystals (˜1%) in the barite fabric imply the presence of H 2S. This was confirmed by clusters of living chemoautotrophic tube worms (1 mm in diameter) found in pores and channels within the barite. Microscopic examination showed that micritic aragonite and Mg-calcite aggregates or crusts are common authigenic precipitations within the barite fabric. Equivalent micritic carbonates and barite carbonate cemented worm tubes were recovered from sediment cores taken in the vicinity of the barite build-up area. Negative δ 13C values of these carbonates (>-43.5‰ PDB) indicate methane as major carbon source; δ 18O values between 4.04 and 5.88‰ PDB correspond to formation temperatures, which are certainly below 5°C. One core also contained shells of Calyptogena sp. at different core depths with 14C-ages ranging from 20 680 to >49 080 yr. Pore water analyses revealed that fluids also contain high amounts of Ba; they also show decreasing SO 42- concentrations and a parallel increase of H 2S with depth. Additionally, S and O isotope data of barite sulfate (δ 34S: 21.0-38.6‰ CDT; δ 18O

  10. Comparison of photon attenuation coefficients of various barite concretes and lead by MCNP code, XCOM and experimental data

    International Nuclear Information System (INIS)

    Highlights: ► We used Monte Carlo method and MCNP-4C code for simulation. ► We simulated linear attenuation coefficients, Mfp and transmission factor for three barites and lead. ► We compared MCNP results and experimental data for various concretes in different energies. ► MCNP results showed a good agreement with experimental data. - Abstract: In this study shielding properties of various barites concretes and lead in three high gamma energies 0.662, 1.173, and 1.332 MeV were investigated using the MCNP-4C code and compared with predictions from the XCOM code and experimental data. In the three selected energies, the simulated and available data values were compared and results showed a good agreement. The results of the three methods show that lead, and pure (100%) barite have higher linear attenuation coefficients and lower transmission factors and mean free path values relative to 50% barite and 0% barite concretes

  11. Transmission properties of barite mortar using X-ray spectra measured with Cd Te detector

    Energy Technology Data Exchange (ETDEWEB)

    Santos, J. C.; Mariano, L.; Costa, P. R. [Universidade de Sao Paulo, Instituto de Fisica, Rua do Matao Travessa R. 187, Cidade Universitaria, 05508-090 Sao Paulo (Brazil); Tomal, A., E-mail: josilene@usp.br [Universidade Federal de Goias, Instituto de Fisica, Campus Samambaia, 74001-970 Goiania (Brazil)

    2014-08-15

    Current methods for calculating X-ray shielding barriers do not take into account spectral distribution of the beam transmitted by the protective material. This consideration is important in dose estimations for radiation workers and general public in diagnostic radiology facilities. The aim of the present study was to estimate barite mortar attenuation curves using X-ray spectra weighted by a workload distribution. These curves were described in units of ambient dose equivalent (H (10)), since it is the radiation quantity adopted by IAEA for dose assessment in medical environment. Attenuation curves were determined using the optimized model for shielding evaluation presented by Costa and Caldas (2002). Workload distribution presented by Simpkin (1996), measured primary spectra and mass attenuation coefficients of barite mortar were used as input data in this model. X-ray beams in diagnostic energy range were generated by an industrial X-ray tube with 3 mm of aluminum additional filtration. Primary experimental spectra were measured by a Cd Te detector and corrected by the response function of detector by means of a stripping procedure. Air kerma measurements were performed using an ionization chamber for normalization purpose of the spectra. The corrected spectra presented good agreement with spectra generated by a semi-empirical model. The variation of the ambient dose equivalent as a function of barite mortar thickness was calculated. Using these data, it was estimated the optimized thickness of protective barrier needed for shielding a particular area in an X-ray imaging facility. The results obtained for primary protective barriers exhibit qualitative agreement with those presented in literature. (Author)

  12. Transmission properties of barite mortar using X-ray spectra measured with Cd Te detector

    International Nuclear Information System (INIS)

    Current methods for calculating X-ray shielding barriers do not take into account spectral distribution of the beam transmitted by the protective material. This consideration is important in dose estimations for radiation workers and general public in diagnostic radiology facilities. The aim of the present study was to estimate barite mortar attenuation curves using X-ray spectra weighted by a workload distribution. These curves were described in units of ambient dose equivalent (H (10)), since it is the radiation quantity adopted by IAEA for dose assessment in medical environment. Attenuation curves were determined using the optimized model for shielding evaluation presented by Costa and Caldas (2002). Workload distribution presented by Simpkin (1996), measured primary spectra and mass attenuation coefficients of barite mortar were used as input data in this model. X-ray beams in diagnostic energy range were generated by an industrial X-ray tube with 3 mm of aluminum additional filtration. Primary experimental spectra were measured by a Cd Te detector and corrected by the response function of detector by means of a stripping procedure. Air kerma measurements were performed using an ionization chamber for normalization purpose of the spectra. The corrected spectra presented good agreement with spectra generated by a semi-empirical model. The variation of the ambient dose equivalent as a function of barite mortar thickness was calculated. Using these data, it was estimated the optimized thickness of protective barrier needed for shielding a particular area in an X-ray imaging facility. The results obtained for primary protective barriers exhibit qualitative agreement with those presented in literature. (Author)

  13. Evidence for the incorporation of lead into barite from waste rock pile materials

    Energy Technology Data Exchange (ETDEWEB)

    COURTIN-NOMADE, ALEXANDRA; SOUBRAND-COLIN, MARILYNE; MARCUS, MATTHEW A.; FAKRA, SIRINE .C

    2008-01-21

    Because Pb is one of the most toxic elements and is found as a major contaminant in mining environments, this study aims to identify the distribution of this element in host phases issued from the alteration of mine wastes. The sampling location was a former mine near Oakland, California (USA). This mine was once a source of sulfide minerals from which sulfuric acid was made. The material discussed in this paper was collected in iron hardpans that were formed within the waste rock pile resulting from the excavation work. In most contaminated environments (soils, mine waste), secondary metal-bearing phases arising from alteration processes are usually fine-grained (from 10 {micro}m to less than 1 {micro}m) and highly heterogeneous, requiring the use of micron-scale techniques. We performed micro-Raman spectroscopy, microscanning X-ray diffraction (SXRD), and microextended X-ray near edge spectroscopy (XANES) to determine the relationships between Pb and a Ba/Fe-rich host phase. Micro-Raman spectroscopy suggests that Pb is preferentially incorporated into barite rather than goethite. Results from micro-Raman experiments show the high sensitivity of this analytical tool to the incorporation of Pb into barite by being especially sensitive to the variations of the S-O bond and showing the characteristic bands due to the contribution of Pb. This association is confirmed and is well-illustrated by micro-SXRD mineral species maps showing the correlation between Pb and barite. Microfocused XANES indicates that Pb is present as Pb{sup 2+}, agreeing with the in situ physicochemical parameters.

  14. Áreas protegidas, desarrollo local y territorio el Parque Nacional Baritú

    OpenAIRE

    Natenzon, Claudia Eleonor

    1999-01-01

    Tras la presentación del tema y de su espacio se realiza un claro planteamiento de los objetivos y la metodología utilizada. A continuación se hace un estudio analitico del espacio hasta convertirse en Parque Nacional, completándose con el marco político-administrativo de la creación, gestión y administración de los parques Nacionales de Argentina. El trabajo se fundamenta en unas fuentes de primera mano, en un trabajo de campo exhaustivo que por la localización del Parque Nacional de Baritú,...

  15. The effect of barite mud on the division of the detector energy window in density logging while drilling

    International Nuclear Information System (INIS)

    In the litho-density logging, formation density and lithology were acquired by calculating the total counts in certain energy window. Therefore, the division of the energy window directly affects the evaluation of density and lithology value. In the process of the energy window division, mud type affects the determination of the range of energy window. In this work, Monte Carlo simulation method was applied to study the range of energy window regarding to water mud and barite mud, respectively. The results show that the range of the energy window with barite mud is less than that of the water mud, and lithology identification will have greater' error in the barite mud. It is important to analyze influencing factors and improve the measurement accuracy of the litho-density logging. (authors)

  16. Determination of attenuation factors for mortar of barite in terms of environmental dose equivalent and effective dose

    International Nuclear Information System (INIS)

    This work addresses the characterization of barite mortars used as Xray shielding materials through the following quantities: mass attenuation coefficient, air kerma, effective dose and ambient dose - H⁎(10). The experiment was carried out with the use of the following reference qualities: RQR4, RQR6, RQR9 e RQR10, specified in accordance with norm IEC 61267: Medical diagnostic Xray equipment - radiation conditions for use in the determination of characteristics. In this study values was determined experimentally for the attenuation of the Cream barite (density 2.99g/cm3, collected in the state of Sao Paulo), Purple barite (density 2.95g/cm3, collected in the state of Bahia) and White barite (density 3.10g/cm3, collected in the state of Paraiba). These materials, in the form of mortar, were disposed in the form of squares namely poof bodies, whose dimensions were 10 x 10 cm and thickness ranging from 3 to 15 mm approximately. In the experimental procedure, these proof bodies were irradiated with a Pantak, model HF320 industrial X-ray apparatus. The potentials applied to the respective X-ray tube were: 60kV, 80kV, 120kV and 150kV at a constant current of 1mA. The attenuation responses in function of thickness, for each of the materials analyzed, were used to draw the attenuation and transmission curves. The efficiency of the barite studied concerning the capacity to attenuate X-ray radiation for X-ray beams ranging from 60 to 150 kV indicated

  17. Estimation of genetic risk and detriment from barite examinations of the digestive system in Malaga (Spain)

    International Nuclear Information System (INIS)

    The objective of the study is to estimate the populations involved in barite examinations of the digestive apparatus. The values of genetically significant dose (DGS), somatically significant dose (DSS) and damage (G) are presented, as derived from the calculation of dose-area, doses in organs and effective doses. At first glance, these complex examinations contribute higher values than the simple examinations. However, our data demonstrate the opposite: DGS = 0.9 mSv; DSS = 1.89 mSv and G = 0.28 radiogenetic cancers per year. These values contradict the data determined for simple examinations for the same population. Although the reasons for this are multiple, the principal underlying cause might be the average age of the patients. These changes are more emphasized in the DGS, which affects the doses in the gonads of the patients after the irradiation. These results must be further compared with other work done in other countries

  18. Discovery of hydrothermal venting community at the base of Cambrian barite in Guizhou Province, Western China:Implication for the Cambrian biological explosion

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The barite deposit in the Niutitang Formation of Lower Cambrian, in Tianzhu County, Guizhou Province, western China, is a superlarge barite deposit with about 2 × 109 tons of reserves: Mineral, petrological and geochemical studies reveal that this barite deposit belongs to a hydrothermal sedimentary deposit. Microscopic observations indicate that a lot of algae, sponge spicules and tube-type fossils are well-preserved in this barite section, and moreover, those fossils share most characteristics of the deep-sea hydrothermal venting community in the modern Pacific. We suggest that the hydrothermal venting community was thriving in hydrothermal vent in early Cambrian, and it is of great significance for elucidating the geological background of the "Cambrian explosion".

  19. Microtexture and distribution of minerals in hydrothermal Barite-Silica chimney from the Franklin seamount, SW Pacific: Constraints on mode of formation.

    Digital Repository Service at National Institute of Oceanography (India)

    Ray, D.; Kota, D.; Das, P.; SuryaPrakash, L.; Khedekar, V.D.; Paropkari, A.L.; Mudholkar, A.V.

    crystals of different habit types. Geologia Croatica 52, 59-65. Sasaki, N., and Watanuki, K., 1983. Variation in chemical composition of naturally occurring lead bearing barite (hokutolite) having crystallized since 1953 at Tamagawa hot spring...

  20. Characterization of barite and crystal glass as attenuators in X-ray and gamma radiation shieldings; Caracterizacao da barita e do vidro cristal como atenuadores na blindagem das radiacoes X e gama

    Energy Technology Data Exchange (ETDEWEB)

    Almeida Junior, Airton Tavares de

    2005-03-15

    Aiming to determine the barium sulphate (BaSO{sub 4}) ore and crystal glass attenuation features, both utilized as shieldings against ionizing X and gamma radiations in radiographic installations, a study of attenuation using barite plaster and barite concrete was carried out, which are used, respectively, on wall coverings and in block buildings. The crystal glass is utilized in screens and in windows. To do so, ten plates of barite plaster and three of barite concrete with 900 cm{sup 2} and with an average thickness ranging from 1 to 5 cm, and three plates of crystal glass with 323 cm{sup 2} and with thicknesses of 1, 2 and 4 cm were analyzed. The samples were irradiated with X-rays with potentials of 60, 80, 110 and 150 kilovolts, and also with {sup 60}Co gamma rays. Curves of attenuation were obtained for barite plaster and barite concrete (mGy/mA.min) and (mGy/h), both at 1 meter, as a function of thickness and curve of transmission through barite plaster and barite concrete as a function of the thickness. The equivalent thicknesses of half and tenth value layers for barite plaster, barite concrete and crystal glass for all X-Ray energies were also determined. (author)

  1. Multi-stage barites in partially melted UHP eclogite: implications for fluid/melt activities during deep continental subduction in the Sulu orogenic belt

    Science.gov (United States)

    Wang, Songjie; Wang, Lu

    2015-04-01

    Barite (BaSO4) is well-known from deep-sea sedimentary environments but has received less attention to its presence in high-grade metamorphic rocks. Recently, barite in ultrahigh pressure (UHP) eclogite has drawn increasing attention from geologists, especially in the Dabie-Sulu orogen, since it is an important indicator for high-salinity fluid events, thus aiding in further understanding HP-UHP fluid / melt evolution. However, its formation time and mechanism in UHP eclogite are still controversial, with three representative viewpoints: (1) Liu et al. (2000) found barite-anhydrite-coesite inclusions in zircon and interpreted them to have formed by UHP metamorphic fluids; (2) Zeng et al. (2007) recognized isolated barite within K-feldspar (Kfs) and Quartz (Qz) surrounded by radial cracks in omphacite, and interpreted Kfs+Qz to be reaction products of potassium-rich fluid/melt and coesite, with the barite formed by prograde metamorphic fluids; (3) Gao et al. (2012) and Chen et al. (2014) found barite-bearing Multiphase Solid (MS) inclusions within garnet and omphacite and assumed that the barite formed by phengite breakdown possibly caused by eclogite partial melting during exhumation, though no direct evidence were proposed. The controversy above is mainly due to the lack of direct formation evidence and absence of a clear link with the metamorphic evolution of UHP eclogite along the subduction-exhumation path. We report detailed petrological and micro-structural analyses revealing four types of barites clearly linked with (1) the prograde, (2) earlier stage of partial melting and (3) later stage of crystallization differentiation, as well as (4) high-grade amphibolite-facies retrogression of a deeply subducted and partially melted intergranular coesite-bearing eclogite from Yangkou Bay, Sulu Orogen. Round barite inclusions (type-I) within UHP-stage garnet and omphacite are formed by internally buffered fluids from mineral dehydration during prograde metamorphism

  2. Evaluation of the effect of indigenous mycogenic silver nanoparticles on soil exo-enzymes in barite mine contaminated soils

    Science.gov (United States)

    Gaddam, Durga Prameela; Devamma, Nagalakshmi; Prasad, Tollamadugu Naga Venkata Krishna Vara

    2015-04-01

    The biosynthesis of nanoparticles has received increasing attention due to the growing need to develop safe, cost-effective and environmentally friendly technologies for nanoscale materials synthesis. In this report, silver nanoparticles (AgNPs) were synthesized by treating aqueous Ag+ ions with the culture supernatants of indigenous fungal species of Fusarium solani isolated from barite mine contaminated soils. The formation of AgNPs might be an enzyme-mediated extracellular reaction process. The localized surface plasmon resonance of the formed AgNPs was recorded using UV-VIS spectrophotometer and was characterized using the techniques transmission electron microscopy, particle size analyzer, Fourier transform-infrared spectroscopy (FT-IR), particle size (dynamic light scattering) and zeta potential. The synthesized AgNPs were stable, polydispersed with the average size of 80 nm. FT-IR spectra reveals that proteins and carboxylic groups present in the fungal secrets might be responsible for the reduction and stabilization of the silver ions. Applied to the barite mine contaminated soils, concentration of AgNPs and incubation period significantly influences the soil exo-enzymatic activities, viz., urease, phosphatase, dehydrogenase and β-glucosidase. To the best of our knowledge, this is the first report on this kind of work in barite mine contaminated soils.

  3. Barite: a case study of import reliance on an essential material for oil and gas exploration and development drilling

    Science.gov (United States)

    Bleiwas, Donald I.; Miller, M. Michael

    2015-01-01

    Global dependence on a limited number of countries for specific mineral commodities could lead to sudden supply disruptions for the United States, and barite is one such commodity. Analyses of barite supply amounts and sources for the United States are demonstrative of mineral commodities on which the country is import reliant. Mineral commodity trade flows can be analyzed more easily than import reliances for commodities in which U.S. domestic demand is primarily met by materials contained within manufactured products, as with the rare-earth elements in cellular phones and computers. Barite plays an essential role as a weighting material in drilling muds used in oil and gas drilling, primarily to prevent the explosive release of gas and oil during drilling. The Nation’s efforts to become more energy independent are based largely on the domestic oil and gas industry’s ability to explore and develop onshore and offshore fuel deposits. These activities include increased efforts by the United States to locate and recover oil and gas within unconventional deposits, such as those in the Bakken, Eagle Ford, and Marcellus Formations, using advanced drilling technologies.

  4. TETRAHEDRITE FROM THE DUBRAVE - DUGI DOL BARITE DEPOSITS, KREŠEVO, BOSNIA AND HERZEGOVINA

    Directory of Open Access Journals (Sweden)

    Ivan Jurković

    1997-12-01

    Full Text Available he chemical composition of the tetrahedrite from the barite deposit Dubrave - Dugi Dol, south of the town Kreševo, Bosnia, hosted by Devonian Dolomite is as follows: (Cu10,65Ag0,073Hg0,0310,75(Fe0,81Zn0,941,75(Sb3,57As0,34Bi0,0043,91S13,00. Cation proportions are: Me2+ :Me3+ :S = 3.20:1.00:3.33. The 34S = -10.91 %o. The calculated formula is in good correspondence with the compositions of other analyzed tetrahedrites from the whole Middle Bosnian Schist Mountains. These results as those of the fluid inclusion studies of gangue minerals suggests the generation of tetrahedrites from highly homogenized, hot (190-310 C, high saline (24.2-26.3 wt% NaCl equiv. mineralizing solutions generated by mixing of ascending deep seated upper mantle (Hg, F, Cu-bearing and metamorphogenic lower crust (Zn, Fe, Ag, Au-bearing fluids with descending highly evolved Upper Permian saline formation waters. The obtained data exclude the applicability of the fractional crystallization generation model.

  5. Mass attenuation coefficients of X-rays in different barite concrete used in radiation protection as shielding against ionizing radiation

    International Nuclear Information System (INIS)

    The attenuation coefficient depends on the incident photon energy and the nature of the materials. In order to minimize exposure to individuals. Barite concrete has been largely used as a shielding material in installations housing gamma radiation sources as well as X-ray generating equipment. This study was conducted to evaluate the efficacy of different mixtures of barite concrete for shielding in diagnostic X-ray rooms. The mass attenuation coefficient (μ/ρ). The mass attenuation coefficients have been measured by employing the CdTe detector model XR-100T. The distance between the source and the exposed surface of all samples was measured by SSD light indicator of machine which was 350 cm. The slope of the linear plot of the intensity transmitted versus specimen thickness would yield the attenuation coefficient. The mass attenuation coefficients (μ/ρ) were compared with the tabulations based upon the results of the XCOM program. The rectangular barite concrete blocks in different thicknesses from were used for the radiation attenuation test. The experimental values were compared with theoretical values WinXcom. The plots of the logarithm of transmitted intensity versus specimen thickness were linear for all the samples and the µ/ρ was obtained from the plots by linear regression over the 25%-2% transmission range, under good geometrical condition. There is a good agreement between theoretical and experimental values, within the 9%. In fact over the entire transmission range of 25-2% the experimental and theoretical values agree well for both the energies. (authors)

  6. Determination of radiation attenuation coefficients of heavyweight- and normal-weight concretes containing colemanite and barite for 0.663 MeV γ-rays

    International Nuclear Information System (INIS)

    Highlights: → Some concrete were determined photon radiation absorbent for 0.663 keV. → It was concluded that barite was effective. → As known, colemanite was good absorbent to prevent for neutron transmission. → As a neutron absorbent, colemanite would be preferred to normal aggregate. - Abstract: Accurate measurements have been made to determine radiation transmission of concretes produced with barite, colemanite and normal aggregate by using beam transmission method for 0.663 MeV γ-rays energy of 137Cs radioactive isotopes by using NaI(Tl) scintillation detector. Linear and mass attenuation coefficients of thirteen heavy- and four normal-weight concretes were calculated. It was determined that the linear attenuation coefficient (μ, cm-1) decreased with colemanite concentration and increased with barite concentration in both type of the concretes. Mass attenuation coefficient values of our concretes were compared with the values proposed by the United States National Institute of Standards and Technology (NIST).

  7. Genesis of the zinc-lead-barite deposits in the northern Iraq: ore mineralogy, geochemistry, fluid inclusions, lead isotopes and sulfur isotopes implications

    International Nuclear Information System (INIS)

    Zinc - leaed - barite deposits hosted by carbonate rocks are studied mineralogically, geochemically and genetically. These deposits (Lefan, lower Banik, Menin and Upper Banik) locate at the Nortgeren Thrust Zone, Northern Iraq. They consistt of sulfides as sphalerite, galena and pyrite, and sulfates as barite. Fluid inclusions observed in barite contain heavy oil associated with aqueous chloride-rich fluids (13% -15.5% wt equv. NaC1). The temperature of formation of barite is suggested to be 50-60 degree. The sulfur isotope composition (δ34S) of early generated galena is 0.36 per mil. This value is close to the hydrothermal magmatic sulfur origin. The δ34S of late generated galena is 6.41 per mil. This value indicates that the hydrothermal magmatic fluids were partially mixeed with oilfield brine connate waters. The δ34S of barite ranges from 16.64 to 24.23 per mil. These values indicate high isotopeic fractionation that caused by descending meteoric waters which diluted the ascending ore-bearing fluids. The lead isotope compostion (204pb, 206pb, 207pb and 208pb) of galeana has revealed that lead was derived from the crust reservoir. Ore metals (Zn, Pb, Fe, and Ba) may have been originated from oilfield brine waters that may have partially been mixed with the hydrothermal fluids of magmatic origin that supplied sulfur. These fluides have migrated upward as chloride and sulfide complexes along fractures and faults possibly after crustal extension and rifting during Alpine orogeny in the Paleocene. Zinc - lead - barite deposits could be classified as epithermal, eigenetic strata-bound of Mississippi Vally type (MVT) deposits, lithologically and structurally controlled within Cretaceous carbonates. (authors).

  8. Using synchrotron X-ray diffraction (SXRD) for studying the BaSO4 formation kinetics and the effect of inhibitors on Barite formation

    International Nuclear Information System (INIS)

    The precipitation of barium sulphate from aqueous supersaturated solutions has been widely studied as it consists one of the most well known problems in the oil industry. Formation of barite and other insoluble scale types (metal sulphates, calcium carbonate and silicates) occurs due to the incompatibility of the injected seawater with the formation water during their mixing in the reservoirs. The inorganic salts gradually adhere to production tubing and equipment parts leading to serious flow assurance issues and further to reduction in the performance of the petroleum facilities. Barium sulphate scale is characterized by extremely low solubility. It resists many chemical methods of removal including treatments with strong acids. Inhibition of barium sulphate by chemicals is generally recognized as the most appropriate approach for flow assurance. In this study Synchrotron X-Ray Diffraction was used in-situ to investigate the formation of barium sulphate on a stainless steel surface at high temperatures. For the first time in-situ SXRD measurements of BaSO4 formed in the presence of foreign ions (Sr2+, Ca2+ etc) are presented. The formation kinetics of BaSO4 on the surface has been determined and the crystallographic nature of the barite was investigated. In addition the effect of Diethylenetriamine - penta - methylenephosphonic acid (DETPMP) and Poly phosphinecarboxylic acid (PPCA) on barium sulphate was examined at two temperatures. The barite crystal faces present on the surface after the treatment with inhibitors were detected. The lattice planes recorded with the in-situ SXRD measurements revealed that the presence of Sr2+ in the initial formation water resulted in the co-precipitation of Sr2+ within the barite lattice. The in-situ SXRD measurements allowed the assessment of information on the kinetics and crystallography of the formed scale in the absence and presence of inhibitors. The crystallography of the barite revealed high sensitivity to temperature

  9. Regional stratigraphy and distribution of epigenetic stratabound celestine, fluorite, barite and Pb-Zn deposits in the MVT province of northeastern Mexico

    Science.gov (United States)

    González-Sánchez, Francisco; Camprubí, Antoni; González-Partida, Eduardo; Puente-Solís, Rafael; Canet, Carles; Centeno-García, Elena; Atudorei, Viorel

    2009-04-01

    Northeastern Mexico hosts numerous epigenetic stratabound carbonate-hosted low-temperature hydrothermal deposits of celestine, fluorite, barite and zinc-lead, which formed by replacement of Mesozoic evaporites or carbonate rocks. Such deposits can be permissively catalogued as Mississippi Valley-type (MVT) deposits. The deposits studied in the state of Coahuila are associated with granitic and metasedimentary basement highs (horsts) marginal or central to the Mesozoic Sabinas Basin. These horsts controlled the stratigraphy of the Mesozoic basins and subsequently influenced the Laramide structural pattern. The Sabinas Basin consists of ~6,000-m-thick Jurassic to Cretaceous siliciclastic, carbonate and evaporitic series. The MVT deposits are mostly in Barremian and in Aptian-Albian to Cenomanian formations and likely formed from basinal brines that were mobilized during the Laramide orogeny, although earlier diagenetic replacement of evaporite layers (barite and celestine deposits) and lining of paleokarstic cavities in reef carbonates (Zn-Pb deposits) is observed. Fluid inclusion microthermometry and isotopic studies suggest ore formation due to mixing of basinal brines and meteoric water. Homogenization temperatures of fluid inclusions range from 45°C to 210°C; salinities range from 0 to 26 wt.% NaCl equiv., and some inclusions contain hydrocarbons or bitumen. Sulfur isotope data suggest that most of the sulfur in barite and celestine is derived from Barremian to Cenomanian evaporites. Regional geology and a compilation of metallogenic features define the new MVT province of northeastern Mexico, which comprises most of the state of Coahuila and portions of the neighboring states of Nuevo León, Durango and, perhaps extends into Zacatecas and southern Texas. This province exhibits a regional metal zonation, with celestine deposits to the south, fluorite deposits to the north and barite and Zn-Pb deposits mostly in the central part.

  10. The Bulong Gold Deposit-a Quartz-Barite Vein Type Gold Deposit in Xinjiang:Geological Characteristics and S, He and Ar Isotopic Compositions

    Institute of Scientific and Technical Information of China (English)

    YANG Fuquan; WANG Yitian; MAO Jingwen

    2004-01-01

    The Bulong gold deposit, located in the southwest Tianshan in China, occurs in the Upper Devonian finegrained clastic rocks. The gold orebodies are controlled by an gently inclined interlayer fractured zone. They are hosted only in quartz-barite veins though there are barite veins and quartz veins in the ore district. The δ34S values of pyrite in the ores range from 14.6‰ to 19.2‰ and those of barite from 35.0‰o to 39.6‰, indicating that the sulfur was derived from the strata. 3He/4He ratios of fluid inclusions in pyrite are 0.24-0.82 R/Ra, approximating to that of the crust. The 40Ar/36Ar ratios range from 338 to 471, slightly higher than that of the atmosphere. 40Ar/4He ratios of ore fluids range from 0.015 to 0.412 with a mean of 0.153. Helium and argon isotope compositions of fluid inclusions show that the ore fluids of the Bulong gold deposit were mainly derived from the crust.

  11. Dual gradient drilling: barite separation from the mud using hydrocyclones; Perfuracao com duplo gradiente: a separacao da barita do fluido de perfuracao utilizando hidrociclones

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Aline T.; Medronho, Ricardo A. [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Escola de Quimica

    2004-07-01

    The proximity of the pores pressure and fracture pressure curves in deep water drilling makes it an expensive and complicated operation. It is possible to minimize this problem by reducing the pressure inside the riser at the sea floor level. Injecting low density drilling mud at that point is an alternative, producing a condition called as dual gradient drilling. Hydrocyclones are simple apparatuses and their high capacity and efficiency make them appropriate for operations were the occupied floor space plays an important hole, as in offshore drilling. The idea behind this work is to divide the drilling mud in two streams, one more concentrated in barite for re-injection into the drilling column, and other more diluted for injecting into the riser at the sea floor. In this work, CFD - computational fluid dynamics - was used to investigate barite separation from drilling mud using hydrocyclones. The results indicate that the injection of a lower density mud, less concentrate in barite, in the riser at sea floor level may be a possible and less complicated alternative for dual gradient drilling. (author)

  12. The influence of impurities on the dissolution of Ca- and Sr-bearing barite at room temperature

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The reaction path in the (Ba, Sr, Ca)SO4 solid-solution aqueous-solution (SSAS) system was experimentally studied using a batch-reactor method. The effect of the impurities "fluorite" and "iron sulfides" admixed in a natural barite sample on the reaction path was followed by analyzing the aqueous solution continuously. The dissolution and precipitation of the impurity "fluorite" affected strongly the reaction path in the SSAS system, especially the Ca/Sr/Ba ratio in the aqueous solution. This influence became stronger with decreasing CaSO4 in the solid solution. The dissolution and precipitation of fluorite could hinder the CaSO4 component from dissolving into water, and reduce the release rate of SO42 - from the solid solution to the aqueous solution and the removing rate of Ba2+ from the aqueous solution. In the presence of fluorite and sulfides, the aqueous Ba2 + and Sr2 + concentrations were controlled by the dissolution-precipitation of the end-members BaSO4 and SrSO4, respectively; the aqueous F- , Ca2+ and SO42- concentrations were controlled by the dissolution-precipitation of fluorite. The incongruent dissolution of the ( Ba, Sr, Ca) SO4 solid solution caused the solid phase to become progressively more enriched in the more insoluble component (BaSO4) , while the aqueous composition shifted towards the more soluble end-members (SrSO4 and CaSO4 ) as equilibrium was approached to.

  13. Mineralization Zoning in Yindongzi-Daxigou Barite-Siderite, Silver-Polymetallic Deposits in the Qinling Orogen, China

    Institute of Scientific and Technical Information of China (English)

    方维萱; 胡瑞忠; 黄转莹

    2001-01-01

    The Yindongzi-Daxigou strata-bound barite-siderite, silver-polymetallic deposits discovered in the Qinling orogen are hosted within flysch facies in a deep-water fault-controlled basin on the passive northern margin of the Qinling microplate. The orebodies occur in a series of hydrothermal depositional rocks. Mineralization zoning is characterized by Fe-Ba←Ba-Cu←Pb-Ag→Cu-Ag→Pb→Au. This is obviously a gradational transition mineralization from ventproximal mineralization to more distal mineralization. In this gradational transition between Chefanggou and Yindongzi, vent-proximal mineralization consists of silver-polymetallic orebodies (Pb-Ag), which is the center of hydrothermal mineralization. The Chefanggou Ba-Cu ore district in the west and the Yindongzi Cu-Ag ore district in the east represent vent lateral mineralization. Distal mineralization in the west is represented by the Daxigou Fe-Ba ore district while distal mineralization in the east is represented by the Pb ore district. Thick massive, laminated barren albite chert and jasperite, sometimes with minor silver-ploymetallic mineralization of commercial importance, and pyritization in rocks feature more distal mineralization. Geochemical anomalies of Au-As associations are found in ankerite phyllite and muddy sandstone.Actually, Au deposits are dominantly controlled by the late brittle-ductile shear zone.

  14. Fluid evolution and mineralogy of Mn-Fe-barite-fluorite mineralizations at the contact of the Thuringian Basin, Thüringer Wald and Thüringer Schiefergebirge in Germany

    Directory of Open Access Journals (Sweden)

    Majzlan Juraj

    2016-02-01

    Full Text Available Numerous small deposits and occurrences of Mn-Fe-fluorite-barite mineralization have developed at the contact of the Thuringian Basin, Thüringer Wald and Thüringer Schiefergebirge in central Germany. The studied mineralizations comprise the assemblages siderite+ankerite-calcite-fluorite-barite and hematite-Mn oxides-calcite-barite, with the precipitation sequence in that order within each assemblage. A structural geological analysis places the origin of the barite veins between the Middle Jurassic and Early Cretaceous. Primary fluid inclusions contain water vapour and an aqueous phase with NaCl and CaCl2 as the main solutes, with salinities mostly between 24–27 mass. % CaCl2 eq. Th measurements range between 85 °C and 160 °C in barite, between 139 °C and 163 °C in siderite, and between 80 °C and 130 °C in fluorite and calcite. Stable isotopes (S, O point to the evaporitic source of sulphur in the observed mineralizations. The S,C,O isotopic compositions suggest that barite and calcite could not have precipitated from the same fluid. The isotopic composition of the fluid that precipitated barite is close to the sea water in the entire Permo–Mesozoic time span whereas calcite is isotopically distinctly heavier, as if the fluids were affected by evaporation. The fluid evolution in the siliciclastic/volcanic Rotliegend sediments (as determined by a number of earlier petrological and geochemical studies can be correlated with the deposition sequence of the ore minerals. In particular, the bleaching of the sediments by reduced Rotliegend fluids (basinal brines could be the event that mobilized Fe and Mn. These elements were deposited as siderite+ankerite within the Zechstein carbonate rocks and as hematite+Mn oxides within the oxidizing environment of the Permian volcanic and volcanoclastic rocks. A Middle-Jurassic illitization event delivered Ca, Na, Ba, and Pb from the feldspars into the basinal brines. Of these elements, Ba was

  15. Determination of half-value layers and tenth-value layer to barite as shielding against X radiation in radiological protection

    International Nuclear Information System (INIS)

    The barium mortar has been widely used as radiation shielding material for X and gamma radiations in Brazil, by presenting some advantages as the high rate of efficiency in radiation shielding, the easy handling and application, the facility to be found in the national market and low cost. The determination of the half-value layers (HVL) and tenth-value layer (TVL) of different types of barite becomes the major factor to characterize the attenuation of these materials, in order to ensure the efficiency and quality of projects shielding, by ensuring the safety of workers occupationally exposed to radiation and of individuals to the public. Thus, plates of different thickness of mortar of barite were made for determination of their HVL and TVL. The plates were irradiated with X-ray qualities for radiological protection according to standard ISO 4037. A system of CdTe spectrometry was used to acquire spectra transmitted, in the presence of each plate, and their combinations. The areas of the spectra obtained, depending on the total thickness of the plates used in the arrangement were used to determine the attenuation curves. From these curves obtained in this work was to establish the HVL and TVL

  16. Novel Barite Chimneys at the Loki's Castle Vent Field Shed Light on Key Factors Shaping Microbial Communities and Functions in Hydrothermal Systems

    Science.gov (United States)

    Steen, Ida H.; Dahle, Håkon; Stokke, Runar; Roalkvam, Irene; Daae, Frida-Lise; Rapp, Hans Tore; Pedersen, Rolf B.; Thorseth, Ingunn H.

    2016-01-01

    In order to fully understand the cycling of elements in hydrothermal systems it is critical to understand intra-field variations in geochemical and microbiological processes in both focused, high-temperature and diffuse, low-temperature areas. To reveal important causes and effects of this variation, we performed an extensive chemical and microbiological characterization of a low-temperature venting area in the Loki's Castle Vent Field (LCVF). This area, located at the flank of the large sulfide mound, is characterized by numerous chimney-like barite (BaSO4) structures (≤ 1 m high) covered with white cotton-like microbial mats. Results from geochemical analyses, microscopy (FISH, SEM), 16S rRNA gene amplicon-sequencing and metatranscriptomics were compared to results from previous analyses of biofilms growing on black smoker chimneys at LCVF. Based on our results, we constructed a conceptual model involving the geochemistry and microbiology in the LCVF. The model suggests that CH4 and H2S are important electron donors for microorganisms in both high-temperature and low-temperature areas, whereas the utilization of H2 seems restricted to high-temperature areas. This further implies that sub-seafloor processes can affect energy-landscapes, elemental cycling, and the metabolic activity of primary producers on the seafloor. In the cotton-like microbial mats on top of the active barite chimneys, a unique network of single cells of Epsilonproteobacteria interconnected by threads of extracellular polymeric substances (EPS) was seen, differing significantly from the long filamentous Sulfurovum filaments observed in biofilms on the black smokers. This network also induced nucleation of barite crystals and is suggested to play an essential role in the formation of the microbial mats and the chimneys. Furthermore, it illustrates variations in how different genera of Epsilonproteobacteria colonize and position cells in different vent fluid mixing zones within a vent field

  17. Open system sulphate reduction in a diagenetic environment - Isotopic analysis of barite (δ34S and δ18O) and pyrite (δ34S) from the Tom and Jason Late Devonian Zn-Pb-Ba deposits, Selwyn Basin, Canada

    Science.gov (United States)

    Magnall, J. M.; Gleeson, S. A.; Stern, R. A.; Newton, R. J.; Poulton, S. W.; Paradis, S.

    2016-05-01

    Highly positive δ34S values in sulphide minerals are a common feature of shale hosted massive sulphide deposits (SHMS). Often this is attributed to near quantitative consumption of seawater sulphate, and for Paleozoic strata of the Selwyn Basin (Canada), this is thought to occur during bacterial sulphate reduction (BSR) in a restricted, euxinic water column. In this study, we focus on drill-core samples of sulphide and barite mineralisation from two Late Devonian SHMS deposits (Tom and Jason, Macmillan Pass, Selwyn Basin), to evaluate this euxinic basin model. The paragenetic relationship between barite, pyrite and hydrothermal base metal sulphides has been determined using transmitted and reflected light microscopy, and backscatter electron imaging. This petrographic framework provides the context for in-situ isotopic microanalysis (secondary ion mass spectrometry; SIMS) of barite and pyrite. These data are supplemented by analyses of δ34S values for bulk rock pyrite (n = 37) from drill-core samples of un-mineralised (barren), siliceous mudstone, to provide a means by which to evaluate the mass balance of sulphur in the host rock. Three generations of barite have been identified, all of which pre-date hydrothermal input. Isotopically, the three generations of barite have overlapping distributions of δ34S and δ18O values (+22.5‰ to +33.0‰ and +16.4‰ to +18.3‰, respectively) and are consistent with an origin from modified Late Devonian seawater. Radiolarian tests, enriched in barium, are abundant within the siliceous mudstones, providing evidence that primary barium enrichment was associated with biologic activity. We therefore propose that barite formed following remobilisation of productivity-derived barium within the sediment, and precipitated within diagenetic pore fluids close to the sediment water interface. Two generations of pyrite are texturally associated with barite: framboidal pyrite (py-I), which has negative δ34S values (-23‰ to -28

  18. Determination of attenuation factors for mortar of barite in terms of environmental dose equivalent and effective dose; Determinacao de fatores de atenuacao para argamassa de barita em termos do equivalente de dose ambiental e dose efetiva

    Energy Technology Data Exchange (ETDEWEB)

    Almeida Junior, Airton T.; Campos, L.L.R., E-mail: airtontavares@uol.com.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Araujo, F.G.S. [Universidade Federal de Ouro Preto (UFOP), Ouro Preto, MG (Brazil); Santos, M.A.P. [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil); Nogueira, M.S., E-mail: mnogueira@cdtn.br [Centro de Desenvolvimeto da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2014-07-01

    This work addresses the characterization of barite mortars used as Xray shielding materials through the following quantities: mass attenuation coefficient, air kerma, effective dose and ambient dose - H⁎(10). The experiment was carried out with the use of the following reference qualities: RQR4, RQR6, RQR9 e RQR10, specified in accordance with norm IEC 61267: Medical diagnostic Xray equipment - radiation conditions for use in the determination of characteristics. In this study values was determined experimentally for the attenuation of the Cream barite (density 2.99g/cm{sup 3}, collected in the state of Sao Paulo), Purple barite (density 2.95g/cm{sup 3}, collected in the state of Bahia) and White barite (density 3.10g/cm{sup 3}, collected in the state of Paraiba). These materials, in the form of mortar, were disposed in the form of squares namely poof bodies, whose dimensions were 10 x 10 cm and thickness ranging from 3 to 15 mm approximately. In the experimental procedure, these proof bodies were irradiated with a Pantak, model HF320 industrial X-ray apparatus. The potentials applied to the respective X-ray tube were: 60kV, 80kV, 120kV and 150kV at a constant current of 1mA. The attenuation responses in function of thickness, for each of the materials analyzed, were used to draw the attenuation and transmission curves. The efficiency of the barite studied concerning the capacity to attenuate X-ray radiation for X-ray beams ranging from 60 to 150 kV indicated.

  19. Study On Beneficiation Technology Of Dong Pao Rare-Earth-Barite-Fluorite With Two Product Plans About Content And Recovery Of Rare-Earth Fine Ores

    International Nuclear Information System (INIS)

    The ore sample used in the research was taken from the F3 ore bodies and the sample of the F7, F9 and F16 ore bodies which contain the average of 5.98% TR2O3; they are multi-metals ore which is difficult to enrich, highly weather with very complex ingredients. The process of the experiment is the ore is crushed, ground, screened and classified reasonably to -0.1 mm and divided into 3 particle size with the following technique: (1) -0.020 mm is primary sludge and the rare-earth fine ore; (2) 0.075-1 mm is gotten through the sludge concentrating table with the output is the 2 parts: the heavy part which is dried magnetic separator with high magnetism to get the rare-earth fine ore and the light one; (3) Light minerals, non-magnetic and ferromagnetic minerals group are ground together to 85% of them get size within -0.075 mm then mix it with 0.020-0.075 mm group. Using flotation separator, get barite-rare earth mixture and fluorite. After that, we separate this mixture by secondary flotation and get refined rare earth, barite and fluorite mineral. The result of the theme: (1) product plan A-rare-earth fine ore has TR2O3 content archive 42.07% with recovery is 69.70%; (2) product plan B-rare-earth fine ore has TR2O3 content archive 29.64% with recovery is 80.01%. (author)

  20. 贵州镇宁乐纪泥盆系重晶石矿热水沉积特征%Hydrothermal Venting-Flowing Sedimentation Characteristics of Devonian Barite Deposits from Leji,Zhenning County,Guizhou Province

    Institute of Scientific and Technical Information of China (English)

    高军波; 杨瑞东; 陶平; 魏怀瑞; 刘坤

    2012-01-01

    The Devonian barite deposits located in Zhenning County,Guizhou Province have proved reserves of 33.02×106 t,belonging to large-scale ore deposits.Research on sedimentation structures and tectonic characteristics related to the barite deposits reveal the coexistence of a variety of structures like laminar structures,barite-banded structure,brecciated structure,barite-fragmental structure and massive structure,etc.,which are similar to those of the Tianzhu-Dahebian barite deposit,the hydrothermal barite rocks of Gutan in Guangxi Province and the hydrothermal water sedimentary barite rocks of Erlangping Group from north Qinling Mountains.Several types of sedimentary characteristics,such as hydrothermal venting channel phases formed in submarine hydrothermal venting,unitary hydrothermal lithofacies and hydrothermally mixed synsedimentary phases,were identified widely in barite orebeds in Zhenning,Guizhou.Similar to Devonian hydrothermal sedimentary rocks(deposits) from Qinling,those sedimentary phases and lithofacies features found in Zhenning characterize a hydrothermal turbidity current sedimentation phase.Sedimentary structures,constructions and lithofacies features of the orebed record well the information of submarine hydrothermal venting and its evolution,the sedimentation rhythm characteristics reveal the intensity of hydrothermal venting-flowing was weak-strong-weak.Hence,barite deposits in Zhenning were formed in submarine hydrothermal venting sedimentation,and the hydrothermal sedimentary structures,constructions and hydrothermal lithofacies features make them ideal places for research on ancient hydrothermal venting diagenesis,metallogenesis and hydrothermal lithofacies categorization.%贵州镇宁乐纪泥盆系重晶石矿床地质储量3 302万t,属大型矿床类型。通过对矿床沉积结构、构造特征研究发现,矿床(体)中分布:纹层状构造、条带状构造、角砾状构造、碎屑状构造、块状构造等,它们与天

  1. Rereach on the Integrated Utilization Technology of a Fluorite-barite Ore%萤石重晶石共生矿综合利用技术研究

    Institute of Scientific and Technical Information of China (English)

    曾小波; 刘人辅; 张新华

    2012-01-01

    A low-grade fluorite-barite ore from southeast of Chongqing municipality was determined as the object of this study. The result of the closed circuit test was satisfactory using the following flotation technological process which was based on the reseach of substance component and process mineralogy. Firstly, get the bulk concentrate about fluoritc and banle by bulk flotation. Secondly, recover fluorite from the bulk concentrate. And recover barite ore at last. The CaF2 grade of fluorite concentrate is 97.84% with the CaF2 recovery-rate 84.83%, the BaSO4 grade of barite concentrate is 92.68% with the BaSO4 recovery-rate 80.67%.%以渝东南某低品位萤石重晶石共生矿为研究对象,在物质组成和工艺矿物学研究的基础上,采用“混合浮选-优选萤石-再选重晶石”的全浮选工艺流程,获得了满意的技术指标:萤石精矿CaF2品位97.84%,回收率84.83%;重晶石精矿BaSO4品位92.68%,回收率80.67%.

  2. Determination of barium, strontium and nine minor and trace elements in impure barite and strontianite by inductively-coupled plasma atomic-emission spectrometry after dissolution in disodium ethylenediaminetetraacetate.

    Science.gov (United States)

    Gupta, J G

    1991-10-01

    A new method has been developed for the determination of barium, strontium, silicon and nine minor and trace elements of barite and strontianite associated with gangue materials. It involves dissolution of the sample by boiling under reflux with a concentrated solution of disodium ethylenedi-aminetetraacetate (EDTA-2Na) in the presence of ammonium hydroxide. Barite and strontianite dissolve quantitatively under this condition, and any associated silicate and sulphide mineral impurities, remaining insoluble, are filtered off and ignited to constant weight in a platinum crucible. Silica is determined gravimetrically by heating the residue with concentrated sulphuric and hydrofluoric acids, followed by ignition to oxides. The residue is fused with sodium bisulphate and dissolved in dilute sulphuric acid. After suitable dilution of the EDTA-2Na solution, Ba, Sr, Be, Co, Cr, Cu, La, Ni, V, Yb and Zn are determined by inductively-coupled plasma atomic-emission spectrometry (ICP-AES). The bisulphate fusion product is separately analysed by ICP-AES, and the elements found are combined with those obtained from the EDTA-2Na solution. The replicate values of this work compare well with each other and with other values obtained by independent methods. PMID:18965264

  3. Geochemical Characters and Geological Significance of REE of Siliceous Rock in Devonian Barite Deposit in Zhenning,Guizhou%贵州镇宁重晶石矿中硅质岩稀土元素地球化学研究

    Institute of Scientific and Technical Information of China (English)

    高军波; 杨瑞东; 陶平; 魏怀瑞

    2011-01-01

    通过对镇宁泥盆系重晶石矿中硅质岩稀土元素地球化学特征研究,发现硅质岩稀土总量较低,轻稀土富集,δCe呈弱的负异常,δEu呈负异常到正异常,{La/Sm}N和{Gd/Yb}N值表明轻稀土分异强;通过∑REE、Ce/Ce*、Eu/Eu*、{La/Ce}N和{La/Lu}N参数综合分析,硅质岩沉积成岩过程中有明显的热水参与,属热水喷流成因。重晶石矿与该硅质岩紧密共生,故亦为热水喷流成因,它们形成于台沟相带,受控于晚古生代裂陷作用下的水城-紫云-南丹同沉积深大断裂的构造环境。%The siliceous rocks in the barite deposits of Devonian from Zhenning country revealed some characteristics as following: lower ∑REE,comparatively enrichment in LREE,slightly anomal negative for Ce,and negative to positive for Eu.{La/Sm}N and {Gd/Yb}N features show that the fractionation of LREE was Strong while HREE was weak.Characteristics of ∑REE,Ce/Ce*,Eu/Eu*,{La/Ce}N and {La/Lu}N indicate that during the diagenetic process of the siliceous rocks obvious evidences related to involvement of hydrothermal venting-flowing were observed,indicating its hydrothermal genesis,the paragenetic relationship of hydrothermal sedimentogenic silicious rocks and barite deposits manifest that the barite deposits were formed by hydrothermal exhalative mineralization.They were deposited in the platform basin facies that controled by a syngenetic deep faults structure of Shuicheng-Ziyun-Nandan during the late Palaeozoic.

  4. Study of dung, urine, and milk of selected grazing animals as bioindicators in environmental geoscience--a case study from Mangampeta barite mining area, Kadapa District, Andhra Pradesh, India.

    Science.gov (United States)

    Raghu, V

    2015-01-01

    The ancient scientific Sanskrit texts of Ayurveda (science of longevity) deal with waters, plants, and animals in relation to human health. Based on the studies mentioned in Ayurveda and modern literature, biological responses of grazing animals in Mangampeta barite mining area in Kadapa District, Andhra Pradesh, were studied. A non-mineralized Tirupati area in Chittoor District, Andhra Pradesh, was selected for the purpose of comparison. In these areas, certain animal products of selected grazing animals were studied if they could be used as tools in mineral exploration. Samples of dung, urine, and milk from cow, bullock, she-buffalo, he-buffalo, sheep, and goat were collected from these two areas during winter and summer seasons. Goat dung was found to have lowest moisture content and highest organic matter while goat urine contained highest amounts of organic matter and ash content. All these animal products were analyzed for 11 trace elements. The concentration of trace elements released through dung, urine, and milk widely varied in different animal species with seasonal variations. The elemental concentration was higher in dung and lower in urine, when compared to that of milk. The concentration of all elements in dung, urine, and milk of all animals, in both the areas, was higher in winter than that in summer. Dung represents the metabolic process of the whole animal and reflects the dietary conditions whether fed on natural or inorganic supplement. It can be inferred that dung, urine, and milk of any animal can be used as tools in mineral exploration during winter, while during summer, only dung can be useful. The dung of goat when compared to that of the other cattle serves as a better tool in environmental studies as goat depends almost entirely on natural vegetation without human interference. PMID:25416966

  5. Paragenesis and chemical characteristics of the celsian-hyalophane-K-feldspar series and associated Ba-Cr micas in barite-bearing strata of the Mesoarchaean Ghattihosahalli Belt, Western Dharwar Craton, South India

    Science.gov (United States)

    Raith, Michael M.; Devaraju, Tadasore C.; Spiering, Beate

    2014-04-01

    The upper greenschist - lower amphibolite facies, argillaceous to chemical-exhalative metasedimentary sequence of the Mesoarchaean Ghattihosahalli Schist Belt (GHSB), southern India, has been examined with a special focus on the paragenesis and solid solution characteristics of barian feldspars and associated dioctahedral Ba-Cr-bearing micas. Barian feldspars occur as untwinned porphyroblasts in a recrystallized finely banded matrix of barite, quartz and minor white mica. Idioblastic celsian (Cls98-76Or2-20Ab1-8) and hyalophane (Cls55-39Or35-51Ab10) predate the greenschist-facies foliation, whereas xenoblastic hyalophane (Cls44-35Or45-59Ab8-17) and mantles on celsian (Cls45-35Or42-60Ab13-5) as well as xenoblastic barian K-feldspar (Cls6Or90Ab2) postdate the last fabric-defining event. The preservation of extremely complex zoning patterns down to the micron-scale shows that diffusional homogenization did not operate at fluid-present low to medium-grade conditions (350-550 °C, 3-5 kb). Microstructures indicate that at these conditions barian feldspars deform exclusively by brittle fracturing and do not undergo recrystallization. Barian feldspar compositions confirm the positive correlation of Na-content with temperature and the existence of a narrow asymmetric compositional gap (Cls90-85↔Cls55, ~350 °C) which probably closes at lower amphibolite facies conditions (Xc ~Cls75; Tc ~550 °C). White micas are solid solutions of the end-members muscovite, ganterite (Ba0.5 K0.5)Al2(Al1.5Si2.5)O10(OH)2, paragonite, celadonite with a significant substitution of [VI]Al by Cr. Zoning is a common feature with cores being enriched in Ba. The data document extensive Ba substitution for K from muscovite to ganterite, exclusively controlled by the coupled substitution [XII]K + [IV]Si ↔ [XII]Ba + [IV]Al and strongly dependent on bulk composition. The extent of solid solution from (Ms+Gnt) towards paragonite and celadonite end-members is controlled by the miscibility gap in the

  6. Study of Gamma-Ray Shielding Properties of Barite Concrete Including CRTs at Different Energies with Monte Carlo Method%重晶石混凝土中混入CRTs的屏蔽性能MC模拟研究

    Institute of Scientific and Technical Information of China (English)

    程鹏亮; 葛良全; 张庆贤; 李秋实; 严峻; 刘俊

    2014-01-01

    基于MCNP5对重晶石混凝土中混入不同比例的报废阴极X射线管瓶锥部分的屏蔽性能进行模拟研究。通过对不同能量的γ射线穿过屏蔽体的模拟研究,得出四种能量的γ射线在各种比例混凝土中的出射光谱、线衰减系数、透射率及半吸收厚度。模拟结果表明:对于同一种能量的γ射线随着CRTs比例的上升,混凝土的屏蔽性能逐渐减弱,但半吸收厚度相差不超过1cm。研究结果为CRTs型混凝土应用于辐射防护领域的可行性提供了模拟实验支持,同时对新型屏蔽材料的研发提供了一定的参考,从而为报废阴极X射线管的回收利用开辟了新的市场,也为废弃物中重金属的污染提供了治理措施。%This paper compares the shielding capability of the concrete that is produced by mixing different pro-portion of the neck portion of the scrap color cathode X-ray tube into the barite concrete based on MCNP5. The exit spectrum, line attenuation coefficient, transmittance and half thickness of absorption of γ-rays with four kinds of energies (0.662 MeV、1 MeV、2 MeV、3 MeV) can be obtained from the simulation of these fourγ-rays passing though the different concretes.The results suggest that the concrete ’ s shielding capability is gradually weakened with the increase of the proportion of CRTs for the same energyγ-ray, but the half thick-ness of absorption will not exceed more than 1cm.The conclusion provides some supports on the application of CRT-concrete in radiation protection and offers some reference in the development of new shielding materials. Meanwhile, it not only opens new markets for the recycle of the scrap color cathode X-ray tube, but also pro-vides some control measures for the pollution of heavy metal in the garbage.

  7. Delineation of areas having elevated electrical conductivity, orientation and characterization of bedrock fractures, and occurrence of groundwater discharge to surface water at the U.S. Environmental Protection Agency Barite Hill/Nevada Goldfields Superfund site near McCormick, South Carolina

    Science.gov (United States)

    Chapman, Melinda J.; Huffman, Brad A.; McSwain, Kristen Bukowski

    2015-01-01

    During October 2012 through March 2013, the U.S. Geological Survey (USGS), in cooperation with the U.S. Environmental Protection Agency (EPA) Region 4, Superfund Section, conducted borehole geophysical logging, surface geophysical surveys, and water-quality profiling in selected wells and areas to characterize or delineate the extent of elevated subsurface electrical conductivity at the EPA Barite Hill/Nevada Goldfields Superfund site near McCormick, South Carolina. Elevated electrical conductivity measured at the site may be related to native rock materials, waste rock disposal areas used in past operations, and (or) groundwater having elevated dissolved solids (primarily metals and major ions) related to waste migration. Five shallow screened wells and four open-borehole bedrock wells were logged by using a suite of borehole tools, and downhole water-quality profiles were recorded in two additional wells. Well depths ranged from about 26 to 300 feet below land surface. Surface geophysical surveys based on frequency-domain electromagnetic and distributed temperature sensing (DTS) techniques were used to identify areas of elevated electrical conductivity (Earth materials and groundwater) and potential high dissolved solids in groundwater and surface water on land and in areas along the northern unnamed tributary at the site.

  8. Molecular-scale mechanisms of crystal growth in barite

    OpenAIRE

    Pina Martínez, Carlos Manuel; Becker, Udo; Risthaus, Peter; Bosbach, Dirk; Putnis, Andrew

    1998-01-01

    Models of crystal growth have been defined by comparing macroscopic growth kinetics with theoretical predictions for various growth mechanisms. The classic Burton–Cabrera–Frank (BCF) theory predicts that spiral growth at screw dislocations will dominate near equilibrium. Although this has often been observed, such growth is sometimes inhibited, which has been assumed to be due to the presence of impurities. At higher supersaturations, growth is commonly modelled by twodim...

  9. The effects of fumed silica and barite on the aluminum resistance of alumina castables

    Science.gov (United States)

    Afshar, Saied; Gaubert, Christophe; Allaire, Claude

    2003-11-01

    A study of the effects of microsilica and barium sulfate as additives in high-tabular alumina castables on cold and hot modulus of rupture, porosity, thermal shock, and corrosion resistance to aluminum attack is reported in this article. This investigation underlined the importance of the quality of fumed silica on the physical and mechanical properties of refractory castables, and also confirmed the importance of celsian formation during firing in the protection of refractory against aluminum attack.

  10. Spectra Transmitted by Mortar Barite in x-ray Qualities Applied in Diagnostic Radiology as Shielding

    Science.gov (United States)

    Almeida, A. T., Jr.; Araújo, F. G. S.; Nogueira, M. S.; Santos, M. A. P.

    2016-07-01

    Concrete which contains water, cement and aggregate, is widely used in building construction such as medical hospitals. The CdZnTe spectrometry system was used to acquire the transmitted spectra in the RQR qualities and the stripping procedure was performed by taking into account both the contributions of efficiency and x-ray escape fraction, experimentally determined. The samples were prepared in rectangular plate format with dimensions of (5 x 5) cm with thicknesses varying from 0.2cm to 2cm and exposed to x-ray beams generated. The HVL and the mean energy in this energy range was determined.

  11. Estimation of effective dose in patients from barite examinations of the digestive system in Malaga (Spain)

    International Nuclear Information System (INIS)

    The purpose of this research is to present dose reference values of patients in complex explorations. A plane ionization camera was used to obtain the values of the dose-area product (Gy/Square cm). By means of the method described in the NRPB R-262 report, the effective dose values have been determined for each projection used (mSV). The product values of the dose-area and effective dose have been obtained for oesophagogrammes; for oesophago-gastro-duodenal studies; for intestinal transitions; for enteroclisis and for opaque enemas

  12. 75 FR 5041 - Grant of Authority for Subzone Status, Excalibar Minerals LLC (Barite Milling), New Iberia...

    Science.gov (United States)

    2010-02-01

    ... Iberia, Louisiana, (FTZ Docket 21-2009, filed 5/6/09); Whereas, notice inviting public comment has been given in the Federal Register (74 FR 23394, 5/19/09) and the application has been processed pursuant to...), New Iberia, Louisiana Pursuant to its authority under the Foreign-Trade Zones Act of June 18, 1934,...

  13. Strategic planning and performance measurement using Fuzzy DEMATEL: A case study of Iran Kaolin and Barite company

    OpenAIRE

    Abolfazl Danaei; Mohammad Foroughi Jabbari; Leila Omidifar

    2013-01-01

    This paper presents an empirical investigation to measure the performance of a mining firm in province of Semnan, Iran based on fuzzy fuzzy Decision Making Trial and Evaluation Laboratory (DEMATEL) technique. The proposed study of this paper uses strength, weakness, opportunity and threat (SWOT) technique to analyze the firm and using DEMATEL rank various items based on their relative importance. Based on the results of our survey, cost reduction and increase investment in mining sector are t...

  14. Strategic planning and performance measurement using Fuzzy DEMATEL: A case study of Iran Kaolin and Barite company

    Directory of Open Access Journals (Sweden)

    Abolfazl Danaei

    2013-10-01

    Full Text Available This paper presents an empirical investigation to measure the performance of a mining firm in province of Semnan, Iran based on fuzzy fuzzy Decision Making Trial and Evaluation Laboratory (DEMATEL technique. The proposed study of this paper uses strength, weakness, opportunity and threat (SWOT technique to analyze the firm and using DEMATEL rank various items based on their relative importance. Based on the results of our survey, cost reduction and increase investment in mining sector are the most important components of this survey. The study also compares the results with similar study, which has recently been accomplished and we believe the proposed model is capable of detecting possible threats and helping us provide possible actions.

  15. Determination of attenuation properties of massive ceramic bricks cladded with mortars containing barite used as protective barrier for radiodiagnostic rooms

    International Nuclear Information System (INIS)

    The purpose of this work is to determine the properties of attenuation of the walls built with massive ceramic bricks to be used as protection barriers in environments of Medicine and Dentistry, when submitted to X-ray diagnosis. Massive ceramic bricks are used thoroughly in constructions as a calking element. The properties of attenuation of these materials were obtained starting from the application of the model of Archer to a group of attenuation curves with wide beams generated in the tensions of 70, 80, 100, 120, 140 and 150 kVp. A radiological equipment of constant potential was used in the Laboratory of IEE/USP, two cameras of ionization of 6cm3, coupled to two radiation monitors. The results show that for a tension of 100kVp, the thickness of 10cm of wall made with massive ceramic bricks corresponds to 1mm of lead. (author)

  16. The rheological behavior of fracture-filling cherts: example of Barite Valley dikes, Barberton Greenstone Belt, South Africa

    Directory of Open Access Journals (Sweden)

    M. Ledevin

    2014-05-01

    Full Text Available A 100 m-thick complex of near-vertical carbonaceous chert dikes marks the transition from the Mendon to Mapepe Formations (3260 Ma in the Barberton Greenstone Belt, South Africa. Fracturing was intense in this area, as shown by the profusion and width of the dikes (ca. 1 m on average and by the abundance of completely shattered rocks. The dike-and-sill organization of the fracture network and the upward narrowing of some of the large veins indicate that at least part of the fluid originated at depth and migrated upward in this hydrothermal plumbing system. Abundant angular fragments of silicified country rock are suspended and uniformly distributed within the larger dikes. Jigsaw-fit structures and confined bursting textures indicate that hydraulic fracturing was at the origin of the veins. The confinement of the dike system beneath an impact spherule bed suggests that the hydrothermal circulations were triggered by the impact and located at the external margin of a large crater. From the geometry of the dikes and the petrography of the cherts, we infer that the fluid that invaded the fractures was thixotropic. On one hand, the injection of black chert into extremely fine fractures is evidence for low viscosity at the time of injection; on the other hand, the lack of closure of larger veins and the suspension of large fragments in a chert matrix provide evidence of high viscosity soon thereafter. The inference is that the viscosity of the injected fluid increased from low to high as the fluid velocity decreased. Such rheological behavior is characteristic of media composed of solid and colloidal particles suspended in a liquid. The presence of abundant clay-sized, rounded particles of silica, carbonaceous matter and clay minerals, the high proportion of siliceous matrix and the capacity of colloidal silica to form cohesive 3-D networks through gelation, account for the viscosity increase and thixotropic behavior of the fluid that filled the veins. Stirring and shearing of the siliceous mush as it was injected imparted a low viscosity by decreasing internal particle interactions; then, as the flow rate declined, the fluid became highly viscous as the inter-particulate bonds (siloxane bonds, Si-O-Si were reconstituted. The gelation of the chert was rapid and the structure persisted at low temperature (T < 200 °C before fractures were sealed and chert indurated.

  17. The rheological behavior of fracture-filling cherts: example of Barite Valley dikes, Barberton Greenstone Belt, South Africa

    Science.gov (United States)

    Ledevin, M.; Arndt, N.; Simionovici, A.

    2014-05-01

    A 100 m-thick complex of near-vertical carbonaceous chert dikes marks the transition from the Mendon to Mapepe Formations (3260 Ma) in the Barberton Greenstone Belt, South Africa. Fracturing was intense in this area, as shown by the profusion and width of the dikes (ca. 1 m on average) and by the abundance of completely shattered rocks. The dike-and-sill organization of the fracture network and the upward narrowing of some of the large veins indicate that at least part of the fluid originated at depth and migrated upward in this hydrothermal plumbing system. Abundant angular fragments of silicified country rock are suspended and uniformly distributed within the larger dikes. Jigsaw-fit structures and confined bursting textures indicate that hydraulic fracturing was at the origin of the veins. The confinement of the dike system beneath an impact spherule bed suggests that the hydrothermal circulations were triggered by the impact and located at the external margin of a large crater. From the geometry of the dikes and the petrography of the cherts, we infer that the fluid that invaded the fractures was thixotropic. On one hand, the injection of black chert into extremely fine fractures is evidence for low viscosity at the time of injection; on the other hand, the lack of closure of larger veins and the suspension of large fragments in a chert matrix provide evidence of high viscosity soon thereafter. The inference is that the viscosity of the injected fluid increased from low to high as the fluid velocity decreased. Such rheological behavior is characteristic of media composed of solid and colloidal particles suspended in a liquid. The presence of abundant clay-sized, rounded particles of silica, carbonaceous matter and clay minerals, the high proportion of siliceous matrix and the capacity of colloidal silica to form cohesive 3-D networks through gelation, account for the viscosity increase and thixotropic behavior of the fluid that filled the veins. Stirring and shearing of the siliceous mush as it was injected imparted a low viscosity by decreasing internal particle interactions; then, as the flow rate declined, the fluid became highly viscous as the inter-particulate bonds (siloxane bonds, Si-O-Si) were reconstituted. The gelation of the chert was rapid and the structure persisted at low temperature (T sealed and chert indurated.

  18. The rheological behavior of fracture-filling cherts: example from Barite Valley dikes, Barberton greenstone Belt, South Africa.

    Science.gov (United States)

    Ledevin, Morgane; Arndt, Nicholas; Simionovici, Alexandre

    2014-05-01

    A 100m-thick complex of black carbonaceous chert dikes marks the transition from the Mendon to Mapepe Formations (3260 Ma) in the Barberton Greenstone Belt, South Africa. Fracturing was intense in this area, as shown by the profusion and width of the chert dikes (ca. 1m on average) and by the abundance of completely shattered rocks. Similar structures occur in many greenstones worldwide. Here we investigate (1) the origin of the dikes and (2) the nature of the material that precipitated to form the fracture-filling chert. The dike-and-sill organization of the plumbing system and the upward narrowing of some of the large veins indicate that at least part of the fluid originated at depth and migrated upward. Abundant angular fragments of silicified country rock are suspended and uniformly distributed within the larger dikes. Jigsaw-fit structures and confined bursting textures indicate that hydraulic fracturing was at the origin of the fractures, a particularity attributed to the confinement of the hydrothermal system below an impermeable cape of chert. The location of the dikes beneath an impact spherule bed leads us to propose that the hydrothermal circulation was related to the impact. The present site may have been located at the external margin of a large crater. The geometry of the dikes and the petrography of the cherts indicate that the fluid that invaded the fractures was thixotropic. The injection of black chert into extremely fine fractures is evidence oflow viscosity at the time of injection while the lack of closure of larger veins below eroded country blocks and the suspension of fragments in a chert matrix provides evidence of high viscosity soon thereafter. The inference is that the viscosity of the injected fluid increased from low to high as the fluid velocity decreased. Such rheological behavior is characteristic of media composed of solid and colloidal particles suspended in a fluid. The presence of abundant clay-sized particles of silica, carbonaceous matter and phyllosilicates, the high proportion of siliceous matrix and the capacity of colloidal silica to form cohesive 3D networks, accounts for the viscosity increase and thixotropic behavior of the fluid that filled the veins. Stirring and shearing of the fluid as it was injected imparted a low viscosity by decreasing internal particle interactions; then, as the flow rate declined, the fluid became highly viscous as the inter-particulate bonds were reconstituted. The gelation of the chert was rapid, probably within a day after it was injected, and the structure persisted for several months to years under low temperature conditions (Tsealed and the chert indurated.

  19. The rheological behaviour of fracture-filling cherts: example of Barite Valley dikes, Barberton Greenstone Belt, South Africa

    OpenAIRE

    M. Ledevin; Arndt, N.; Davaille, A.; Ledevin, R.; Simionovici, A.

    2015-01-01

    In the Barberton Greenstone Belt, South Africa, a 100–250 m thick complex of carbonaceous chert dikes marks the transition from the Mendon Formation to the Mapepe Formation (3260 Ma). The sub-vertical- to vertical position of the fractures, the abundance of highly shattered zones with poorly rotated angular fragments and common jigsaw fit, radial structures, and multiple injection features point to repetitive hydraulic fracturing that released overpressured fluids trapped wi...

  20. The rheological behavior of fracture-filling cherts: example of Barite Valley dikes, Barberton Greenstone Belt, South Africa

    OpenAIRE

    M. Ledevin; Arndt, N.; Simionovici, A.

    2014-01-01

    A 100 m-thick complex of near-vertical carbonaceous chert dikes marks the transition from the Mendon to Mapepe Formations (3260 Ma) in the Barberton Greenstone Belt, South Africa. Fracturing was intense in this area, as shown by the profusion and width of the dikes (ca. 1 m on average) and by the abundance of completely shattered rocks. The dike-and-sill organization of the fracture network and the upward narrowing of some of the large veins indicate that at...

  1. Decommissioning of the research reactor ASTRA in Seibersdorf, Austria: Determination of exemption limits at the Barite-concrete of the neutron activated biological shield to minimize radioactive waste

    International Nuclear Information System (INIS)

    The 10 MW multipurpose M.T.R. research reactor ASTRA at Arcs was in successful operation for 39 years (1960 to 1999) and after the decision of the government to shut it down it was necessary to decommission and dismantle the reactor. A team consisting of former reactor crew staff members was set up to perform the decommissioning. Working instructions for handling and operating sequences and radiation protection were developed. An extensive documentation describes the project. The planning took into account that all the work and operations for decommissioning could be performed inside the existing buildings (confinement or pump room) with the ventilation and radiological monitoring systems in operation. Hence, virtually no possibility for a release of activity to the environment during the whole decommissioning process would exist. In immediate succession and still under the operating license, all experimental facilities and components of the reactor within the vicinity of the core or in intermediate storage within the building (e.g. old beam-tube-inserts) were removed and treated in a first stage of dismantling from 2001 to 2003. In 2002 an environmental impact statement was prepared, the public hearing was held on December 19, 2002 to be followed by a license to decommission, which was granted on April 08, 2003 and was legalized in May 2003. It was intended to take down the structures of the biological shield by cutting blocks of between 7 and 9 tons (limited by the 10-ton-capacity of the crane) from the inactive zones in multiple section planes using wire-cutting techniques, and to get clearance for the material by referencing the surfaces and by additional internal probing.Actual work on the second state of dismantling could only be started after May 2003. It comprised the dismantling of the primary and secondary cooling facilities and the removal of he upper, inactive part of the biological shield (roughly 1600 tons).A building directly attached to the reactor was erected to give ample room for clearance measurements and procedures. It was almost complete by the end of 2003. In preparation of the intended cutting work on the upper, inactive part of the biological shield, working platforms were installed. In the pool and in the upper hot cell additional measures were taken to control the drain of the cutting fluid and to remove concrete and steel particles from the solution. Calculations had shown that in total about 36 tons of cake were to be expected, which should be more or less inactive waste. Therefore careful collection and preparations to achieve clearance were essential. High costs can be avoided by comparatively minor efforts, if essential parts of the removed materials can be cleared either directly for re-use, for re-use via building remainder-mass dumps or storage in remainder-mass-dumps. So for financial reasons, minimising the amount of materials designated for final repositories or intermediate storage facilities is a primary target. (authors)

  2. Geology and stable isotope geochemistry of Paleoarchean sulfur. Formation, preservation and geobiology of ancient pyrite and barite. (Utrecht Studies in Earth Sciences 031)

    NARCIS (Netherlands)

    Roerdink, D.L.

    2013-01-01

    Sulfur isotopes in ancient sulfate and sulfide minerals provide a comprehensive record of microbial processes involved in the early sulfur cycle on Earth. However, the interpretation of these isotopic signatures requires information on the geological context of such samples, because abiotic reaction

  3. Determination of total mass attenuation coefficients, effective atomic numbers and electron densities for different shielding materials used in radiation protection

    Energy Technology Data Exchange (ETDEWEB)

    Almeida J, A. T. [FUNDACENTRO, Centro Regional de Minas Gerais, Brazilian Institute for Safety and Health at Work, Belo Horizonte, 30180-100 Minas Gerais (Brazil); Nogueira, M. S. [Center of Development of Nuclear Technology / CNEN, Av. Pte. Antonio Carlos 6627, 31270-901 Belo Horizonte, Minas Gerais (Brazil); Santos, M. A. P., E-mail: mnogue@cdtn.br [Regional Center for Nuclear Science / CNEN, 50.740-540 Recife, Pernambuco (Brazil)

    2015-10-15

    Full text: In this paper, the interaction of X-rays with some shielding materials has been studied for materials containing different amounts of barite and aggregates. The total mass attenuation coefficient (μ{sub t}) for three shielding materials has been calculated by using WinXCOM program in the energy range from RQR qualities (RQR-4, RQR-6, RQR-9, and RQR-10). They were: cream barite (density 2.99 g/cm{sup 3} collected in the State of Sao Paulo), purple barite (density 2.95 g/cm{sup 3} collected in the State of Bahia) and white barite (density 3.10 g/cm{sup 3} collected in the State of Paraiba). The chemical analysis was carried out by an X-ray fluorescence spectrometer model EDX-720, through dispersive energy. The six elements of the higher concentration found in the sample and analyzed by Spectrophotometry of Energy Dispersive X-ray for the samples were Ba(60.9% - white barite), Ca(17,92% - cream barite), Ce(3,60% - white barite), Fe(17,16% - purple barite), S(12,11% - white barite) and Si(29,61% - purple barite). Also, the effective atomic number (Z{sub eff}) and the effective electron density (N{sub eff}) were calculated using the values of the total mass attenuation coefficient. The dependence of these parameters on the incident photon energy and the chemical composition has been examined. (Author)

  4. Determination of total mass attenuation coefficients, effective atomic numbers and electron densities for different shielding materials used in radiation protection

    International Nuclear Information System (INIS)

    Full text: In this paper, the interaction of X-rays with some shielding materials has been studied for materials containing different amounts of barite and aggregates. The total mass attenuation coefficient (μt) for three shielding materials has been calculated by using WinXCOM program in the energy range from RQR qualities (RQR-4, RQR-6, RQR-9, and RQR-10). They were: cream barite (density 2.99 g/cm3 collected in the State of Sao Paulo), purple barite (density 2.95 g/cm3 collected in the State of Bahia) and white barite (density 3.10 g/cm3 collected in the State of Paraiba). The chemical analysis was carried out by an X-ray fluorescence spectrometer model EDX-720, through dispersive energy. The six elements of the higher concentration found in the sample and analyzed by Spectrophotometry of Energy Dispersive X-ray for the samples were Ba(60.9% - white barite), Ca(17,92% - cream barite), Ce(3,60% - white barite), Fe(17,16% - purple barite), S(12,11% - white barite) and Si(29,61% - purple barite). Also, the effective atomic number (Zeff) and the effective electron density (Neff) were calculated using the values of the total mass attenuation coefficient. The dependence of these parameters on the incident photon energy and the chemical composition has been examined. (Author)

  5. Radioisotope analyzer of barium

    International Nuclear Information System (INIS)

    Principle of operation and construction of radioisotope barium sulphate analyzer type MZB-2 for fast determination of barium sulphate content in barite ores and enrichment products are described. The gauge equipped with Am-241 and a scintillation detector enables measurement of barium sulphate content in prepared samples of barite ores in the range 60% - 100% with the accuracy of 1%. The gauge is used in laboratories of barite mine and ore processing plant. 2 refs., 2 figs., 1 tab. (author)

  6. The Hemlo gold deposit, Ontario: a geochemical and isotopic study

    International Nuclear Information System (INIS)

    The Hemlo deposit, near Marathon, Ontario, is one of the largest gold deposits in North America. It is stratiform within Archean metamorphosed volcano-sedimentary rocks. The main ore zone is composed of pyritic, sericitic schist, and massive barite. This is the first report of stratiform barite in the Archean of North America, but other occurrences have since been found west of Hemlo. The mineralization is substantially enriched in Au, Mo, Sb, Hg, Tl and V and lacks carbonate. Because of metamorphism and deformation of the body its genesis is uncertain. 87Sr/86Sr of 0.7017 for barite from the deposit is similar to that of the sedimentary barite west of Hemlo and to initial ratios of contemporaneous volcanic rocks. At the base of the main ore zone, barite with delta34S of +8 to +12 per mille was deposited with approx. 0 per mille pyrite. Upward, both barite and pyrite get isotopically lighter, with minimum values for pyrite, to -17.5 per mille, in non-baritic schist forming the upper part of the ore zone. In drill section, Au grades correlate with the isotopic composition of pyrite. This, and the association of fractionated sulphide with sulphate, suggests that Au, pyrite and barite were deposited contemporaneously. The results are discussed. (author)

  7. Submarine Hydrothermal Venting-Flowing Sedimentary Characters of the Cambrian Shanggongtang and Dahebian Barite Deposits,Tianzhu County, Guizhou Province%贵州天柱上公塘-大河边寒武纪重晶石矿床海底热水喷流沉积结构、构造特征

    Institute of Scientific and Technical Information of China (English)

    杨瑞东; 魏怀瑞; 鲍淼; 王伟; 王强

    2007-01-01

    贵州天柱寒武系重晶石矿床属世界上最大的重晶石矿床,其储量达到2亿吨以上.通过系统的野外调查,发现其中包含有大量的海底热水(液)喷流沉积形成的脉状构造、冲刷构造、饼状体构造、柱状体构造、块状构造、斑状构造、水平纹层构造、碳质膜壳构造等沉积构造和沉积构造序列,同时具有热水(液)喷流成因的黄铜矿、闪锌矿、黄铁矿、钡冰长石等典型矿物.建立了较为完整的天柱寒武系重晶石矿床沉积序列,为这一超大型矿床的成因提供了更直接的证据.

  8. A relict sulfate-methane transition zone in the mid-Devonian Marcellus Shale

    Science.gov (United States)

    Niu, Danielle; Renock, Devon; Whitehouse, Martin; Leone, James; Rowe, Harry; Landis, Joshua; Hamren, Keith; Symcox, Carl W.; Sharma, Mukul

    2016-06-01

    A barium-enriched interval of Marcellus Shale (Middle Devonian Oatka Creek Formation) from a core in Chenango County, NY contains ∼100 μm diameter ellipsoidal grains with variable mineralogical compositions between pure barite and pure pyrite endmembers. Petrographic characterization and in-situ sulfur isotope analysis by Secondary Ion Mass Spectrometry (SIMS) was performed to better understand the diagenetic conditions under which these grains form and are preserved in the shale. Textural relationships suggest partial to complete pseudomorphic replacement of ellipsoidal barite by pyrite. Spatially, the ellipsoidal grains are concentrated in discrete layers parallel to original bedding and intervals within these layers often contain grains with similar degrees of replacement. The fraction of barite replaced by pyrite between these intervals can vary significantly, which is remarkable considering these intervals are separated by stratigraphic distances on the order of mm to cm in the shale (depths equivalent to deposition over 10's-1000's of years). The mean δ34S of barite and pyrite in ellipsoidal grains is 63.3 ± 3.6‰ and 2.2 ± 3.0‰, respectively, indicating that the grains are authigenic. Mass balance calculations based on density and stoichiometric differences between barite and pyrite indicate that reduction of sulfate from barite alone cannot be the sole source of sulfur in the replaced grains: only ∼23% of sulfur in pyrite comes from the dissolution of barite while the remainder derives from an additional source with δ34S = -17.6 ± 1.3‰. We suggest that pseudomorphic replacement of barite led first to the formation of greigite (Fe3S4), where one mole of sulfur was provided by barite and the other three moles of sulfur were contributed by FeS(aq); the latter formed by reaction of Fe2 + with sulfide from microbial sulfate reduction. Transformation of greigite to pyrite occurred via the sulfur addition and/or iron loss pathways. These

  9. SOURCE ASSESSMENT: CHEMICAL AND FERTILIZER MINERAL INDUSTRY, STATE-OF-THE-ART

    Science.gov (United States)

    Air and water pollutants are generated during the conversion of naturally occurring minerals into suitable forms for use in chemical and fertilizer production. These minerals are barite, borates, fluorspar, lithium minerals, mineral pigments, phosphate rock, potash, salt, sodium ...

  10. Biogeochemistry of 226Ra in contaminated bottom sediments and oilfield waste pits

    International Nuclear Information System (INIS)

    Solubility of 226Ra in sediments contaminated by produced water discharges was investigated using integrated microcosm, geochemical modelling and field sampling techniques. These studies strongly indicate that the biogeochemical control on 226Ra solubility in these sediments is coprecipitation with barite (BaSO4). The role of barite was confirmed by selective extractions of contaminated sediments, geochemical measurements of solution saturation, theoretical coprecipitation calculations, and direct measurement of barite using X-ray diffraction. Despite elevated activities that are three orders of magnitude higher than background, fluxes of 226Ra from these contaminated sediments are of the same order of magnitude as those measured in natural systems. Remobilization of 226Ra was observed in the Humble Bayou sediment under anaerobic, sulfate-reducing conditions. Management of these contaminated sites will involve understanding the role of barite solid-solution chemistry on the fate and mobility of 226Ra. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  11. Sub-lethal effects of water-based drilling muds on the deep-water sponge Geodia barretti.

    Science.gov (United States)

    Edge, Katelyn J; Johnston, Emma L; Dafforn, Katherine A; Simpson, Stuart L; Kutti, Tina; Bannister, Raymond J

    2016-05-01

    Offshore oil and gas activities can result in the discharge of large amounts of drilling muds. While these materials have generally been regarded as non-toxic to marine organisms, recent studies have demonstrated negative impacts to suspension feeding organisms. We exposed the arctic-boreal sponge Geodia barretti to the primary particulate components of two water-based drilling muds; barite and bentonite. Sponges were exposed to barite, bentonite and a natural reference sediment at a range of total suspended solid concentrations (TSS = 0, 10, 50 or 100 mg/L) for 12 h after which we measured a suite of biomarker responses (lysosomal membrane stability, lipid peroxidation and glutathione). In addition, we compared biomarker responses, organic energy content and metal accumulation in sponges, which had been continuously or intermittently exposed to suspended barite and natural sediment for 14 d at relevant concentrations (10 and 30 mg TSS/L). Lysosomal membrane stability was reduced in the sponges exposed to barite at 50 and 100 mg TSS/L after just 12 h and at 30 mg TSS/L for both continuous and intermittent exposures over 14 d. Evidence of compromised cellular viability was accompanied by barite analysis revealing concentrations of Cu and Pb well above reference sediments and Norwegian sediment quality guidelines. Metal bioaccumulation in sponge tissues was low and the total organic energy content (determined by the elemental composition of organic tissue) was not affected. Intermittent exposures to barite resulted in less toxicity than continuous exposure to barite. Short term exposures to bentonite did not alter any biomarker responses. This is the first time that these biomarkers have been used to indicate contaminant exposure in an arctic-boreal sponge. Our results illustrate the potential toxicity of barite and the importance of assessments that reflect the ways in which these contaminants are delivered under environmentally realistic conditions. PMID

  12. Insights from stable S and O isotopes into biogeochemical processes and genesis of Lower Cambrian barite–pyrite concretions of South China

    Digital Repository Service at National Institute of Oceanography (India)

    Goldberg, T.; Mazumdar, A.; Strauss, H.; Shields, G.

    into two halves along the long axis of the concretions. One half was polished for microsampling of pyrite and barite using dentist?s drill with tungsten carbide bit attachment. Prior to sampling a detailed textural study was performed by using incident... in size. Visual estimation of mineral content (volume percentages) was made with a petrographic microscope. Polished sections through the concretions reveals concentric layering of pyrite around the core and near the margins (Fig. 3A). Barite content...

  13. Radioisotope barium sulphate gauge MZB-2

    International Nuclear Information System (INIS)

    A method and the gauge for measuring content of barium sulphate are described. The gauge is intended for fast determination of barium sulphate in barite ore and in output products of the enrichment process. The measuring range 60-100% of BaSO4, accuracy ±1% and measuring time 60 s were reached. The barium sulphate gauge is used in barite mine ''Boguszow'' in Poland. (author)

  14. Attenuation characteristics of materials used in radiation protection as radiation shielding

    International Nuclear Information System (INIS)

    Crystal glass has been widely used as shielding material in gamma radiation sources as well as x-ray generating equipment to replace the plumbiferous glass, in order to minimize exposure to individuals. In this work, ten plates of crystal glass, with dimensions of 20cm x 20cm and range of thicknesses from 0.5 to 2.0 cm, and barite concrete were irradiated with potential constants of 60kV, 80kV, 110kV, 150kV and gamma radiation of 60Co. The curves of attenuation and of transmission were obtained for crystal glass, barite plaster and barite concrete (mGy/mA.min) at 1 meter as a function of thickness.Crystal glass has been widely used as shielding material in gamma radiation sources as well as x-ray generating equipment to replace the plumbiferous glass, in order to minimize exposure to individuals. In this work, ten plates of crystal glass, with dimensions of 20cm x 20cm and range of thicknesses from 0.5 to 2.0 cm, and barite concrete were irradiated with potential constants of 60kV, 80kV, 110kV, 150kV and gamma radiation of 60Co. The curves of attenuation and of transmission were obtained for crystal glass, barite plaster and barite concrete (mGy/mA.min) at 1 meter as a function of thickness. (author)

  15. GEOLOGY AND GEOCHEMISTRY OF THE MINERALIZATION FROM THE GORNJI VAKUF AREA, BOSNIA

    Directory of Open Access Journals (Sweden)

    Ivan Jurović

    1994-12-01

    Full Text Available In the Gornji Vakuf area, which is built up of Palaeozoic sediments and metarhyolites, the authors investigated 47 ore occurrences by geological and different geochemical methods. They distinguish; (a alluvial, diluvial and fluvio-glacial placers; (b epigenetic hydrothermal barite-sideritc-tetrahedrite veins located in the Silurian-Devonian schist complex and Upper Permian, and almost monomineralic barite (± tetrahedri-te veins, breccias and bodies in the Middle Devonian carbonate complex; (c post-kinematic monomineralic metamorpho-genic quartz deposits interlaying the schists. The hydrothermal deposits have common characteristics as follows: location exclusively in Palaeozoic strata, epigenetic character; simple, monotonous paragencsis (barite ± siderite as main nonmetallic minerals and Hg-tetrahedrite as preponderant ore mineral; siderite characterized by high CaO, MgO and low MnO content; all tetrahedrites are Hg, Ag, Au, Hi-bearing; barite with average content of 2.9 wt% of SrS04. The stable isotope study revealed:  34S= + 15.0‰ in barites, -10.1‰ in tetrahedrites,  18O = -9.6‰ and  l3C = -3.7‰ in siderites. The microthermometric measurements gave: Th=+200 ºC. in barites. The very close similarity of all above mentioned results with those found in the minerals of the Kreševo area deposits, urged the authors to assign also the Gornji Vakuf area deposits to the post-Variscan tectonic event.

  16. Zonation of Microbial Communities by a Hydrothermal Mound in the Atlantis II Deep (the Red Sea)

    KAUST Repository

    Wang, Yong

    2015-10-20

    In deep-sea geothermal rift zones, the dispersal of hydrothermal fluids of moderately-high temperatures typically forms subseafloor mounds. Major mineral components of the crust covering the mound are barite and metal sulfides. As a result of the continental rifting along the Red Sea, metalliferous sediments accumulate on the seafloor of the Atlantis II Deep. In the present study, a barite crust was identified in a sediment core from the Atlantis II Deep, indicating the formation of a hydrothermal mound at the sampling site. Here, we examined how such a dense barite crust could affect the local environment and the distribution of microbial inhabitants. Our results demonstrate distinctive features of mineral components and microbial communities in the sediment layers separated by the barite crust. Within the mound, archaea accounted for 65% of the community. In contrast, the sediments above the barite boundary were overwhelmed by bacteria. The composition of microbial communities under the mound was similar to that in the sediments of the nearby Discovery Deep and marine cold seeps. This work reveals the zonation of microbial communities after the formation of the hydrothermal mound in the subsurface sediments of the rift basin.

  17. Phase relation of CaSO4 at high pressure and temperature up to 90 GPa and 2300 K

    Science.gov (United States)

    Fujii, Taku; Ohfuji, Hiroaki; Inoue, Toru

    2016-05-01

    Calcium sulfate (CaSO4), one of the major sulfate minerals in the Earth's crust, is expected to play a major role in sulfur recycling into the deep mantle. Here, we investigated the crystal structure and phase relation of CaSO4 up to ~90 GPa and 2300 K through a series of high-pressure experiments combined with in situ X-ray diffraction. CaSO4 forms three thermodynamically stable polymorphs: anhydrite (stable below 3 GPa), monazite-type phase (stable between 3 and ~13 GPa) and barite-type phase (stable up to at least 93 GPa). Anhydrite to monazite-type phase transition is induced by pressure even at room temperature, while monazite- to barite-type transition requires heating at least to 1500 K at ~20 GPa. The barite-type phase cannot always be quenched from high temperature and is distorted to metastable AgMnO4-type structure or another modified barite structure depending on pressure. We obtained the pressure-volume data and density of anhydrite, monazite- and barite-type phases and found that their densities are lower than those calculated from the PREM model in the studied P-T conditions. This suggests that CaSO4 is gravitationally unstable in the mantle and fluid/melt phase into which sulfur dissolves and/or sulfate-sulfide speciation may play a major role in the sulfur recycling into the deep Earth.

  18. Geochemistry and mineralogy of the radioactive minerals associated with some pegmatite veins of the Ukma-Nawahatu-Hursi sector, Purulia Dist., W.B., in the precambrian Chhotanagpur gneissic complex

    International Nuclear Information System (INIS)

    Some barite-bearing pegmatites in the Ukma-Nawahatu-Hursi sector (23° 25'-26'N, 86° 02'-04'E) of the Purulia dist., West Bengal, have association of radioactive minerals in the form of coarse grained pitchblack lumps and irregular patches. This radioactive belt of about 15 km length running through Ukma, Nawahatu and Hursi areas follows ENE-WSW trending shear zone. The barite-bearing pegmatites occur as lenses or lenticular veins hosted by garnetiferous sillimanite-biotite-quartz-schist or occasionally by migmatite. Near Nawahatu the radioactive barite-pegmatite vein occurs at or near the junction between footwall amphibolite and hangingwall garnetiferous schist. The pegmatite veins have mainly followed the schistosity of the host rock and dip 70°-80° towards south

  19. Distribution of major, trace and rare-earth elements in surface sediments of the Wharton Basin, Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N.; Rao, Ch.M.; Higgs, N.C.; Colley, S.; Parthiban, G.

    . (1980) and Bishop (1988 ) found that Ba in suspended particles is predominantly in the form of barite and con- cluded that it has been formed in the upper water column by the breakdown of organic matter, re- lease of Ba, and formation barite...: 35-47. Matsumoto, R., Minai, Y. and Iijima, A., 1985. Manganese content, cerium anomaly and rate of sedimentation as aids in the characterization and classification of deep-sea sed- iments. In: N. Nasu, K. Kobayashi, S. Uyeda, I. Kushiro and H...

  20. Mineral resources of Cactus Plain and East Cactus Plain Wilderness Study Areas, La Paz County, Arizona

    Energy Technology Data Exchange (ETDEWEB)

    Tosdal, R.M.; Eppinger, R.G.; Erdman, J.A.; Hanna, W.F.; Pitkin, J.A.; Blank, H.R. Jr.; O' Leary, R.M.; Watterson, J.R. (US Geological Survey (US)); Kreidler, T.J. (US Bureau of Mines (US))

    1990-01-01

    This paper reports on geologic, geochemical, and geophysical studies in the Cactus Plain and East Cactus Plain Wilderness Study Areas outlined in areas with moderate to high potential for gold, silver, copper, lead, zinc, barite, fluorite, manganese, and sand suitable for foundry, fracturing, and abrasive uses and low resource potential for beryllium, uranium and bentonitic clays.

  1. 40 CFR 436.101 - Specialized definitions.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Specialized definitions. 436.101 Section 436.101 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS MINERAL MINING AND PROCESSING POINT SOURCE CATEGORY Barite Subcategory §...

  2. Composite membranes for alkaline electrolysis based on polysulfone and mineral fillers

    Science.gov (United States)

    Burnat, Dariusz; Schlupp, Meike; Wichser, Adrian; Lothenbach, Barbara; Gorbar, Michal; Züttel, Andreas; Vogt, Ulrich F.

    2015-09-01

    Mineral-based membranes for high temperature alkaline electrolysis were developed by a phase inversion process with polysulfone as binder. The long-term stability of new mineral fillers: wollastonite, forsterite and barite was assessed by 8000 h-long leaching experiments (5.5 M KOH, 85 °C) combined with thermodynamic modelling. Barite has released only 6.22 10-4 M of Ba ions into the electrolyte and was selected as promising filler material, due to its excellent stability. Barite-based membranes, prepared by the phase inversion process, were further studied. The resistivity of these membranes in 5.5 M KOH was investigated as a function of membrane thickness and total porosity, hydrodynamic porosity as well as gas purities determined by conducting electrolysis at ambient conditions. It was found that a dense top layer resulting from the phase inversion process, shows resistivity values up to 451.0 ± 22 Ω cm, which is two orders of magnitude higher than a porous bulk membrane microstructure (3.89 Ω cm). Developed membranes provided hydrogen purity of 99.83 at 200 mA cm-2, which is comparable to previously used chrysotile membranes and higher than commercial state-of-the-art Zirfon 500utp membrane. These cost-effective polysulfone - barite membranes are promising candidates as asbestos replacement for commercial applications.

  3. Mineral resources of Cactus Plain and East Cactus Plain Wilderness Study Areas, La Paz County, Arizona

    International Nuclear Information System (INIS)

    This paper reports on geologic, geochemical, and geophysical studies in the Cactus Plain and East Cactus Plain Wilderness Study Areas outlined in areas with moderate to high potential for gold, silver, copper, lead, zinc, barite, fluorite, manganese, and sand suitable for foundry, fracturing, and abrasive uses and low resource potential for beryllium, uranium and bentonitic clays

  4. Determination of carbon in uranium and its compounds; Determinacion de carbono en uranio metal y sus compuestos

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Garcia, M. M.

    1972-07-01

    This paper collects the analytical methods used our laboratories for the determination of carbon in uranium metal, uranate salts and the oxides, fluorides and carbides of uranium. The carbon is usually burned off in a induction or resistance oven under oxygen flow. The CO{sub 2} is collected in barite solution. Where it is backtitrated with potassium biphthalate. (Author)

  5. Textural and mineralogical study of the San Gregorio de Polanco mesozoic basic dams

    International Nuclear Information System (INIS)

    This work is about the preliminary results of petrographic study in Mesozoic basic dikes located around San Gregorio de Polanco (Tacuarembo department. Uruguay). The textural mineralogical study conducted by scanning electron microscopy confirms the presence of significant late hydrothermal activity which are represented by the conspicuous presence of interstitial barite mineralization level

  6. NONMETALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>20131601 Gao Junbo(College of Resources and Environmental Engineering,Guizhou University,Guiyang 550003,China);Yang Ruidong Hydrothermal Venting-Flowing Sedimentation Characteristics of Devonian Barite Deposits from Leji,Zhenning County,Guizhou Province(Acta Sedimentologica Sinica,ISSN1000-0550,CN62-1038/P,30(3),

  7. Determination of carbon in uranium and its compounds

    International Nuclear Information System (INIS)

    This paper collects the analytical methods used our laboratories for the determination of carbon in uranium metal, uranate salts and the oxides, fluorides and carbides of uranium. The carbon is usually burned off in a induction or resistance oven under oxygen flow. The CO2 is collected in barite solution. Where it is backtitrated with potassium biphthalate. (Author)

  8. Excess Barium as a Paleoproductivity Proxy: A Reevaluation

    Science.gov (United States)

    Eagle, M.; Paytan, A.

    2001-12-01

    Marine barite may serve as a proxy to reconstruct past export production (Dymond, 1992). In most studies sedimentary barite accumulation is not measured directly, instead a parameter termed excess barium (Baexs), also referred to as biogenic barium, is used to estimate the barite content. Baexs is defined as the total Ba concentration in the sediment minus the Ba associated with terrigenous material. Baexs is calculated by normalization to a constant Ba/Al ratio, typically the average shale ratio. This application assumes that (1) all the Ba besides the fraction associated with terrigenous Al is in the form of barite (the phase related to productivity) (2) the Ba/Alshale is constant in space and time (3) all of the Al is associated with terrigenous matter. If these assumptions are invalidated however, this approach lead to significant errors in calculating export production rates. To test the validity of the use of Baexs as a proxy for barite we compared the Baexs in a wide range of core top sediments from different oceanic settings to the barite content in the same cores. We found that Baexs frequently overestimated the Ba fraction associated with barite and in several cases significant Baexs was measured in the cores where no barite was observed. We have also used a sequential leaching protocol (Collier and Edmond 1984) to determine Ba association with organic matter, carbonates, Fe-Mn hydroxides and silicates. While terrigenous Ba remains an important fraction, in our samples 25-95% of non-barite Ba was derived from other fractions, with Fe-Mn oxides contributing the most Ba. In addition we found that the Ba/Al ratio in the silicate fraction of our samples varied considerably from site to site. The above results suggest that at least two of the underlying assumptions for employing Baexs to reconstruct paleoproductivity are not always valid and previously published data from (Murray and Leinen 1993) indicate that the third assumption may also not hold in every

  9. A new barite–colemanite concrete with lower neutron production in radiation therapy bunkers

    International Nuclear Information System (INIS)

    Highlights: ► Photoneutron production from barite concrete is higher than ordinary concrete. ► The effect of adding colemanite to barite was studied by Monte Carlo simulation. ► Results showed lower photoneutron production for barite–colemanite concretes. ► Results showed reduced attenuation and compressive strength for new concretes. -- Abstract: The purpose of the current was to design a new high density concrete with low photoneutron production rate for radiation therapy bunker constructions. We used MCNPX Monte Carlo (MC) code for photoneutron productions in a radiation therapy bunker. The validated MC model of Varian Clinac 2100 C/D, 18 MeV photon beam and a radiation therapy bunkers made of barite was used for photoneutron calculations. Colemanite mineral with weight fraction of 5% and 10% was added to the barite concrete in bunker walls. Photoneutrons absorbed doses at beam isocenter and at the maze entrance door were calculated. The Barite–colemanite concretes with two different compositions were built and their linear attenuation coefficients were measured against Cobalt-60, 9 and 18 MeV photon beams. MC results showed that adding 5% and 10% Colemanite to Barite concrete reduces photoneutron production rate 7% and 16% respectively. However, experimental measurement of photon attenuation showed its lower photon attenuation coefficient and reduced mechanical properties. The results indicated that adding colemanite reduces photoneutrons received by the maze entrance door, but its photon attenuation and mechanical properties were compromised accordingly. Further studies on proposed concrete composition to enhance its mechanical properties are recommend.

  10. The carbonatite-marble dykes of Abyan Province, Yemen Republic: the mixing of mantle and crustal carbonate materials revealed by isotope and trace element analysis

    Science.gov (United States)

    Le Bas, M. J.; Ba-Bttat, M. A. O.; Taylor, R. N.; Milton, J. A.; Windley, B. F.; Evins, P. M.

    2004-09-01

    Dykes of carbonate rocks, that cut gneisses in the Lowder-Mudiah area of southern Yemen, consist of dolomite and/or calcite with or without apatite, barite and monazite. Petrographic observations, mineralogical, XRF and ICP-MS analyses reveal that some of the carbonate rocks are derived from sedimentary protoliths, whereas others are magmatic calcio- and magnesio-carbonatites some of which are mineralized with barite-monazite. The interbanded occurrence and apparent contemporary emplacement of these different rock types within individual dykes, backed by Sr Nd isotope evidence, are interpreted to show that intrusion of mantle-derived carbonatite magma was accompanied by mobilization of crustal marbles. That took place some 840 Ma ago but the REE-mineralization is dated at ca. 400 Ma.

  11. Dissolution of alkaline earth sulfates in the presence of montmorillonite

    Science.gov (United States)

    Eberl, D.D.; Landa, E.R.

    1985-01-01

    In a study of the effect of montmorillonite on the dissolution of BaSO4 (barite), SrSO4 (celestite), and 226Ra from U mill tailings, it was found that: (1) More of these substances dissolve in an aqueous system that contains montmorillonite than dissolve in a similar system without clay, due to the ion exchange properties of the clay; (2) Na-montmorillonite is more effective in aiding dissolution than is Ca-montmorillonite; (3) the amount of Ra that moves from mill tailings to an exchanger increases as solution sulfate activity decreases. Leaching experiments suggest that 226Ra from H2SO4-circuit U mill tailings from Edgemont, South Dakota, is not present as pure Ra sulfate or as an impurity in anhydrite or gypsum; it is less soluble, and probably occurs as a trace constituent in barite.

  12. Evidence for ancient atmospheric xenon in Archean rocks and implications for the early evolution of the atmosphere

    Science.gov (United States)

    Pujol, M.; Marty, B.; Burnard, P.; Hofmann, A.

    2012-12-01

    The initial atmospheric xenon isotopic composition has been much debated over the last 4 decades. A Non radiogenic Earth Atmospheric xenon (NEA-Xe) composition has been proposed to be the best estimate of the initial signature ([1]). NEA-Xe consists of modern atmospheric Xe without fission (131-136Xe) or radioactive decay (129Xe) products. However, the isotope composition of such non-radiogenic xenon is very different to that of potential cosmochemical precursors such as solar or meteoritic Xe, as it is mass-fractionated by up to 3-4 % per amu relative to the potential precursors, and it is also elementally depleted relative to other noble gases. Because the Xe isotopic composition of the Archean appears to be intermediate between that of these cosmochemical end-members and that of the modern atmosphere, we argued that isotopic fractionation of atmospheric xenon did not occur early in Earth's history by hydrodynamic escape, as postulated by all other models ([1], [2], [3]), but instead was a continuous, long term process that lasted during at least the Hadean and Archean eons. Taken at face value, the decrease of the Xe isotopic fractionation from 1.6-2.1 % amu-1 3.5 Ga ago ([4]) to 1 % amu-1 3.0 Ga ago (Ar-Ar age in fluid inclusions trapped in quartz from the same Dresser Formation, [5]) could reflect a secular variation of the atmospheric Xe signature. Nevertheless, up until now, all data showing an isotopic mass fractionation have been measured in rocks and fluids from the same formation (Dresser Formation, Western Australia, aged 3.5 Ga), and have yet to be confirmed in rocks from different locations. In order to better constrain xenon isotopic fractionation of the atmosphere through time, we decided to analyze barites from different ages, geological environments and metamorphism grade. We started this study with barite from the Fig Tree Formation (South Africa, aged 3.26 Ga). This barite was sampled in old mines so have negligible modern exposure time. It is

  13. Buffer liquid for separating hydrocarbon-base drilling mud and water-base plugging mud

    Energy Technology Data Exchange (ETDEWEB)

    Mukhin, L.K.; Leonidova, A.I.; Rybal ' chenko, V.S.; Shchavelev, N.I.; Strubalina, N.V.

    1984-01-01

    The purpose of the invention is to improve the washing effect and separating capacity of liquid by forming a hydrophobic mixing zone on the edge with the drilling mud on a hydrocarbon base and the hydrophilic mixing zone on the edge with the water-base plugging mud. This goal is reached because the buffer liquid for separating the hydrocarbon-base drilling mud and the water-base plugging mud containing water, diesel fuel and OP-4 emulsifier, monoalkylphenyl ethers of polyethylene glycol based on polymer distillate also contain barite with the following ratio of components, % by mass: diesel fuel 17.0-51.0, water 12.0-59.0, OP-4 emulsifier, monoalkylphenyl esters of polyethylene glycol based on polymer distillate 0.25-1.0, barite 8.0-70.0.

  14. [Species composition and distribution of foraminifers in the Deryugin Basin (Sea of Okhotsk)].

    Science.gov (United States)

    Khusid, T A; Domanov, M M; Svinininnikov, A M

    2006-01-01

    Analysis of the composition and quantitative distribution of foraminifers in bathyal sediments collected at 14 stations in the Deryugin Basin and at 11 stations in other regions of the Sea of Okhotsk, Sea of Japan, and North Pacific demonstrated specific foraminifer complex in the basin at depths from 1650 to 1800 m associated with cold barite/methane seeps. Oligomixed biocenosis with prevailing agglutinated foraminifers and Saccorhiza ramosa as the dominant was shown to develop in these zones. PMID:16634440

  15. Near shore submarine hydrothermal activity in Bahia Banderas, western Mexico

    OpenAIRE

    F. J. Núñez Cornú; Rosa María Prol Ledesma; A. Cupul Magaña; C. Suárez Plascencia

    2000-01-01

    Shallow submarine hydrothermal activity was detected in the Bahía de Banderas area, Mexico. Volcanic-type tremors were recorded by portable seismological stations onshore. Vent samples suggest a depositional sequence dominated by carbonates in the first stage (calcite and dolomite), followed by apatite and late barite veins. Layers of sequential deposition of sulfides were also observed, and are interpreted as cyclic variations of sulphur fugacity.

  16. Gulf of Mexico mud toxicity limitations

    Energy Technology Data Exchange (ETDEWEB)

    Dunn, H.E.; Beardmore, D.H. (Phillips Petroleum Co., Bartlesville, OK (USA)); Stewart, W.S. (Drilling Specialties Co. (US))

    1989-10-01

    Because of the Environmental Protection Agency's recent toxicity limits on drilling mud discharges for offshore Gulf of Mexico, Phillips Petroleum conducted a mud toxicity study based on both field and lab tests. The study, discussed in this article, found the polyanionic cellulose-sulfomethylated quebracho-chrome lignosulfonate mud Phillips had been using would comfortably pass the toxicity limitations. The study also found barite and thinners were of low toxicity, and hydrocarbons and surfactants were highly toxic.

  17. El proyecto de El Berrocal: síntesis preliminar

    OpenAIRE

    Pardillo, J.; Pelayo, M.; García, M.; Marín, C.; Hernández, A.; Tunero, M.; G??mez, P.; De La Cruz, B.; Pérez del Villar, L.; Rivas, P

    1993-01-01

    El Berrocal is an international research project on the natural radionuclide migration in a fissured granitic environment. This project is being carried out in the El Berrocal zone, north of the village of Nombela (Toledo). The gelogical formation studied is a granitic pluton with an epithermal vein-type mineralization comprising quartz, sphalerite, pyrite and chalcopyrite; and pitchblende, pyrite, carbonates and barite. The activities of the project are focused on the structural, lithol...

  18. Possible thermal spring deposit in the Arad area, Israel

    Energy Technology Data Exchange (ETDEWEB)

    Issar, A. (Geological Survey of Israel); Eckstein,Y.; Bogoch, R.

    1969-01-01

    A dolomite-chert breccia body, cemented by a hematite-geothite-barite-calcite mineral assemblage was found in the Arad area. This assemblage, plus the presence of anomalous quantities of various elements, particularly molybdenum, and the goethite-hematite relationship, suggest a thermal mineral spring deposit from a hypogene water source. The mineralogy and paragenesis of the deposit are discussed, and a normative analysis is tabulated.

  19. A thermodynamic investigation of barium and calcium sulfate stability in sediments at an oceanic ridge axis (Juan de Fuca, ODP legs 139 and 169)

    OpenAIRE

    Monnin, Christophe; Balleur, Sabine; Goffé, Bruno

    2003-01-01

    We have used a new thermodynamic model of barium and calcium sulfate solubilities in multicomponent electrolyte solutions (Monnin, 1999) to investigate the stabilities of barite and anhydrite in seawater or in marine sediment porewaters at high temperature and pressure. As a further test supplementing those previously carried out during model development, we have calculated the temperature at which standard seawater becomes saturated with respect to anhydrite. The model predicts that, upon he...

  20. A Study on the Role of Pre-Gelatinized Starch (PGS) in the Non Damaging Drilling Fluid (NDDF) for the Tipam Sand of Geleki Oilfield of Upper Assam Basin

    OpenAIRE

    Prasenjit Talukdar; Subrata Borgohain Gogoi

    2015-01-01

    The drilling of the wells from surface to target location with conventional drilling fluids may impair production and ultimate recovery by failing to adequately connect the reservoir with the wellbore by damaging the producing interval. One of the most common ways of damaging a formation is the filtration loss. Non Damaging Drilling Fluid (NDDF) is a clay and barite free environmental friendly polymer mud system mostly used in pay zone sections of development wells and specifically in horizon...

  1. La porosidad en las areniscas triásicas (Rama Aragonesa de la Cordillera Ibérica)

    OpenAIRE

    J Arribas; Soriano, J.

    1984-01-01

    Triassic sandstone's porosity (Buntsandstein and Muschelkalk facies) from the Aragonesa Branch of the Iberian Range are studied, firstly at the sediment primary porosity calculation and secondly the porosity-reducing processes are analyzed. Processes creating secondary sandstone porosity can be established (dissolution and fracturing) by the textural and genetic caracterization of the sandstone's voids. The dissolution of potassium feldspar, carbonate cement and barite cement, is related with...

  2. Bulk Density Adjustment of Resin-Based Equivalent Material for Geomechanical Model Test

    OpenAIRE

    Pengxian Fan; Haozhe Xing; Linjian Ma; Kaifeng Jiang; Mingyang Wang; Zechen Yan; Xiang Fang

    2015-01-01

    An equivalent material is of significance to the simulation of prototype rock in geomechanical model test. Researchers attempt to ensure that the bulk density of equivalent material is equal to that of prototype rock. In this work, barite sand was used to increase the bulk density of a resin-based equivalent material. The variation law of the bulk density was revealed in the simulation of a prototype rock of a different bulk density. Over 300 specimens were made for uniaxial compression test....

  3. Environmental geochemistry of the polymetallic ore deposits: Case studies from the Rude and the Sv. Jakob historical mining sites, NW Croatia

    OpenAIRE

    Strmić Palinkaš, Sabina; A. Palinkaš, Ladislav; Kuzmanović, Maja; Martinić, Maša; Kampić, Štefica; Dogančić, Dragana; Obhođaš, Jasmina

    2013-01-01

    This paper presents the results of the sampling surveys carried out in order to evaluate the environmental impact of the Rude and the Sv. Jakob historical mining sites, NW Croatia. The studied polymetallic ore deposits are differing in the mineralogical and geochemical features as well as in the host rock lithology. The Rude Fe-Cu-Pb-Zn-Ba deposit is hosted by Permian siliciclastic sediments. Siderite, hematite, galena, sphalerite, chalcopyrite, pyrite, barite and gypsum are the major ore mi...

  4. Experimental comparison of gamma attenuations by glasses, lead, iron and concretes

    International Nuclear Information System (INIS)

    The authors report the experimental determination, for lead glasses of density 3.3, 4.2, 5.2 and 6.2, of thicknesses equivalent to thicknesses given for lead, iron, ordinary concrete and barite concrete for Cobalt 60 and Caesium 137 radiations. Results are presented under the form of curves. Attenuation measurements made on this opportunity and those made on various hot cells have been compared with theoretical attenuation curves produced in another CEA document

  5. Bioavailability of heavy metals in drilling muds

    OpenAIRE

    Schaanning, M.; Ruus, A.; Bakke, T.; Hylland, Ketil; Olsgard, Frode

    2002-01-01

    Experimental work on uptake of metals from sediments spiked with barite, ilmenite and hematite were performed using the ragworm Nereis diversicolor and the netted dog whelk Hinia (Nassarius) reticulata as test organisms. The present report also provides a brief review of recent litterature on biological effects of metals in drill cuttings, including relevant results from the UKOOA Drill Cuttings Initiative - an international research programme completed in December 2001. The review suggest lo...

  6. Performance study and influence of radiation emission energy and soil contamination level on γ-radiation shielding of stabilised/solidified radionuclide-polluted soils

    International Nuclear Information System (INIS)

    This work focuses on the stabilisation/solidification (S/S) of radionuclide-polluted soils at different 232Th levels using Portland cement alone and with barite aggregates. The potential of S/S was assessed applying a full testing protocol and calculating γ-radiation shielding (γRS) index, that included the measurement of soil radioactivity before and after the S/S as a function of the emission energy and soil contamination level. The results indicate that setting processes are strongly dependent on the contaminant concentration, and for contamination level higher than 5%, setting time values longer than 72 h. The addition of barite aggregates to the cement gout leads to a slight improvement of the S/S performance in terms of durability and contaminant leaching but reduces the mechanical resistance of the treated soils samples. Barite addition also causes an increase in the γ-rays shielding properties of the S/S treatment up to about 20%. Gamma-ray measurements show that γRS strongly depends on the energy, and that the radioactivity with the contamination level was governed by a linear trend, while, γRS index does not depend on the radionuclide concentration. Results allow the calculated γRS values and those available from other experiments to be applied to hazard radioactive soil contaminations. - Highlights: • We assess the effects of 232Th contamination on performance of S/S treated soil. • We assess the γ-radiation shielding of the S/S materials as a function of energy. • We report a full testing protocol for assessing S/S resistance performance. • Emission energy influences the γ radiation shielding of the S/S. • Barite gives high γ-radiation shielding and low contaminant leaching

  7. Relationship Between Composition, Structure and Permeability of Drilling Filter Cakes Relations entre la composition, la structure et la perméabilité des cakes de forage

    OpenAIRE

    Durand C.; Lecourtier J.; Rosenberg E.; Loeber L.

    2006-01-01

    During drilling operations there is a need to build mud cakes as impervious as possible on the wall of the borehole to prevent damage by fluid loss. To establish the relationship between the filtration properties of mud filter cakes and their structure, drilling fluids containing montmorillonite clay, flexible (Drispac) or rigid (xanthan) anionic polymers, electrolytes and barite were investigated. Standard API filtration and polymer adsorption measurements were performed. The cake structure ...

  8. A salt diapir-related Mississippi Valley-type deposit: The Bou Jaber Pb-Zn-Ba-F deposit, Tunisia: Fluid inclusion and isotope study

    Science.gov (United States)

    Bouhlel, Salah; Leach, David; Johnson, Craig A.; Marsh, Erin; Salmi-Laouar, Sihem; Banks, David A.

    2016-01-01

    The Bou Jaber Ba-F-Pb-Zn deposit is located at the edge of the Bou Jaber Triassic salt diapir in the Tunisia Salt Diapir Province. The ores are unconformity and fault-controlled and occur as subvertical column-shaped bodies developed in dissolution-collapse breccias and in cavities within the Late Aptian platform carbonate rocks, which are covered unconformably by impermeable shales and marls of the Fahdene Formation (Late Albian–Cenomanian age). The host rock is hydrothermally altered to ankerite proximal to and within the ore bodies. Quartz, as fine-grained bipyramidal crystals, formed during hydrothermal alteration of the host rocks. The ore mineral assemblage is composed of barite, fluorite, sphalerite, and galena in decreasing abundance. The ore zones outline distinct depositional events: sphalerite-galena, barite-ankerite, and fluorite. Fluid inclusions, commonly oil-rich, have distinct fluid salinities and homogenization temperatures for each of these events: sphalerite-galena (17 to 24 wt% NaCl eq., and Th from 112 to 136 °C); ankerite-barite (11 to 17 wt% NaCl eq., and Th from 100 to 130 °C); fluorite (19 to 21 wt% NaCl eq., Th from 140 to 165 °C). The mean temperature of the ore fluids decreased from sphalerite (125 °C) to barite (115 °C) and increased during fluorite deposition (152 °C); then decreased to ∼110 °C during late calcite precipitation. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses of fluid inclusions in fluorite are metal rich (hundreds to thousands ppm Pb, Zn, Cu, Fe) but the inclusions in barite are deficient in Pb, Zn, Cu, Fe. Inclusions in fluorite have Cl/Br and Na/Br ratios of several thousand, consistent with dissolution of halite while the inclusions analysed in barite have values lower than seawater which are indicative of a Br-enriched brine derived from evaporation plus a component of halite dissolution. The salinity of the barite-hosted fluid inclusions is less than obtained

  9. Evaluation of drilling mud dispersion models at SOEI Tier 1 sites : part 1 North Triumph, Fall 1999

    International Nuclear Information System (INIS)

    This report presents the results of a project in which the latest version of the benthic boundary layer transport (bblt) model was evaluated using existing observational data from drill sites at the Sable Offshore Energy Platform (SOEP) Tier 1 drill sites from 1998-1999 when water-based drilled muds were released into the environment. The bblt model was used to simulate the drift and dispersion of suspended drilling muds near North Triumph site south of Sable Island. The simulations focused on the presence of barium sulfate (BaSO4), or barite, a compound which has an impact on sea scallops. The model successfully reproduced the very low concentration observed during the Environmental Effects Monitoring program. It was also capable of predicting barite concentrations over the entire drilling program. Barite concentrations were greater than 100 μg per litre within a few kilometres of the rig. In order to validate this prediction, there were no EEM observations during periods of active drilling mud discharge. Comparisons with other bblt simulations at Hibernia suggest that dispersion at the North Triumph site was much higher than at Hibernia in a similar water depth on the northeast Grand Banks of Newfoundland. 24 refs., 6 tabs., 28 figs

  10. An assessment of the redistribution of Barium during diagenesis of Marcellus Shale

    Science.gov (United States)

    Renock, D.; Symcox, C.; Lanids, J. D.; Sharma, M.

    2012-12-01

    Produced water from the hydrofracturing of Marcellus Shale have been reported to contain barium at concentrations >4000 ppm (Gregory et al, 2011). Understanding the reactions responsible for the leaching of Ba into produced water is important for improving the economic viability of gas extraction and to mitigate environmental concerns. Core samples of Marcellus Shale from New York and Pennsylvania were shown to contain Ba in the range of 400-2200 μg/g. In some of these samples, barite (BaSO4) grains are shown to be partially replaced by pyrite (massive and framboidal varieties) suggesting that Ba is remobilized in the zone of sulfate reduction sometime after sedimentation. Sequential extraction experiments show Ba being released into buffered acetic acid (carbonate fraction), aqua regia (sulfide fraction), and hydrofluoric acid (silicate fraction) extractions despite ~50% of the barium remaining undissolved as barite. Laser ablation ICP-MS showed negligible concentrations of Ba in calcite veins and elevated concentrations in areas of the shale that are predominantly clay + organics. These results suggest that some of the Ba is associated with the clay fraction of the shale (e.g., sorbed to clay surfaces as a result of the anoxic dissolution of barite). These results may inform future strategies for mitigating the release of barium into produced water.

  11. DOLOMITE AS AN ALTERNATIVE WEIGHTING AGENT IN DRILLING FLUIDS

    Directory of Open Access Journals (Sweden)

    M. J. BADRUL

    2007-08-01

    Full Text Available A series of experimental tests have been conducted to assess the suitability of using dolomite as an alternative weighting agent in drilling fluids. Currently, barite is widely used as weighting agent in drilling fluids slurry to ensure proper weights are achieved. However, barite contains toxic materials which make it unattractive from health and environment point of views. This is especially true when drilling operations are offshore, where most of the used drilling fluids will be dumped back into the sea. In this work, rheological properties of dolomite blend drilling fluids slurry were studied. Dolomite rocks were first crushed to produce dolomite powder, before being mixed with water and bentonite at various proportions. A total of 10 samples which contains various percentages of water, bentonite and dolomite were studied. For each sample, its rheological properties were determined. Such properties include density from mud balance, viscosity from viscometer, filtrate loss from API filter press and gel strength. The effect of aging on the properties of drilling fluids was also studied. From the study, it is concluded that Sample E, which consists of 70% dolomite by weight, produces the most stable drilling fluids. It is also observed that the amount of 336 g of dolomite in the sample shows the similar physical and rheological properties to that of the 480 g barite in the sample although the density for both samples is not same.

  12. Triple oxygen and multiple sulfur isotope constraints on the evolution of the post-Marinoan sulfur cycle

    Science.gov (United States)

    Crockford, Peter W.; Cowie, Benjamin R.; Johnston, David T.; Hoffman, Paul F.; Sugiyama, Ichiko; Pellerin, Andre; Bui, Thi Hao; Hayles, Justin; Halverson, Galen P.; Macdonald, Francis A.; Wing, Boswell A.

    2016-02-01

    Triple oxygen isotopes within post-Marinoan barites have played an integral role in our understanding of Cryogenian glaciations. Reports of anomalous Δ17O values within cap carbonate hosted barites however have remained restricted to South China and Mauritania. Here we extend the Δ17O anomaly to northwest Canada with our new measurements of barites from the Ravensthroat cap dolostone with a minimum Δ17O value of - 0.75 ‰. For the first time we pair triple oxygen with multiple sulfur isotopic data as a tool to identify the key processes that controlled the post-Marinoan sulfur cycle. We argue using a dynamic 1-box model that the observed isotopic trends both in northwest Canada and South China can be explained through the interplay between sulfide weathering, microbial sulfur cycling and pyrite burial. An important outcome of this study is a new constraint placed on the size of the post-Marinoan sulfate reservoir (≈0.1% modern), with a maximum concentration of less than 10% modern. Through conservative estimates of sulfate fluxes from sulfide weathering and under a small initial sulfate reservoir, we suggest that observed isotopic trends are the product of a dynamic sulfur cycle that saw both the addition and removal of the Δ17O anomaly over four to five turnovers of the post-Marinoan marine sulfate reservoir.

  13. Sulfate in the Palaeoarchean Ocean: Localized Enrichment or Variable Preservation?

    Science.gov (United States)

    Mason, P. R. D.; Roerdink, D. L.; Galic, A.; Martin, W.

    2015-12-01

    The Archean oceans are thought to have been depleted in sulfate, reflecting widespread anoxic conditions and limited input of oxidized sulfur species from atmospheric photolysis. This is supported by the paucity of sulfate-bearing minerals and the relatively limited mass-dependent sulfur isotope fractionation in the majority of the Archean geological record. An exception to this is the occurrence of barite deposits in the Palaeoarchean (3.5-3.2 Ga) which indicate spatial or temporal increases in sulfate concentration. The origin and extent of these enrichments remains controversial and has been difficult to assess due to limited and highly variable data. Here we compile an extensive new database of SIMS multiple sulfur isotope data for pyrite and barite from across the Barberton Greenstone Belt in South Africa in order to further investigate the extent and origin of any sulfate enrichment. Individual pyrites were measured with good stratigraphic and petrographic control. Pyrite δ56Fe was used to further delineate pyrite populations and pathways of pyrite formation. Our new sulfur isotope data support conventional models where a positive Δ33S was derived from heterogeneous photolytic elemental S, with negative Δ33S capturing a homogenized marine sulfate reservoir. Pyrite multiple S isotope data closely track the abundance of barite, suggesting that marine sulfate levels were generally low and that sulfate increases were sporadic and localized. We speculate that the subsequent Neoarchean scarcity was controlled by biological evolution.

  14. Regional Fluid Flow and Basin Modeling in Northern Alaska

    Science.gov (United States)

    Kelley, Karen D., (Edited By)

    2007-01-01

    INTRODUCTION The foothills of the Brooks Range contain an enormous accumulation of zinc (Zn) in the form of zinc sulfide and barium (Ba) in the form of barite in Carboniferous shale, chert, and mudstone. Most of the resources and reserves of Zn occur in the Red Dog deposit and others in the Red Dog district; these resources and reserves surpass those of most deposits worldwide in terms of size and grade. In addition to zinc and lead sulfides (which contain silver, Ag) and barite, correlative strata host phosphate deposits. Furthermore, prolific hydrocarbon source rocks of Carboniferous and Triassic to Early Jurassic age generated considerable amounts of petroleum that may have contributed to the world-class petroleum resources of the North Slope. Deposits of Zn-Pb-Ag or barite as large as those in the Brooks Range are very rare on a global basis and, accordingly, multiple coincident favorable factors must be invoked to explain their origins. To improve our understanding of these factors and to contribute to more effective assessments of resources in sedimentary basins of northern Alaska and throughout the world, the Mineral Resources Program and the Energy Resources Program of the U.S. Geological Survey (USGS) initiated a project that was aimed at understanding the petroleum maturation and mineralization history of parts of the Brooks Range that were previously poorly characterized. The project, titled ?Regional Fluid Flow and Basin Modeling in Northern Alaska,? was undertaken in collaboration with industry, academia, and other government agencies. This Circular contains papers that describe the results of the recently completed project. The studies that are highlighted in these papers have led to a better understanding of the following: *The complex sedimentary facies relationships and depositional settings and the geochemistry of the sedimentary rocks that host the deposits (sections 2 and 3). *The factors responsible for formation of the barite and zinc deposits

  15. Experimental method for determining mixed-phase precipitation kinetics from synthetic geothermal brine

    International Nuclear Information System (INIS)

    Highlights: • Sulfate precipitation rates are studied in a saline solution at 75 °C and 150 °C. • Strontium and calcium bearing barite precipitates at both temperatures. • Precipitation proceeds faster at the lower temperature. • More calcium and strontium are in the barite crystals at higher temperatures. • Crystal growth proceeds according the Ostwald ripening model. - Abstract: A batch reactor design for determining precipitation kinetics from an experimental (i.e. laboratory made) geothermal brine is presented. The purpose of the method is to improve techniques for predicting scaling risks in basin-hosted, enhanced geothermal systems (EGS). The method is applied to determining kinetic rate laws for alkali-earth metal sulfate precipitation in the Na–Ca–Ba–Sr–Cl–SO4–H2O system, which are a set of components commonly found in sedimentary basin brines, worldwide. The method of integral rates was used to determine alkali-earth metal precipitation kinetic rate laws for solutions reacting over 4 h at 75 °C and 150 °C. At 75 °C, the rate law for total sulfate precipitation is rate = 0.0137 * [SO42−]2. At 150 °C, the rate law for total sulfate precipitation is rate = 0.011 * [SO42−]2. All precipitants are found to be barite, with minor amounts of calcium and strontium incorporated into the barite structure. If only barite precipitation is considered, the rate coefficients become 0.045 and 0.025 at 75 °C and 150 °C, respectively. The precipitants’ specific reactive surface areas are estimated for each time step and temperature and are qualitatively observed to decrease as the reactions progress. The (1) the reaction order, (2) the rate coefficient and (3) the change in specific reactive surface area over time are the three parameters required to develop reactive transport models of mineral precipitation in a geothermal power plant. All three of these parameters can be determined with the method employed in this study. Results from

  16. A salt diapir-related Mississippi Valley-type deposit: the Bou Jaber Pb-Zn-Ba-F deposit, Tunisia: fluid inclusion and isotope study

    Science.gov (United States)

    Bouhlel, Salah; Leach, David L.; Johnson, Craig A.; Marsh, Erin; Salmi-Laouar, Sihem; Banks, David A.

    2016-08-01

    The Bou Jaber Ba-F-Pb-Zn deposit is located at the edge of the Bou Jaber Triassic salt diapir in the Tunisia Salt Diapir Province. The ores are unconformity and fault-controlled and occur as subvertical column-shaped bodies developed in dissolution-collapse breccias and in cavities within the Late Aptian platform carbonate rocks, which are covered unconformably by impermeable shales and marls of the Fahdene Formation (Late Albian-Cenomanian age). The host rock is hydrothermally altered to ankerite proximal to and within the ore bodies. Quartz, as fine-grained bipyramidal crystals, formed during hydrothermal alteration of the host rocks. The ore mineral assemblage is composed of barite, fluorite, sphalerite, and galena in decreasing abundance. The ore zones outline distinct depositional events: sphalerite-galena, barite-ankerite, and fluorite. Fluid inclusions, commonly oil-rich, have distinct fluid salinities and homogenization temperatures for each of these events: sphalerite-galena (17 to 24 wt% NaCl eq., and Th from 112 to 136 °C); ankerite-barite (11 to 17 wt% NaCl eq., and Th from 100 to 130 °C); fluorite (19 to 21 wt% NaCl eq., Th from 140 to 165 °C). The mean temperature of the ore fluids decreased from sphalerite (125 °C) to barite (115 °C) and increased during fluorite deposition (152 °C); then decreased to ˜110 °C during late calcite precipitation. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses of fluid inclusions in fluorite are metal rich (hundreds to thousands ppm Pb, Zn, Cu, Fe) but the inclusions in barite are deficient in Pb, Zn, Cu, Fe. Inclusions in fluorite have Cl/Br and Na/Br ratios of several thousand, consistent with dissolution of halite while the inclusions analysed in barite have values lower than seawater which are indicative of a Br-enriched brine derived from evaporation plus a component of halite dissolution. The salinity of the barite-hosted fluid inclusions is less than obtained simply by the

  17. A salt diapir-related Mississippi Valley-type deposit: the Bou Jaber Pb-Zn-Ba-F deposit, Tunisia: fluid inclusion and isotope study

    Science.gov (United States)

    Bouhlel, Salah; Leach, David L.; Johnson, Craig A.; Marsh, Erin; Salmi-Laouar, Sihem; Banks, David A.

    2016-01-01

    The Bou Jaber Ba-F-Pb-Zn deposit is located at the edge of the Bou Jaber Triassic salt diapir in the Tunisia Salt Diapir Province. The ores are unconformity and fault-controlled and occur as subvertical column-shaped bodies developed in dissolution-collapse breccias and in cavities within the Late Aptian platform carbonate rocks, which are covered unconformably by impermeable shales and marls of the Fahdene Formation (Late Albian-Cenomanian age). The host rock is hydrothermally altered to ankerite proximal to and within the ore bodies. Quartz, as fine-grained bipyramidal crystals, formed during hydrothermal alteration of the host rocks. The ore mineral assemblage is composed of barite, fluorite, sphalerite, and galena in decreasing abundance. The ore zones outline distinct depositional events: sphalerite-galena, barite-ankerite, and fluorite. Fluid inclusions, commonly oil-rich, have distinct fluid salinities and homogenization temperatures for each of these events: sphalerite-galena (17 to 24 wt% NaCl eq., and Th from 112 to 136 °C); ankerite-barite (11 to 17 wt% NaCl eq., and Th from 100 to 130 °C); fluorite (19 to 21 wt% NaCl eq., Th from 140 to 165 °C). The mean temperature of the ore fluids decreased from sphalerite (125 °C) to barite (115 °C) and increased during fluorite deposition (152 °C); then decreased to ˜110 °C during late calcite precipitation. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses of fluid inclusions in fluorite are metal rich (hundreds to thousands ppm Pb, Zn, Cu, Fe) but the inclusions in barite are deficient in Pb, Zn, Cu, Fe. Inclusions in fluorite have Cl/Br and Na/Br ratios of several thousand, consistent with dissolution of halite while the inclusions analysed in barite have values lower than seawater which are indicative of a Br-enriched brine derived from evaporation plus a component of halite dissolution. The salinity of the barite-hosted fluid inclusions is less than obtained simply by the

  18. S, C, O, H Isotope Data and Noble Gas Studies of the Maoniuping LREE Deposit, Sichuan Province, China: A Mantle Connection for Mineralization

    Institute of Scientific and Technical Information of China (English)

    TIAN Shihong; DING Tiping; MAO Jingwen; LI Yanhe; YUAN Zhongxin

    2006-01-01

    The Maoniuping REE deposit, located about 22 km to the southwest of Mianning, Sichuan Province, is the second largest light REE deposit in China, subsequent to the Bayan Obo Fe-Nb-REE deposit in the Inner Mongolia Autonomous Region. Tectonically, it is located in the transitional zone between the Panxi rift and the Longmenshan-Jinpingshan orogenic zone. It is a carbonatite vein-type deposit hosted in alkaline complex rocks. The bastnaesite-barite, bastnaesite-calcite, and bastnaesitemicrocline lodes are the main three types of REE ore lodes. Among these, the first lode is distributed most extensively and its REE mineralization is the strongest. The δ34SV-CDT values of the barites in the ore of the deposit vary in a narrow range of +5.0 to +5.1‰ in the bastnaesite-calcite lode and +3.3 to +5.9‰ in the bastnaesite-barite lode, showing the isotopic characteristics of magma-derived sulfur. The δ13CV-PDB values and the δ18OV-SMOW values in the bastnaesite-calcite lode range from -3.9 to -6.9‰ and from +7.3 to +9.7 ‰, respectively, which fall into the range of "primary carbonatites", showing that carbon and oxygen in the ores of the Maoniuping deposit were derived mainly from a deep source. The δ13CV-PDB values of fluid inclusions vary from -3.0 to -5.6‰, with -3.0 to -4.0‰ in the bastnaesitecalcite lode and -3.0 to -5.6‰ in the bastnaesite-barite lode, which show characteristics of mantlederived carbon. The δDv-SMOW values of fluid inclusions range from -57 to -88‰, with -63 to -86‰ in the bastnaesite-calcite lode and -57 to -88‰ in the bastnaesite-barite lode, which show characteristics of mantle-derived hydrogen. The δ18OH2OV-SMOW values vary from +7.4 to +8.6‰ in the bastnaesitecalcite lode, and +6.7 to +7.8‰ in the bastnaesite-barite lode, almost overlapping the range of +5.5 to +9.5‰ for magmatic water. The 4He content, R/Ra ratios are (13.95 to 119.58)×10-6 (cm3/g)STP and 0.02 to 0.11, respectively, and 40Ar/36Ar is 313 ± 1 to 437

  19. Multiple sulfur-isotope signatures in Archean sulfates and their implications for the chemistry and dynamics of the early atmosphere

    Science.gov (United States)

    Muller, Élodie; Philippot, Pascal; Rollion-Bard, Claire; Cartigny, Pierre

    2016-07-01

    Sulfur isotopic anomalies (∆33S and ∆36S) have been used to trace the redox evolution of the Precambrian atmosphere and to document the photochemistry and transport properties of the modern atmosphere. Recently, it was shown that modern sulfate aerosols formed in an oxidizing atmosphere can display important isotopic anomalies, thus questioning the significance of Archean sulfate deposits. Here, we performed in situ 4S-isotope measurements of 3.2- and 3.5-billion-year (Ga)-old sulfates. This in situ approach allows us to investigate the diversity of Archean sulfate texture and mineralogy with unprecedented resolution and from then on to deconvolute the ocean and atmosphere Archean sulfur cycle. A striking feature of our data is a bimodal distribution of δ34S values at ˜+5‰ and +9‰, which is matched by modern sulfate aerosols. The peak at +5‰ represents barite of different ages and host-rock lithology showing a wide range of ∆33S between ‑1.77‰ and +0.24‰. These barites are interpreted as primary volcanic emissions formed by SO2 photochemical processes with variable contribution of carbonyl sulfide (OCS) shielding in an evolving volcanic plume. The δ34S peak at +9‰ is associated with non–33S-anomalous barites displaying negative ∆36S values, which are best interpreted as volcanic sulfate aerosols formed from OCS photolysis. Our findings confirm the occurrence of a volcanic photochemical pathway specific to the early reduced atmosphere but identify variability within the Archean sulfate isotope record that suggests persistence throughout Earth history of photochemical reactions characteristic of the present-day stratosphere.

  20. Origin of the fluids associated with granodiorite-hosted, Sb-As-Au-W mineralisation at Dúbrava (Nízke Tatry Mts, Western Carpathians)

    Science.gov (United States)

    Chovan, M.; Hurai, V.; Sachan, H. K.; Kantor, J.

    1995-02-01

    Mineral parageneses of the polymetallic, Sbrich deposit at Dúbrava has been formed during five separated stages. A fluid inclusion study demonstrates that the earliest stages with scheelite, molybdenite and arsenopyrite have been associated with immiscible CO2 (± CH4)-rich, low-saline fluids at temperatures between 300 and 400 °C and pressures as much as 2 kbar. Deposition of the main, superimposed ores, stibnite and zinckenite, has been intimately connected with circulation of aqeuous, moderately saline fluids (15.5 23.5 wt% NaCl equiv.) upon epithermal conditions. Salinity of the aqueous fluids associated with tetrahedrite is clustered around 10 wt% NaCl equiv. Quartz from the latest, barite stage has precipitated from aqueous fluids enriched in divalent cations. These fluids are believed to be genetically linked with Triassic evaporite formations preserved in the region. Temperature-salinity diagrams constructed from microthermometry data indicate influx of diluted meteorite water in the stibnite, tetrahedrite and barite stages. Isotopic data are in accordance with model. The δ 18O values between -9.3‰ and +1.5‰ have been derived for water in equilibrium with quartz, coexisting with sphalerite, tetrahedrite and barite, thus confirming the participation of isotopically lighter meteoric waters in the mineral-forming solutions. The ( δ 18O) values between +3.3‰ and +8.5‰ estimated for the water associated with the scheelite and arsenopyrite stages, are suggestive for the majority of metamorphic and/or magmatic water in the mineral-forming, CO2-rich solutions.

  1. Alteration of rhyolitic (volcanic) glasses in natural Bolivian salt lakes. - Natural analogue for the behavior of radioactive waste glasses in rock salt repositories

    International Nuclear Information System (INIS)

    Alteration experiments with the R7T7 glass in three salt brines, saturated respectively in MgCl2, MgCl2-CaCl2 and NaCl, showed that the solubilities of most radionuclides are controlled by the secondary phases. Nd, La, and Pr are trapped in powellite, Ce in cerianite, U in coffinite, and Sr is partially immobilized in barite. There is a good similarity between the secondary phases formed experimentally on volcanic glasses and the R7T7 glass altered in MgCl2CaCl2-saturated brine (formation of hydrotalcite and chlorite-serpentine at short-term and saponite at long-term). These results support the use of volcanic glasses alteration patterns in Mg-rich solutions (seawater, brines) to understand the long-term behavior of nuclear waste glasses and to evaluate the stability of the secondary phases. The study of the sediments of Uyuni (Bolivia) showed that the corrosion rate of the rhyolitic glass in brines at 10 C is 12 to 30 time lower than those of rhyolitic glasses altered in high dilute conditions. The neoformed phases in the sediments are: Smectite, alunite, pyrite, barite, celestite and cerianite. The low alteration rate of rhyolitic glasses in brines and the formation of secondary phases such as smectite, barite and cerianite (also formed during the experimental alteration of the R7T7 glass), permit us to expect the low alteration of nuclear waste glasses at long-term in brines and the trapping of certain radionuclides in secondary phases. (orig.)

  2. Multiple sulfur-isotope signatures in Archean sulfates and their implications for the chemistry and dynamics of the early atmosphere.

    Science.gov (United States)

    Muller, Élodie; Philippot, Pascal; Rollion-Bard, Claire; Cartigny, Pierre

    2016-07-01

    Sulfur isotopic anomalies (∆(33)S and ∆(36)S) have been used to trace the redox evolution of the Precambrian atmosphere and to document the photochemistry and transport properties of the modern atmosphere. Recently, it was shown that modern sulfate aerosols formed in an oxidizing atmosphere can display important isotopic anomalies, thus questioning the significance of Archean sulfate deposits. Here, we performed in situ 4S-isotope measurements of 3.2- and 3.5-billion-year (Ga)-old sulfates. This in situ approach allows us to investigate the diversity of Archean sulfate texture and mineralogy with unprecedented resolution and from then on to deconvolute the ocean and atmosphere Archean sulfur cycle. A striking feature of our data is a bimodal distribution of δ(34)S values at ∼+5‰ and +9‰, which is matched by modern sulfate aerosols. The peak at +5‰ represents barite of different ages and host-rock lithology showing a wide range of ∆(33)S between -1.77‰ and +0.24‰. These barites are interpreted as primary volcanic emissions formed by SO2 photochemical processes with variable contribution of carbonyl sulfide (OCS) shielding in an evolving volcanic plume. The δ(34)S peak at +9‰ is associated with non-(33)S-anomalous barites displaying negative ∆(36)S values, which are best interpreted as volcanic sulfate aerosols formed from OCS photolysis. Our findings confirm the occurrence of a volcanic photochemical pathway specific to the early reduced atmosphere but identify variability within the Archean sulfate isotope record that suggests persistence throughout Earth history of photochemical reactions characteristic of the present-day stratosphere. PMID:27330111

  3. Mineralogy of the P-12 K-Ti-richterite diopside olivine lamproite from Wajrakarur, Andhra Pradesh, India: implications for subduction-related magmatism in eastern India

    Science.gov (United States)

    Kaur, Gurmeet; Mitchell, Roger H.

    2016-04-01

    The P-12 "para-kimberlite" from Wajrakarur consists of forsteritic olivine, Al-Na-poor diopside, Fe-Ti-rich, Al-poor phlogopite, K-Ti-richterite, spinel, perovskite, cymrite, apatite, barite, Ba-Sr- bearing calcite, gittinsite, witherite, strontianite, and hydrogrossular (hydrogarnet). The rock also contains small clasts consisting dominantly of calcite, with lesser Ba-Sr-bearing calcite, cymrite, barite, strontianite, witherite, apatite, and hydrogrossular. Two generations of forsteritic olivine (Fo80-93) crystals are present: common phenocrystal-to-microphenocrystal; and rare anhedral macrocrystic olivines. Phlogopite occurs as microphenocrysts and as groundmass poikilitic plates with inclusions of spinel, perovskite, apatite, and chlorite pseudomorphs (after pyroxene). Phlogopites also occur as reaction rims around olivine crystals. The phlogopites have extremely low Al2O3 (2.2-3.8 wt.%), moderate-to-high FeO (6.9-16 wt.%), TiO2(1.9-4.6 wt.%), and Na2O (0.4-2.7 wt.%) contents and are enriched in fluorine (up to 6.0 wt.%) and considered to be tetraferriphlogopite. The pyroxenes occur in five parageneses as: (1) phenocrysts and microphenocrysts; (2) small slender crystals(time from the groundmass carbonate-chlorite mesostasis of a lamproite. Square-to-rectangular crystals of cymrite and hydrogrossular occur in the carbonate clasts and groundmass material. Barite anhedra commonly occur in the carbonate clasts together with witherite, strontianite, and Ba-Sr-bearing calcite. The texture and compositions of olivine, phlogopite, spinel, and K-Ti-richterite, together with the presence of cymrite pseudomorphs, possibly after potassium feldspar, demonstrate that this intrusion is a bona fide olivine lamproite and not a kimberlite. It is postulated that this, and other lamproites, located adjacent to the Eastern Ghats Mobile Belt, are derived by extensional decompressional melting of ancient subduction zones underlying the cratonic regions.

  4. The geological structure and gas presence of the southeastern part of the Mrakovskiy depression

    Energy Technology Data Exchange (ETDEWEB)

    Barykin, I.V.; Chistilin, G.M.; Kamaletdinov, R.A.; Shelenin, A.Sh.

    1983-01-01

    The tectonic structure of the gas promising territory of the Mrakovskiy depresion combined under the name of the Saratov Berkutovskiy gas bearing zone, which can be traced for a distance of up to 120 kilometers, is examined. Analysis of the materials shows the qualitative correspondence of the structural planes of the marking levels of the Carboniferous and the lower Permian inside the allochthonous and autochthonous complexes. The effect of barite on the productive levels, the basic types of collectors and the required complex of oil field and geophysical studies is examined.

  5. Joint Egypt/United States report on Egypt/United States cooperative energy assessment. Volume 2 of 5 Vols. Annex 1

    Energy Technology Data Exchange (ETDEWEB)

    1979-04-01

    Detailed summaries are presented of Egypt's indigenous energy resources from the U.S. Geological Survey assessments; preliminary information collected early in 1977 from files, reports, and publications existing in the U.S.; and data gathered during one-month assessment program in March--April 1978. Detailed reports are given on oil and gas, coal and oil shale, uranium and thorium, geothermal energy, water resources, and energy-related minerals/commodities. An assessment of cement-making materials, iron ore, manganese, aluminium, barite, bentonite, copper, chromium, nickel, titanium, and miscellaneous metals used in steel making is presented.

  6. Geochemistry and mineralogy of the radioactive minerals associated with some pegmatite veins of the Ukma-Nawahatu Hursi sector, Purulia district, W.B., in the Precambrian Chhotanagpur Gneissic complex

    International Nuclear Information System (INIS)

    Some barite-bearing pegmatites in the Ukma-Nawahatu-Hursi sector (23° 25 min - 26 sec N, 86° 02 min - 04 sec E) in Purulia dist., West Bengal, have association of radioactive minerals in the form of coarse-grained pitchblack lumps and irregular patches. The present author and his associates first reported the occurrence of this radioactive belt along a ENE-WSW shearzone during their fieldwork in November, 1978. Groundborne radiometric survey and isorad mapping has established a radioactive high zone of about 15 km length running through Ukma, Nawahatu and Hursi areas. Mineralogical studies of the radioactive minerals have revealed the occurrence of Chevkinite, Aeschynite, Brannerite, Allanite, Uraninite, Tyuyamunite, Davidite, Euxenite, Samarskite, Thorutite, Autunite, Cerianite, in association with quartz, barite, microcline as the principal minerals and various minor minerals like biotite, vermiculite, hornblende, augite, orthoclase, celsian, muscovite, calcite, epidote, zoisite, ilmenite, sphene, rutile, hematite, magnetite, anatase, galena and sodic plagioclase. The barite-bearing pegmatites occur as lenses or lenticular veins hosted by garnetiferous sillimanite-biotite-quartz-schist or occasionally by migmatite. Near Nawahatu the radioactive barite-pegmatite vein occurs at or near the junction between the footwall amphibolite and hangingwall garnetiferous schist. The pegmatite veins have followed mainly schistosity of the host rock and dip at 70°-80° towards south. Chemical analyses of individual radioactive minerals by SEM-EDX and also of the bulk radioactive lumps by ICP-MS have shown significant concentration of U, Tb and Rare earths. Minor and trace element analyses also record notable contents of Zr, Ga, Sc, Pb, Zn, Nb, Cu, Ni, V, Cr, As, W, Pd, Ag and TI. Details of chemical analytical data are presented here. Chemically active fluids generated during metamorphism, metasomatism and granitic activity appear to have played a significant role in the

  7. Seasonal variations of rare earths and yttrium distribution in the lowland Havel River, Germany, by agricultural fertilization and effluents of sewage treatment plants

    International Nuclear Information System (INIS)

    Highlights: • Seasonal variations of REE abundance in surface waters depending on agricultural fertilisation and drainage flux. • Control of Eu in surface water by barite as a component of common NPK fertilisers. • Variation of anthropogenic Gd chelates in surface water due to sewage treatment management. - Abstract: REE and Y (REY) distribution in the lowland Havel River passing the Federal State of Berlin, Germany, depends on contributions of point sources such pharmaceutical and high-tech industries, acid water from the open pit lignite mining, and medical application of very stable organic Gd chelates. Another omnipresent dispersed source of REY are water-soluble Ca-phosphates containing micro-amounts of Eu(II)-bearing barite as components of common agricultural fertilizers. After distribution in the field during the cold season (October through March) these Ca-phosphates dissolve and secondary phosphates and calcite precipitate both being enriched in light REE. Heavy REE are preferably exported by runoff together with part of the micro-contaminant barite leading to high Yb/Nd ratios in the Havel water and REY distribution patterns with only small Eu deficits. During the warm season (April through September) light REE together with phosphate are leached from secondary soil minerals by runoff. The micro-component barite is retained in vegetation-covered soil. Thus, REY patterns of Havel water show significant Eu deficits. The high Gd anomalies result from medical applications of Gd-chelates which after urination pass the sewage treatment plants. The seasonal variations of total Gd in the Havel River are artifacts based on seasonal locally varied discharge of effluents from sewage treatment plants. The natural Gd concentration of 8 pmol/l in the northern Havel is enhanced to 3300 pmol/l, when the Havel River leaves Berlin territory. The elimination of phosphate from Lake Tegel water affects the fractionation of REE but not the concentration of total Gd

  8. Some engineering properties of heavy concrete added silica fume

    Energy Technology Data Exchange (ETDEWEB)

    Akkaş, Ayşe [Suleyman Demirel University Teknoloji Fakültesi, Isparta (Turkey); Başyiğit, Celalettin; Esen, Serap [Suleyman Demirel University, Mühendislik Fakültesi, Isparta (Turkey)

    2013-12-16

    Many different types of building materials have been used in building construction for years. Heavy concretes can be used as a building material for critical building as it can contain a mixture of many heavy elements. The barite itself for radiation shielding can be used and also in concrete to produce the workable concrete with a maximum density and adequate structural strength. In this study, some engineering properties like compressive strength, elasticity modules and flexure strength of heavy concretes’ added Silica fume have been investigated.

  9. Elemental composition of airborne dust in the shale shaker house during an offshore drilling operation

    DEFF Research Database (Denmark)

    Hansen, A.B.; Larsen, E.; Hansen, L.V.; Lyngsaae, M.; Kunze, H.

    1991-01-01

    During 2 days of an offshore drilling operation in the North Sea, 16 airborne dust samples from the atmosphere of the Shale Shaker House were collected onto filters. During this operation, drilling mud composed of a water slurry of barite (BaSO4) together with minor amounts of additives, among th...... coupled plasma-mass spectrometry). The total amount of dust collected varied from 0.04 to 1.41 mg m-3 with barium (Ba) as the single most abundant element. The open shale shakers turned out to be the major cause of generation of dust from the solid components of the drilling mud....

  10. Sedimentary uranium deposit of the Ipora/Amorinopolis region, state of Goias, Brazil

    International Nuclear Information System (INIS)

    The uranium mineralization is chiefly found within arkosic sandstones at the base of the Devonian Ponta Grossa Formation. The ore is tabular and concordant with the bedding, the controls being simultaneously litho-stratigraphical and biochemical. Narrow permeable horizons of arkosic sandstone lie between impermeable shale and siltstone layers. Within the permeable horizon, the fossil remains (probably brachiopods) are replaced by uranium minerals. The oxidized iron minerals may have acted as to insulate and preserve the secondary soluble uranium minerals. The mineral paragenesis is represented by renardite, meta - autunite I, fourmarierite, Koninckite, ranquilite, meta-uranocircite II, barite, apatite, calophane, wavelite, varscite, an unnamed uranium mineral, quartz, calcedony, goethite, lepidocrocite and hematite. (Author)

  11. Sulfur isotope analysis of aerosol particles by NanoSIMS

    OpenAIRE

    Winterholler, Bärbel

    2007-01-01

    A new method to measure the sulfur isotopic composition of individual aerosol particles by NanoSIMS has been developed and tested on several standards such as barite (BaSO4), anhydrite (CaSO4), gypsum (CaSO4·2H2O), mascagnite ((NH4)2SO4), epsomite (MgSO4·7H2O), magnesium sulfate (MgSO4·xH2O), thenardite (Na2SO4), boetite (K2SO4) and cysteine (an amino acid). This ion microprobe technique employs a Cs+ primary ion beam and measures negative secondary ions permitting the analysis of sulfur isot...

  12. Internal friction studies of particulate filled polypropylene

    International Nuclear Information System (INIS)

    Internal friction of injection-molded polypropylene with various fractions of magnetite, barite, copper, talc, strontium ferrite and glass fibers was measured in the temperature range 170-425 K with frequencies of 0.1-100 Hz. Peaks of the α- and α'-relaxation were found while no peak of the β-relaxation was detected. At high temperatures a drastic increase of the loss factor superposes the α'-peak. The crystallinity of the filled polypropylene varies in the range from 23% to 35%. The samples consist of α- and β-crystallites depending on the material and amount of filler

  13. 連続繊維ロープとコンクリートとの付着特性

    OpenAIRE

    関島, 謙蔵||セキジマ, ケンゾウ||Kenzo, Sekijima; 出雲, 淳一||イズモ, ジュンイチ||IZUMO, Junichi

    2011-01-01

    Continuous Fiber Rope is made of Aramid fiber or Vinylon fiber and shaped in the form of rope as reinforcement for concrete members.It is characterized by a lightweight,a high tensile strength and an excellent durability compared with steel reinforcing bar.It has also a good transportability,and it is flexible to be easily arranged at a construction site.The authors have already investigated not only the tensile properties of Continuous Fiber Rope but also the capacities of some kinds of spli...

  14. The clayey fissural fillings associated with N100º-110ºE fractures at the El Berrocal uranium mine (Sierra de Gredos, Spain): characterization, genesis and retention capacity of radioactive and other elements

    OpenAIRE

    Pérez del Villar, L.; De La Cruz, B.; Cózar, J. S.; Pardillo, J.; Gómez, P.; Turrero, M. J.; Rivas, P.; Reyes, E.; Delgado, A; Caballero, E.

    1993-01-01

    The clayey fissural fillings (< 60 ¼m and < 2 μm fractions) associated with the N100-110 ºE fractures, at the El Berrocal U mine, have been studied in relation to the natural radionuclide migration/retention processes in a fissured granitic environment. The fracture filled with pyrite, chalcopyrite, sphalerite, galena-bearing quartz, later mineralized by pyrite, pitchblende, carbonate and barite also belongs to that fracture seto According to the data obtained by X-ray diffraction, thermal ...

  15. A deposit model for carbonatite and peralkaline intrusion-related rare earth element deposits: Chapter J in Mineral deposit models for resource assessment

    Science.gov (United States)

    Verplanck, Philip L.; Van Gosen, Bradley S.; Seal, Robert R., II; McCafferty, Anne E.

    2014-01-01

    Carbonatite and alkaline intrusive complexes, as well as their weathering products, are the primary sources of rare earth elements. A wide variety of other commodities have been exploited from carbonatites and alkaline igneous rocks including niobium, phosphate, titanium, vermiculite, barite, fluorite, copper, calcite, and zirconium. Other elements enriched in these deposits include manganese, strontium, tantalum, thorium, vanadium, and uranium. Carbonatite and peralkaline intrusion-related rare earth element deposits are presented together in this report because of the spatial, and potentially genetic, association between carbonatite and alkaline rocks. Although these rock types occur together at many locations, carbonatite and peralkaline intrusion-related rare earth element deposits are not generally found together.

  16. Fluid—Melt and Fluid Inclusions in Mianning REE Deposit,Sichuan Southwest Cina

    Institute of Scientific and Technical Information of China (English)

    牛贺才; 林茂青; 等

    1997-01-01

    Abundant fluid-melt inclusions are found in the aegirine-augite-barite pegmatite and carbonatite veins in the Mianning REE deposit,Sichuan,They were trapped in early stage fluorite and quartz from a salt-melt system at temperatures higher than 5000℃,Meanwhile,fluid inclusions are also present in alrge amounts in bastnaesite.Homogenized between 150 and 270℃,these inclusions are thought to be representative of the physico-chemical conditions of REE mineralization.These results show that the Mianning REE deposit is of typical hydrothermal origin developed from a salt-melt system.

  17. Geochemical features of Kulunda plain lakes (Altay region, Russia)

    Science.gov (United States)

    Kolpakova, M. N.; Shvartsev, S. L.; Borzenko, S. V.; Isupov, V. P.; Shatskaya, S. S.

    2016-03-01

    Geochemical specifics of lake water of the Kulunda Steppe territory (Altay region, Russia) are studied. The results show that in the territory mainly chloride and less soda lakes with sodium compound are developed. It is presented that calcite and soda saturation indexes (SI) of lake water increase with growth of pH, but decrease in such minerals as gypsum and barite. The opposite situation is typical for SI depending on the salinity. It is revealed that evaporation, secondary mineral formation and various biological processes have the greatest impact on accumulation of elements in solution.

  18. Sulfide geochronology along the Endeavour Segment of the Juan de Fuca Ridge

    OpenAIRE

    Jamieson, John; Hannington, Mark D.; Clague, David A.; Kelley, Deborah S.; Delaney, John R.; Holden, James F.; Tivey, Margaret K.; Kimpe, Linda E.

    2013-01-01

    Forty-nine hydrothermal sulfide-sulfate rock samples from the Endeavour Segment of the Juan de Fuca Ridge, northeastern Pacific Ocean, were dated by measuring the decay of 226Ra (half-life of 1600 years) in hydrothermal barite to provide a history of hydrothermal venting at the site over the past 6000 years. This dating method is effective for samples ranging in age from ∼200 to 20,000 years old and effectively bridges an age gap between shorter- and longer-lived U-series dating techniques fo...

  19. Leaching of 226Ra from components of uranium mill tailings

    Science.gov (United States)

    Landa, E.R.

    1991-01-01

    A sequential extraction procedure was used to characterize the geochemical forms of 226Ra retained by mixtures of quartz sand and a variety of fine-grained rock and mineral species. These mixtures had previously been exposed to the sulfuric acid milling liquor of a simulated acid-leach uranium milling circuit. For most test cases, the major fraction of the 226Ra was extracted with 1 mol/1 NH4Cl and was deemed to be exchangeable. However, 226Ra retained by the barite-containing mixture was resistant to both 1 mol/1 NH4Cl and 1 mol/HCHCl extraction. ?? 1991.

  20. The biochemical and histoanatomical response of some woody species to anthropic impact in Suceava County, Romania

    OpenAIRE

    Elena CIORNEA; Irina BOZ; IONEL, ELENA; COJOCARU, SABINA IOANA; DUMITRU, Gabriela

    2015-01-01

    The use of extractive mining technologies in various areas of Suceava, Romania (C?limani Mountains - sulfur, Tarni?a-Ostra - copper and barite, and Crucea-Botuşana - uranium) has resulted in the accumulation of surplus chemicals with direct action on the ecosystem. The aim of this study was to analyze the possible damage on some woody species (Picea abies L., Populus tremulaL., Salix alba L., Betula verrucosa Ehrh.,and Larix decidua Mill.) and their adaptive and phytoremediation capacity thro...

  1. Potentially Conductive Channels in Fracture Cements of Low Permeability Rocks

    Science.gov (United States)

    Wright, E.; Landry, C. J.; Eichhubl, P.

    2015-12-01

    Natural fractures in shale reservoirs are frequently filled with mineral cement that lacks any residual fracture porosity that is visible under the petrographic microscope. These fully cemented fractures are generally interpreted to be impermeable for fluid flow. Scanning electron microscopy of calcite, dolomite, and barite fracture cements from a variety of shale reservoirs, prepared using broad ion beam milling, provides evidence of open to partially healed elongate pores that are on the order of hundreds of nanometers in aperture. In calcite fracture cement, these pores have consistent apertures of about 100 nm. In dolomite and barite, apertures are up to 500 nm. These pores have been previously overlooked because traditional thin sectioning and polishing destroys sub-micron details of the fracture cement pore structure. Ion milling preserves these details with a minimum of sample damage during sample preparation. Electron backscatter diffraction shows that these pores occur along grain boundaries within the blocky or columnar fracture cement. While partially healed, these pores, arranged along grain boundaries, are frequently sufficiently well connected acting as channels for fluid flow along and across fully cemented natural fractures. In shale reservoirs of ultra-low matrix permeability, these grain boundary channels may thus provide fracture permeability significantly contributing to reservoir production where intersected or indirectly reactivated by hydraulic fractures.

  2. Study of opposite-sign dimuon production in high-energy neutrino-nucleon interactions

    Energy Technology Data Exchange (ETDEWEB)

    Strongin, B.; Bofill, J.; Friedman, J.I.; Fuess, S.; Goodman, M.C.; Kendall, H.W.; Kistiakowsky, V.; Lyons, T.; Osborne, L.S.; Pitt, R.; Schneekloth, U.; Taylor, F.E. (Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (USA)); Bogert, D.; Koizumi, G.; Stutte, L. (Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (USA)); Abolins, M.; Brock, R.; Cobau, W.; Hatcher, R.; Owen, D.; Perkins, G.; Tartaglia, M.; Weerts, H. (Michigan State University, E. Lansing, Michigan 48824 (USA)); Belusevic, R.; Walker, J.K.; White, A.; Womersley, J. (University of Florida, Gainseville, Florida 32611 (USA))

    1991-05-01

    Results are presented of a study of opposite-sign dimuon events observed in a fine-grained neutrino detector exposed to the Fermilab Tevatron wide-band neutrino beam. A total of 300 background-corrected {mu}{sup +}{mu}{sup {minus}} events induced by incident neutrinos and antineutrinos with energies up to 500 GeV were accumulated. The data were analyzed in terms of a model based on charm-quark production followed by semileptonic decay of the charmed meson. The Cabibbo-Kobayashi-Maskawa matrix terms were found to be {vert bar}{ital U}{sub {ital c}{ital d}}{vert bar}{sup 2}=0.0378{plus minus}0.0127 (stat){sub {minus}0.0082}{sup +0.0099} (syst), and {kappa}{vert bar}{ital U}{sub {ital c}{ital s}}{vert bar}{sup 2}=0.391{plus minus}0.076 (stat){sub {minus}0.066}{sup +0.097} (syst). The ratio of the strange to nonstrange sea in the nucleon, {kappa}=2{ital S}/({ital {bar U}}+{ital {bar D}}), was measured to be 0.407{plus minus}0.075 (stat){sub {minus}0.069}{sup +0.103} (syst).

  3. Ironstones of the Olary Block, South Australia: the use of RNAA and INAA to understand their genesis.

    Energy Technology Data Exchange (ETDEWEB)

    Plimer, I.R. [Melbourne Univ., Parkville, VIC (Australia); Lottermoser, B.G.; Ashley, P.M.; Lawrie, D.C. [New England Univ., Armidale, NSW (Australia). Dept. of Geology

    1996-12-31

    Reactor neutron activation analysis (RNAA) , instrumental neutron activation analysis (INAA) and electron microprobe analysis of ironstones and barite from the Olary Block indicate that these deposits are geochemically similar to modem and ancient submarine hydrothermal precipitates. Geochemical analyses generally show low Mn, Pb, Zn, As and Sb concentrations and elevated Au and Cu values. Major (Al, Si) and trace (REE, Th, U, PGEs) element data show that the ironstones and barite rocks are of hydrothermal origin and that mixing occurred between oxidised (and possibly hypersaline) surficial waters and a hydrothermal fluid similar to that from modem sites of submarine exhalation. Such geochemical similarities imply rapid burial in the volcano-sedimentary pile or sub-seafloor replacement. The REE patterns in the iron formations demonstrate a range from low temperature reduced hydrothermal precipitates, seawater and oxidised hydrothermal precipitates. Geochemical signatures are due to precipitation from hydrothermal fluids of lower temperature with further influence by prolonged exposure to the overlying water column and subaqueous oxidation. 7 refs.

  4. Mineralogical and geochemical characterization of hydrocarbon seep sediments from the Gulf of Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Canet, Carles; Prol-Ledesma, Rosa Maria; Mortera-Gutierrez, Carlos; Linares, Carlos [Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, Coyoacan 04510, Mexico (Mexico); Escobar-Briones, Elva [Instituto de Ciencias del Mar y Limnologia, Unidad Academica Sistemas Oceanograficos y Costeros, A. P. 70-305 Ciudad Universitaria, Coyoacan 04510, Mexico (Mexico); Lozano-Santa Cruz, Rufino; Cienfuegos, Edith; Morales-Puente, Pedro [Instituto de Geologia, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, Coyoacan 04510, Mexico (Mexico)

    2006-06-15

    A common characteristic of the Gulf of Mexico (GOM) seafloor, hydrocarbon seepage produces asphalt volcanism, brine pools, gas hydrates and authigenic carbonates. We studied authigenic carbonates from two areas: Green Canyon (Louisiana slope, 1000mbsl) and the Chapopote diapir (abyssal plain, southwestern GOM, 2900mbsl). Carbonates consist of oily, matrix-supported limestones with variable porosity and a fine-grained matrix of calcite. They occur in Green Canyon as both concretions formed below the seafloor and as slabs of seabed pavements. In each case, the carbonates are mudstones with a mud matrix consisting of high-Mg calcite, disseminated pyrite and detrital quartz. The carbonate slabs have vug microporosity and contain barite that occurs as vug lining. The precipitation of barite results from a reaction between barium-rich and sulfate-free seep fluids and downwards-diffusing seawater. The carbonates in Chapopote occur in relation to tar flows and form crusts of wackestones with bivalve shells. The matrix is composed by low-Mg calcite with disseminated pyrite and detrital quartz. The carbonate mud shows depletion in {sup 13}C, with {delta}{sup 13}C between -36.9%% and -23.0%%. Carbonates precipitate as a consequence of anaerobic methane oxidation coupled with seawater sulfate reduction. {delta}{sup 18}O values (3.4-4.4%%) suggest precipitation at temperatures between 5 and 9{sup o}C. (author)

  5. Geochemistry and Mineralogy of Tuff in Zhongliangshan Mine, Chongqing, Southwestern China

    Directory of Open Access Journals (Sweden)

    Jianhua Zou

    2016-05-01

    Full Text Available Coal-bearing strata that host rare metal deposits are currently a hot issue in the field of coal geology. The purpose of this paper is to illustrate the mineralogy, geochemistry, and potential economic significance of rare metals in the late Permian tuff in Zhongliangshan mine, Chongqing, southwestern China. The methods applied in this study are X-ray fluorescence spectrometry (XRF, inductively coupled mass spectrometry (ICP-MS, X-ray diffraction analysis (XRD plus Siroquant, and scanning electron microscopy in conjunction with an energy-dispersive X-ray spectrometry (SEM-EDX. The results indicate that some trace elements including Li, Be, Sc, V, Cr, Co, Ni, Cu, Zn, Ga, Zr, Nb, Cd, Sb, REE, Hf, Ta, Re, Th, and U are enriched in the tuff from Zhongliangshan mine. The minerals in the tuff mainly include kaolinite, illite, pyrite, anatase, calcite, gypsum, quartz, and traces of minerals such as zircon, florencite, jarosite, and barite. The tuff is of mafic volcanic origin with features of alkali basalt. Some minerals including florencite, gypsum, barite and a portion of anatase and zircon have been derived from hydrothermal solutions. It is suggested that Zhongliangshan tuff is a potential polymetallic ore and the recovery of these valuable elements needs to be further investigated.

  6. Materials Synthesis Of Barium Hexa ferrite Used Local Natural Resources

    International Nuclear Information System (INIS)

    The magnetic materials of barium hexa ferrites, Ba O.6Fe2O3 successfully synthesized by powder metallurgy method used local natural resources from materials waste of steel fabrication (HSM, CRM), waste of polymer fabrication (LK) as well as iron sands (PBA). These waste as well as iron sands were the main resources of iron oxide, Fe2O3. The barium oxide used in this experiments are from BaCO3 product of Merck, and BaCO4 which is commercially available in the market as barite. Phase identification by x-ray diffraction technique show the synthesized magnetic materials are agreed with the available commercial product, (SUMI). The energy product maximum (BH)max measured by vibrating sample magnetometer (VSM) for the samples used HSM-, CRM- and BaCO3 as basic materials are 1.141 MGOe and 1.136 MGOe while SUMI is 1.142 MGOe. However for the samples made from LK-, PBA- used of BaCO3 or CRM- with barite, the energy product maximum (BH)max are relatively lower than commercial product

  7. Availability of special local rock materials for using in radiation shielding concrete

    International Nuclear Information System (INIS)

    Concrete is an excellent and versatile material for using in radiation shielding of nuclear power plants, hot cells and medical facilities that deal with ionizing radiations, Because it is easy controlled with composition and density by using aggregates with high specific gravity such as Barite, Hematite, Magnetite, or minerals with high hydrogen content such as Serpentine. This research offered the essential information about local resources rocks and minerals can be used in this inclination, as aggregates for heavy/high hydrion concrete. The present work indicates that iron ores, which located in RAJO-EFREEN is better than other locations like ANTI-LEBANON or AL-KADMOUS. While the heavy beach sands in AL-BASSIT are the best compared with other locations on the Syrian seaside, because it has acceptable percentage of heavy mineral. Barite concretions were found in KALAMON, HOMS and other sites, which its percentages approach 50%, but however in small quantities. Finally, high hydrion concrete can be used by Serpentinite were found with high Serpentine percentage in BAYER and BASSIT blocks. (author)

  8. Regional sulphur isotope studies of epithermal Au-Ag-Pb-Zn-Cu deposits in the Hauraki Goldfield, South Auckland

    International Nuclear Information System (INIS)

    The Hauraki Goldfield is a major epithermal gold-silver province associated with andesite-dacite-rhyolite volcanism of Miocene-Pliocene age. Sulphur isotopes of minerals from 14 epithermal deposits were analysed during this study. Sulphide mineral δ34SCDT values range from -2.2 to +4.1 per thousand, whereas barite is around +18.8 per thousand. When added to previous studies, overall averages of +2 per thousand for sulphides (σ =±1.4, n=394) and +20.6 per thousand for barite (σ=±2.8, n=13) are obtained. Selected sphalerite-galena pair fractionations indicate temperatures above 250 deg. C and probably <350 deg. C for Pb-Zn-Cu dominated mineralisation. The sulphur isotopic composition of the total sulphur in solution was around +2 per thousand, indicating that the sulphur was derived from Tertiary volcanic magmas with slight crustal contamination. This interpretation replaces our previous hypothesis that sulphur was hydro-thermally leached from Mesozoic sediments. (author). 18 refs., 3 figs., 1 tab

  9. A drilling mud

    Energy Technology Data Exchange (ETDEWEB)

    Ana, I.; Musat, V.; Necula, C.; Popeseu, F.; Vasile, I.

    1980-09-30

    The subject of the patent is a cementing drilling mud, which contains nonionogenic surfacants, cementing agents, antifoaming agents, stabilizing agents and filtration reduction agents. The solution consists of a suspension of activated bentonite with a seeming viscosity of 2 to 20 centipoise, with an additive of 10 kilograms per cubic meter of nonionogenic surfacant of the ethylene glycol-propylene oxide type with 5 to 15 moles of propylene oxide, 2.5 to 10 kilograms per cubic meter of hydroxide of an alkaline metal or ammonium, primarily KOH, 30 to 60 kilograms per cubic meter of an inhibitor, that is, a mixture of lignosulfonate, humate and chromate of a metal, preferably potassium, in a ratio of 6 to 3 to 1, 0.5 to 2 kilograms per cubic meter of a chloride type electrolyte, preferably KC1, 5 to 20 kilograms per cubic meter of a filtration reducing agent, that is, natural cellulose, polycarbamide or nitride, 40 to 50 liters per cubic meter of oil product, preferably diesel fuel and a weighting material, magnetite, barite, CaCO3, metallurgic slag, preferably barite.

  10. Long-lived activation products in TRIGA Mark II research reactor concrete shield: calculation and experiment

    Science.gov (United States)

    Žagar, Tomaž; Božič, Matjaž; Ravnik, Matjaž

    2004-12-01

    In this paper, a process of long-lived activity determination in research reactor concrete shielding is presented. The described process is a combination of experiment and calculations. Samples of original heavy reactor concrete containing mineral barite were irradiated inside the reactor shielding to measure its long-lived induced radioactivity. The most active long-lived (γ emitting) radioactive nuclides in the concrete were found to be 133Ba, 60Co and 152Eu. Neutron flux, activation rates and concrete activity were calculated for actual shield geometry for different irradiation and cooling times using TORT and ORIGEN codes. Experimental results of flux and activity measurements showed good agreement with the results of calculations. Volume of activated concrete waste after reactor decommissioning was estimated for particular case of Jožef Stefan Institute TRIGA reactor. It was observed that the clearance levels of some important long-lived isotopes typical for barite concrete (e.g. 133Ba, 41Ca) are not included in the IAEA and EU basic safety standards.

  11. Chronic toxicity and physical disturbance effects of water- and oil-based drilling fluids and some major constituents on adult sea scallops (Placopecten magellanicus)

    International Nuclear Information System (INIS)

    Adult sea scallops, Placopecten magellanicus, were exposed in the laboratory under environmentally representative conditions to different types and concentrations of used operational drilling fluids and their major constituents. Threshold waste concentrations causing reductions in somatic and/or reproductive tissue growth are: greater than 10 mg1-1 for used water-based mud (WBM); 2 mg 1-1 for bentonite; and less than 0.5 mg1-1 for barite and used oil-based mud (OBM). Chronic exposure to OBM caused high mortalities at concentrations as low as 1.0 mg1-1. Non-nutritious particles in the food supply (all wastes) and chemical toxicity (OBM and perhaps barite) affected the growth rate and survival of sea scallops by altering physiological state (scope for growth) and nutritional condition (O:N ratio). The value of scope growth (SFG) calculations for assessing the relative chronic toxicity of the drilling wastes was demonstrated by the close relation observed between SFG and actual growth measurements. These results show that chronic intermittent exposure of sea scallops to dilute concentrations of operational drilling wastes, characterized by acute lethal tests as practically non-toxic, can affect growth, reproductive success and survival. (author)

  12. Assessment of barium sulphate formation and inhibition at surfaces with synchrotron X-ray diffraction (SXRD)

    International Nuclear Information System (INIS)

    The precipitation of barium sulphate from aqueous supersaturated solutions is a well-known problem in the oil industry often referred to as 'scaling'. The formation and growth of barite on surfaces during the oil extraction process can result in malfunctions within the oil facilities and serious damage to the equipment. The formation of barium sulphate at surfaces remains an important topic of research with the focus being on understanding the mechanisms of formation and means of control. In situ synchrotron X-ray diffraction (SXRD) was used to investigate the formation of barium sulphate on a stainless steel surface. The effect of Poly-phosphinocarboxylic acid (PPCA) and Diethylenetriamine-penta-methylenephosphonic acid (DETPMP) which are two commercial inhibitors for barium sulphate was examined. The in situ SXRD measurements allowed the identification of the crystal faces of the deposited barite in the absence and presence of the two inhibitors. The preferential effect of the inhibitors on some crystal planes is reported and the practical significance discussed.

  13. Mineralogía e inclusiones fluidas en La Baritina: tope de lamineralización de manganeso de la Sierra de Ambargasta, provincia de Córdoba Mineralogy and fluid inclusion of LaBaritina: theuppermost sector of the manganese mineralization of sierra de Ambargasta, province of Córdoba

    Directory of Open Access Journals (Sweden)

    Pablo Rodrigo Leal

    2009-06-01

    Full Text Available En este trabajo se describe lamineralogía y las inclusiones fluidas del sector más superficial de unyacimiento epitermal de manganeso. El área de estudio comprende el sectorcentral de una mineralización mayor y se caracteriza por la abundancia deminerales de ganga, compuestos por baritina, calcita y ópalo con cantidadessubordinadas de calcedonia, cuarzo y óxidos de manganeso. Sus texturas y susparagénesis minerales evidencian varios pulsos de precipitación. Los espaciosabiertos entre los cristales mayores de baritina fueron ocupados por calcita yópalo, que son especies frecuentes hacia el final del proceso mineralizador.Calcedonia y cuarzo sólo se observan dentro de pequeñas cavidades. Lasinclusiones fluidas fueron estudiadas en muestras de cuarzo, baritina ycalcita. Se componen de H2O, NaCl y cantidades menores de CaCl2y MgCl2. La calcita y la baritina presentan una salinidad promediode aproximadamente 4,18 %wt NaCleq. mientras que el cuarzo evidenciasalinidades cercanas a los 5,26%wt NaCleq. Las temperaturas de homogeneizacióntambién son diferentes para cada especie: el cuarzo muestra una temperaturapromedio de 148°C, mientras que la baritina y la calcita parecen tenertemperaturas ligeramente mayores (184° y 171°C respectivamente. Todos losdatos compilados en este trabajo sugieren que este distrito representa uno delos sectores más superficiales del yacimiento mineral. Las elevadas cantidadesde minerales no metalíferos evidencian que esta área, a diferencia de lasotras, fue particularmente activa durante las etapas finales del procesomineralizador.In this paper the mineralogy and fluidinclusion of the upper sector of an epithermal manganese deposit are described.The study area comprises the central sector of a bigger mineralised zone wherenon-ore mineral are the most common ones and are composed of barite, calciteand opal with fewer amounts of chalcedony, quartz and manganese oxides. Theirtextures and their assemblages allow

  14. Cierco Pb-Zn-Ag vein deposits: Isotopic and fluid inclusion evidence for formation during the mesozoic extension in the pyrenees of Spain

    Science.gov (United States)

    Johnson, C.A.; Cardellach, E.; Tritlla, J.; Hanan, B.B.

    1996-01-01

    The Cierco Pb-Zn-Ag vein deposits, located in the central Pyrenees of Spain, crosscut Paleozoic metasedimentary rocks and are in close proximity to Hercynian granodiorite dikes and plutons. Galena and sphalerite in the deposits have average ??34S values of -4.3 and -0.8 per mil (CDT), respectively. Coexisting mineral pairs give an isotopic equilibration temperature range of 89?? to 163??C which overlaps with the 112?? to 198??C range obtained from primary fluid inclusions. Coexisting quartz has a ??18O value of 19 ?? 1 per mil (VSMOW). The fluid which deposited these minerals is inferred to have had ??18OH2o and ??34SH2s values of 5 ?? 1 and -1 ?? 1 per mil, respectively. Chemical and microthermometric analyses of fluid inclusions in quartz and sphalerite indicate salinities of 3 to 29 wt percent NaCl equiv with Na+ and Ca2+ as the dominant cations in solution. The Br/Cl and I/Cl ratios differ from those characteristic of magmatic waters and pristine seawater, but show some similarity to those observed in deep ground waters in crystalline terranes, basinal brines, and evaporated seawater, Barite, which postdates the sulfides, spans isotopic ranges of 13 to 21 per mil, 10 to 15 per mil, and 0.7109 to 0.7123 for ??34S, ??18O, and 87Sr/86Sr, respectively. The three parameters are correlated providing strong evidence that the barites are products of fluid mixing. We propose that the Cierco deposits formed along an extensional fault system at the margin of a marine basin during the breakup of Pangea at some time between the Early Triassic and Early Cretaceous. Sulfide deposition corresponded to an upwelling of hydrothermal fluid from the Paleozoic basement and was limited by the amount of metals carried by the fluid. Barite deposition corresponded to the waning of upward flow and the collapse of sulfate-rich surface waters onto the retreating hydrothermal plume. Calcite precipitated late in the paragenesis as meteoric or marine waters descended into the fault system

  15. Photon attenuation characteristics of radiation shielding materials

    International Nuclear Information System (INIS)

    In the design and construction of installation housing high intensity radiation sources and other radiation generating equipment, a variety of shielding materials are used to minimise exposure to individual. Among the materials, lead is best known for radiation shielding characteristics due to their high density and atomic number. Commercial and barium enriched cement, apart from better compressive strength, smoother surface finish and high abrasion resistance, offers adequate shielding to gamma radiations. Although photon attenuation data are available in literature, it is necessary to test these commercially available material experimentally for their radiation shielding efficiency before putting them in to regular use. In the present work, attenuation characteristics of lead. commercial cement and barium enriched cement supplied by a manufacturing firm have been studied for photons of 662 and 1250keV from Cs-137 and Co-60. The radiographic sources of Cs-137 and Co-60 of radioactive strength of 260 and 30 mCi respectively were utilised in the present investigation. Experimental measurements were done with gamma radiography survey meter MR 4500A placed at a distance of 2 meters from the source. Attenuation coefficients for photons in commercial cement, barite and lead were determined experimentally through photon transmission measurements performed under broad beam counting geometry. The absorbers used were in form of thin sheets of lead, commercial cements and barite of uniform thicknesses. These thin sheets were weighed accurately on an analytical balance and from their measured area, thicknesses proportional to area density in gram.cm-2 were determined. The average thickness of each absorber varied from a few milligram to several gram per cm-2. Higher thicknesses were obtained by stacking the absorbers with each other. Each absorber of specified thickness was interposed between the source and detector such that the primary beam is incident normally on its

  16. Thermal, physico-chemical and biological alteration of organic components and genesis of sulfide mineralisation : the La Florida Zn-Pb deposit (Cantabria, Spain); Processus d`alteration thermique, physico-chimique et biologique de constituants organiques et genese d`une mineralisation sulfuree : le gite Zn-Pb de La Florida (Cantabria, Espagne)

    Energy Technology Data Exchange (ETDEWEB)

    Hu, M.A.; Disnar, J.R.; Barbanson, L. [Orleans Univ. (France); Suarez-Ruiz, I. [Carbon Ins., (Spain)

    1998-08-01

    Conditions of mineralisation and related alteration processes of the La Florida Zn-Pb deposit from Cantabria, Spain are summarized. The stratiform ore deposit is composed of sphalerite, galena and barite and is hosted by Cretaceous dolostones. The geochemistry of hydrocarbons and organic compounds associated with the deposit was documented by coupled gas chromatography-mass spectrometry, optical reflectometry and fluorescence. Results indicate the immaturity of the organic compounds in the deposit. The proposed genetic model for the deposit involves migration of hydrothermal fluids that would have carried the metals and the organic matter necessary for in-situ hydrogen sulfide production and mineralisation. Sulfate reduction by bacteria introduced during meteoric water infiltration is believed to have occurred at the expense of allochthonous organic material. 65 refs., 3 tabs., 8 figs.

  17. Hydrogeochemical and stream-sediment reconnaissance, orientation study, Ouachita Mountain area, Arkansas. National Uranium Resource Evaluation Program

    Energy Technology Data Exchange (ETDEWEB)

    Steele, K. F.

    1982-08-01

    A hydrogeochemical ground water orientation study was conducted in the multi-mineralized area of the Ouachita Mountains, Arkansas in order to evaluate the usefulness of ground water as a sampling medium for uranium exploration in similar areas. Ninety-three springs and nine wells were sampled in Clark, Garland, Hot Springs, Howard, Montgomery, Pike, Polk, and Sevier Counties. Manganese, barite, celestite, cinnabar, stibnite, copper, lead, and zinc are present. The following parameters were determined: pH, conductivity, alkalinity, U, Br, Cl, F, He, Mn, Na, V, Al, Dy, NO/sub 3/, NH/sub 3/, SO/sub 4/, and PO/sub 4/. The minerals appear to significantly affect the chemistry of the ground water. This report is issued in draft form, without detailed technical and copy editing. This was done to make the report available to the public before the end of the National Uranium Resource Evaluation.

  18. A study of the distribution of rare-metals in kuroko-type ore

    Energy Technology Data Exchange (ETDEWEB)

    Murao, S. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), North Ryde, NSW (Australia). Div. of Exploration Geoscience]|[Geological Survey of Japan, Tsukuba, Ibaraki (Japan); Sie, S.H.; Suter, G.F. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), North Ryde, NSW (Australia). Div. of Exploration Geoscience

    1996-12-31

    We have performed PIXE analysis of kuroko-type ore from the JADE hydrothermal site of the Okinawa Trough, Japan using the proton microprobe (PIXEPROBE). We analysed five kinds of ores dredged from the sea floor: (I) barite ore with small sulfide dissemination; (2) sphalerite-pyrite chimney; (3) pyrite ore; (4) sulfide veinlets in strongly altered rock; and (5) pyrite megacrystals in strongly altered rock. The analyses revealed that the trace element distribution is regulated by the occurrence mode of the ore, and within each ore, by the crystal structure. The distribution suggests that the hydrothermal system for kuroko ore formation is quite heterogeneous and its chemistry is controlled by local factors such as difference in temperature, and that in-situ PIXE analyses are essential for effective beneficiation strategy for the rare-metals from kuroko-type ore. (authors). 10 refs., 1 tab.

  19. Hydrothermal zebra dolomite in the Great Basin, Nevada--attributes and relation to Paleozoic stratigraphy, tectonics, and ore deposits

    Science.gov (United States)

    Diehl, S.F.; Hofstra, A.H.; Koenig, A.E.; Emsbo, P.; Christiansen, W.; Johnson, Chad

    2010-01-01

    In other parts of the world, previous workers have shown that sparry dolomite in carbonate rocks may be produced by the generation and movement of hot basinal brines in response to arid paleoclimates and tectonism, and that some of these brines served as the transport medium for metals fixed in Mississippi Valley-type (MVT) and sedimentary exhalative (Sedex) deposits of Zn, Pb, Ag, Au, or barite. Numerous occurrences of hydrothermal zebra dolomite (HZD), comprised of alternating layers of dark replacement and light void-filling sparry or saddle dolomite, are present in Paleozoic platform and slope carbonate rocks on the eastern side of the Great Basin physiographic province. Locally, it is associated with mineral deposits of barite, Ag-Pb-Zn, and Au. In this paper the spatial distribution of HZD occurrences, their stratigraphic position, morphological characteristics, textures and zoning, and chemical and stable isotopic compositions were determined to improve understanding of their age, origin, and relation to dolostone, ore deposits, and the tectonic evolution of the Great Basin. In northern and central Nevada, HZD is coeval and cogenetic with Late Devonian and Early Mississippian Sedex Au, Zn, and barite deposits and may be related to Late Ordovician Sedex barite deposits. In southern Nevada and southwest California, it is cogenetic with small MVT Ag-Pb-Zn deposits in rocks as young as Early Mississippian. Over Paleozoic time, the Great Basin was at equatorial paleolatitudes with episodes of arid paleoclimates. Several occurrences of HZD are crosscut by Mesozoic or Cenozoic intrusions, and some host younger pluton-related polymetallic replacement and Carlin-type gold deposits. The distribution of HZD in space (carbonate platform, margin, and slope) and stratigraphy (Late Neoproterozoic Ediacaran-Mississippian) roughly parallels that of dolostone and both are prevalent in Devonian strata. Stratabound HZD is best developed in Ediacaran and Cambrian units, whereas

  20. Conductive carbon-clay nanocomposites from petroleum oily sludge.

    Science.gov (United States)

    Andrade, Patricia Fernanda; Azevedo, Thiago Figueiredo; Gimenez, Iara F; Souza Filho, Antonio Gomes; Barreto, Ledjane Silva

    2009-08-15

    Oily sludge samples formed in water-oil separation tanks from a petroleum industry were collected, characterized and heat-treated at different temperatures, in order to yield carbon-clay composites. EDX microanalysis, XRD and FTIR data revealed that before carbonization the oily sludge was formed mainly by a mixture of quartz, montmorillonite, calcite, barite and oil residues. After carbonization, mineral phases present were mainly quartz, anorthite and gehlenite, in addition to graphitic and disordered carbon domains, according to XRD, Raman and TEM measurements. A preliminary evaluation of the electrical conductivity performed by Impedance Spectroscopy revealed that the composites formed are conductive, exhibiting conductivity values typical of semiconductors, in contrast to the precursor material. PMID:19261382

  1. Geology and age of the Lac a la Perdrix fenite, southern Gatineau district, Quebec

    International Nuclear Information System (INIS)

    The Lac a Ia Perdrix fenite lies in the Central Metasedimentary Belt of the Grenville Province. This 30 m wide fenite, adjacent to a narrow calciocarbonatite sill, replaces diopside-oligoclase gneiss and is composed of magnesio-arfvedsonite, aegirine, microcline, albite, and fluorapatite. Near the contact with carbonatite, it contains appreciable monazite and barite whereas aegirine virtually disappears. Fenitization probably took place early in the igneous stage of carbonatite development. A Pb/U monazite age of 1026 ± 2 Ma is thought to date fenite formation. Together with published data, this age shows that carbonatite intruded metamorphic rocks near the close of the Grenville Orogeny. (author). 33 refs., 4 tabs., 5 figs

  2. BUFFALO PEAKS WILDERNESS STUDY AREA, COLORADO.

    Science.gov (United States)

    Hedlund, D.C.; Wood, R.H.

    1984-01-01

    Field investigations were conducted to evaluate the mineral-resource potential of the Buffalo Peaks Wilderness Study Area, Colorado. On the basis of this study there is a probable mineral-resource potential for silver vein and bedding replacement deposits along the Weston Pass fault zone, for hydrothermal vein-type uranium deposits in the vicinity of the Parkdale iron pit, and for gold vein deposits in the parts of the Granite and Four Mile districts that are within the wilderness study area. A probable barite resource potential occurs at Rough and Tumbling Creek and near Spring Creek on the east side of the study area. There is little promise for the occurrence of energy resources.

  3. Discovery of Cu-Zn, Cu-Sn intermetallic minerals and its significance for genesis of the Mianning-Dechang REE Metallogenic Belt, Sichuan Province, China

    Institute of Scientific and Technical Information of China (English)

    XIE Yuling; HOU Zengqian; XU Jiuhua; YUAN Zhongxin; BAI Ge; LI Xiaoyu

    2006-01-01

    Mianning-Dechang Himalayan REE Metallogenetic Belt in Sichuan Province lies along the western margin of the Yangtze Craton. We have conducted detailed mineralogical studies on ore minerals collected from Maoniuping and Dalucao, the two largest deposits in the belt. With optical microscope, SEM/EDS, and EPMA, three rare intermetallic minerals, i.e., zinccopperite (Cu2Zn), Sn- bearing native copper, and Cu-bearing jupiter were found to occur in the main ore along with barite, fluorite, apatite, sulfide and bastnaesite. Since the conditions under which zinccopperite and Sn- bearing native copper formed are quite unique, finding of these minerals, for the first time in domestic REE deposits, has significant implications for the genesis of the ore deposits in which they occur. In comparison with Cu-Zn intermetallic minerals in other occurrences, we propose that the formation of this REE metallogenetic belt is associated with fast upwelling of the Himalayan magma from deep source.

  4. Reported industrial minerals occurrences and permissive areas for other occurrences in the Islamic Republic of Mauritania, (phase V, deliverable 89): Chapter R in Second projet de renforcement institutionnel du secteur minier de la République Islamique de Mauritanie (PRISM-II)

    Science.gov (United States)

    Langer, William H.

    2015-01-01

    Previous PRISM reports discuss a variety of industrial minerals. Gypsum, phosphate, salt, stone, sulfur, and ilmenite command the majority of the attention in the earlier geologic reports. (Ilmenite is evaluated in a separate U.S. Geological Survey report in the current study). Asbestos, arsenic, barite, fluorite, and kaolin are listed in indices (occurrence datasets) as potential mineral resources (Marsh and Anderson, 2015), but previous reports do not elaborate on their development potential. Beryl, described herein with the discussions of pegmatites, is also listed in indices of potential mineral resources, but has not been described in terms of its industrial mineral potential. Short discussions on the potential for cement (carbonate rocks), glass sand, peat, and sillimanite resources are included in this report.

  5. Decommissioning of the ASTRA research reactor: Dismantling of the biological shield

    Directory of Open Access Journals (Sweden)

    Meyer Franz

    2006-01-01

    Full Text Available The paper describes the dismantling of the inactive and activated areas of the biological shield of the ASTRA research reactor at the Austrian Research Center in Seibersdorf. The calculation of the parameters determining the activated areas at the shield (reference nuclide, nuclide vector in the barite concrete and horizontal and vertical reduction behaviors of activity concentration and the activation profiles within the biological shield for unrestricted release, release restricted to permanent deposit and radioactive waste are presented. Considerations of located activation anomalies in the shield, e.g. in the vicinities of the beam-tubes, were made according to the reactor's operational history. Finally, an overview of the materials removed from the biological shield is given.

  6. A study of the distribution of rare-metals in kuroko-type ore

    International Nuclear Information System (INIS)

    We have performed PIXE analysis of kuroko-type ore from the JADE hydrothermal site of the Okinawa Trough, Japan using the proton microprobe (PIXEPROBE). We analysed five kinds of ores dredged from the sea floor: (I) barite ore with small sulfide dissemination; (2) sphalerite-pyrite chimney; (3) pyrite ore; (4) sulfide veinlets in strongly altered rock; and (5) pyrite megacrystals in strongly altered rock. The analyses revealed that the trace element distribution is regulated by the occurrence mode of the ore, and within each ore, by the crystal structure. The distribution suggests that the hydrothermal system for kuroko ore formation is quite heterogeneous and its chemistry is controlled by local factors such as difference in temperature, and that in-situ PIXE analyses are essential for effective beneficiation strategy for the rare-metals from kuroko-type ore. (authors). 10 refs., 1 tab

  7. He isotopes constraints to the origin of hydrothermal fluids: application to the fluorite mineralizations of Asturias (N Spain)

    International Nuclear Information System (INIS)

    Helium isotopes have been measured in fluorite and sulphides in order to obtain conclusive means of assessing the involvement of mantle and crustally derived volatiles in F-Ba deposits from Asturias (N of Spain). Fluorite mineralizations are hosted in Mesozoic (Permotriassic) and Paleozoic age rocks. Mineralization is composed of fluorite, barite, calcite, dolomite, quartz and sulphides, and shares the characteristics of most Mississippi Valley Type (MVT) deposits associated with rifting events related to the opening of the Atlantic Ocean. The 3He/4He values of the Asturias ore fluids (≤ 0,1 Ra) indicate a crustal fluid source and exclude the involvement of a mantle helium component. These values are consistent with the acceptance of the existing basinal model for MVT genesis and sedimentary brines migration, with the lack of igneous activity in the area contemporary with the mineralization, and also consistent with similar helium isotope data recorded in other fluorite deposits in Europe. (Author) 24 refs.

  8. Cinnabar, arsenian pyrite and thallium-enrichment in active shallow submarine hydrothermal vents at Paleochori Bay, Milos Island, Greece

    Science.gov (United States)

    Kati, Marianna; Voudouris, Panagiotis; Valsami-Jones, Eugenia; Magganas, Andreas; Baltatzis, Emmanouil; Kanellopoulos, Christos; Mavrogonatos, Constantinos

    2015-04-01

    We herein report the discovery of active cinnabar-depositing hydrothermal vents in a submarine setting at Paleochori Bay, within the offshore southeastern extension of the Milos Island Geothermal Field, South Aegean Active Volcanic Arc. Active, low temperature (up to 115 °C) hydrothermal venting through volcaniclastic material has led to a varied assemblage of sulfide and alteration mineral phases in an area of approximately 1 km2. Our samples recovered from Paleochori Bay are hydrothermal edifices composed of volcaniclastic detrital material cemented by pyrite, or pure sulfide (mainly massive pyrite) mounts. Besides pyrite and minor marcasite, the hydrothermal minerals include cinnabar, amorphous silica, hydrous ferric oxides, carbonates (aragonite and calcite), alunite-jarosite solid solution and Sr-rich barite. Among others, growth textures, sieve-textured pyrite associated with barite, alunite-jarosite solid solution and hydrous ferric oxides rims colloform-banded pyrite layers. Overgrowths of arsenian pyrite layers (up to 3.2 wt. % As and/or up to 1.1 wt. % Mn) onto As-free pyrite indicate fluctuation in As content of the hydrothermal fluid. Mercury, in the form of cinnabar, occurs in up to 5 μm grains within arsenian pyrite layers, usually forming distinct cinnabar-enriched micro-layers. Hydrothermal Sr-rich barite (barite-celestine solid solution), pseudocubic alunite-jarosite solid solution and Mn- and Sr-enriched carbonates occur in various amounts and closely associated with pyrite and/or hydrous ferric oxides. Thallium-bearing sulfides and/or sulfosalts were not detected during our study; however, hydrous ferric oxides show thallium content of up to 0.5 wt. % Tl. The following scenarios may have played a role in pyrite precipitation at Paleochori: (a) H2S originally dissolved in the deep fluid but separated upon boiling could have reacted with oxygenated seawater under production of sulphuric acid, thus causing leaching and dissolution of primary iron

  9. Recycling of mill scale in sintering process

    Directory of Open Access Journals (Sweden)

    El-Hussiny N.A.

    2011-01-01

    Full Text Available This investigation deals with the effect of replacing some amount of Baharia high barite iron ore concentrate by mill scale waste which was characterized by high iron oxide content on the parameters of the sintering process., and investigation the effect of different amount of coke breeze added on sintering process parameters when using 5% mill scale waste with 95% iron ore concentrate. The results of this work show that, replacement of iron ore concentrate with mill scale increases the amount of ready made sinter, sinter strength and productivity of the sinter machine and productivity at blast furnace yard. Also, the increase of coke breeze leads to an increase the ready made sinter and productivity of the sintering machine at blast furnace yard. The productivity of the sintering machine after 5% decreased slightly due to the decrease of vertical velocity.

  10. Determination of lead content in concentrates by radiometric method

    International Nuclear Information System (INIS)

    A procedure was developed for X-ray radiometric measurement of lead concentrations in samples. 220 samples containing 20-70% of lead, up to 13% of zinc and 3-20% of barite were studied experimentally using the above method. The measurements were made employing a single-channel differential analyzer with a scintillation detector based on a FEU-35 photomultiplier and a 30x25 Mm NaJ monocrystal. 75Se served as a radiation source. The results of the measurements and the chemical analysis data were treated by the method of least squares. The mean-square error of a single determination of lead content in the samples using the procedure described never exceeded +- 0.52% abs. (absolute)

  11. Characterization of Japanese color sticks by energy dispersive X-ray fluorescence, X-ray diffraction and Fourier transform infrared analysis

    Energy Technology Data Exchange (ETDEWEB)

    Manso, M. [Centro de Fisica Atomica, Universidade de Lisboa, Faculdade de Ciencias, Av. Prof. Gama Pinto 2, 1649-003 Lisboa (Portugal); Valadas, S. [Chemistry Department, Evora Chemistry Centre and HERCULES Centre, University of Evora, Rua Romao Ramalho, 59 Evora (Portugal); Pessanha, S.; Guilherme, A. [Centro de Fisica Atomica, Universidade de Lisboa, Faculdade de Ciencias, Av. Prof. Gama Pinto 2, 1649-003 Lisboa (Portugal); Queralt, I. [Laboratory of X-ray Analytical Applications, Institute of Earth Sciences ' Jaume Almera' , CSIC, Sole Sabaris s/n. 08028 Barcelona (Spain); Candeias, A.E. [Chemistry Department, Evora Chemistry Centre and HERCULES Centre, University of Evora, Rua Romao Ramalho, 59 Evora (Portugal); Carvalho, M.L., E-mail: luisa@cii.fc.ul.p [Centro de Fisica Atomica, Universidade de Lisboa, Faculdade de Ciencias, Av. Prof. Gama Pinto 2, 1649-003 Lisboa (Portugal)

    2010-04-15

    This work comprises the use of energy dispersive X-ray fluorescence (EDXRF), X-ray diffraction (XRD) and Fourier transformed infrared (FTIR) techniques for the study of the composition of twentieth century traditional Japanese color sticks. By using the combination of analytical techniques it was possible to obtain information on inorganic and organic pigments, binders and fillers present in the sticks. The colorant materials identified in the sticks were zinc and titanium white, chrome yellow, yellow and red ochre, vermillion, alizarin, indigo, Prussian and synthetic ultramarine blue. The results also showed that calcite and barite were used as inorganic mineral fillers while Arabic gum was the medium used. EDXRF offered great potential for such investigations since it allowed the identification of the elements present in the sample preserving its integrity. However, this information alone was not enough to clearly identify some of the materials in study and therefore it was necessary to use XRD and FTIR techniques.

  12. Decommissioning of the ASTRA research reactor - dismantling of the biological shield

    International Nuclear Information System (INIS)

    The paper describes the dismantling of the inactive and activated areas of the biological shield of the ASTRA research reactor at the Austrian Research Center in Seibersdorf. The calculation of the parameters determining the activated areas at the shield (reference nuclide, nuclide vector in the barite concrete and horizontal and vertical reduction behaviors of activity concentration) and the activation profiles within the biological shield for unrestricted release, release restricted to permanent deposit and radioactive waste are presented. Considerations of located activation anomalies in the shield, e. g. in the vicinities of the beam-tubes, were made according to the reactor's operational history. Finally, an overview of the materials removed from the biological shield is given. (author)

  13. Mineral chemistry of mica-pyroxenite xenoliths in neoproterozoic ultrapotassic syenitic magmas, NE Brazil

    International Nuclear Information System (INIS)

    Mica-pyroxenite xenoliths found in Neo Proterozoic ultrapotassic syenitic magmas northeastern Brazil, present modal phases, textural relationships, bulk-rock and mineral chemistries compatible with metasomatic alteration, they suffered in the mantle source. These inclusions are mainly composed of diopside-salite ( >80% of the bulk rock), with subordinate, in variable amounts, F-rick phlogopite, calcite, hyalophane, sphene, apatite and traces of barite. Corrosion of pyroxene is observed in the vicinity of these late space-filling materials. In this paper, mineral chemistry data for the pyroxenite xenoliths are used to explain the chemical fingerprints of their host syenites, and to show that xenoliths record metasomatism in the mantle source, for the ultrapotassic magmas in this part of Brazil. 12 figs., 1 tab

  14. Geochemical interpretation of groundwaters from Finnsjoen, Sweden

    International Nuclear Information System (INIS)

    Computer calculations with aqueous speciation models (WATEQ3 and EQ3NR) give a picture of the water-rock interactions. The mineral saturation indices of calcite, strontianite, rhodochrosite, and siderite show that the concentration levels of Ca2+, Sr2+, Mn2+ and Fe2+ are probably fixed by the aqueous carbonate system and its minerals. However, unreasonably high saturation indices of calcite (up to + 1.7) confirm the uncertainties in the pH-values. Computer simulations with the EQ6 code show that CO2(g) outgassing/ingassing might have contributed errors in the pH measurements during the sampling procedure. EQ6 simulations also show that mixing of waters from different aquifers might have induced transient over- or undersaturation of carbonate minerals. Equilibrium between groundwaters and fluorite and barite appear to fix the concentrations of F- and Ba2+ respectively. (orig./DG)

  15. Evaluation of the Cerro Solo nuclear ore, province of Chubut. Geological characteristics of the deposit and of the basin. Pt. 2

    International Nuclear Information System (INIS)

    The Cerro Solo uranium ore deposit, is located 420 km west from Trelew city, Chubut province, in the extra-andean. The geologic environment belongs to the northwest edge portion of the intracratonic San Jorge Gulf Basin. The uraniferous district is named Pichinanes Ridge district. The mineralization lies 25 to 130 m depth, and is hosted by Los Adobes formation aged Aptian-Albian, made up by conglomerates, sandstones, coarse-sandstones and less abundant siltstones and claystones. The Cerro Solo ore deposit that belongs to the sandstone type-uranium occurrences are lenticular or tabular shaped, associated with organic material and pyrite, generally roughly parallel to the bedding (Trend-Type). The uranium minerals are uraninite and coffinite associated with organic material and pyrite, and frequently hematite, goethite, calcite, siderite and barite are observed. (Author)

  16. BAKOVIĆI THE BIGEST GOLD DEPOSIT OF BOSNIA AND HERZEGOVINA

    Directory of Open Access Journals (Sweden)

    Ivan Jurković

    1995-12-01

    Full Text Available Tectonic setting, para genesis, structure and texture of ores, sulphide sulphur isotopic composition allign the Bakovići veiny deposit in the group of polymetallic, postmagmatic hydrothermal deposits in the Mid-Bosnian Schist Mountains area. Crude ore is rich in gold (15 g/t. Main ore mineral is gold-bearing pyrite; quartz and siderite are the main gangue minerals Accessories are: tetrahedrite, arsenopyrite, chalcopyrjte, stibnite, galena, barite, gypsum. Production between 1895-1938 gave 2.24 t of gold and 7.47 t of silver. The Bakovići deposit was the biggesl producer of gold in Bosnia and Herzegovina. The deposit is relaled to the Late Variscan rhyolite magmatism.

  17. Radium 226 in the deep north-eastern Atlantic Ocean

    International Nuclear Information System (INIS)

    With reference to the distribution of radium-226 in the western equatorial and north-eastern deep Atlantic Ocean it was possible to establish structures in the correlations of radium-226 to its chemical homologue Ba and dissolved SiO2. An 11-box model of the deep Atlantic Ocean was used to obtain information on the size of the radium-226 and Ba sources. The soil source derives mainly from the dissolution of barite. For the first time, an evaluation of the radium-226 flow resulting from the dissolution of particulate matter is presented. The box model and the radium-226 concentrations measured put down the value as 23-46·10-21 mol/m2s. (DG)

  18. Method for monitoring drilling materials for gamma ray activity

    International Nuclear Information System (INIS)

    In the preferred and illustrated embodiment taught herein, method steps for monitoring of raw materials to be used in drilling mud are disclosed. The materials are monitored for radioactivity. Procedures for taking such measurements are disclosed, and the extent of gamma radioactivity in the raw materials used in drilling mud is, determined. This is correlated to the increased radiation attributable to mud made from these materials and the effect the mud would have on gamma ray measuring logs. An alternate procedure for testing drilling mud, typically at the well site, is also disclosed. The method detects mud radioactivity from any additives including barite, potassium chloride, well cuttings or others. Excessive background levels due to mud gamma radioactivity in a well may very well mask the data obtained by various logging procedures dependent on gamma radiation. Procedures are also described for either rejecting mud which is too radioactive or correcting the log measurements for mud effects

  19. A refined genetic model for the Laisvall and Vassbo Mississippi Valley-type sandstone-hosted deposits, Sweden: constraints from paragenetic studies, organic geochemistry, and S, C, N, and Sr isotope data

    Science.gov (United States)

    Saintilan, Nicolas J.; Spangenberg, Jorge E.; Samankassou, Elias; Kouzmanov, Kalin; Chiaradia, Massimo; Stephens, Michael B.; Fontboté, Lluís

    2016-06-01

    The current study has aimed to refine the previously proposed two-fluid mixing model for the Laisvall (sphalerite Rb-Sr age of 467 ± 5 Ma) and Vassbo Mississippi Valley-type deposits hosted in Ediacaran to Cambrian sandstone, Sweden. Premineralization cements include authigenic monazite, fluorapatite, and anatase in the Upper Sandstone at Laisvall, reflecting anoxic conditions during sandstone burial influenced by the euxinic character of the overlying carbonaceous middle Cambrian to Lower Ordovician Alum Shale Formation ( δ 13Corg = -33.0 to -29.5 ‰, δ 15Norg = 1.5 to 3.3 ‰, 0.33 to 3.03 wt% C, 0.02 to 0.08 wt% N). The available porosity for epigenetic mineralization, including that produced by subsequent partial dissolution of pre-Pb-Zn sulfide calcite and barite cements, was much higher in calcite- and barite-cemented sandstone paleoaquifers (29 % by QEMSCAN mapping) than in those mainly cemented by quartz (8 %). A major change in the Laisvall plumbing system is recognized by the transition from barite cementation to Pb-Zn sulfide precipitation in sandstone. Ba-bearing, reduced, and neutral fluids had a long premineralization residence time (highly radiogenic 87S/86Sr ratios of 0.718 to 0.723) in basement structures. As a result of an early Caledonian arc-continent collision and the development of a foreland basin, fluids migrated toward the craton and expelled Ba-bearing fluids from their host structures into overlying sandstone where they deposited barite upon mixing with a sulfate pool ( δ 34Sbarite = 14 to 33 ‰). Subsequently, slightly acidic brines initially residing in pre-Ediacaran rift sediments in the foredeep of the early Caledonian foreland basin migrated through the same plumbing system and acquired metals on the way. The bulk of Pb-Zn mineralization formed at temperatures between 120 and 180 °C by mixing of these brines with a pool of H2S ( δ 34S = 24 to 29 ‰) produced via thermochemical sulfate reduction (TSR) with oxidation of

  20. Diagenesis of silica-rich mounded chalk, the Coniacian Arnager Limestone, Denmark

    DEFF Research Database (Denmark)

    Buus Madsen, Heine; Stemmerik, Lars; Surlyk, Finn

    precipitation of opal-CT. The opal-CT formed at temperatures around 17°C, the precipitation lowered the silica activity and the Si/Al ratio of the pore water, resulting in precipitation of clinoptilolite, feldspar and smectite. Calcite formed synchronouslywith the latest clinoptilolite.Minoramounts of quartz...... precipitated in pore water with low silica activity during maximum burial, probably to depths of 200-250 m. The dissolution of sponge spicules and decomposition of the sponge tissue also resulted in the release of Ba2+, Sr2+,Mg2+, Ca2+ and CO3 2-, facilitating precipitation of barite and dolomite...... consist of twomicrofacies, spiculiticwackestone and bioturbated spiculitic wackestone, containing 10-22% and 7-12% moulds after spicules, respectively. Subsequent to deposition and shallow burial, dissolution of siliceous sponge spicules increased the silica activity of the pore water and initiated...

  1. Isolation and characterisation of barium sulphate and titanium oxides in monument crusts

    International Nuclear Information System (INIS)

    Black crusts from historical ornamental materials contain Ba and Ti. These elements are in low proportion, making their determination difficult and especially the characterisation of the phases in which they are present. For this reason, works on the mineralogical composition of the two elements in black crusts is scarce. Thus the isolation, previous to their characterisation, is important for the study of the surface layer in altered monuments. An acid attack for the isolation of barium sulphate and titanium oxides in black crusts from polluted areas has been used. The acid employed is a mixture of HF, HNO3 and HClO4. The residue isolated by acid attack was analysed by energy dispersive X-ray fluorescence and X-ray diffraction. It was characterised, and the percentages of barite (barium sulphate), anatase (titanium oxide), and rutile (titanium oxide) phases present in the surface layers were calculated

  2. Optimization of shielding of radiodiagnostic and radiotherapeutic units

    International Nuclear Information System (INIS)

    The application is pointed out of the principles of optimal protection against ionizing radiation, in calculating the shielding at radiodiagnostic and radiotherapeutic workplaces at which only X-ray equipment with a voltage of up to 400 kV is used. It is pointed out that an equivalent dose rate may be generally determined which it is purposeful to achieve by shielding rooms and areas adjoining the examination room or radiotherapy area. In order to calculate the shielding using a barite mixture the optimal weekly values of dose equivalent are given in dependence on the voltage of the X-ray tube. Thicknesses of shielding layers by which these values may be obtained are given for radiodiagnostic and radiotherapeutic areas with instruments with a voltage of up to 250 kV. (author)

  3. Micro-PIXE characterization of amorphous silica globules from a hydrothermal field on the sea floor of Okinawa, Southern Japan

    International Nuclear Information System (INIS)

    During the examination of the representative specimens, a barite ore and a polymetallic chimney, from the JADE hydrothermal field of Okinawa Trough, many amorphous silica globules of approximately 10 to 50 micrometers in diameter were found as isolated sphere or bunchy aggregation. We performed micro-PIXE analyses of the globules to check the effectiveness of the method to such soft and vulnerable material, and to understand the geochemical characteristics. The result shows that amorphous silica can include various kinds of elements in lithophile, chalcophile and siderophile categories. The trace element distribution of the globules indicates that amorphous silica could be a good monitor of geochemical environment; and implies that the chemical variation of ore often in a mineral field is mainly derived by change in local physicochemical conditions of single mineralizing fluid rather than multiple injection of the solution. (author)

  4. Re-Os dating of pyrite from Giant Bayan Obo REE-Nb-Fe deposit

    Institute of Scientific and Technical Information of China (English)

    LIU Yulong; YANG Gang; CHEN Jiangfeng; DU Andao; XIE Zhi

    2004-01-01

    Six pyrite samples from the giant Bayan Obo REE-Nb-Fe deposit are dated by Re-Os technique. Pyrite studied is associated with barite and separated from a vein cutting REE mineralization. Pyrites analyzed contain 16-30 ng Re and 0.10-0.16 ng Os, and yield a Caledonian isochron age of 439 ± 86 Ma. High Re/Os ratio, low Os concentration and highly radiogenic Os isotopic ratios of these samples suggest that they are of crustal origin. The northern margin of the North China Block was a passive continental margin, but not a subduction zone with enormous volcanic activities in the Early Paleozoic Era. Our Re-Os result provides new evidences, showing that Bayan Obo deposit experienced a thermal disturbance of crustal origin in the Caledonian time and some isotopic systems recorded only the time of the disturbance, not the mineralization age.

  5. Gamma ray shielding and structural properties of Bi2O3-PbO-B2O3-V2O5 glass system

    Science.gov (United States)

    Kaur, Kulwinder; Singh, K. J.; Anand, Vikas

    2014-04-01

    The present work has been undertaken to evaluate the applicability of Bi2O3-PbO-B2O3-V2O5 glass system as gamma ray shielding material. Gamma ray mass attenuation coefficient has been determined theoretically using WinXcom computer software developed by National Institute of Standards and Technology. A meaningful comparison of their radiation shielding properties has been made in terms of their half value layer parameter with standard radiation shielding concrete 'barite'. Structural properties of the prepared glass system have been investigated in terms of XRD and FTIR techniques in order to check the possibility of their commercial utility as alternate to conventional concrete for gamma ray shielding applications.

  6. Monte Carlo simulations for optimization of neutron shielding concrete

    Science.gov (United States)

    Piotrowski, Tomasz; Tefelski, Dariusz; Polański, Aleksander; Skubalski, Janusz

    2012-06-01

    Concrete is one of the main materials used for gamma and neutron shielding. While in case of gamma rays an increase in density is usually efficient enough, protection against neutrons is more complex. The aim of this paper is to show the possibility of using the Monte Carlo codes for evaluation and optimization of concrete mix to reach better neutron shielding. Two codes (MCNPX and SPOT — written by authors) were used to simulate neutron transport through a wall made of different concretes. It is showed that concrete of higher compressive strength attenuates neutrons more effectively. The advantage of heavyweight concrete (with barite aggregate), usually used for gamma shielding, over the ordinary concrete was not so clear. Neutron shielding depends on many factors e.g. neutron energy, barrier thickness and atomic composition. All this makes a proper design of concrete as a very important issue for nuclear power plant safety assurance.

  7. Panorama of mining activities in France during 1996

    International Nuclear Information System (INIS)

    Viewed by the French ores and metals industry, 1996 was a grey year. In Metropolitan France, the production of energy raw materials (hydrocarbons, coal, uranium) and metals (Fe, AU, Ag) continued to decrease and, unless new outlets are found, this trend is likely to continue to reach a near zero level by the year 2005. As against this, mine production (mainly Ni, Au) in France's Overseas Departments and Territories is on the increase. The industrial minerals sector showed divergent trends: a decrease for potassium, sulphur and fluorite due to dwindling reserves; stability for certain products such as salt, silica, etc. on the local (French/European) market; an increase for products such as barite, talc and andalusite, among others. Overall, the return from industrial minerals in France is on the decline, representing on increasingly smaller percentage of the mineral raw materials (MRM) sector. (authors)

  8. Hydrogeochemical and stream-sediment reconnaissance, orientation study, Ouachita Mountain area, Arkansas. National Uranium Resource Evaluation Program

    International Nuclear Information System (INIS)

    A hydrogeochemical ground water orientation study was conducted in the multi-mineralized area of the Ouachita Mountains, Arkansas in order to evaluate the usefulness of ground water as a sampling medium for uranium exploration in similar areas. Ninety-three springs and nine wells were sampled in Clark, Garland, Hot Springs, Howard, Montgomery, Pike, Polk, and Sevier Counties. Manganese, barite, celestite, cinnabar, stibnite, copper, lead, and zinc are present. The following parameters were determined: pH, conductivity, alkalinity, U, Br, Cl, F, He, Mn, Na, V, Al, Dy, NO3, NH3, SO4, and PO4. The minerals appear to significantly affect the chemistry of the ground water. This report is issued in draft form, without detailed technical and copy editing. This was done to make the report available to the public before the end of the National Uranium Resource Evaluation

  9. Sustainable Management of Flowback Water during Hydraulic Fracturing of Marcellus Shale for Natural Gas Production

    Energy Technology Data Exchange (ETDEWEB)

    Vidic, Radisav [Univ. of Pittsburgh, PA (United States)

    2015-01-24

    This study evaluated the feasibility of using abandoned mine drainage (AMD) as make- up water for the reuse of produced water for hydraulic fracturing. There is an abundance of AMD sources near permitted gas wells as documented in this study that can not only serve as makeup water and reduce the demand on high quality water resources but can also as a source of chemicals to treat produced water prior to reuse. The assessment of AMD availability for this purpose based on proximity and relevant regulations was accompanied by bench- and pilot-scale studies to determine optimal treatment to achieve desired water quality for use in hydraulic fracturing. Sulfate ions that are often present in AMD at elevated levels will react with Ba²⁺ and Sr²⁺ in produced water to form insoluble sulfate compounds. Both membrane microfiltration and gravity separation were evaluated for the removal of solids formed as a result of mixing these two impaired waters. Laboratory studies revealed that neither AMD nor barite formed in solution had significant impact on membrane filtration but that some produced waters contained submicron particles that can cause severe fouling of microfiltration membrane. Coagulation/flocculation was found to be an effective process for the removal of suspended solids and both bench- and pilot-scale studies revealed that optimal process conditions can consistently achieve the turbidity of the finished water below 5 NTU. Adjusting the blending ratio of AMD and produced water can achieve the desired effluent sulfate concentration that can be accurately predicted by chemical thermodynamics. Co-treatment of produced water and AMD will result in elevated levels of naturally occurring radioactive materials (NORM) in the solid waste generated in this process due to radium co-precipitation with barium sulfate. Laboratory studies revealed that the mobility of barite that may form in the subsurface due to the presence of sulfate in the fracturing fluid can be

  10. Groundwater seepage from the Ranger uranium mine tailings dam: radioisotopes of radium, thorium and actinium. Supervising Scientist report 106

    International Nuclear Information System (INIS)

    Monitoring of bores near the Ranger uranium mine tailings dam has revealed deterioration in water quality in several bores since 1983. In a group of bores to the north of the dam, increases have been observed of up to 500 times for sulphate concentrations and of up to 5 times for 226Ra concentrations. Results are presented here of measurements of members of the uranium, thorium and actinium decay series in borewater samples collected between 1985 and 1993. In particular, measurements of all four naturally-occurring radium isotopes have been used in an investigation of the mechanism of radium concentration changes. For the most seepage-affected bores the major findings of the study include: 228Ra/226Ra 223Ra /226Ra and 224Ra/228Ra ratios all increased over the course of the study; barium concentrations show high seasonal variability, being lower in November than May, but strontium concentrations show a steady increase with time. Calculations show that the groundwater is probably saturated with respect to barite but not with respect to celestite or anglesite; sulphide concentrations are low in comparison with sulphate, and are higher in November than in May; and 227Ac concentrations have increased with time, but do not account for the high 223Ra/226Ra ratios. It is concluded on the basis of these observations that increases in Ra isotope concentrations observed in a number of seepage-affected bores arise from increases in salinity leading to desorption of radium from adsorption sites in the vicinity of the bore rather by direct transport of radium from the tailings. Increased salinity is also causing the observed increases in 227Ac and strontium concentrations, while formation of a barite solid phase in the groundwater is causing the removal of some radium from solution. This is the cause of the increasing radium isotope ratios noted above

  11. Paleomagnetism of the Red Dog Zn-Pb massive sulfide deposit in northern Alaska

    Science.gov (United States)

    Lewchuk, Michael T.; Leach, D.L.; Kelley, K.D.; Symons, David T. A.

    2004-01-01

    Paleomagnetic methods have isolated two ancient magnetizations in and around the Paleozoic shale-hosted Red Dog ore deposit in northern Alaska. A high-latitude, westerly magnetization carried by magnetite, termed characteristic remanent magnetization A, was found in rocks that have barite and/or substantial quartz replacement of barite. An intermediate- to low-latitude, southerly magnetization (characteristic remanent magnetization B) is carried by pyrrhotite and was found in rocks dominated by galena and sphalerite. The ages the two components are constrained by their relationship with geochemistry, radiometric age dating, and hypotheses for the Mesozoic tectonic history of the Brooks Range. Characteristic remanent magnetization A fails the fold test so it must postdate the end of Brookian orogenesis (??? 150 Ma). It is always found with replacement quartz that has a radiometric date (white mica from a vug, 39Ar/40Ar) of 126 Ma. The paleolatitude for characteristic remanent magnetization B is too shallow to be Mesozoic or younger, regardless of the model for the tectonic origin of northern Alaska, and must predate Brookian orogenesis. Geologic mapping suggests that most of the ore is syngenetic, formed at 330 to 340 Ma, and a radiometric date (Re-Os on pyrite) yields an age of 338 Ma. Since characteristic remanent magnetization B predates deformation, is found in mineralized rocks and is carried by pyrrhotite, it was probably acquired during the mineralizing process as well. The combined radiometric ages and paleomagnetic data sets can be best interpreted by assuming that northern Alaska was part of an accreted terrane that was translated northward by about 30?? into its current location relative to the rest of North America and then rotated counterclockwise by 50?? to 70??. This tectonic interpretation yields plausible magnetization ages for both characteristic remanent magnetization A and B. Geologic evidence, isotopic ages, and paleomagnetic data indicate

  12. Geophysical expression of a buried niobium and rare earth element deposit: the Elk Creek carbonatite, Nebraska, USA

    Science.gov (United States)

    Drenth, Benjamin J.

    2014-01-01

    The lower Paleozoic Elk Creek carbonatite is a 6–8-km-diameter intrusive complex buried under 200 m of sedimentary rocks in southeastern Nebraska. It hosts the largest known niobium deposit in the U.S. and a rare earth element (REE) deposit. The carbonatite is composed of several lithologies, the relations of which are poorly understood. Niobium mineralization is most enriched within a magnetite beforsite (MB) unit, and REE oxides are most concentrated in a barite beforsite unit. The carbonatite intrudes Proterozoic country rocks. Efforts to explore the carbonatite have used geophysical data and drilling. A high-resolution airborne gravity gradient and magnetic survey was flown over the carbonatite in 2012. The carbonatite is associated with a roughly annular vertical gravity gradient high and a subdued central low and a central magnetic high surrounded by magnetic field values lower than those over the country rocks. Geophysical, borehole, and physical property data are combined for an interpretation of these signatures. The carbonatite is denser than the country rocks, explaining the gravity gradient high. Most carbonatite lithologies have weaker magnetic susceptibilities than those of the country rocks, explaining why the carbonatite does not produce a magnetic high at its margin. The primary source of the central magnetic high is interpreted to be mafic rocks that are strongly magnetized and are present in large volumes. MB is very dense (mean density 3200  kg/m3) and strongly magnetized (median 0.073 magnetic susceptibility), producing a gravity gradient high and contributing to the aeromagnetic high. Barite beforsite has physical properties similar to most of the carbonatite volume, making it a poor geophysical target. Geophysical anomalies indicate the presence of dense and strongly magnetized rocks at depths below existing boreholes, either a large volume of MB or another unknown lithology.

  13. Lead and sulfur isotopes of Guarn Halfaya and Bou Grine deposits associated to salt dome cap rocks (Diapirs zone, Northern Tunisia): sources of metals and genetic model

    Science.gov (United States)

    Jemmali, N.; Souissi, F.; Carranza, E. J. M.; Vennemann, T. W.

    2012-04-01

    The Pb-Zn ores districts at Guarn Halfaya and Bou Grine are hosted mainly by the dolostones in the contact breccias between Triassic and Upper Cretaceous and by Upper Cretaceous limestones. The mineralization occurs as lenticular, impregnations, substitutions, replacements, stratiform, vein, dissemination, and stockwork. A complex polymetallic sulfide assemblage typifies the main ore stage, dominated by sphalerite and galena, pyrite with minor chalcopyrite, arsenopyrite, and sulfosalt (grey copper). Limestone, barite and celestite dominate the gangue, with lesser calcite. Barite and celestite intergrown with main ore-stage sulfides of Oum Edeboua has δ34S values of 12.7 to 15.0 ‰, consistent with the derivation of sulfate from Triassic evaporites form the study area (12.8<δ34S<14.0 ‰). The δ34S values for sulfides of the both study area range from 2.6 to 9.5 ‰. These positive δ34S values are likely due to abiotic thermally-driven abiotic sulfate reduction (TSR) of Triassic sulfates at depth. However, the presence of bacterial relics suggests involvement of bacterially-mediated sulfate reduction (BSR). The lead isotope composition is homogeneous with 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratio ranging between from 18.723 to 18.783, 15.667 to 15.685, and 38.806 to 38.889, respectively, and plot between the upper crust and orogene curves of Zartman and Doe (1981) which imply involvement of a well-mixed multi-source reservoir of Pb at depth. The syn-diagenetic mineralization in the Bahloul Formation and the calculate of model age suggest a Late Cretaceous age, correspond to a NE-SW to ENE-WSS regional extensional tectonic events, which likely favored migration of mineralizing fluids and eventual deposition at Guarn Halfaya and Bou Grine.

  14. Mineralization, geochemistry, fluid inclusion and sulfur stable isotope studies in the carbonate hosted Baqoroq Cu-Zn-As deposit (NE Anarak

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Jazi

    2015-10-01

    Full Text Available Introduction The Baqoroq Cu-Zn-As deposit is located northeast of the town ofAnarak in Isfahan province, in theeast central areaof Iran. Copper mineralization occursin upper cretaceous carbonate rocks.Studyof thegeologyof the Nakhlak area, the location ofa carbonate-hosted base metaldeposit, indicatesthe importance of stratigraphic, lithological and structural controls in the placement of this ore deposit. (Jazi et al., 2015.Some of the most world’s most important epigenetic, stratabound and discordant copperdeposits are the carbonate hosted Tsumeb and Kipushi type deposits,located in Africa. The Baqoroq deposit is believed to be of this type. Materials and methods In the current study, fifty rock samples were collected from old tunnels and surface mineralization. Twenty-two thin sections, ten polished sections and four thin-polished sections were prepared for microscopic study. Ten samples were selected for elemental analysis by ICP-OES (Inductively coupled plasma optical emission spectrometry by the Zar Azma Company (Tehran and AAS (Atomic absorption spectrometry at the Ferdowsi University of Mashhad. Seven doubly polished sections of barite mineralization were prepared for microthermometric analysis. Homogenization and last ice-melting temperatures were measured using a Linkam THMSG 600 combined heating and freezing stage at Ferdowsi University of Mashhad. Sulfur isotopes of five barite samples were determined by the Iso-Analytical Ltd. Company of the UK. The isotopic ratios are presented in per mil (‰notation relative to the Canyon Diablo Troilite. Results The upper Cretaceoushost rocks of the Baqoroq deposit include limestone, sandstone, and conglomerate units. Mineralization is controlled by two main factors: lithostratigraphy and structure. Epigenetic Cu-Zn mineralizationoccurs in ore zones as stratabound barite and barite-calcite veins and minor disseminated mineralization. Open space filling occurred as breccia matrix

  15. Sulfide geochronology along the Endeavour Segment of the Juan de Fuca Ridge

    Science.gov (United States)

    Jamieson, John W.; Hannington, Mark D.; Clague, David A.; Kelley, Deborah S.; Delaney, John R.; Holden, James F.; Tivey, Margaret K.; Kimpe, Linda E.

    2013-07-01

    Forty-nine hydrothermal sulfide-sulfate rock samples from the Endeavour Segment of the Juan de Fuca Ridge, northeastern Pacific Ocean, were dated by measuring the decay of 226Ra (half-life of 1600 years) in hydrothermal barite to provide a history of hydrothermal venting at the site over the past 6000 years. This dating method is effective for samples ranging in age from ˜200 to 20,000 years old and effectively bridges an age gap between shorter- and longer-lived U-series dating techniques for hydrothermal deposits. Results show that hydrothermal venting at the active High Rise, Sasquatch, and Main Endeavour fields began at least 850, 1450, and 2300 years ago, respectively. Barite ages of other inactive deposits on the axial valley floor are between ˜1200 and ˜2200 years old, indicating past widespread hydrothermal venting outside of the currently active vent fields. Samples from the half-graben on the eastern slope of the axial valley range in age from ˜1700 to ˜2925 years, and a single sample from outside the axial valley, near the westernmost valley fault scarp is ˜5850 ± 205 years old. The spatial relationship between hydrothermal venting and normal faulting suggests a temporal relationship, with progressive younging of sulfide deposits from the edges of the axial valley toward the center of the rift. These relationships are consistent with the inward migration of normal faulting toward the center of the valley over time and a minimum age of onset of hydrothermal activity in this region of 5850 years.

  16. A major light rare-earth element (LREE) resource in the Khanneshin carbonatite complex, southern Afghanistan

    Science.gov (United States)

    Tucker, Robert D.; Belkin, Harvey E.; Schulz, Klaus J.; Peters, Stephen G.; Horton, Forrest; Buttleman, Kim; Scott, Emily R.

    2012-01-01

    The rapid rise in world demand for the rare-earth elements (REEs) has expanded the search for new REE resources. We document two types of light rare-earth element (LREE)-enriched rocks in the Khanneshin carbonatite complex of southern Afghanistan: type 1 concordant seams of khanneshite-(Ce), synchysite-(Ce), and parisite-(Ce) within banded barite-strontianite alvikite, and type 2 igneous dikes of coarse-grained carbonatite, enriched in fluorine or phosphorus, containing idiomorphic crystals of khanneshite-(Ce) or carbocernaite. Type 1 mineralized barite-strontianite alvikite averages 22.25 wt % BaO, 4.27 wt % SrO, and 3.25 wt % ∑ LREE2O3 (sum of La, Ce, Pr, and Nd oxides). Type 2 igneous dikes average 14.51 wt % BaO, 5.96 wt % SrO, and 3.77 wt % ∑ LREE2O3. A magmatic origin is clearly indicated for the type 2 LREE-enriched dikes, and type 1 LREE mineralization probably formed in the presence of LREE-rich hydrothermal fluid. Both types of LREE mineralization may be penecontemporaneous, having formed in a carbonate-rich magma in the marginal zone of the central vent, highly charged with volatile constituents (i.e., CO2, F, P2O5), and strongly enriched in Ba, Sr, and the LREE. Based on several assumptions, and employing simple geometry for the zone of LREE enrichment, we estimate that at least 1.29 Mt (million metric tonnes) of LREE2O3 is present in this part of the Khanneshin carbonatite complex.

  17. Geophysical expression of a buried niobium and rare earth element deposit: the Elk Creek carbonatite, Nebraska, USA

    Science.gov (United States)

    Drenth, B.; Phillips, J. D.; Kass, A.; Krahenbuhl, R. A.

    2014-12-01

    The lower Paleozoic Elk Creek carbonatite is a 6-8 kilometer diameter intrusive complex buried under 200 meters of sedimentary rocks in southeastern Nebraska. It hosts the largest known niobium deposit in the U.S. and a rare earth element (REE) deposit. The carbonatite is composed of several lithologies, the relations of which are poorly understood. Niobium mineralization is most enriched within a magnetite beforsite unit, and REE oxides are concentrated in a barite beforsite unit. The carbonatite intrudes Proterozoic country rocks. A high-resolution airborne gravity gradient and magnetic survey was flown over the carbonatite in 2012. The carbonatite is associated with an annular vertical gravity gradient high with a subdued central low, and a central magnetic high surrounded by magnetic field values lower than those over the country rocks. Geophysical, borehole, and physical property data are combined for an interpretation of these signatures. The carbonatite is denser than the country rocks, explaining the gravity gradient high. Most carbonatite lithologies have weaker magnetic susceptibilities than those of the country rocks, explaining why the carbonatite produces a magnetic low at its margin. The primary source of the central magnetic high is interpreted to be mafic rocks that are strongly magnetized and are present in large volumes. Magnetite beforsite is very dense (mean density 3200 kg/m3) and strongly magnetized (median 0.073 SI magnetic susceptibility), producing a gravity gradient high and contributing to the aeromagnetic high. Barite beforsite has physical properties similar to most of the carbonatite volume, making it a poor geophysical target. Geophysical anomalies indicate the presence of dense and strongly magnetized rocks at depths below existing boreholes, either a large volume of magnetite beforsite or another unknown lithology. Studies are underway to investigate possible effects of alteration and magnetic remanence, and to better constrain the

  18. Site investigation SFR. Fracture mineralogy and geochemistry of borehole sections sampled for groundwater chemistry and Eh. Results from boreholes KFR01, KFR08, KFR10, KFR19, KFR7A and KFR105

    Energy Technology Data Exchange (ETDEWEB)

    Sandstroem, Bjoern (WSP Sverige AB (Sweden)); Tullborg, Eva-Lena (Terralogica AB, Grabo (Sweden))

    2011-01-15

    This report is part of the complementary site investigations for the future expansion of SFR. The report presents the results obtained during a detailed mineralogical and geochemical study of fracture minerals in drill cores from borehole section sampled for groundwater chemistry and where downhole Eh measurements have been performed. The groundwater redox system comprises not only the water, but also the bedrock/fracture mineral system in contact with this water. It is thus important to gain knowledge of the solid phases in contact with the groundwater, i.e. the fracture minerals. The samples studied for mineralogy and geochemistry, here reported, were selected to represent the fracture surfaces in contact with the groundwater in the sampled borehole sections and will give input to the hydrogeochemical model (SFR SDM). The mineralogy was determined using SEM-EDS and XRD and the geochemistry of fracture filling material was analysed by ICP-AES and ICP-QMS. The most common fracture minerals in the samples are mixed layer clay (smectite-illite), illite, chlorite, calcite, quartz, adularia and albite. Other minerals identified in the borehole sections include laumontite, pyrite, barite, chalcopyrite, hematite, Fe-oxyhydroxide, muscovite, REE-carbonate, allanite, biotite, asphaltite, galena, sphalerite, arsenopyrite, uranium phosphate, uranium silicate, Y-Ca silicate, monazite, xenotime, harmotome and fluorite. There are no major differences between the fracture mineralogy of the investigated borehole sections from SFR and the fracture mineralogy of the Forsmark site investigation area. The four fracture mineral generations distinguished within the Forsmark site investigation are also found at SFR. However, some differences have been observed: 1) Barite and uranium minerals are more common in the SFR fractures, 2) clay minerals like mixed layer illite-smectite and illite dominates in contrast to Forsmark where corrensite is by far the most common clay mineral and, 3

  19. Occurrence and mobilization of radium in fresh to saline coastal groundwater inferred from geochemical and isotopic tracers (Sr, S, O, H, Ra, Rn)

    International Nuclear Information System (INIS)

    Highlights: • The radium (Ra) isotope association with groundwater salinity is locally variable. • Water from 2 coastal aquifers exhibits at least one apparent Ra removal mechanism. • Ra may be removed by multiple mechanisms (e.g. adsorption, BaSO4 precipitation). • Adsorption and coprecipitation depend on local geochemical and redox conditions. • Other isotopes (87Sr/86Sr, δ34S–SO42-,δ18O–SO42-) trace solute sources and redox state. - Abstract: Salinization in groundwater systems can induce water–rock interaction, including the release of naturally-occurring trace elements of health significance such as radium (Ra), with possible implications for the usability of water resources in addition to the increase of dissolved solids (TDS) concentrations. In general, radium mobility is limited by chemical removal mechanisms including adsorption onto clays and/or Mn and Fe oxides, exchange processes, and coprecipitation with secondary barite. In order to examine the effect of aquifer salinity gradients on the distribution of naturally-occurring Ra in fresh to saline groundwater and the relationship to water–rock interaction and Ra removal mechanisms, two contrasting systems were investigated: the shallow unconfined coastal aquifer in Agadir (southwestern Morocco) and the confined Cretaceous (Cape Fear) and Pliocene (Yorktown) aquifers of the Atlantic Coastal Plain (North Carolina, USA). Geochemical and isotopic indicators of salinity sources (e.g. cation ratios, δ18O, δ2H, Br−/Cl−, δ34S–SO42-,δ18O–SO42-) were used to identify the relative contributions of seawater and other saline waters and subsequent geochemical modification by water–rock interaction. Radium activities (224Ra, 226Ra, 228Ra), radon-222, alkaline earth metal (Mg, Ca, Sr, Ba) concentrations and ratios, and 87Sr/86Sr ratios were analyzed to identify water–rock interaction processes affecting alkaline earth metals including Ra. The Morocco coastal aquifer is generally oxic

  20. Geochemical Characteristics and Metallogenic Mechanism of the Mayuan Pb-Zn Deposit on the Northern Margin of Yangtze Plate%扬子板块北缘马元铅锌矿地球化学特征及成矿机制探讨

    Institute of Scientific and Technical Information of China (English)

    刘淑文; 李荣西; 刘云华; 曾荣

    2016-01-01

    位于扬子板块北缘的马元铅锌矿呈似层状产于震旦系灯影组角砾状白云岩中,矿石矿物为闪锌矿、方铅矿,脉石矿物有白云石、重晶石和少量石英、萤石、方解石等。本文着重对主要矿石及脉石矿物的锶、硫同位素和稀土元素地球化学特征进行对比研究,以探讨其成矿机制。早期沉淀产物闪锌矿流体包裹体及白云石的87Sr/86Sr比值为0.71111~0.71241,表明Sr来源以壳源锶为主;晚期重晶石87Sr/86Sr比值为0.70918和0.70971,表明重晶石中的锶主要来源于海水锶,有少量壳源锶加入。早期产物白云石、闪锌矿和方铅矿的稀土元素具有类似热卤水特征的明显正Eu异常(去掉特高值后平均值为1.99),而晚期重晶石则具有类似海水特征的负 Ce 异常(0.26)。硫同位素表现出富重硫(δ34S>12‰)的特点,表明硫可能主要来源于海相硫酸盐。还原硫的形成机制为硫酸盐的热化学还原作用,有机质如甲烷可能充当了还原剂。闪锌矿、方铅矿及重晶石的δ34S值各自集中分布在较小的范围内且同位素分馏达到平衡,暗示金属、还原硫和硫酸根可能是同一成矿流体搬运的。矿质沉淀机制可能是地层中循环的富含放射性锶以及多种金属元素的成矿热卤水与下渗的海水(或大气降水)混合导致的。早期沉淀白云石、闪锌矿以及方铅矿的流体以热卤水为主,晚期与重晶石沉淀有关的流体则具有相对富含海水(或大气降水)的特点。%The Mayuan stratabound Pb-Zn deposit in Nanzheng of Shaanxi Province is located on the northern margin of the Yangtze Plate, and the orebodies are stratiform and hosted in breciated dolostone of the Sinian Dengying Formation. The ore minerals are mainly sphalerite and galena, and the gangue minerals comprise dolomite, barite, and small amounts of quartz, fluorite and calcite. This study mainly focused on the strontium, sulfur isotopes and the

  1. Fluid inclusion and sulfur stable isotope evidence for the origin of the Ahangran Pb-Ag deposit

    Directory of Open Access Journals (Sweden)

    Mohammad Maanijou

    2015-10-01

    Full Text Available Introduction The Ahangaran Pb-Ag deposit is located in the Hamedan province, west Iran, 25 km southeast of the city of Malayer . . The deposit lies in the strongly folded Sanandaj-Sirjan tectonic zone, in which the ore bodies occur as thin lenses and layers. The host rocks of the deposit are Early Cretaceous carbonates and sandstones that are unconformably underlain by Jurassic rocks. Ore minerals include galena, pyrite, chalcopyrite, pyrrhotite and supergene iron oxide minerals. Gangue minerals consist of barite, dolomite, chlorite, calcite and quartz. The mineralization occurs as open-space fillings, veins, veinlets, disseminations, and massive replacements. Alteration consists of silicification, sericitization, and dolomitization. In this study, we carried out studies of mineralogy, microthermometry of fluid inclusions and sulfur isotopes to determine the source of sulfur and the physico-chemical conditions of formation. Materials and methods Seventy samples of different host rocks, alteration, and mineralization were collected from surface outcrops and different tunnels. Twenty of the samples were prepared for mineralogical studies at Tarbiat Modarres University in Tehran and 25 for petrological studies at the University of Bu-Ali Sina. Fluid-inclusion studies were done on 5 samples of quartz and calcite at Pouya Zamin Azin Company in Tehran using a Linkam THM 600 model heating-freezing stage (with a range of -196 to 480ºC. The accuracy and precision of the homogenization measurements are about ±1°C. Salinity estimates were determined from the last melting temperatures of ice, utilizing the equations by Bodnar and Vityk (1994 and for CO2 fluids using equations by Chen (1972. Nine samples of sulfides and barite were crushed and separated by handpicking under binocular microscope and powdered with agate mortar and pestle. About one gram of each sample was sent to the Stable Isotope and ICP/MS Laboratory of Queen’s University, Canada for

  2. Volcanic degassing, hydrothermal circulation and the flourishing of early life on Earth: A review of the evidence from c. 3490-3240 Ma rocks of the Pilbara Supergroup, Pilbara Craton, Western Australia

    Science.gov (United States)

    Van Kranendonk, Martin J.

    2006-02-01

    New data gathered during mapping of c. 3490-3240 Ma rocks of the Pilbara Supergroup in the Pilbara Craton show that most bedded chert units originated as epiclastic and evaporative sedimentary rocks that were silicified by repeated pulses of hydrothermal fluids that circulated through the footwall basalts during hiatuses in volcanism. For most cherts, fossil hydrothermal fluid pathways are preserved as silica ± barite ± Fe-bearing veins that cut through the footwall and up to the level of individual bedded chert units, but not above, indicating the contemporaneity of hydrothermal silica veining and bedded chert deposition at the end of volcanic eruptive events. Silica ± barite ± Fe-bearing vein swarms are accompanied by extensive hydrothermal alteration of the footwall to the bedded chert units, and occurred under alternating high-sulphidation and low-sulphidation conditions. These veins provided pathways to the surface for elements leached from the footwall (e.g., Si, Ba, Fe) and volcanogenic emissions from underlying felsic magma chambers (e.g., CO 2, H 2S/HS -, SO 2). Stratigraphic evidence of shallowing upward and subsequent deepening associated with the deposition of Warrawoona Group cherts is interpreted to relate to the emplacement of subvolcanic laccoliths and subsequent eruption and/or degassing of these magmas. Heat from these intrusions drove episodes of hydrothermal circulation. Listric normal faulting during caldera collapse produced basins with restricted circulation of seawater. Eruption of volcanogenic emissions into these restricted basins formed brine pools with concentration of the volcanogenic components, thereby providing habitats suitable for early life forms. Fossil stromatolites from two distinct stratigraphic units in the North Pole Dome grew in shallow water conditions, but in two very different geological settings with different morphologies. Stratiform and domical stromatolites in the stratigraphically lower, c. 3490 Ma, Dresser

  3. Inclusiones fluidas e isotopos estables en la ganga de los yacimientos de manganeso del norte de la provincia de Córdoba Fluid inclusions and stable isotopes in non-ore minerals of the manganese ore deposits in the north of the Córdoba province

    Directory of Open Access Journals (Sweden)

    P.R. Leal

    2002-09-01

    Full Text Available En este trabajo se analizan las características físico-químicas asociadas a la precipitación de la ganga de yacimientos epitermales de manganeso. Estos minerales fueron formados principalmente durante la etapa póstuma del sistema, el cual es posible dividir espacialmente en tres sectores en función del mineral más abundante. En esta oportunidad se estudia el sector austral donde el mineral más común es la calcita. El análisis microtermométrico de las inclusiones fluidas sobre muestras de calcita, baritina y fluorita, hizo posible obtener salinidades del fluido de 2,7 y 4% eq. en peso NaCl y temperaturas inferiores a 100°C. Los estudios de isótopos de 13C, 18O y 34S en calcita y baritina permitieron determinar la fuente meteórica de los fluidos asociados a su precipitación. Al mismo tiempo los valores de d13C en calcita se consideran el resultado de un fluido en equilibrio con CO2 atmosférico y cantidades menores de carbono producto de la disolución de compuestos orgánicos. Por otro lado, los valores de d34S de la baritina pueden ser explicados por un fluido con H2S que resulta de la disolución de sulfuros de las rocas de caja. Finalmente, se postula la presencia de dos fluidos. Un fluido ascendente fue el responsable de la precipitación de la baritina en la zona donde el H2S se oxida a SO4=; al mismo tiempo, éste pudo también formar fluorita y variedades de sílice conforme su temperatura desciende. La existencia de un fluido descendente permite explicar la generación de calcita por calentamiento del mismo.In this paper the non-ore minerals of the southern sector of this deposit are studied. Microthermometric analysis on calcite, barite and fluorite show fluid salinities of 2.7 and 4% wt eq. NaCl, and temperatures below 100°C. Isotopes of 13C, 18O and 34S allow to determine a meteoric source for the fluids associated to their precipitation. The d13C values obtained in calcite are considered the result of a fluid in

  4. Assessment of technological solutions for removal of radium discharged to sea from offshore oil and gas installations

    International Nuclear Information System (INIS)

    On the Norwegian sector of the North-Sea the oil- and gas-producing fields Troll B and C are the main contributors to radium discharged to the sea (190 GBq/a 226Ra and 150 GBq/a 228Ra). Thus, to observe effects caused by the emission of radioactivity and to consider remedial action one should focus on these two installations. Both installations are now operated by Statoil. In a previous comprehensive study of the speciation of discharged radium the conclusion was that it is impossible to detect any effect from radiation doses. The incremental doses due to the emissions were found to be in the nSv-range. The study covered precipitation by sulfate in the sea water, absorption on organic and inorganic materials, uptake in cod eggs and in juvenile cod, effect on sediment living organisms, background levels of pelagic fish and in sediments, and modeling of the distribution in the water column as well the distribution along the coastal stream. Despite the lack of radiation effects, an assessment of possible technological solution for removal of the radium has been undertaken. Such methods must meet the severe requirements imposed by the oil recovery process at Troll B and C: High produced water rates (>1000 m3/h), high salinity and content of water soluble carboxylic acids originating from the crude oil, in addition to a relatively high content of barium (3 550 tonnes/a). For implementation on an offshore installation the footprint and weight of the equipment would have to be as low as possible. It is also imperative that the radiation doses to operators are as low as possible. This puts strict requirements on the shielding of the absorbents accumulating 226Ra and 228Ra. No commercially available methods were identified, but one new conceptual method based on absorption of radium on barite has been proposed. Barite is also a good shielding material. Tests performed at Institute for Energy Technology show, however, that the kinetics of the chemical exchange process is far

  5. Assessment of technological solutions for removal of radium discharged to sea from offshore oil and gas installations

    Energy Technology Data Exchange (ETDEWEB)

    Eriksen, Dag Oeistein [Primus.inter.pares AS, Kongsberggata 20, NO-0468 Oslo (Norway); Hylland, Ketil [University of Oslo (Norway); Andersen, Knut Inge [Statoil ASA (Norway); Sidhu, Rajdeep Singh [Institute for Energy Technology - IFE (Norway)

    2014-07-01

    On the Norwegian sector of the North-Sea the oil- and gas-producing fields Troll B and C are the main contributors to radium discharged to the sea (190 GBq/a {sup 226}Ra and 150 GBq/a {sup 228}Ra). Thus, to observe effects caused by the emission of radioactivity and to consider remedial action one should focus on these two installations. Both installations are now operated by Statoil. In a previous comprehensive study of the speciation of discharged radium the conclusion was that it is impossible to detect any effect from radiation doses. The incremental doses due to the emissions were found to be in the nSv-range. The study covered precipitation by sulfate in the sea water, absorption on organic and inorganic materials, uptake in cod eggs and in juvenile cod, effect on sediment living organisms, background levels of pelagic fish and in sediments, and modeling of the distribution in the water column as well the distribution along the coastal stream. Despite the lack of radiation effects, an assessment of possible technological solution for removal of the radium has been undertaken. Such methods must meet the severe requirements imposed by the oil recovery process at Troll B and C: High produced water rates (>1000 m{sup 3}/h), high salinity and content of water soluble carboxylic acids originating from the crude oil, in addition to a relatively high content of barium (3 550 tonnes/a). For implementation on an offshore installation the footprint and weight of the equipment would have to be as low as possible. It is also imperative that the radiation doses to operators are as low as possible. This puts strict requirements on the shielding of the absorbents accumulating {sup 226}Ra and {sup 228}Ra. No commercially available methods were identified, but one new conceptual method based on absorption of radium on barite has been proposed. Barite is also a good shielding material. Tests performed at Institute for Energy Technology show, however, that the kinetics of the

  6. Deep aquifer as driver for mineral authigenesis in Gulf of Alaska sediments (IODP Expedition 341, Site U1417)

    Science.gov (United States)

    Zindorf, Mark; März, Christian; Wagner, Thomas; Strauss, Harald; Gulick, Sean P. S.; Jaeger, John M.; LeVay, Leah J.

    2016-04-01

    Bacterial sulphate reduction plays a key role in authigenic mineral formation in marine sediments. Usually, decomposition of organic matter follows a sequence of microbial metabolic pathways, where microbial sulphate reduction leads to sulphate depletion deeper in the sediment. When sulphate is consumed completely from the pore waters, methanogenesis commences. The contact of sulphate- and methane-containing pore waters is a well-defined biogeochemical boundary (the sulphate-methane transition zone, SMTZ). Here authigenic pyrite, barite and carbonates form. Pyrite formation is directly driven by bacterial sulphate reduction since pyrite precipitates from produced hydrogen sulphide. Barite and carbonate formation are secondary effects resulting from changes of the chemical milieu due to microbial activity. However, this mineral authigenesis is ultimately linked to abiotic processes that determine the living conditions for microorganisms. At IODP Site U1417 in the Gulf of Alaska, a remarkable diagenetic pattern has been observed: Between sulphate depletion and methane enrichment, a ~250 m wide gap exists. Consequently, no SMTZ can be found under present conditions, but enrichments of pyrite indicate that such zones have existed in the past. Solid layers consisting of authigenic carbonate-cemented sand were partly recovered right above the methane production zone, likely preventing continued upward methane diffusion. At the bottom of the sediment succession, the lower boundary of the methanogenic zone is constrained by sulphate-rich pore waters that appear to originate from a deeper source. Here, a well-established SMTZ exists, but in reversed order (sulphate diffusing up, methane diffusing down). Sulphur isotopes of pyrite reveal that sulphate reduction here does not occur under closed system conditions. This indicates that a deep aquifer is actively recharging the deep sulphate pool. Similar deep SMTZs have been found at other sites, yet mostly in geologically

  7. Radionuclide concentrations in oil extraction and production processes in Northeast Brazil

    International Nuclear Information System (INIS)

    Since the beginning of the twentieth century the presence of naturally occurring radioactive material (NORM) was detected in the water and oil extracted from wells both onshore and offshore. The oil is extracted together with water and sediments which contain radionuclides of the uranium and thorium series. Among the radionuclides present, especial attention should be given to 226Ra and 228Ra, due to its long half-life and importance, from the radiological point of view. The objective of this work was to identify the natural radionuclides in the oil industry, to determine their activity concentration, and from these results, to evaluate the risks the employees of the oil industry are exposed to. Samples of sludge, scale and produced water extracted with the oil were collected from three oil processing stations in the state of Sergipe, Brazil. The activity concentrations of the radionuclides were determined in the solid samples before and after the extraction of the oil. The chemical and mineralogical composition of the samples without oil was evaluated. Water samples, on the other hand, were analyzed for their contents of radionuclides and barium concentration. It was observed that the activity concentrations of the analyzed radionuclides (226Ra, 228Ra, 228Th and 210Pb) in sludge and scales were very high when compared with the literature, particularly much higher than the values for 226Ra and 228Ra obtained for sludge and scales from the oil platforms near the city of Campos, state of Rio de Janeiro. The maximum concentration values for 226Ra, 228Ra, 228Th and 210Pb (3,500, 2,195, 2,248.6 and 201 kBq kg-1, respectively) were obtained for the scales after the extraction of the oil. The analysis of the samples showed that barium sulphate (barite) and strontium sulphate (celestite) are the main constituents of the scales, while carbonates and silicates, together with other compounds are the components of sludge. A correlation between barium, 226Ra and 228Ra was

  8. Geologic setting, sedimentary architecture, and paragenesis of the Mesoproterozoic sediment-hosted Sheep Creek Cu-Co-Ag deposit, Helena embayment, Montana

    Science.gov (United States)

    Graham, Garth; Hitzman, Murray W.; Zieg, Jerry

    2012-01-01

    The northern margin of the Helena Embayment contains extensive syngenetic to diagenetic massive pyrite horizons that extend over 25 km along the Volcano Valley-Buttress fault zone and extend up to 8 km basinward (south) within the Mesoproterozoic Newland Formation. The Sheep Creek Cu-Co deposit occurs within a structural block along a bend in the fault system, where replacement-style chalcopyrite mineralization is spatially associated mostly with the two stratigraphically lowest massive pyrite zones. These mineralized pyritic horizons are intercalated with debris flows derived from synsedimentary movement along the Volcano Valley-Buttress fault zone. Cominco American Inc. delineated a geologic resource of 4.5 Mt at 2.5% Cu and 0.1% Co in the upper sulfide zone and 4 Mt at 4% Cu within the lower sulfide zone. More recently, Tintina Resources Inc. has delineated an inferred resource of 8.48 Mt at 2.96% Cu, 0.12% Co, and 16.4 g/t Ag in the upper sulfide zone. The more intact upper sulfide zone displays significant thickness variations along strike thought to represent formation in at least three separate subbasins. The largest accumulation of mineralized sulfide in the upper zone occurs as an N-S–trending body that thickens southward from the generally E trending Volcano Valley Fault and probably occupies a paleograben controlled by normal faults in the hanging wall of the Volcano Valley Fault. Early microcrystalline to framboidal pyrite was accompanied by abundant and local barite deposition in the upper and lower sulfide zones, respectively. The sulfide bodies underwent intense (lower sulfide zone) to localized (upper sulfide zone) recrystallization and overprinting by coarser-grained pyrite and minor marcasite that is intergrown with and replaces dolomite. Silicification and paragenetically late chalcopyrite, along with minor tennantite in the upper sulfide zone, replaces fine-grained pyrite, barite, and carbonate. The restriction of chalcopyrite to inferred

  9. Radionuclide concentrations in oil extraction and production processes in Northeast Brazil; Teores de radionuclideos em processos de extracao e de producao de petroleo no nordeste do Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Gazineu, Maria Helena Paranhos

    2005-06-15

    Since the beginning of the twentieth century the presence of naturally occurring radioactive material (NORM) was detected in the water and oil extracted from wells both onshore and offshore. The oil is extracted together with water and sediments which contain radionuclides of the uranium and thorium series. Among the radionuclides present, especial attention should be given to {sup 226}Ra and {sup 228}Ra, due to its long half-life and importance, from the radiological point of view. The objective of this work was to identify the natural radionuclides in the oil industry, to determine their activity concentration, and from these results, to evaluate the risks the employees of the oil industry are exposed to. Samples of sludge, scale and produced water extracted with the oil were collected from three oil processing stations in the state of Sergipe, Brazil. The activity concentrations of the radionuclides were determined in the solid samples before and after the extraction of the oil. The chemical and mineralogical composition of the samples without oil was evaluated. Water samples, on the other hand, were analyzed for their contents of radionuclides and barium concentration. It was observed that the activity concentrations of the analyzed radionuclides ({sup 226}Ra, {sup 228}Ra, {sup 228}Th and {sup 210}Pb) in sludge and scales were very high when compared with the literature, particularly much higher than the values for {sup 226}Ra and {sup 228}Ra obtained for sludge and scales from the oil platforms near the city of Campos, state of Rio de Janeiro. The maximum concentration values for {sup 226}Ra, {sup 228}Ra, {sup 228}Th and {sup 210}Pb (3,500, 2,195, 2,248.6 and 201 kBq kg{sup -1}, respectively) were obtained for the scales after the extraction of the oil. The analysis of the samples showed that barium sulphate (barite) and strontium sulphate (celestite) are the main constituents of the scales, while carbonates and silicates, together with other compounds are the

  10. Lead and barium sources in Cambrian siliciclastics and sediment provenance of a sector of the Taconic Orogen, Quebec: a mixing scenario based on Pb-isotopic evidence

    Science.gov (United States)

    Schrijver, K.; Zartman, R.E.; Williams-Jones, A. E.

    1994-01-01

    To test the hypothesis that siliciclastic rocks constituted the major source of Pb and Ba in barite-galena deposits of the Taconic Orogen, we determined Pb-isotope ratios in galena, barren rocks and contained minerals, as well as concentrations of Pb, U, Th and Ba in the latter (detrital feldspars, sandstones, mudstones, rock clasts and carbonate cements and clasts). Ranges in 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb of 28 galena samples are 17.96-18.05, 15.56-15.59 and 37.75-37.93, respectively; ranges for 41 barren rocks and minerals are 16.17-23.31, 15.26-15.86 and 35.98-42.51, respectively. The lowest ratios are in feldspar, and the highest in carbonate and mudstone. Values of the mudstones samples overlap those of galena when corrected for in situ decay of U and Th since galena precipitation (???450 Ma). We thus propose that mudstones constituted a source of lead. Corrected ratios for anomalously Pb-rich mudstones are virtually identical to galena-Pb ratios and may be due to contamination by lead-bearing brines. Assuming that burial diagenesis did not disturb the Pb-isotope values of sandstones, these rocks contributed only a minor fraction of lead to the galena, estimated at ???20% for one deposit. The source of barite-Ba was probably perthite. Low Ba and Pb concentrations of sandstone adjacent to this deposit, compared to high concentrations remote from it, support leaching of barium (and minor lead) from feldspar penecontemporaneous with feldspar dissolution. Geological data indicate that the provenance of the siliciclastic rocks was mainly from Grenville terrane. A comparison of our Pb-isotopic data for Taconic perthite with those of Grenville K-feldspar, as well as ratios of trace elements, support this provenance for both sandstones and mudstones. The presence of carbonate platforms peripheral to the orogen, and the Middle Ordovician-Middle Devonian depositional range of the studied and Mississippi Valley type deposits north (Newfoundland) and south (U

  11. The mobility of radium-226 and trace metals in pre-oxidized subaqueous uranium mill tailings

    Energy Technology Data Exchange (ETDEWEB)

    Martin, A.J.; Crusius, J.; Jay McNee, J.; Yanful, E.K

    2003-07-01

    The exchange of {sup 226}Ra and trace metals across the tailings-water interface and the mechanisms governing their mobility were assessed via sub-centimetre resolution profiling of dissolved constituents across the tailings-water interface in Cell 14 of the Quirke Waste Management Area at Rio Algom's Quirke Mine, near Elliot Lake, Ontario, Canada. Shallow zones (<1.5 m water depth) are characterized by sparse filamentous vegetation, well-mixed water columns and fully oxygenated bottom waters. Profiles of dissolved O{sub 2}, Fe and Mn indicate that the tailings deposits in these areas are sub-oxic below tailings depths of {approx}3 cm. These zones exhibit minor remobilization of Ra in the upper 5 cm of the tailings deposit; {sup 226}Ra fluxes at these sites are relatively small, and contribute negligibly to the water column activity of {sup 226}Ra. The shallow areas also exhibit minor remobilization of Ni, As, Mo and U. The release of these elements to the water cover is, however, limited by scavenging mechanisms in the interfacial oxic horizons. The presence of thick vegetation (Chara sp.) in the deeper areas (>2 m water depth) fosters stagnant bottom waters and permits the development of anoxia above the benthic boundary. These anoxic tailings are characterized by substantial remobilization of {sup 226}Ra, resulting in a relatively large flux of {sup 226}Ra from the tailings to the water column. The strong correlation between the porewater profiles of {sup 226}Ra and Ba (r{sup 2}=0.99), as well as solubility calculations, indicate that the mobility of Ra is controlled by saturation with respect to a poorly ordered and/or impure barite phase [(Ra,Ba)SO{sub 4}]. In the anoxic zones, severe undersaturation with respect to barite is sustained by microbial SO{sub 4} reduction. Flux calculations suggest that the increase in {sup 226}Ra activity in the water cover since 1995 (from <0.5 to 2.5 Bq l{sup -1}) can be attributed to an increase in the spatial

  12. Calc-alkaline Magmatic Activities and Related Mineralization in the Northwest of the Lut Block (Eastern Iran)

    Science.gov (United States)

    Saadat, S.; Stern, C.; Hadizadeh, H.; Ghoorchi, M.

    2008-12-01

    The Lut Block of Eastern Iran has significant mineral potential based on its tectonic setting, geologic evolution, Tertiary igneous rock cover and old mining records. In the Ahang prospecting area (~ 40Km2), located in northwest of the Lut block, magmatic activities started in Eocene with the eruption of mafic to intermediate extrusives, mainly andesites. These rocks are intruded by Oligocene-Miocene monzodiorite and quartz monzonite stocks and cut by felsic dikes. Intrusive rocks are meta-aluminous and belong to the high-K calc-alkaline series. The results of REE analysis show that these rocks are enriched in La relative to Yb. Their ratios of Ta+Yb versus Rb suggest the VAG (volcanic arc granites) geotectonic regime for their origin. Propylitic, sericitic, argillic and silicification alteration zones are well developed in this area. Based on heavy minerals studies of stream sediments, Wulfenite, Stolzite, Galena, Sphalerite, Diaboleite, Dechenite, Mimetite, Pyrite, Celestine, Barite, Flourite, Malachite and Sapphire are present in this area. Geochemical analysis of stream sediment samples indicates considerable anomalous zones of W, Pb, Zn, Cu, Au, As, Sb and also Ba and F. Mineralization as veins, veinlet and minor stockwork are mainly controlled by structural features and brecciated zones. Mineralization occurs in three types: Quartz- Hematite- Galena (high grade of Pb, Zn, Au, As, W); Quarts- Pyrite- Chalcopyrite and Galena (high grade of Cu, Mo, Ag, Zn, Pb), and Quartz- Barite- Celestine- Galena and flurine (high grade of F, Sr, Ba, Pb). The range of value for these elements in mineralized rock samples are: Cu (5-1500ppm), Mo (0.5-109ppm), Pb (20ppm-14%), Zn (8ppm-7.8%), W (5-1350ppm), As (1-723ppm), Ag (0.5-56.5ppm), Au (7ppb-7.8ppm). According to the field observations and data presented here, this area has a high potential for base-metal, W and Au mineral exploration. Keywords: Calc-alkaline magmatism, Lut Block, mineralization, Iran

  13. Mineralogical, textural, geochemical and thermometric characteristics of Central Anatolian fluorites (Turkey): Tracing the origin of post-magmatic fluids

    Science.gov (United States)

    Cosanay, Pelin; Mutlu, Halim; Koc, Sükrü; Cevik, Nihal; Oztürk, Ceyda; Varol, Ece

    2016-04-01

    In this study, we investigate the spatial distribution of fluorite veins in Central Anatolia with emphasis on mineralogical, textural, geochemical and thermometric variations. The studied fluorite mineralizations (Kaman, Akçakent, Pöhrenk and Şefaatli mineralizations from west to east) are located on northern part of Kırşehir Massif which is a part of Central Anatolian Crystalline Complex that is bordered by the İzmir-Ankara-Erzincan Suture Zone. The Kaman, Akçakent and Şefaatli fluorite deposits are formed in association with magmatic rocks such as syenite and monzonite / monzodiorite in composition which are of Upper Cretaceous age. Fluorite in these deposits occurs as purple- and green-colored stockwork veins and/or disseminations along fault/fracture systems and is accompanied by quartz and rare pyrite. The Pöhrenk ore, however, is precipitated as space filling-breccia type within karstic voids of Eocene limestones and marl levels. The silicification/carbonatization and barite occurrences are found as the main alteration and secondary products of mineralization. Thickness of fluorite veins is between 2 and 30 cm. ΣREE contents of host rocks and fluorite veins are in the range of 2-806 ppm and 20-390 ppm, respectively. In element variation diagrams constructed for both host rocks and fluorite mineralizations, LREE concentrations are found to be greater than HREEs. REE contents of green-colored fluorites are about 10-fold higher than those of purple-colored ones. Negative Ce and Eu anomalies indicate high oxygen fugacity for the mineralizing fluids. Fluid inclusion studies indicated three different types of inclusions: 1) two-phase (liquid-vapor) primary and secondary inclusions, 2) single-phase (liquid) primary and secondary inclusions and 3) two-phase (liquid-vapor) and single-phase (liquid) pseudo-secondary inclusions. Results of homogenization temperatures from a number of about 200 measurements chiefly on fluorite and less often quartz and barite

  14. EVALUATIONS OF RADIONUCLIDES OF URANIUM, THORIUM, AND RADIUM ASSOCIATED WITH PRODUCED FLUIDS, PRECIPITATES, AND SLUDGES FROM OIL, GAS, AND OILFIELD BRINE INJECTION WELLS IN MISSISSIPPI

    Energy Technology Data Exchange (ETDEWEB)

    Charles Swann; John Matthews; Rick Ericksen; Joel Kuszmaul

    2004-03-01

    Naturally occurring radioactive materials (NORM) are known to be produced as a byproduct of hydrocarbon production in Mississippi. The presence of NORM has resulted in financial losses to the industry and continues to be a liability as the NORM-enriched scales and scale encrusted equipment is typically stored rather than disposed of. Although the NORM problem is well known, there is little publically available data characterizing the hazard. This investigation has produced base line data to fill this informational gap. A total of 329 NORM-related samples were collected with 275 of these samples consisting of brine samples. The samples were derived from 37 oil and gas reservoirs from all major producing areas of the state. The analyses of these data indicate that two isotopes of radium ({sup 226}Ra and {sup 228}Ra) are the ultimate source of the radiation. The radium contained in these co-produced brines is low and so the radiation hazard posed by the brines is also low. Existing regulations dictate the manner in which these salt-enriched brines may be disposed of and proper implementation of the rules will also protect the environment from the brine radiation hazard. Geostatistical analyses of the brine components suggest relationships between the concentrations of {sup 226}Ra and {sup 228}Ra, between the Cl concentration and {sup 226}Ra content, and relationships exist between total dissolved solids, BaSO{sub 4} saturation and concentration of the Cl ion. Principal component analysis points to geological controls on brine chemistry, but the nature of the geologic controls could not be determined. The NORM-enriched barite (BaSO{sub 4}) scales are significantly more radioactive than the brines. Leaching studies suggest that the barite scales, which were thought to be nearly insoluble in the natural environment, can be acted on by soil microorganisms and the enclosed radium can become bioavailable. This result suggests that the landspreading means of scale disposal

  15. A retrospective analysis of trace metals, C, N and diatom remnants in sediments from the Mississippi River delta shelf.

    Science.gov (United States)

    Turner, R Eugene; Milan, C S; Rabalais, N N

    2004-10-01

    The development of oil and gas recovery offshore of the Mississippi River delta began in shallow water in the 1950s, expanded into deeper waters, and peaked in the 1990s. This area of the outer continental shelf (OCS) is the historical and present location of >90% of all US OCS oil and gas production and reserves. The juxtaposition of its 4000 producing platforms, recovering $10 billion yr(-1) of oil, gas and produced water in the same area where about 28% of the US fisheries catch (by weight) is made and near 40% of the US coastal wetlands, makes this an area worth monitoring for regional pollutant loading. This loading may come from several sources, including sources related to OCS development, but also from the Mississippi River watershed. In this context, any contaminant loading on this shelf may be neither detectable nor significant against a background of climatic or biological variability. We examined the sedimentary record for indicators of industrial byproducts from OCS oil and gas development and of industrial products entering via the Mississippi River, primarily using vanadium (V) and barium (Ba) concentrations normalized for aluminum (Al). Barium is primarily used in drilling muds in the form of barite, whereas V is an important strengthening component of metal alloys, including steel. The fluctuations in the accumulation of Ba, but not V, were coincidental with the presumed use of barite. The fluctuations in V concentration in the sediments were coincidental with the national consumption of V. Copper (Cu), cadmium (Cd) and zinc (Zn) concentrations in sediments fluctuate coincidentally with V, not Ba, thus indicating that the dominant source of these trace metals in offshore sediments were derived from riverine sources, and were not primarily from in situ industrial processes releasing them on the shelf. This is not to suggest that local site-specific contamination is not a significant management or health concern. The low oxygen (hypoxia; Mississippi

  16. Estudio de inclusiones fluidas de las mineralizaciones epitermales de Ag.Baritina.metales de base de Hiendelaencina y de Baritina de Atienza (Sistema Central Español

    Directory of Open Access Journals (Sweden)

    Oyarzun, R.

    1991-08-01

    Full Text Available Fluid inclusion studies on quartz and barite samples from the Hiendelaencina Ag-base metals epithermal deposit (late Hercynian suggest that this mineralization was formed during four hydrothermal stages. Ore stage I was characterized by aqueous-carbonic fluids from which pyrite and arsenopyrite were precipitated. The interaction between probably magmatic-derived fluids (aqueous solutions; Th = 320 – 200º C, 12 eq. wt. % NaCl and meteoric waters (of lower temperature and salinity caused a generalized decrease in both, T and salinity (from 12 eq. wt. % NaCl to 3 eq. wt. % NaCl, thus probably inducing the precipitation of Cu and Zn minerals (ore stage 11. Ore stage 111 (silver stage was characterized by the interaction between fluids of low temperature and contrasted salinities (Th = 100 – 150º C; 3 eq. wt. % NaCl to 18-22 eq. wt. % NaCl. A final and «barren stage » (stage IV resulted in the precipitation of a late generation of quartz and barite.Estudios de inclusiones fluidas en muestras de cuarzo y baritina del yacimiento epitermal argentífero de Hiendelaencina sugieren que esta mineralización se formó a lo largo de cuatro episodios hidrotermales. El estadio mineral I estuvo caracterizado por la presencia de fluidos acuoso-carbónicos que precipitaron pirita y arsenopirita. La interacción entre fluidos de probable origen magmático (soluciones acuosas; Th = 320 – 200º C, 12 % eq. NaCl y fluidos de origen meteórico (de menor temperatura y salinidad causó un decrecimiento generalizado en T y salinidad (desde 12 % eq. NaCl a 3 % eq. NaCl, lo cual probablemente indujo la precipitación de minerales de Cu y Zn (estadio mineral 11. El estadio mineral 111 (estadio argentífero se caracterizó por la interacción entre fluidos de baja temperatura pero de salinidades contrastadas (Th = 100 – 150º C; 3 % eq. NaCl a 18-22 % eq. NaCl. Un estadio final y estéril (estadio mineral IV originó la precipitación de

  17. Compositional Grading in an Impact-produced Spherule Bed, Barberton Greenstone Belt, South Africa: A Key to Condensation History of Rock Vapor Clouds

    Science.gov (United States)

    Krull, A. E.; Lowe, D. R.; Byerly, G. R.

    2003-01-01

    The chemical and physical processes by which spherules form during the condensation of impact-produced rock vapor clouds are poorly understood. Although efforts have been made to model the processes of spherule formation, there is presently a paucity of field data to constrain the resulting theoretical models. The present study examines the vertical compositional variability in a single early Archean spherule bed in the Barberton Greenstone Belt (BGB), South Africa, in order to better identify the process by which impact vapor clouds condense and spherules form and accumulate. The BGB spherule beds are suitable for this type of study because of their great thickness, often exceeding 25cm of pure spherules, due to the massive sizes of the impactors. Two main problems complicate analysis of vertical compositional variability of graded spherule beds: (1) differential settling of particles in both the vapor and water column due to density and size differences and (2) turbulence within the vapor cloud. The present study compares sections of spherule bed S3 from four different depositional environments in the Barberton Greenstone Belt: (1) The Sheba Mine section (SAF-381) was deposited under fairly low energy conditions in deep water, providing a nice fallout sequence, and also has abundant Ni-rich spinels; (2) Jay's Chert section (SAF-380) was deposited in subaerial to shallow-water conditions with extensive post-depositional reworking by currents. The spherules also have preserved spinels; (3) the Loop Road section (loc. SAF-295; samp. KSA-7) was moderately reworked and has only rare preservation of spinels; and (4) the shallow-water Barite Syncline section (loc. SAF-206; samp KSA-1) has few to no spinels preserved and is not reworked. Although all of the spherule beds have been altered by silica diagenesis and K-metasomatism, most of the compositional differences between these sections appear to reflect their diagenetic histories, possibly related to their differing

  18. Health and ecological hazards due to natural radioactivity in soil from mining areas of Nasarawa State, Nigeria.

    Science.gov (United States)

    Aliyu, Abubakar Sadiq; Ibrahim, Umar; Akpa, Chidozie Timothy; Garba, Nuraddeen Nasiru; Ramli, Ahmad Termizi

    2015-01-01

    Nasarawa State is located in north central Nigeria and it is known as Nigeria's home of solid minerals. It is endowed with barite, copper, zinc, tantalite and granite. Continuous releases of mining waste and tailings into the biosphere may result in a build-up of radionuclides in air, water and soil. This work therefore aims to measure the activity concentration levels of primordial radionuclides in the soil/sediment samples collected from selected mines of the mining areas of Nasarawa State. The paper also assesses the radiological and radio ecological impacts of mining activities on the residents of mining areas and their environment. The activity concentrations of primordial radionuclides ((226)Ra, (232)Th and (40)K) in the surface soils/sediment samples were determined using sodium iodide-thallium gamma spectroscopy. Seven major mines were considered with 21 samples taken from each of the mines for radiochemistry analysis. The human health hazard assessment was conducted using regulatory methodologies set by the United Nations Scientific Committee on the Effects of Atomic Radiation, while the radio ecological impact assessment was conducted using the ERICA tool v. 1.2. The result shows that the activity concentrations of (40)K in the water ways of the Akiri copper and the Azara barite mines are 60 and 67% higher than the world average value for (40)K, respectively. In all mines, the annual effective dose rates (mSv y(-1)) were less than unity, and a maximum annual gonadal dose of 0.58 mSv y(-1) is received at the Akiri copper mine, which is almost twice the world average value for gonadal dose. The external hazard indices for all the mines were less than unity. Our results also show that mollusc-gastropod, insect larvae, mollusc-bivalve and zooplankton are the freshwater biotas with the highest dose rates ranging from 5 to 7 µGy h(-1). These higher dose rates could be associated with zinc and copper mining at Abuni and Akiri, respectively. The most exposed

  19. The mobility of radium-226 and trace metals in pre-oxidized subaqueous uranium mill tailings

    International Nuclear Information System (INIS)

    The exchange of 226Ra and trace metals across the tailings-water interface and the mechanisms governing their mobility were assessed via sub-centimetre resolution profiling of dissolved constituents across the tailings-water interface in Cell 14 of the Quirke Waste Management Area at Rio Algom's Quirke Mine, near Elliot Lake, Ontario, Canada. Shallow zones (2, Fe and Mn indicate that the tailings deposits in these areas are sub-oxic below tailings depths of ∼3 cm. These zones exhibit minor remobilization of Ra in the upper 5 cm of the tailings deposit; 226Ra fluxes at these sites are relatively small, and contribute negligibly to the water column activity of 226Ra. The shallow areas also exhibit minor remobilization of Ni, As, Mo and U. The release of these elements to the water cover is, however, limited by scavenging mechanisms in the interfacial oxic horizons. The presence of thick vegetation (Chara sp.) in the deeper areas (>2 m water depth) fosters stagnant bottom waters and permits the development of anoxia above the benthic boundary. These anoxic tailings are characterized by substantial remobilization of 226Ra, resulting in a relatively large flux of 226Ra from the tailings to the water column. The strong correlation between the porewater profiles of 226Ra and Ba (r2=0.99), as well as solubility calculations, indicate that the mobility of Ra is controlled by saturation with respect to a poorly ordered and/or impure barite phase [(Ra,Ba)SO4]. In the anoxic zones, severe undersaturation with respect to barite is sustained by microbial SO4 reduction. Flux calculations suggest that the increase in 226Ra activity in the water cover since 1995 (from -1) can be attributed to an increase in the spatial distribution of anoxic bottom waters caused by increased density of benthic flora. The anoxic, vegetated areas also exhibit minor remobilization with respect to dissolved As, Ni and Zn. The removal of trace metals in the anoxic bottom waters appears to be limited

  20. Transmission curves applied to mammography area using GEANT4

    International Nuclear Information System (INIS)

    Full text: On these days we are using each more and more virtual reality and Monte Carlo Calculation technique to simulate the radiation interaction to biological matter. It come to be used applied on radiation protection. In mammography it has been used to compare different irradiation considerations. This work purpose is to generate a data bank of transmission data applied to different mammographic spectra. The transmission curve as function of different material thickness in a base to estimate shielding thickness. Commonly are used lead as standard-shielding-material in diagnostic radiology area. We built the realistic computational universe, described in GEANT4 (version 9.1), considering: one source point irradiating a scattering-phantom (8 cm thicker, homogeneously composed by BR12), the last one 1,0 m far from the source; a polienergitic spectra from 24 kVp up to 40 kVp were used; a different target-add filtration combination (Mo-30μmMo, Mo-25μmRh, Rh-25μmRh, W-50μmRh, W-60μmMo, W-40μmPd); a sensitive volume - scattering object distance of 1.1 m; a wall 1.0 m far from to scattering-object having 1.60 m high and 1.60 m large with different thickness according the shielding material (lead, concrete, barite concrete, barite mortar, glass-lead). As results were generated graphics showing the behavior and comparing some curves to Legare and NCRP 147 data, that shown good agreement, specially to spectra higher than 30 kVp. It happened because to lower energy spectra lower flux of scattered radiation will cross the shielding-wall. Adjustment equation for each material of transmission data as a function of the thickness, and thickness as a function of the transmission data were build using the Origin software resources. Those adjustment equations complete the data bank and present chi-square test values up than 0.9. We got a data bank transmission curves that showed good agreement on comparing our results to the other authors. However we got a larger data bank

  1. SEDIMENTARY LOW-MANGANESE HEMATITE DEPOSITS OF THE BUKOVICA AREA IN THE NORTHWESTERN MT. PETROVA GORA, CENTRAL CROATIA

    Directory of Open Access Journals (Sweden)

    Milivoj Čop

    1998-12-01

    Full Text Available Middle-Permian Gröden deposits crop out on the surface of 0.8 km in the Bukovica area and on the surface of 0.8 km2 in the Mt. Loskun-jska gora in the NW part of the Petrova gora Mountain. One half of the Bukovica Gröden deposits contains in its lowest parts 1 to 5 m (in average 2.5 m thick hematite bed cutted in blocks by NE-SW stretch¬ing vertical, normal and reverse faults. The hematite bed is unconfor-mably underlain by Lower Permian quartz-wackes (subgraywackes intercalated with shales intercalations. Ore deposit is explored by 308 boreholes (10509 m and by numerous adits, inclines and crosscuts on the underground surface of 0.4 km2 . From 1936 to 1941 and from 1953 to 1969 has been exploited 183000 t of ore with (in wt %: 34.0 Si02, 2.9 Al2O3; 59.0 Fe203; 0.15 MnO; 0.7 CaO; 0.4 MgO; 0.1 P, 0.37 S; 1.25 l.o. ign. Proven remaining ore reserves are 250.000 t. Paragenesis is investigated by microscopy of thin and polished sections, XRD, DTA, AAS analyses and by sedimentological analyses. Paragenesis major minerals are of hematite and quartz, with subordinate stable litho-clasts, muscovite (sericite and scarce kaolinite, calcite, dolomite, and barite. Accessories are zircon, rutile, tourmaline, amphibole, garnet, apatite. Epigenetic veinlets and small nests are built up of quartz or calcite as the main neominerals associated with siderite, barite, kaolinite, pyrite, gypsum. Iron from the Bukovica hematite ore origi¬nated by land weathering during hot climate and transported by rivers and underground waters deposited in river beds, in flood plains and in shallow sea. Precipitation of the Bukovica iron ores took place after the Saalic orogenetic phase. At Hrastno (SE Slovenia and at Rude nearby Samobor (Croatia, similar hematite deposits were found.

  2. U-Th and ESR dating of drilled cores from a giant hydrothermal mounds in South Mariana

    Science.gov (United States)

    Takamasa, A.; Nakai, S.; Sato, F.; Toyoda, S.; Ishibashi, J.

    2012-12-01

    The time scale for hydrothermal activity is an important factor controlling the size of hydrothermal ore deposits and the evolution of chemosynthesis-based communities in a submarine hydrothermal system. We determined the age of hydrothermal deposits samples, both collected samples by submersible and drilled core samples from South Mariana Trough. Samples were collected from four hydrothermal sites, Snail (near the spreading axis), Archean ( 1.5km from the axis), Pika ( 4.9km from the axis) and Urashima ( 4.9km from the axis). 230Th-234U radioactive disequilibrium dating was applied to hydrothermal sufide minerals consisting of pyrite and sphalerite while electron spin resonance (ESR) dating was applied to barite. For 230Th-234U radioactive disequilibrium dating, we carried out magnetic separation for bulk samples, then we digested samples with nitric acid. U and Th were purified by two-step column separations, and isotopic compositions of spiked and unspiked U and Th were measured by a MC-ICP-MS. Analytical methods for ESR age determination were described in a companion abstract by Toyoda et al. We found that the magnetic fractions had significantly higher U/Th ratios, which enabled 230Th-234U age determinations as precise as ±2% (2σ). This probably reflects that pyrite enriched in magnetic fractions has high U/Th ration. In a sulfide crust sample collected from Archean site, the 230Th-234U ages of the sulfide minerals (0.3-2.2 ka) were compared with ESR ages of barites separated from 12 subsamples of the same sulfide crust. ESR ages (0.27 - 1.7 ka) show a spatial pattern broadly resembling that observed in 230Th-234U dating method. While there are some significant offsets, these results illustrate the potential of the two methods for use in provide information on evolution history of a hydrothermal system. Samples from Pika, Archean and Snail sites yield from 0.5 to ~9 ka, from 0.1 to 3 ka and < ~90 a, respectively. The oldest ages from each site are correlated

  3. Biomineralization of radioactive sulfide minerals in strong acidic Tamagawa hot springs

    International Nuclear Information System (INIS)

    Bioaccumulation of radioactive sulfide minerals by bacteria in strong acidic hot spring water was found at Tamagawa Hot Springs, Akita prefecture in Japan. The hot spring water produces Hokutolite of radioactive minerals high radium and radon. The β-ray measurements of sediments and biofilms indicate 1850-2420 and 5700 cpm, respectively, which are 50-100 times higher than that of the water and the air (50-90 cpm). The characteristics of hot spring water show pH (1.2), Eh (140 mV), EC (29 mS/cm), DO (0.8 mg/l), and water temperature (99.5degC), indicating extremely strong acidic and reducing conditions. The hot spring water contains mainly HCl associated with high concentrations of Ca2+, Al3+, Fe2+, HSO4- and SO42-. SEM-EDX and TEM demonstrate some insight into how microorganisms affect the chemistry and microbiological characteristics of the strong acidic surroundings with high S, As, Ba, and Ca contents in biofilms. Especially SEM-EDX, ED-XRF, and STEM-EDX elemental content maps illustrate the distribution of sulfur-bearing compounds of barite (BaSO4), gypsum (CaSO4·2H2O), elemental sulfur (S) and orpiment(As2S3) in the reddish orange biofilms. The presence of a hydrogen sulfide-rich (H2S) thermal spring and gypsum deposits suggest the volatilization of H2S from the spring water, oxidation of the H2S gas to sulfuric acid, and reaction of the sulfuric acid. TEM micrographs of bacteria in the biofilms reveal in detail the intimate connections between biological and mineralogical processes that the cells are entirely accumulated with spherical grains, 100∼200 nm in diameter. The relationship among sulfide minerals, such as barite, gypsum, sulfur, orpiment, and Hakutolite, associated with bacteria implies that heavy metals have been transported from strong acidic hot spring water to sediments through bacteria metabolism. It is possible that the capability of radioactive sulfide biofilms for heavy metal immobilization can be used to counteract the disastrous

  4. Mineralogical characterization of airborne individual particulates in Beijing PM10

    Institute of Scientific and Technical Information of China (English)

    LU Sen-lin; SHAO Long-yi; WU Ming-hong; JIAO Zheng

    2006-01-01

    This work mainly focuses on the mineralogical study of particulate matter(PM10) in Beijing. Samples were collected on polycarbonate filter from April, 2002 to March, 2003 in Beijing urban area. Scanning electronic microscopy coupled with energy dispersive X-ray(SEM/EDX) was used to investigate individual mineral particles in Beijing PM10. 1454 individual mineral particulates from 48 samples were analysed by SEM/EDX. The results revealed that mineral particulates were complex and heterogeneous. 38kinds of minerals in PM10 were identified. The clay minerals, of annual average percentage of 30.1% , were the main composition among the identified minerals, and illite/smectite was the main composition in clay minerals, reaching up to 35%. Annual average percentage of quartz, calcite, compound particulates, carbonates were 13.5%, 10.9%, 11.95%, 10.31%, respectively. Annual average percentage less than 10% were gypsum, feldspar, dolomite, and so on. Fluorite, apatite, halite, barite and chloridize zinc (ZnCl2) were firstly identified in Beijing PM10. Sulfurization was found on surface of mineral particles, suggested extensive atmospheric reaction in air during summer.

  5. Examining the ground layer of St. Anthony from Padua 19th century oil painting by Raman spectroscopy, scanning electron microscopy and X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Vanco, Lubomir, E-mail: lubomir.vanco@stuba.sk [Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Kadlecikova, Magdalena; Breza, Juraj [Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Caplovic, Lubomir [Faculty of Materials Science and Technology, Slovak University of Technology, Paulinska 16, 917 24 Trnava (Slovakia); Gregor, Milos [Faculty of Natural Sciences, Comenius University, Mlynska dolina, 842 15 Bratislava (Slovakia)

    2013-01-01

    Highlights: Black-Right-Pointing-Pointer Raman spectroscopic examination of uncovered and covered paint layers of a real painting. Black-Right-Pointing-Pointer Deconvolution of Raman peaks of lead white. Black-Right-Pointing-Pointer Comparison of results with energy-dispersive analysis and X-ray diffraction. - Abstract: In this paper we studied the material composition of the ground layer of a neoclassical painting. We used Raman spectroscopy (RS) as a prime method. Thereafter scanning electron microscopy combined with energy dispersive spectroscopy (SEM-EDS) and X-ray powder diffraction (XRD) were employed as complementary techniques. The painting inspected was of the side altar in King St. Stephen's Church in Galanta (Slovakia), signed and dated by Jos. Chr. Mayer 1870. Analysis was carried out on both covered and uncovered ground layers. Four principal compounds (barite, lead white, calcite, dolomite) and two minor compounds (sphalerite, quartz) were identified. This ground composition is consistent with the 19th century painting technique used in Central Europe consisting of white pigments and white fillers. Transformation of lead white occurred under laser irradiation. Subdominant Raman peaks of the components were measured. The observed results elucidate useful partnership of RS and SEM-EDS measurements supported by X-ray powder diffraction as well as possibilities and limitations of non-destructive analysis of covered lower layers by RS.

  6. Methane seeps, methane hydrate destabilization, and the late Neoproterozoic postglacial cap carbonates

    Institute of Scientific and Technical Information of China (English)

    JIANG Ganqing; SHI Xiaoying; ZHANG Shihong

    2006-01-01

    Methane hydrates constitute the largest pool of readily exchangeable carbon at the Earth's sedimentary carapace and may destabilize, in some cases catastrophically, during times of global-scale warming and/or sea level changes. Given the extreme cold during Neoproterozoic ice ages, the aftermath of such events is perhaps amongst the most likely intervals in Earth history to witness a methane hydrate destabilization event. The coincidence of localized but widespread methane seep-like structures and textures, methane-derived isotopic signal,low sulfate concentration, marine barites, and a prominent, short-lived carbon isotope excursion (δ13C≤-5‰) from the post-Marinoan cap carbonates (~635 Ma) provides strong evidence for a methane hydrate destabilization event during the late Neoproterozoic postglacial warming and transgression. Methane release from hydrates could cause a positive feedback to global warming and oxidation of methane could result in ocean anoxia and fluctuation of atmospheric oxygen, providing an environmental force for the early animal evolution in the latest Neoproterozoic. The issues that remain to be clarified for this event include the trigger of methane hydrate destabilization, the time of initial methane release, the predicted ocean anoxia event and its relationship with the biological innovation, additional geochemical signals in response to methane release, and the regional and global synchrony of cap carbonate precipitation. The Doushantuo cap carbonate in South China provides one of the best examples of its age for a better understanding of these issues.

  7. The investigation of gamma and neutron shielding properties of concrete including basalt fibre for nuclear energy applications

    International Nuclear Information System (INIS)

    In this study, we would like to draw attention to the prospect of basalt fibre as the main component for concrete reinforcement of NPP. This work describes the computational study of gamma attenuation parameters, the effective atomic number Z(eff) and the effective electron density Ne(eff), of relatively light-weight concrete with chopped basalt fibre used as reinforcement in different mixture rates. We can draw the following conclusions. Basalt fibre is a relatively cheap material that can be used as reinforcement instead of metallic fibers. Basalt fibre has a similar specific gravity to that of concrete elements. Basalt fibre has high chemical and abrasion resistance. Basalt fibre has almost 10 times the tensile strength of steel re-bars. Gamma-ray attenuation coefficients increase with addition of basalt fibre into concrete in every case. The effective atomic number of the concrete increases with the addition of basalt fibre. The results show that basalt fibre reinforced concrete have improved shielding properties against gamma rays in comparison with regular concrete. This result is based on a regular concrete with only basalt fiber reinforcement. We estimate that with addition of standard aggregates for radiation shielding concrete, such as barite, magnetite or hematite, the shielding properties will increase exponentially

  8. Drilling fluids formulation with cationic hydro-soluble polymers as inhibitors reactive shales; Formulacao de fluidos de perfuracao contendo polimeros cationicos hidrossoluveis como inibidores de formacoes reativas

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Carlos Eduardo C. de; Nascimento, Regina Sandra V. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Quimica; Sa, Carlos Henrique [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES)

    2004-07-01

    Poly(diallyldimethylammonium chloride), having different molecular weight, and a copolymer with acrylamide were evaluated as shale inhibitor additive for water based drilling fluid, as well as the compatibility of these polycations with others additives present in the drilling fluid and the testing results for these fluids were compared with those for formulations with commercial cationic polymers from drilling fluids additives suppliers. The ability of the polymers and KCl systems in inhibiting the clay's dispersion were evaluated with hot rolling tests. The others additives, like viscosifier and fluid loss control agent, had their added amount systematically optimized by rheological and filtration tests. All cationic polymers and the electrolyte were able to inhibit the swelling and dispersion of clay and the results showed a synergistic increase in clay inhibition for the combination of polymer and KCl over either additive alone. The results suggested that greater polymer adsorption, implies in lower content of water in clays and better inhibition of swelling and dispersion of the clay. The polycations were compatible with the other additives in drilling fluids and the fluids formulated with these polymers were able to inhibit efficiently the dispersion and disintegration of clay and to keep the cuttings and barite in suspension. (author)

  9. Determination of the mineral stability field of evolving groundwater in the Lake Bosumtwi impact crater and surrounding areas

    Science.gov (United States)

    Loh, Yvonne Sena Akosua; Yidana, Sandow Mark; Banoeng-Yakubo, Bruce; Sakyi, Patrick Asamoah; Addai, Millicent Obeng; Asiedu, Daniel Kwadwo

    2016-09-01

    Conventional graphical techniques, mass balance geochemical modelling, and multivariate statistical methods were jointly applied to hydrogeochemical data of groundwater from the fractured rock aquifer system, and surface water in the Bosumtwi and surrounding areas to reveal evolutionary trends and the characteristics of evolving groundwater in the area. Four clusters distinguished from the Q-mode hierarchical cluster analysis (HCA) comprised three main groundwater associations and one surface water group (lake water). Although both water resources are of low mineralization (TDS < 1000 mg/l), it was observed that the groundwater from the upper catchment with hydrochemical facies dominated by Nasbnd Mgsbnd HCO3-, evolves to Casbnd Mgsbnd and mixed cations HCO3- water types at the lower reaches. The lake water on the other hand is Nasbnd HCO3- water type. Results from principal component analyses (PCA) and other geochemical interpretations distinguished three sources of variations in the hydrochemistry. Saturation indices of possible reactive mineral phases show groundwater undersaturation relative to albite, anorthite, aragonite, barite, calcite, chlorite, chrysotile, dolomite, gypsum, k-felspar and talc, and supersaturation with respect to gibbsite, kaolinite, Ca-montmorillonite and k-mica in the area. The PCA and other geochemical interpretation identify weathering of feldspars and carbonate mineral dissolution as predominantly influencing the hydrochemistry of the groundwater. Hydrolysis of the aluminosilicates causes the groundwater to reach equilibrium with kaolinite. In addition to dissolution of silicates, the chemical composition of the lake water has been influenced by evaporation and consequent carbonate saturation.

  10. Mineralogical, textural, structural and geochemical aspects of Nakhlak lead mine, Isfahan

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Jazi

    2010-11-01

    Full Text Available Nakhlak lead mine is located at the Nakhlak mountain 55 km NE of Anarak town in Isfahan province. The mineralogy is simple; galena and barite are the main primary minerals and cerussite is the main secondary mineral. Sphalerite, pyrite, chalcopyrite, tetrahedrite-tennantite and acanthite occur as minor and trace mineral inclusions in galena. Secondary minerals are anglesite, plattnerite, wulfenite and malachite. The host rock has undergone a pre-mineralization dolomitization process. Four types of dolomite have been identified which saddle dolomite is the most distinguished. Open space filling textures occur in the form of breccia, cockade, crustification and colloform. Analysis of the galena samples indicates presence of many trace elements in galena among which silver is the most important. Element pairs such as Ag-As, Zn-Cd, As-Cu and As-Sb are highly correlated. This correlation may be explained by the presence of inclusions. Ag-Sb-Bi ternary diagram indicates that galena samples from Nakhlak are rich in Ag and Sb and poor in Bi. Sb/Bi (3773 ratio in galena is suggestive of a low temperature of formation for the deposit. The Upper Cretaceous carbonate host rocks and their dolomitization, the stratabound and epigenetic mineralization, the absence of igneous activity, the open space filling texture, the simple mineralogy and geochemistry all point to a Mississippi valley type model for the Nakhlak Pb deposit.

  11. Transport and distribution studies of uranium and its alpha-emitting daughter products on drill core from the Red Desert and Copper Mountain test sites, Wyoming using nuclear emulsions and Po-210. Final report

    International Nuclear Information System (INIS)

    The Po-210 data, disequilibrium measurements, and nuclear-emulsion observations combine to provide an internally consistent picture in which Ra-226 is relatively free to move and is now doing so. Rn-222 is also free to move, but the distance this isotope moves is apparently limited, possibly because of its short half-life. In any case, significant numbers of unsupported Rn-222 atoms do not appear to be transported towards the surface, nor have they decayed to produce a measurable Po-210 gradient. In contrast, the nuclear-emulsion studies show that unsupported Ra-226, some of which is associated with an alpha-active, high-relief mineral phase (possibly barite), is widely dispersed. This unsupported Ra-226 is found both in surface-soil samples as well as throughout the cores. There is a strong suggestion that this unsupported Ra-226 and its longer-lived parents may be responsible for the observed Rn-222 and Po-210 soil anomalies that have been observed at the surface. The exploration geologist may find that these relationships between Ra-226 and Po-210 can be used in the field as an effective radiochemical technique in the search for uranium

  12. Oxygen isotope fractionation factors between anhydrite and water from 100 to 5500C

    International Nuclear Information System (INIS)

    Oxygen isotope exchange between anhydrite and water was studied from 100 to 5500C, using the partial equilibrium method. The exchange rate was extremely low in NaCl solution. In the lower-temperature range, acid solutions were used to produce sufficient reaction to determine the oxygen isotope fractionation factors. The fractionation factors obtained in the present study are definitely different from those given by Lloyd. They are similar to those for the HSO-4-water system studied by Mizutani and Rafter, and are consistently 2 promille higher than those of the barite-water system by Kusakabe and Robinson. The temperature dependence of the oxygen isotope fractionation factors was calculated by the least squares method in which the weight was taken to be inversely proportional to the experimental error. The fractionation is given by: 103 1n α(anhydrite-water) = 3.21 x (103/T)2-4.72. Available delta18O values of natural anhydrite were used to test the validity of this expression. It is shown that this newly revised geothermometer can be successfully applied to natural hydrothermal anhydrite. (orig.)

  13. SOME ASPECTS OF ANTIOXIDANT DEFENSE MECHANISMS IN WOOD SPECIES EXPOSED TO ANTHROPIC POLLUTION IN SUCEAVA COUNTY

    Directory of Open Access Journals (Sweden)

    Marius Viorel Oniciuc

    2013-02-01

    Full Text Available Increased production of reactive oxygen species in plant tissues caused by unfavorableenvironmental conditions is early response to different stresses and may provide cells with resistance against theirformation. The subject of this paper is determination of catalase and peroxidase levels, components of the antioxidantdefense mechanism, in various types of woody plants in order to study the effect of pollution by sulphur and copperexploitation in mining areas on the antioxidant enzymes activity in the leaf material taken from different Gymnospermspecies as Picea abies L.Karst., Larix decidua Mill. and Angyosperms like Salix ssp alba L., Populus tremula, Betulaverrucosa Ehrh. şi Fagus sylvatica L. For this purpose, the measurement of catalase activity was performed using theSinha method (Artenie Vl. et al., 2008, the determination of peroxidase level was carried out on the basis of ortho-dianisidine method (Cojocaru D.C., 2009 and the determination of soluble proteins on Bradford method (Cojocaru etal.,2009. The results obtained lead to the conclusion that both catalase and peroxidase are effective biomarkers ofpollution with sulfur, copper ores and barite but especially the acclimatization of species studied in conditions of chronicexposure.

  14. Thorium research and development in Turkey

    International Nuclear Information System (INIS)

    Turkey has a great potential regarding thorium resources. Thorium exploration activities have been done in the past mainly by state organizations for determining the thorium resources in Turkey. Thorium occurs as complex mineral together with barite, fluorite and rare earth elements (REE). The increase in global demand for REE creates the opportunity for REE production which will also produce thorium as a by-product. The development of nuclear energy program in Turkey provides the stimulus for research and development activities in nuclear technologies. The final declaration of the workshop emphasizes the importance of thorium reserves in Turkey and the necessity for thorium exploration and development activities in order to determine the feasibility of thorium mining and fuel cycle in Turkey. These activities should be conducted together with the development of technologies for separation of these complex minerals and purification of thorium, REE and other minerals to be utilized as commercial products. There are advanced academic research studies on thorium fuel cycle which should be supported by the industry in order to commercialize the results of these studies. Turkey should be integrated to international R and D activities on ADS which is expected to commercialize on medium term. The legislative framework should be developed in order to provide the industrial baseline for nuclear technologies independent from nuclear regulatory activities

  15. Chondritic-like xenon trapped in Archean rocks: A possible signature of the ancient atmosphere

    Science.gov (United States)

    Pujol, Magali; Marty, Bernard; Burgess, Ray

    2011-08-01

    Ancient sedimentary rocks may have retained a record of the past atmospheric composition. We present evidence for the geological preservation of remnants of the Archean atmosphere. Hydrothermal quartz containing fluid inclusions from a core drilled in 3.5 Ga-old terrains at North Pole, (Western Australia), has a Ar-Ar plateau age of 3.0 ± 0.2 Ga. An Archean age is confirmed independently by 130Ba- 130Xe dating of fluid inclusions. Xenon trapped in the present sample and in 3.5 Ga-old barite from the same locality (Pujol et al., 2009; Srinivasan, 1976) presents an isotopic composition intermediate between the atmospheric composition and that of chondritic, or solar, xenon. In contrast, the stable isotopes of neon and krypton are isotopically atmospheric. This observation suggests that the well known but unexplained enrichment of heavy Xe isotopes in the atmosphere relative to cosmochemical (chondritic or solar) end-members was progressive, and not complete ≥ 3 Ga ago. This Xe isotopic fractionation might have taken place during prolongated irradiation of the atmosphere by the ancient Sun.

  16. Productivity control of fine particle transport to equatorial Pacific sediment

    Science.gov (United States)

    Thomas, E.; Turekian, K. K.; Wei, K.-Y.

    2000-09-01

    Accumulation rates of 3He (from cosmic dust), 230Th (produced in the water column), barite (produced in the water column during decay of organic matter), and Fe and Ti (arriving with wind-borne dust) all are positively correlated in an equatorial Pacific core (TT013-PC72; 01.1°N, 139.4°W; water depth 4298 m). These accumulation rates are also positively correlated with the accumulation rates of noncarbonate material. They are not significantly correlated to the mass accumulation rate of carbonate, which makes up the bulk of the sediment. The fluctuations in accumulation rates of these various components from different sources thus must result from variations in some process within the oceans and not from variations in their original sources. Sediment focusing by oceanic bottom currents has been proposed as this process [Marcantonio et al., 1996]. We argue that the variations in the accumulation rates of all these components are dominantly linked to changes in productivity and particle scavenging (3He, 230Th, Fe, Ti) by fresh phytoplankton detritus (which delivers Ba upon its decay) in the equatorial Pacific upwelling region. We speculate that as equatorial Pacific productivity is a major component of global oceanic productivity, its variations over time might be reflected in variations in atmospheric levels of methanesulfonic acid (an atmospheric reaction product of dimethyl sulfide, which is produced by oceanic phytoplankton) and recorded in Antarctic ice cores.

  17. Electrical tomography and magnetic imaging of Zeida's abandoned mine tailings (Morocco)

    Science.gov (United States)

    Lachhab, A.; Dekayir, A.; Benyassine, E. M.; Rouai, M.; Parisot, J. C.; Mathé, P. E.

    2014-12-01

    The Zeida (Pb-Zn) mine was closed since 1985 and contains huge dams of mine waste deposited without adjustment or remediation. These tailings contain large amount of Pb (3000 ppm) and Zn (140 ppm) expressed mainly as galena, wulfenite and barite. The subsurface of the studied area is constituted mainly by weathered granite coved in some places by Triassic red formations. A geophysical survey was conducted by using Electrical Resistivity Tomography (ERT) combined with Magnetic Imagery to explore the subsurface area and understand how the mine waste is interacting with the groundwater. Two-Dimensional ERT revealed the occurrence of rounded structures with high resistivity values corresponding to spherical boulders of weathered granite. Resistivity values within the boulders decrease gradually from the center toward the outer layers. This granite was found to be covered by highly conductive materials from the tailings of the mine reaching a depth extending up to 60 m. Magnetic maps revealed local magnetic anomalies reaching 400 nT due to old buried pipes at the mine site of Zeida. These anomalies correspond to the presence of faults used as pathways to recharge the groundwater reservoir

  18. Reduction of radiocesium transfer to animal products using sustained release boli with ammoniumiron(3)-Hexacyanoferrate(2)

    International Nuclear Information System (INIS)

    A sustained release boulus with the cesium binder ammoniumiron(III) - hexacyanoferrate (AFCF) has been developed as a countermeasure for small ruminants grazing pastures contaminated by radiocesium (134Cs+137Cs). The boli (40-50 g) are produced by compression of a mixture of AFCF, barite and wax. The release of AFCF from boli labelled with 137Cs-iron-hexacyanoferrate complex was studied in laboratory sheep. The release rate followed first order kinetics during the 108 d of observation and decreased from 40 to 22, 110 to 35 and 280 to 25 mg d-1 in sheep treated with 1, 2 or 3 boli respectively. The efficiency of boli in reducing radiocesium transfer to meat and milk was tested in laboratory studies with goats fed 134Cs tracer. Until 40 d after treatment the transfer of radiocesium to milk was reduced by 35%, 60% and 85% in goats given 1, 2 og 3 boli, respectively. The reduction in radiocaesium transfer persisted for 90 d but with a lower efficiency. A similar relationship was found between number of boli and the reduction in radiocesium transfer to meat with an observed maximal reduction of 60%. (au) (20 refs.)

  19. Polymetallic uranium-copper deposits

    International Nuclear Information System (INIS)

    The present report is an addendum to the final report, dated June 30, 1988, on the research program 'Polymetallic uranium-copper deposits' and is concerned with investigations carried out in the Palaeozoic/Mesozoic basins of the Hessian Depression, FRG, in the first half of 1988. The investigations comprised the further compilation of literature data and limited field work; they were related to three objectives and yielded the following results: 1. Additional data were obtained on the geochemistry (in particular U) of the stratiform, polymetallic Cu mineralization of the Kupferschiefer type. The new data confirm the conclusions reached previously within the present research program. 2. The radiometric scanning of samples and of surface exposures and dumps from the historic mining of the 'Ruecken' veins (barite ± Co-Ni-As) in the Richelsdorfer Gebirge area yielded negative results. Follow-up investigations are not justified. 3. The occurrence of collapse structure ('Erdfaelle'), in one case combined with tensional tectonics and possible diapiric phenomena (Sontra graben structure) led to the speculation that some of these structures may host epigenetic polymetallic mineralization. Results have been negative, respectively inconclusive; a direct proof requires deeper drilling. However, based on the lack of any positive indication, follow-up investigations are not justified. (orig./RB)

  20. Registry of Mineral and Petroleum Titles

    Energy Technology Data Exchange (ETDEWEB)

    Maclellan, I. M.; Kaizer, J. L.; McCulloch, P. D.; Ratcliffe, R.; Wenning, A. S. [Nova Scotia Dept. of Natural Resources, Halifax, NS (Canada)

    2000-07-01

    Activities of the Nova Scotia Registry of Mineral and Petroleum Titles are described, including statistical information about staking and mining activity in the province during 1999. In terms of activities, the Registry receives applications and issues licenses and leases for mineral and petroleum rights, receives statements of exploration expenditures and assessment reports that pertain to renewal of licenses and leases, maintains maps showing the disposition of lands under license or lease, and maintains a system of prospector registration. In addition, the Registry processes applications for underground gas storage rights and treasure trove rights and maintains a database of information concerning production and employment in Nova Scotia mines and quarries. At the end 1999 there were 230,660 hectares under exploration licence. Exploration expenditures, including engineering, economic and feasibility studies during 1999 totalled $4.2 million, mostly by junior mining companies searching for industrial mineral commodities. Mining activity during 1999 generated revenues of $340 million. Coal production dropped by 25 per cent, due mainly to the closure of the Phalen Mine. Gypsum production was up to 7.9 million tonnes; shipments of cement, barite and clay products also increased during 1999; salt production remained unchanged from 1998 with 842,000 tonnes. Production of construction aggregates totalled 10.6 million tonnes, down slightly from the year before. Mineral industry employment was roughly 2,500 persons, down by 24 per cent from 1998 levels, due primarily to the closure of the Phalen Mine.

  1. Are Majhgawan-Hinota pipe rocks truly group-I kimberlite?

    Indian Academy of Sciences (India)

    Ravi Shanker; S Nag; A Ganguly; A Absar; B P Rawat; G S Singh

    2001-03-01

    The diamond bearing pipe rocks in Majhgawan–Hinota (more than four pipes) occur as intrusives in sandstones of Kaimur Group. These Proterozoic (974 ± 30–1170 ± 20 Ma) intrusive rocks, occupying the southeastern margin of Aravalli craton, were called as `micaceous kimberlite' in tune with the reported kimberlite occurrences from other parts of the world. Judging from the definition of kimberlite, as approved by the IUGS Subcommission on Systematics of Igneous Rocks, it is not justified to call these rocks as `micaceous kimberlite'. Rather the mineralogical assemblages such as absence of typomorphic mineral monticellite (primary), abundance of phlogopite cognate, frequent presence of barite and primary carbonate mostly as calcite coupled with ultrapotassic and volatile-rich (dominantly H2O) nature and high concentration of incompatible elements (such as Ba, Zr, Th, U), low Th/U ratios, low REE and no Eu-anomaly clearly indicate a close similarity with that of South African orangeites. Thus orangeites of Proterozoic age occur outside the Kaapvaal craton of South Africa which are much younger (200 Ma to 110 Ma) in age.

  2. On preparation of efficiency calibration standards for gamma-ray spectrometers

    International Nuclear Information System (INIS)

    The work on preparation of calibration standards started for the following reasons: development of gamma-spectrometry hardware and software requires adequate quality assurance system; the calibration standards offered by established firms are expensive. Preparation of standards in geometries to our specification would make them even more expensive; the analyst community accepted the idea of uniform quality assurance program and uniform calibration politics. Studied materials were: organic (styropore, ground coffee, tobacco leaves, seeds, flour, semolina, lentils, sugar, ion exchange resins, PTFE powder, rice, beans and bee honey) and inorganic (quartz sand, chalcedony sand, active charcoal, marble powder, zeolite, different clays, barite, soil, perlite, talc powder and their mixtures). Efficiency curves for geometry TB with different densities; Efficiency for different geometries; Comparison with Czech source 540-01, silicone resin, r = 0,98 g/cm3 for Co-60, Co-57, Cs-137 and Cs-139 are presented. Conclusions: A procedure for preparation of mixed-nuclide efficiency calibration standards in different geometries and having different densities has been developed. Advantages: different natural and artificial matrices used; gravimetrically controlled activity application; activated charcoal used as supporter of the activity; the preparation is in the container of the standard and no losses of activity occurs; high degree of activity distribution homogeneity; fixed volume of the standard

  3. Effects of Different Barium Compounds on the Corrosion Resistance of Andalusite-Based Low-Cement Castables in Contact with Molten Al-Alloy

    Science.gov (United States)

    Adabifiroozjaei, Esmaeil; Koshy, Pramod; Rastkerdar, Ebad

    2011-08-01

    An experimental study was conducted to investigate the interfacial phenomena between an Al alloy and andalusite low-cement castables (LCCs) containing fixed contents of barium compounds (BaO, BaSO4, and BaCO3) at 1123 K and 1433 K (850 °C and 1160 °C) using the Alcoa cup test. Interfacial reaction products and phases formed during heat treatment of the refractory samples were characterized using scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS) and X-ray diffraction analysis (XRD). The addition of both BaO and BaSO4 led to a significant reduction of alloy penetration into the refractory. Hexa-celsian formation was observed in both these refractories, which drastically increased their corrosion resistance. Barite decomposition was observed at 1373 K (1100 °C) in the presence of alumina and silica, which was the precursor for hexa-celsian formation. Barium silicates were formed in all samples containing additives; however, this did not have any major influence on the corrosion resistance. Solidified eutectics of BaSi2 and α-BaAl2Si2 formed in all these samples, which acted as an interfacial barrier that prevented additional molten aluminum penetration; however, the positive effect of intermetallic formation was offset by glassy phase formation in samples containing BaCO3 as the additive.

  4. Use of Pb and Sr isotopes on the determination of lead mineralization sources from Ribeira valley - Sao Paulo and Parana states

    International Nuclear Information System (INIS)

    A lead and strontium isotope study was carried out on galena, barite and calcite from Pb-Ag syngenetic stratiform (Perau type) and hydrothermal veins (Panela type) deposits from Vale do Ribeira region (Sao Paulo and Parana states). The leads from the Perau and Panelas type deposits have respectively isotope ratios (sup(206)Pb/ sup(204)Pb 16.157 to 16.505 amd 16.520 to 17.273; sup(207)Pb/ sup(204)Pb = 15.466 to 15.720 and 15.470 to 15.780 and sup(208)Pb/ sup(204)Pb = 36.370 to 36.763 and 37.043 to 38.243), that defined a Stacey and Kramers model ages mainly concentrate within 1.7-1.5Ga. A review of published Pb isotopic compositions for these deposits and considerations of new Sr isotope data and Pb results using plumbotectonics model, indicate that the Perau type mineralizations are related to the syngenetic process and the Pb are derived from upper crust with a short crustal residence time. For the Panelas type deposits the Pb and Sr isotope studies support the conclusion that the ores were emplaced during regional metamorphism and the Pb were derived from lithologically complex source which may include metasedimentary and basement rocks. (author)

  5. Dual origins of epigenetic hydrothermal Ba and Pb-Zn deposits in the Chanarcillo group, Atacama Region, Chile: An example in the Quebrada Galena

    International Nuclear Information System (INIS)

    In the Lower Cretaceous Chanarcillo Group, in the Atacama Region, structurally-controlled vein, disseminated and stratiform base metal mineralization is mainly associated with the intrusive and metasomatic activity of the Cretaceous magmatic arc (Chilean Iron Belt). A distinct group of epigenetic base metal stratiform deposits, involving moderate temperature fluids in part associated with hydrocarbons, is best explained by basinal-scale processes (Cisternas et al., 1999; Lieben et al., 1999). In this study, a dual origin, with more or less prominent involvement of Cretaceous magmatism, has been evidenced for carbonate-hosted Pb-Zn±Ag and Ba deposits and occurrences in the Chanarcillo Group. In the Quebrada Galena (28o05'S, 70o30'W) the presence, within a few kilometers, of such different Ba and Pb-Zn ore occurrence types provides an opportunity to study the relative timing and the possible genetic links between the different mineralizing processes. With this purpose, we firstly describe two deposits with the most contrasting characteristics, the Maria Cristina Zn-Pb-(Ba) skarn deposit, and the Mamina stratiform barite deposit. In a second step, Ba and Pb-Zn deposits and occurrences with intermediate characteristics could help to unravel the relations between these oreforming systems. Fluid inclusions microthermometry, and sulfur and strontium isotopes are used to provide further insight into the nature of ore-forming fluids and source of ore-forming elements, and 40Ar/39Ar dating to constrain the age of the Zn-Pb skarn mineralization (au)

  6. 芳砜纶在制动摩擦材料中的应用%Application of polysulfonamide fibers in brake friction materials

    Institute of Scientific and Technical Information of China (English)

    王慧; 林志峰; 吕亚非

    2009-01-01

    Non-metallic brake friction materials containing polysulfonamide fibers (PSA), basalt fibers, and wol-lastonite as reinforcements, zircon as abrasive, graphite as solid lubricant, vermiculite as noise-reducing filler, barite as cost-reducing filler, and cardanol-based benzoxazine modified phenolic resin as binder have been formulated and their composites were prepared. The presence of PSA was found to depress the friction coefficient and improve the wear rate of the friction composites. The optimal friction performance was obtained with a volume fraction of 9% of PSA.%采用芳砜纶、玄武岩和硅灰石为纤维增强体,锆英石为磨料,石墨为固体润滑剂,蛭石和重晶石分别为降低噪音和成本的填料,腰果酚型苯并嗪改性的酚醛树脂为基体,制备了含芳砜纶的制动摩擦材料.测定了摩擦材料的热衰退性、热恢复性和体积磨损率.结果表明,芳砜纶具有降低摩擦系数和改善体积磨损率的作用,含9%体积分数芳砜纶的制动摩擦材料具有最佳摩擦性能.

  7. Study of 222Rn emanation levels present in naturally occurring radioactive materials - NORM

    International Nuclear Information System (INIS)

    The presence of Naturally Occurring Radioactive Material (NORM), contaminating oil and gas installations, is usual in the petroleum industry, and can be severe enough to expose the workers to elevated levels of radiation. The segregation of contaminated residues although necessary, is still a problem without a satisfactory solution. Currently, the most practical and economic option for discarding this material is to stock it in areas of the installation with controlled access. Certain equipment used in the petroleum industry has scale and sludge that could be associated to important levels of radioactivity. Typically, the scales are mixtures of carbonate and sulphate minerals, such as barite (BaSO4), that easily incorporate 226Ra and 228Ra in their structures. The objective of this work was to measure the emanations of the radon present in NORM samples, via diffusion chambers containing a nuclear track detector (CR-39). The images of α particle tracks emanated by 222Rn registered on CR-39 were observed with a Nikon E400 optic microscope and captured by a Nikon Coolpix digital camera and then stored in a database, to later count the tracks using the computational program, Image Pro plus. Since the number of those tracks resulted proportional to the emanation rate of 222Rn this methodology allowed the comparison of contamination levels in analyzed samples. (author)

  8. Mineralogical studies

    International Nuclear Information System (INIS)

    The mineralogy of WC-series cores from the project area uranium deposit in the San Juan Basin, New Mexico was studied with respect to the deposit and to the paleohydrologic and present hydrologic gradients. Bulk clay analyses, authigenic clay coatings on detrital grains, sulfur minerals, ferric oxide minerals, carbonate minerals, and detrital magnetite-ilmenite were investigated. Among the clays, chlorite/illite seem to offer some indication of the deposit location. More frequent clay coatings are found in the favorable ore horizon along the paleogradient than along the present gradient. Barite is more abundant in the favorable horizon and near ore than elsewhere. Pyrite and other sulfide minerals are relatively sparse in and near the deposit compared to areas away from the deposit. More than two generations of ferric oxide minerals are present in the area and these are deleted in samples nearest ore down the present gradient. Carbonate minerals aremore abundant in lower parts of the favorable zone. 8 figures, 2 tables

  9. influence of severe conditions on the concrete employed in nuclear technology

    International Nuclear Information System (INIS)

    this thesis is mainly concentrating on honing the efficiency of heavy-weight high -performance (HWHP) concrete, developed from local aggregates together with additives that are waste products of other manufacturing processes, for the purpose of producing radiation shields, to attenuate gamma-rays in peaceful active-service facilitations . in other words, the thesis is in attempt to develop a special type of heavy concrete of various advantages that would enhance its performance in severe environment. such advantages may embrace concurrent improvements; such as high specific gravity, workability, high compressive strength, efficient attenuator for gamma radiation, and resistant to elevated temperature along with chemical attack.the named HWHP concrete was mainly prepared using two types of heavy aggregates, ilmenite (iron ore) and barite . in addition usual concrete (dolomite/sand) was also employed in this thesis to compare the obtained HWHP concrete. the practical facet of this thesis accounts for evaluating the influence of severe conditions, concomitantly and consecutively, on mechanical , morphological and attenuation characteristics for the three types of concrete

  10. Research on the additives to reduce radioactive pollutants in the building materials containing fly ash

    International Nuclear Information System (INIS)

    Several kinds of functional additives such as barite, zeolite, ferric oxide, gypsum, and high alumina cement were introduced to prepare a low-radiation cement-based composite to reduce radioactive pollutants contained in fly ash. The effect of content and granularity of the functional additives on the release of radioactive pollutants were investigated. Composites were characterized by X-ray diffraction, Scan electron microscopy. The results indicate that the radioactive pollutants contained in the fly ash can be reduced by adding a proper amount of zeolite, ferric oxide, gypsum, and high alumina cement. The release of radon from fly ash decreases with a decrease in the granularity of additives. Compared with traditional cement-based composite containing fly ash, the release of radon can be reduced 64.8% in these composites, and the release of γ-ray is decreased 45%. Based on the microstructure and phase analysis, we think that by added functional additives, there are favorable to form self-absorption of radioactivity in the interior composites. This cement-based composite will conducive to fly ash are large-scale applied in the field of building materials.

  11. MSWI bottom ash used as basement at two pilot-scale roads: comparison of leachate chemistry and reactive transport modeling.

    Science.gov (United States)

    De Windt, Laurent; Dabo, David; Lidelöw, Sofia; Badreddine, Rabia; Lagerkvist, Anders

    2011-02-01

    The recycling of municipal solid waste incineration bottom ash as aggregates for road basement requires assessing the long-term evolution of leachate chemistry. The Dåva (Sweden) and Hérouville (France) pilot-scale roads were monitored during 6 and 10 years, respectively. Calculated saturation indices were combined to batch test modeling to set a simplified geochemical model of the bottom ash materials. A common reactive transport model was then applied to both sites. At Hérouville, pH and the concentration of most elements quickly drop during the first two years to reach a set of minimum values over 10 years. The decrease is less pronounced at Dåva. The evolutions of pH and major element concentrations are fairly well related to the following pH-buffering sequence: portlandite, C-S-H phases or pseudo-wollastonite and, finally, calcite in equilibrium with atmospheric CO(2). Al(OH)(3), barite, ettringite and monohydrocalcite may also control leachate chemistry. Cu release is correctly modeled by DOM complexation and tenorite equilibrium. Temperature has no significant effect on the modeling of leachate chemistry in the range 5-30°C, except at high pH. Effects at road edges and roadside slopes are important for the release of the less reactive elements and, possibly, for carbonation processes. PMID:20609573

  12. Characterization of elements in elemental sulfur rock using X-ray florescence spectrometer method

    International Nuclear Information System (INIS)

    Most of elemental sulfur are located in volcanic region which associated with some minerals as calcite, dolomite, gypsum, anhydrite, barit and celestite. The earth's crust is estimated as being 0.1% sulfur which occurs mostly as iron and heavy metal sulfides. The aim of this experiment is to know the qualitative and quantitative elements contained that associated with sulfur in elemental sulfur rocks. In these experiment samples were taken from West Java namely Papandayan, Tangkuban Perahu, Ciater, Sibayak-North Sumatra and Cugung Rajabasa-Lampung. Determination of elements contents were done using X-Ray spectrometer fluorescence, based on its energies characteristic. Result of analysis showed that except sulfur, there were impurities elements such P, Ca, Ti, Fe, Zn, Se, Rb, Sr, Zr, and Nb with variation concentration. The most of sulfur content occurs in elemental sulfur rock from Tangkuban Prahu 97.25% and then Papandayan 91.26%, Sibayak 84.9%, Cugung Rajabasa 62.98% and Ciater 64.12%. The samples from Sibayak and Cugung Rajabasa contain silicon (Si) which relative higher, with concentration respectively 7.77% and 13.49 % while sample from Ciater contains iron (Fe) 13.6%. Sulfur elemental rocks from Papandayan and Ciater contained As and Se, so that they are not suggested exploitation. (author)

  13. Nanomodified magnesian schungite protective concrete

    Directory of Open Access Journals (Sweden)

    A.S. Ryzhov

    2010-03-01

    Full Text Available Currently, there is increasing demand for building materials with low permeability to the radioactive gas radon and materials that have protective properties against radiation exposure and non-ionizing radiation. Formulations have been developed and now special building flooring and plaster radiation protective mixtures are commercially available. With the acceleration the pace of development of nuclear energy safe utilization of liquid and solid radioactive waste is a vital task for the survival of humanity.With the use of innovative magnesian barite and magnesian schungite composites opportunities to solidify LRW and solid radioactive waste monolithing are expanded. Magnesium-schungite nanostructured concrete exceed heavy concrete on Portland cement by gamma radiation and strength characteristics reducing multiplicity. Formulations are protected by a patent for an invention.The paper shows a clear advantage of magnesia cement (compared with Portland cement in terms of specific mass energy parameters Em and Wm. The data demonstrates that the magnesia cement is characterized by higher parameters of maximum frequency of oscillation of the atoms ?m, which, apparently, is the key to explaining the increased protection (shielding properties of materials based on magnesia cement mixed with shungite of gamma radiation and exposure to radiofrequency electromagnetic radiation the range.Magnesium-schungite radiation-shielding materials are approved by Rospotrebnadzor for use for collective protection to reduce the income of radon in indoor air, gamma and x-ray production, residential, public and administrative buildings, as well as in food, pharmaceutical, medical and child care.

  14. Investigations regarding the anthropic impact on the Krebs cycle dehydrogenases system on certain wood-species in mining areas, Suceava county

    Directory of Open Access Journals (Sweden)

    Marius Viorel Oniciuc

    2013-03-01

    Full Text Available The Krebs cycle, a second stage of cellular respiration that occurs in the mitochondrion of the leafcell and consist in a multistep processes plays a central role in catabolism of organic fuel molecules. The miningextraction technologies for both underground and surface, the preparation of copper ore and barite applied in Tarnia,respectively to the sulphur in Calimani Mountain and the excess of these elements in natural environment may causemalfunction of ecosystem. The dehydrogenases of Krebs cycle can give information on the type and the duration of theeffects of pollutants on the metabolic activity in leaves, to subsequent area pollution, therefore, the aim of the presentstudy has been to determine these effects on this enzymatic system activity. For this reason, the isocitrate dehydrogenase,the -ketoglutate dehydrogenase, the succinate ehydrogenase and the malate dehydrogenase activity was determined using the spectrophotometric method with triphenyl-tetrazolium and the analysis of experimental results shows the differences from one sample to another sample of closely related species specificity, but also the effect of environmentalfactors.

  15. He isotopes constraints to the origin of hydrothermal fluids: application to the fluorite mineralizations of Asturias (N Spain); Contribucion de los isotopos de He al origen de los fluidos hidrotermales: aplicacion al estudio de las mineralizaciones de fluorita de Asturias (N de Espana) (Author) 24 refs.

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, V.; Martin-Crespo, T.; Vindel, E.; Corbella, M.; Cardellach, E.

    2010-07-01

    Helium isotopes have been measured in fluorite and sulphides in order to obtain conclusive means of assessing the involvement of mantle and crustally derived volatiles in F-Ba deposits from Asturias (N of Spain). Fluorite mineralizations are hosted in Mesozoic (Permotriassic) and Paleozoic age rocks. Mineralization is composed of fluorite, barite, calcite, dolomite, quartz and sulphides, and shares the characteristics of most Mississippi Valley Type (MVT) deposits associated with rifting events related to the opening of the Atlantic Ocean. The 3{sup H}e/4{sup H}e values of the Asturias ore fluids ({<=} 0,1 Ra) indicate a crustal fluid source and exclude the involvement of a mantle helium component. These values are consistent with the acceptance of the existing basinal model for MVT genesis and sedimentary brines migration, with the lack of igneous activity in the area contemporary with the mineralization, and also consistent with similar helium isotope data recorded in other fluorite deposits in Europe. (Author) 24 refs.

  16. Study of the emanation levels of 222Rn present in Naturally Occurring Radioactive Materials - NORM

    International Nuclear Information System (INIS)

    The presence of Naturally Occurring Radioactive Material (NORM), contaminating oil and gas facilities, is a common fact in the petroleum industry, and can be severe enough to expose the workers to elevated levels of radiation. Thus, contaminated residues need to be segregated but, this is still a problem without a satisfactory solution. Currently, the most practical and economic option for discarding this material is to stock it in areas of the facility whose access is controlled. Certain equipment used in the petroleum industry has scale and sludge that could be associated to important levels of radioactivity. Typically, the scale is a mixture of carbonate and sulphate minerals, such as barite (BaSO4), that easily incorporates 226Ra and 228Ra in its structures. The objective of this work was to measure the emanations of the radon present in these NORM samples, via diffusion chambers containing a nuclear track detector (CR-39). The images of particle alpha tracks emanated by 222Rn registered on CR-39 were observed with a Nikon E400 optic microscope and captured by a Nikon Coolpix digital camera and then stored in a database, to later count the tracks using the computational program, Image Pro plus. Being that the emanation rate of 222Rn was proportional to the number of these tracks the methodology permitted the comparison of contamination levels of the analyzed samples. (author)

  17. Fluid Inclusion Study of Quartz Xenocrysts in Mafic Dykes from Kawant Area, Chhota Udaipur District, Gujarat, India

    Directory of Open Access Journals (Sweden)

    Randive Kirtikumar

    2015-09-01

    Full Text Available Unusual mafic dykes occur in the proximity of the Ambadongar Carbonatite Complex, Lower Narmada Valley, Gujarat, India. The dykes contain dense population of quartz xenocrysts within the basaltic matrix metasomatised by carbonate-rich fluids. Plagioclase feldspars, relict pyroxenes, chlorite, barite, rutile, magnetite, Fe-Ti oxides and glass were identified in the basaltic matrix. Quartz xenocrysts occur in various shapes and sizes and form an intricate growth pattern with carbonates. The xenocrysts are fractured and contain several types of primary and secondary, single phase and two-phase fluid inclusions. The two-phase inclusions are dominated by aqueous liquid, whereas the monophase inclusions are composed of carbonic gas and the aqueous inclusions homogenize to liquid between 226°C and 361°C. Majority of the inclusions are secondary in origin and are therefore unrelated to the crystallization of quartz. Moreover, the inclusions have mixed carbonic-aqueous compositions that inhibit their direct correlation with the crustal or mantle fluids. The composition of dilute CO2-rich fluids observed in the quartz xenocrysts appear similar to those exsolved during the final stages of evolution of the Amba Dongar carbonatites. However, the carbonates are devoid of fluid inclusions and therefore their genetic relation with the quartz xenocrysts cannot be established.

  18. Radium and barium removal through blending hydraulic fracturing fluids with acid mine drainage.

    Science.gov (United States)

    Kondash, Andrew J; Warner, Nathaniel R; Lahav, Ori; Vengosh, Avner

    2014-01-21

    Wastewaters generated during hydraulic fracturing of the Marcellus Shale typically contain high concentrations of salts, naturally occurring radioactive material (NORM), and metals, such as barium, that pose environmental and public health risks upon inadequate treatment and disposal. In addition, fresh water scarcity in dry regions or during periods of drought could limit shale gas development. This paper explores the possibility of using alternative water sources and their impact on NORM levels through blending acid mine drainage (AMD) effluent with recycled hydraulic fracturing flowback fluids (HFFFs). We conducted a series of laboratory experiments in which the chemistry and NORM of different mix proportions of AMD and HFFF were examined after reacting for 48 h. The experimental data combined with geochemical modeling and X-ray diffraction analysis suggest that several ions, including sulfate, iron, barium, strontium, and a large portion of radium (60-100%), precipitated into newly formed solids composed mainly of Sr barite within the first ∼ 10 h of mixing. The results imply that blending AMD and HFFF could be an effective management practice for both remediation of the high NORM in the Marcellus HFFF wastewater and beneficial utilization of AMD that is currently contaminating waterways in northeastern U.S.A. PMID:24367969

  19. Fate of Radium in Marcellus Shale Flowback Water Impoundments and Assessment of Associated Health Risks.

    Science.gov (United States)

    Zhang, Tieyuan; Hammack, Richard W; Vidic, Radisav D

    2015-08-01

    Natural gas extraction from Marcellus Shale generates large quantities of flowback water that contain high levels of salinity, heavy metals, and naturally occurring radioactive material (NORM). This water is typically stored in centralized storage impoundments or tanks prior to reuse, treatment or disposal. The fate of Ra-226, which is the dominant NORM component in flowback water, in three centralized storage impoundments in southwestern Pennsylvania was investigated during a 2.5-year period. Field sampling revealed that Ra-226 concentration in these storage facilities depends on the management strategy but is generally increasing during the reuse of flowback water for hydraulic fracturing. In addition, Ra-226 is enriched in the bottom solids (e.g., impoundment sludge), where it increased from less than 10 pCi/g for fresh sludge to several hundred pCi/g for aged sludge. A combination of sequential extraction procedure (SEP) and chemical composition analysis of impoundment sludge revealed that Barite is the main carrier of Ra-226 in the sludge. Toxicity characteristic leaching procedure (TCLP) (EPA Method 1311) was used to assess the leaching behavior of Ra-226 in the impoundment sludge and its implications for waste management strategies for this low-level radioactive solid waste. Radiation exposure for on-site workers calculated using the RESRAD model showed that the radiation dose equivalent for the baseline conditions was well below the NRC limit for the general public. PMID:26154523

  20. Accumulation of fossil fuels and metallic minerals in active and ancient rift lakes

    Science.gov (United States)

    Robbins, E.I.

    1983-01-01

    A study of active and ancient rift systems around the world suggests that accumulations of fossil fuels and metallic minerals are related to the interactions of processes that form rift valleys with those that take place in and around rift lakes. The deposition of the precursors of petroleum, gas, oil shale, coal, phosphate, barite, Cu-Pb-Zn sulfides, and uranium begins with erosion of uplifted areas, and the consequent input of abundant nutrients and solute loads into swamps and tectonic lakes. Hot springs and volcanism add other nutrients and solutes. The resulting high biological productivity creates oxidized/reduced interfaces, and anoxic and H2S-rich bottom waters which preserves metal-bearing organic tissues and horizons. In the depositional phases, the fine-grained lake deposits are in contact with coarse-grained beach, delta, river, talus, and alluvial fan deposits. Earthquake-induced turbidites also are common coarse-grained deposits of rift lakes. Postdepositional processes in rifts include high heat flow and a resulting concentration of the organic and metallic components that were dispersed throughout the lakebeds. Postdepositional faulting brings organic- and metal-rich sourcebeds in contact with coarse-grained host and reservoir rocks. A suite of potentially economic deposits is therefore a characteristic of rift valleys. ?? 1983.

  1. [Multi-spectroscopy applied to study on a late neolithic colored stone from Yuhui Site in Huaihe Basin].

    Science.gov (United States)

    Wang, Hai-gang; Jin, Zheng-yao; Xie, Zhi; Fan, An-chuan; Yan, Li-feng; Zhu, Bing-quan; Wang, Ji-huai

    2013-09-01

    The unearthing of a large number of red-yellow colored stones in Yuhui Site, Bengbu city, Anhui province of China, which was the only site of Longshan culture appointed by "Origin of the Chinese Civilization Project" in the Huaihe River basin, has drawn a widespread attention in archaeology. The present research was undertaken to examine elements, mineral composition and thermal history of one red-yellow color stone in different positions, classified according to specialized colors, by means of synchrotron radiation X-ray fluorescence (SR-XRF), X-ray diffraction (XRD), laser Raman spectroscopy (LRS), electron probe micro-analysis (EPMA) and thermoluminescence (TL). The results show that the main body of the color stone is limonite with a large amount of quartz inclusion. The yellow substances on the surface layer of the color stone were identified as goethite (alpha-FeOOH), and the red ones as red ochre (alpha-Fe2O3+clay+silica). The internal yellow brown substances inside the stone are mainly aphanitic goethite with a number of chromites and manganese dioxide, and also with small quantity of barite and bismuth. And the color stones are without historical firing treatment. These kinds of special polymetallic ores with unique nature and complex geologic history, which were unearthed in the late neolithic site with large numbers, may be closely related to some kind of primitive religious beliefs and special sacrificial practices. PMID:24369621

  2. Very heavy iron-punching concretes

    International Nuclear Information System (INIS)

    The present report deals with all the heavy iron-punching concretes, metallic wastes produced by the transformation industry. After a detailed description of the physical properties of metallic aggregates, a classification of heavy mortars is given, into three main categories: steel-shot grouts d = 5,3 - 6; steel-shot grouts mixed with a mineral d = 3,7 - 4,2; injection heavy grouts d = 3,5 - 4. The following chapter describes iron-punching concretes the most used in the atomic industry: iron-punching concretes mixed with cast-iron - iron-punching concretes mixed with magnetite; iron-punching concretes mixed with barite; iron-punching concretes mixed with limonite; iron-punching concretes mixed with boron. The compositions of these concretes are given together with their physical and mechanical characteristics. Numerous diagrams make it possible to find rapidly the proportions of the constituents of these concretes as a function of the required density. Technical advice and specifications are given in an appendix together with a bibliography of these heavy concretes. (author)

  3. Mineralogical-geochemical features of travertines of the modern continental hydrotherms: A G-1 well, Tunka depression, Baikal rift zone

    Science.gov (United States)

    Soktoev, B. R.; Rikhvanov, L. P.; Ilenok, S. S.; Baranovskaya, N. V.; Taisaev, T. T.

    2015-07-01

    The mineral and chemical composition of travertines is studied in the modern discharge zone of the hydrothermal fluids of the Tunka depression, Baikal rift zone. The matrix of travertines is mostly made up of aragonite and calcite, which host about 20 mineral phases of Ag, Au, Pb, Cu, Sb, Sn, Fe, and other chemical elements. Similar rocks have previously been found in areas of modern submarine ore formation and tectonically active structures of the crust (New Zealand, the Cheleken Peninsula and others). Our materials confirm the opinion of some researchers who study modern hydrothermal ore formation in spreading zones that the formation of hydrothermal deposits requires favorable geochemical barriers rather than significant contents of metals in thermal waters. It is shown that microbial communities, concentrating chemical elements playing an important role in formation of ore mineralization in the discharge zones of thermal waters may be these barriers. According to our data, at the territory of the Tunka depression, thermal carbonic waters with endogenic components are delivered to the upper crustal horizons, involved in the existing hydrogeological systems, mixed with waters of active water exchange, and contribute to their chemical composition. This is manifested in the specific elemental and micromineral (Au, Ag, etc.) composition of the limescale of drinking water. In this local discharge zone, an effect of radioactive orphans has been found, which is similar to that established in barite chimneys from the Juan-de-Fuca Ridge.

  4. Experimental investigation of geochemical and mineralogical effects of CO2 sequestration on flow characteristics of reservoir rock in deep saline aquifers

    Science.gov (United States)

    Rathnaweera, T. D.; Ranjith, P. G.; Perera, M. S. A.

    2016-01-01

    Interactions between injected CO2, brine, and rock during CO2 sequestration in deep saline aquifers alter their natural hydro-mechanical properties, affecting the safety, and efficiency of the sequestration process. This study aims to identify such interaction-induced mineralogical changes in aquifers, and in particular their impact on the reservoir rock’s flow characteristics. Sandstone samples were first exposed for 1.5 years to a mixture of brine and super-critical CO2 (scCO2), then tested to determine their altered geochemical and mineralogical properties. Changes caused uniquely by CO2 were identified by comparison with samples exposed over a similar period to either plain brine or brine saturated with N2. The results show that long-term reaction with CO2 causes a significant pH drop in the saline pore fluid, clearly due to carbonic acid (as dissolved CO2) in the brine. Free H+ ions released into the pore fluid alter the mineralogical structure of the rock formation, through the dissolution of minerals such as calcite, siderite, barite, and quartz. Long-term CO2 injection also creates a significant CO2 drying-out effect and crystals of salt (NaCl) precipitate in the system, further changing the pore structure. Such mineralogical alterations significantly affect the saline aquifer’s permeability, with important practical consequences for the sequestration process. PMID:26785912

  5. Assessment of industrial minerals and rocks in the controlled area

    International Nuclear Information System (INIS)

    Yucca Mountain in Nye County, Nevada, is a potential site for a permanent repository for high-level nuclear waste in Miocene ash flow tuff. The Yucca Mountain controlled area occupies approximately 98 km2 that includes the potential repository site. The Yucca Mountain controlled area is located within the southwestern Nevada volcanic field, a large area of Miocene volcanism that includes at least four major calderas or cauldrons. It is sited on a remnant of a Neogene volcanic plateau that was centered around the Timber Mountain caldera complex. The Yucca Mountain region contains many occurrences of valuable or potentially valuable industrial minerals, including deposits with past or current production of construction aggregate, borate minerals, clay, building stone, fluorspar, silicate, and zeolites. The existence of these deposits in the region and the occurrence of certain mineral materials at Yucca Mountain, indicate that the controlled area may have potential for industrial mineral and rock deposits. Consideration of the industrial mineral potential within the Yucca Mountain controlled area is mainly based on petrographic and lithologic studies of samples from drill holes in Yucca Mountain. Clay minerals, zeolites, fluorite, and barite, as minerals that are produced economically in Nevada, have been identified in samples from drill holes in Yucca Mountain

  6. Recovery of NORM from scales generated by oil extraction.

    Science.gov (United States)

    Al Attar, Lina; Safia, Bassam; Ghani, Basem Abdul; Al Abdulah, Jamal

    2016-03-01

    Scales, containing naturally occurring radioactive materials (NORM), are a major problem in oil production that lead to costly remediation and disposal programmes. In view of environmental protection, radio and chemical characterisation is an essential step prior to waste treatment. This study focuses on developing of a protocol to recover (226)Ra and (210)Pb from scales produced by petroleum industry. X-ray diffractograms of the scales indicated the presence of barite-strontium (Ba0.75Sr0.25SO4) and hokutolite (Ba0.69Pb0.31SO4) as main minerals. Quartz, galena and Ca2Al2SiO6(OH)2 or sphalerite and iron oxide were found in minor quantities. Incineration to 600 °C followed by enclosed-digestion and acid-treatment gave complete digestion. Using (133)Ba and (210)Pb tracers as internal standards gave recovery ranged 87-91% for (226)Ra and ca. 100% for (210)Pb. Radium was finally dissolved in concentrated sulphuric acid, while (210)Pb dissolved in the former solution as well as in 8 M nitric acid. Dissolving the scales would provide better estimation of their radionuclides contents, facilitate the determination of their chemical composition, and make it possible to recycle NORM wastes in terms of radionuclides production. PMID:26773509

  7. Tannins in Mineral Processing and Extractive Metallurgy

    Directory of Open Access Journals (Sweden)

    Jordan Rutledge

    2015-08-01

    Full Text Available This study provides an up to date review of tannins, specifically quebracho, in mineral processing and metallurgical processes. Quebracho is a highly useful reagent in many flotation applications, acting as both a depressant and a dispersant. Three different types of quebracho are mentioned in this study; quebracho “S” or Tupasol ATO, quebracho “O” or Tupafin ATO, and quebracho “A” or Silvafloc. It should be noted that literature often refers simply to “quebracho” without distinguishing a specific type. Quebracho is most commonly used in industry as a method to separate fluorite from calcite, which is traditionally quite challenging as both minerals share a common ion—calcium. Other applications for quebracho in flotation with calcite minerals as the main gangue source include barite and scheelite. In sulfide systems, quebracho is a key reagent in differential flotation of copper, lead, zinc circuits. The use of quebracho in the precipitation of germanium from zinc ores and for the recovery of ultrafine gold is also detailed in this work. This analysis explores the wide range of uses and methodology of quebracho in the extractive metallurgy field and expands on previous research by Iskra and Kitchener at Imperial College entitled, “Quebracho in Mineral Processing”.

  8. Structural properties of Bi2O3-B2O3-SiO2-Na2O glasses for gamma ray shielding applications

    Science.gov (United States)

    Kaur, Kulwinder; Singh, K. J.; Anand, Vikas

    2016-03-01

    Glass samples of the xBi2O3-(0.70-x)B2O3-0.15SiO2-0.15Na2O (where x=0 up to 0.5 mol fraction) have been prepared in the laboratory by using melt quenching technique. 137Cs source has been used for experimental measurements of mass attenuation coefficient of γ-rays at 662 keV. Mass attenuation coefficient of our glass samples has been compared with standard nuclear radiation shield "barite concrete". It has been concluded that bismuth containing glass samples can be potential candidates for γ-ray shielding applications. Glasses must have appreciable elastic moduli values for their practical utility as γ-ray shields which are related to coordination number and non-bridging oxygens. Structural properties including coordination number and non-bridging oxygens of the structural units of the glass system have been estimated from the detailed analysis of Optical, Raman and FTIR spectra. Reported investigations can contribute to the development of transparent gamma ray shields.

  9. Pyrobitumen related to silver-copper deposits in a Cretaceous volcanic-sedimentary sequence: Talcuna district, Coquimbo, Chile

    Directory of Open Access Journals (Sweden)

    Jimena Cucurella

    2005-01-01

    Full Text Available In recent years, hydrocarbons have been observed in some stratabound copper deposits inthe Cretaceous volcanic-sedimentary sequences in north and central Chile. At the “21 de Mayo” and“Socavon 2001” mines in the Talcuna district in north-central Chile (2930’–2945’ S/7045’–7100’ W,pyrobitumen is associated with ore minerals in Lower Cretaceous rocks. In this district, recent investigationsdemonstrate that the ore mineralization, traditionally regarded to be of stratabound (manto type, has bothstructural and lithological controls. Paragenetic relations reflect a hydrothermal emplacement of boththe pyrobitumen and the ore and gangue minerals, while isotopic analyses suggest an organic marineprovenance of the former. Reflectivity 2.0–2.4% indicates the maturity of the pyrobitumen. Its occurrence isspatially related to sulphide mineralization (chalcopyrite, bornite, chalcocite and to barren zones, especiallyin the walls of fractures and faults that were channels for post-ore diorite dikes. Organic matter was probablyhydrothermally mobilized from limestones of the Arqueros Formation and precipitated first in the ore zonesand then in fractured post-ore dikes. Hydrothermal fluids sealed in calcite and barite related to thepyrobitumen reveal homogenization temperatures ranging from 180 to 320C and salinities from 6.5 to21 wt.% NaCl equivalent. These data characterize the mineralization as a moderate- to low-temperatureevent involving fluids of considerable salinity.

  10. Examining the ground layer of St. Anthony from Padua 19th century oil painting by Raman spectroscopy, scanning electron microscopy and X-ray diffraction

    International Nuclear Information System (INIS)

    Highlights: ► Raman spectroscopic examination of uncovered and covered paint layers of a real painting. ► Deconvolution of Raman peaks of lead white. ► Comparison of results with energy-dispersive analysis and X-ray diffraction. - Abstract: In this paper we studied the material composition of the ground layer of a neoclassical painting. We used Raman spectroscopy (RS) as a prime method. Thereafter scanning electron microscopy combined with energy dispersive spectroscopy (SEM–EDS) and X-ray powder diffraction (XRD) were employed as complementary techniques. The painting inspected was of the side altar in King St. Stephen's Church in Galanta (Slovakia), signed and dated by Jos. Chr. Mayer 1870. Analysis was carried out on both covered and uncovered ground layers. Four principal compounds (barite, lead white, calcite, dolomite) and two minor compounds (sphalerite, quartz) were identified. This ground composition is consistent with the 19th century painting technique used in Central Europe consisting of white pigments and white fillers. Transformation of lead white occurred under laser irradiation. Subdominant Raman peaks of the components were measured. The observed results elucidate useful partnership of RS and SEM–EDS measurements supported by X-ray powder diffraction as well as possibilities and limitations of non-destructive analysis of covered lower layers by RS.

  11. Determination of barium in surface and ground waters at Centro Experimental Aramar area

    International Nuclear Information System (INIS)

    Barium can be found in waters up to 1 mg L-1 and came from natural sources such as sedimentary rocks erosion rich in feldspar and barite. Also anthropogenic activities can release this element such as oil and gas industry, agricultural defensives, chemical industry and waste disposal. At high doses, barium can be harmful to human central nervous system and can also cause high blood pressure, heart problems, fatigue and anxiety. The water potability defined by Brazilian's Ministry of Healthy sets barium concentration up to 0.7 mg L-1 and official regulation defines the same limit of this element to superficial waters (according CONAMA resolution 357/2005) and ground waters (Sao Paulo state regulation). In this work, barium was analyzed monthly in superficial waters from 4 different sampling locations, located in a ratio of 10-km-long from Centro Experimental Aramar (CEA) at Ipanema River, during one year, in order to evaluate the river in different conditions (seasons, temperature and rain period). The ground water was collected every six months. The analytical technique applied was ICP OES and the method conditions were optimized: wavelength, linearity, signal background ratio, detection and quantification limits. Data obtained in this work will contribute to evaluate the presence of barium at CEA region and nearby in order to compare it with current Brazilian regulations. (author)

  12. Well logging with natural gamma radiation

    International Nuclear Information System (INIS)

    An invention is described for use in natural gamma radiation well logging in which measurements taken in a borehole are used in the search for valuable underground resources such as oil or gas. The invention comprises deriving a log of natural gamma radiation detected in selected energy windows for a selected borehole depth interval and converting it into a log of the selected subsurface materials, e.g. Th, U, K. This log is corrected for the effects of 1) either a gamma ray emitter in the borehole fluid, e.g. potassium salts and/or 2) a gamma ray attenuator in the borehole fluid, e.g. a strong attenuator such as barite and/or hematite. The Th, U, K log is particularly useful in the exploration of oil and gas resources since the Th, U, K concentrations are a good indication as to the presence, type and volume of shale and clay in the formations surrounding the borehole. (U.K.)

  13. Revitalisation thermal column drive train control system

    International Nuclear Information System (INIS)

    Revitalisation thermal columns propulsion train control system is very urgent to be implemented because of the test results and observation, control system performance is not normal, there are several components that must be renewed. Components includes MCB, magnetic contactors, push buttons, indicator lights and wiring. Drive motor is used to power 1.5 kW 3 phase, 380 volts and 50 Hz, nominal current (In = 3.75 A). Thermal column is one of the irradiation facility at the Kartini reactor has a beam-shaped room of measuring 1.2 X 1.2 X 1.6 m contains graphite blocks 10.2 X 10.2 X 127 cm(1) and is tangentially connected to the Kartini reactor core. Graphite blocks mounted reflector extends from the outer side to the inner surface of the door closer. Door closer contains barite concrete as radiation shielding and can be moved forward and backward to close and to open using a rotating motor to spin the wheel transmission system for running on rails. (author)

  14. Assessment of industrial minerals and rocks in the controlled area

    Energy Technology Data Exchange (ETDEWEB)

    Castor, S.B. [Nevada Bureau of Mines and Geology, Reno, NV (United States); Lock, D.E. [Mackay School of Mines, Reno, NV (United States)

    1996-08-01

    Yucca Mountain in Nye County, Nevada, is a potential site for a permanent repository for high-level nuclear waste in Miocene ash flow tuff. The Yucca Mountain controlled area occupies approximately 98 km{sup 2} that includes the potential repository site. The Yucca Mountain controlled area is located within the southwestern Nevada volcanic field, a large area of Miocene volcanism that includes at least four major calderas or cauldrons. It is sited on a remnant of a Neogene volcanic plateau that was centered around the Timber Mountain caldera complex. The Yucca Mountain region contains many occurrences of valuable or potentially valuable industrial minerals, including deposits with past or current production of construction aggregate, borate minerals, clay, building stone, fluorspar, silicate, and zeolites. The existence of these deposits in the region and the occurrence of certain mineral materials at Yucca Mountain, indicate that the controlled area may have potential for industrial mineral and rock deposits. Consideration of the industrial mineral potential within the Yucca Mountain controlled area is mainly based on petrographic and lithologic studies of samples from drill holes in Yucca Mountain. Clay minerals, zeolites, fluorite, and barite, as minerals that are produced economically in Nevada, have been identified in samples from drill holes in Yucca Mountain.

  15. Mineralization Zoning in Yindongzi—Daxigou Barite—Siderite,Silver—Polymetallic Deposits in the Qinling Orogen,China

    Institute of Scientific and Technical Information of China (English)

    方维萱; 胡瑞忠; 等

    2001-01-01

    The Yindongzi-Daxigou strata-bound barite-siderite,silver-polymetallic deposits discovered in the Qinling orogen are hosted within flysch facies in a deep-water fault-controlled basin on the passive northern margin of the Qinling microplate.The orebodies occur in a series of hydrothermal depositonal rocks.Mineralization zoning is characterized by Fe-Ba←Ba-Cu←Pb-Ab→Cu-Ag→Pb→Au.This is obviously a gradational transition mineralization from ventproximal mineralization to more distal mineralization.In this gradational transition between Chefanggou and Yindongzi,vent-proximal mineralization consists of silver-polymetallic orebodies(Pb-Ag),which is the center of hydrothermal mineralization.The Chefanggou Ba-Cu ore district in the west and the Yindongzi Cu-Ag ore district in the east represent vent lateral mineralization.Distal mineralization in the west is represented by the Daxigou Fe-Ba ore district while distal mineralization in te east is represented by the Pb ore district.Thick massive,laminated barren albite chert and jasperite,sometimes with minor silver-ploymetallic mineralization of commercial importance,and pyritization in rocks feature more distal mineralization.Geochemical anomalies of Au-As associations are found in ankerite phyllite and muddy sandstone.Actually,Au deposits are dominantly controlled by the late brittle-ductile shear zone.

  16. Lead oxides filled isophthalic resin polymer composites for gamma radiation shielding applications

    International Nuclear Information System (INIS)

    Particulate polymer composites of isophthalic resin (ISO) filled with three lead oxides (PbO, PbO2 and Pb3O4) were prepared with different filler concentrations and investigated for radiation shielding properties of gamma rays from 133Ba (80 KeV and 356 KeV), 137Cs (662 KeV) and 60Co (1173 KeV and 1337 KeV) point sources. Among the three composite combinations, ISO+PbO composites yield better density values than the other two due to high density of the filler which contains large lead fraction and fine dispersability in the polymer matrix. Dispersion and particle size of filler were also studied by morphological analysis of the composites using SEM. Attenuation coefficients were found to increase with the increased filler content in the composites. ISO+PbO composites have found to outperform than ISO+PbO2 and ISO+Pb3O4 composites. Excellent performance of ISO+PbO composites can be attributed to their high lead content as well as fine filler dispersion in the polymer matrix. Further, these ISO+PbO composites perform as strong contenders to conventional shielding materials such as barite, steel and concrete at low gamma ray energies. Even at higher gamma ray energies, they perform satisfactorily and are very much comparable to steel and concrete. (author)

  17. Bulk additive system reduces mud costs and waste

    International Nuclear Information System (INIS)

    Today, personnel safety and environmental acceptability are high priorities in oil and gas operations. Many advances have been made, but packaging and handling of drilling mud has not changed in 35 years. In most cases, bulk barite is available, however, drilling muds are typically built from chemicals contained in 50 to 100-lb sacks or 5-gal buckets. Materials must be physically opened by rig personnel and mixed into drilling mud. Chemical exposure liability, and lifting or housekeeping related injuries associated with large quantities of packaging pose serious occupational safety risk. Figures from OSHA (1986) indicate that of 1,492 serious injury cases in Louisiana oil and gas operations, 42% were to back and lower extremities, 3% were eye injuries and 1% were chemical burns. Although exact figures are not available, experience suggests that a significant number of injuries are related to mud product physical handling. Another problem with current mud packaging is generated waste. Mud material lost because of broken sacks, inefficient transfer and as residue is unacceptable. Most mud engineers agree that 5 to 15% of mud products are lost or damaged on typical offshore jobs, depending on weather. When material that is spilled or left in packages, probably 2 to 3%, is added, the total is significant. Reusable containers for drilling mud products and manifold system design effectively eliminate these problems

  18. Quantitative analyses of glass via laser-induced breakdown spectroscopy in argon

    Science.gov (United States)

    Gerhard, C.; Hermann, J.; Mercadier, L.; Loewenthal, L.; Axente, E.; Luculescu, C. R.; Sarnet, T.; Sentis, M.; Viöl, W.

    2014-11-01

    We demonstrate that elemental analysis of glass with a measurement precision of about 10% can be performed via calibration-free laser-induced breakdown spectroscopy. Therefore, plasma emission spectra recorded during ultraviolet laser ablation of different glasses are compared to the spectral radiance computed for a plasma in local thermodynamic equilibrium. Using an iterative calculation algorithm, we deduce the relative elemental fractions and the plasma properties from the best agreement between measured and computed spectra. The measurement method is validated in two ways. First, the LIBS measurements are performed on fused silica composed of more than 99.9% of SiO2. Second, the oxygen fractions measured for heavy flint and barite crown glasses are compared to the values expected from the glass composing oxides. The measured compositions are furthermore compared with those obtained by X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy. It is shown that accurate LIBS analyses require spectra recording with short enough delays between laser pulse and detector gate, when the electron density is larger than 1017 cm- 3. The results show that laser-induced breakdown spectroscopy based on accurate plasma modeling is suitable for elemental analysis of complex materials such as glasses, with an analytical performance comparable or even better than that obtained with standard techniques.

  19. Evaluation of X-ray spectra transmitted by different concrete compositions

    Science.gov (United States)

    Costa, P. R.; Vieira, D. V.; Naccache, V. K.; Ferreira, K. R.; Priszkulnik, S.

    2015-11-01

    Additional shielding material must frequently be incorporated to medical facilities in order to comply with radiation protection requirements when using radiation sources. Typical materials for shielding walls, floor and ceiling are the lead, concrete and barite. In the present work, a group of four concrete compositions was evaluated by using broad beam transmission curves and transmitted spectra in the range of X-ray energies used for diagnostic imaging. The studied concretes were classified as ordinary concrete (Type C), concrete with addition of hematite (Types H1 and H2) and concrete with addition of steel grit (Type S). Concrete with steel grit shows be more efficient as shielding material of the three heavy types concrete studied. The two mixes of concrete and hematite are practically equivalent from the radioprotection point of view. However, the granulation difference between them might be important to other fields, as shielding is not the only function of concrete in the building structure. Although they are not as efficient as concrete with steel grit, they may be a shielding option in a facility with low shielding requirement.

  20. Determination of barium in surface and ground waters at Centro Experimental Aramar area

    Energy Technology Data Exchange (ETDEWEB)

    Matoso, Erika, E-mail: ematoso@hotmail.com [Centro Tecnologico da Marinha em Sao Paulo (CEA/CTMS), Ipero, SP (Brazil). Centro Experimental Aramar; Cadore, Solange, E-mail: cadore@iqm.unicamp.br [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Instituto de Quimica. Departamento de Quimica Analica

    2015-07-01

    Barium can be found in waters up to 1 mg L{sup -1} and came from natural sources such as sedimentary rocks erosion rich in feldspar and barite. Also anthropogenic activities can release this element such as oil and gas industry, agricultural defensives, chemical industry and waste disposal. At high doses, barium can be harmful to human central nervous system and can also cause high blood pressure, heart problems, fatigue and anxiety. The water potability defined by Brazilian's Ministry of Healthy sets barium concentration up to 0.7 mg L{sup -1} and official regulation defines the same limit of this element to superficial waters (according CONAMA resolution 357/2005) and ground waters (Sao Paulo state regulation). In this work, barium was analyzed monthly in superficial waters from 4 different sampling locations, located in a ratio of 10-km-long from Centro Experimental Aramar (CEA) at Ipanema River, during one year, in order to evaluate the river in different conditions (seasons, temperature and rain period). The ground water was collected every six months. The analytical technique applied was ICP OES and the method conditions were optimized: wavelength, linearity, signal background ratio, detection and quantification limits. Data obtained in this work will contribute to evaluate the presence of barium at CEA region and nearby in order to compare it with current Brazilian regulations. (author)

  1. Workload weighed transmission curves of Brazilian shielding materials: computer simulations

    International Nuclear Information System (INIS)

    Computer simulations were performed using modified TBC Model (Costa,P.R. et al, Health Physics 92(1),2007) through the MathCad program generating primary X-ray spectra in the range of 60 to 150 kV. Elemental compositions of five commercial barite concretes used for shielding diagnostic facilities were obtained from fluorescence spectroscopy. The NIST X-COM software was used in order to getting the mass attenuation coefficient of each sample. Mass density of every one sample was measured by using Archimedes method. These densities were combined to the results of the mass attenuation coefficients for obtaining the linear attenuation coefficients of each sample under study. These densities were combined to the results of the mass attenuation coefficients for getting the linear attenuation coefficients of every one sample. Transmitted spectra were calculated through applying Beer Law. This operation was performed for obtaining the transmission curve calculated by energy integration of these spectra. The method proposed by Archer et. al (MedPhys.21(9);1994) was used for obtaining α, β and γ coefficients for each kV evaluated and for each shielding materials. (author)

  2. Mercury contamination from mine and natural sources in Harley Gulch, downstream from the Abbott and Turkey Run Mercury Mines, Lake County, California

    Science.gov (United States)

    Hothem, R. L.; Rytuba, J. J.; Goldstein, D.; Brussee, B.

    2011-12-01

    The Abbott and Turkey Run Mercury (Hg) mine area in central California has released Hg tailings into the Harley Gulch watershed since 1862. Harley Gulch flows into Cache Creek which is a significant source of Hg into San Francisco Bay Delta. Thermal mine water effluent emanating from the Turkey Run adit flows into the upper part of the watershed. Despite remediation efforts, Hg tailings and enriched sediment remain in the Harley Gulch wetlands and in the creek downstream from the mine area. Water, sediment, and biota have been sampled from below the mine area to 15 km downstream to the confluence with Cache Creek in order to assess the impact of Hg on water quality and biota. Two previously unrecognized natural sources of Hg in the watershed are connate groundwater with elevated levels of Hg, and biogenic sediment composed of phytoplankton that accumulates in the upper part of the watershed during the dry season. The connate groundwater source contains isotopically-heavy Mg-Ca-Cl-CO3-SO4 water that has elevated concentrations of Ba, W, Ti, and Hg. This water first enters Harley Gulch in the central part of the wetland immediately downstream from the mine area and continues to contribute water downstream for a distance of 1.5 km. It is both chemically and isotopically distinct from the thermal mine water effluent from the Turkey Run adit. The biogenic source consists of blooms of phytoplankton that accumulate to a thickness of up to 0.2 m. Phytoplankton have a large bioaccumulation factor of Hg and monomethyl mercury (MMeHg) that results in a high concentrations of Hg and MMeHg (Hg: 5-25 μg/g, MMeHg 5.2 ng/g) in the biogenic sediment. The tan biogenic sediment at the surface consists of living diatoms and below it is a layer of black reduced biogenic sediment consisting of diatom fragments with micron- to submicron-sized FeS, HgS, and barite grains. Sulfate-reducing bacteria reduce sulfate to sulfide in the pore waters of the biogenic sediment that reacts with

  3. Characteristics and Origin of Sedimentary-Related Manganese Layers in Timor Island, Indonesia

    Directory of Open Access Journals (Sweden)

    Arifudin Idrus

    2014-07-01

    Full Text Available DOI: 10.17014/ijog.v8i4.169Sedimentary-related manganese layers have been discovered in South Central Timor Regency, Timor Island, Indonesia, which is tectonically active and being uplifted due to north-trending tectonic collision between Timor Island arc and Australian continental crust. The manganese layers of 2 to 10 cm-wide interbed with deep sea sedimentary rocks including reddish - reddish brown claystone, radiolarian chert, slate, marl as well as white and pinkish calcilutite of Nakfunu Formations. Stratigraphically, the rock formations are underlain by Bobonaro Formation. Two types of manganese ores found comprise manganese layers and manganese nodule. The manganese layers strongly deformed, lenticular, and segmented, are composed of manganite [MnO(OH], groutite [MnO(OH], pyrolusite (MnO2, lithioporite (Al,Li MnO2(OH2, and hollandite [Ba (Mn4+, Mn2+8O16] associated with gangue minerals including calcite, quartz, limonite [FeO(OH], hematite (Fe2O3, and barite (BaSO4. Whilst the nodule type is only composed of manganite and less limonite. Geochemically, the manganese layers have grade of 63 - 72 wt.% MnO, whereas the nodule one has grade of 63 - 69 wt.% MnO. Generally, iron in Mn ore is very low ranging from 0.2 to 1.54 wt.% Fe2O3, averaged 0.76 wt.%. Hence, Fe/Mn ratio which is very low (0.003 - 0.069, typically indicates a sedimentary origin, which is also supported by petrologic and petrographic data showing layering structure of manganite and lithioporite crystal/grain. Trace element geochemistry indicates that manganese ore was precipitated in a reduction condition. Rare earth element (REE analysis of manganese ore shows an enrichment of cerium (Ce suggesting that the ore is basically originated in a marine environment. The manganese nodule is interpreted to be formed by chemical concretion process of unsoluble metals (i.e. mangan, iron in seawater (hydrogenous and precipitated on deep sea bottom. On the other hand, the manganese

  4. Geology, isotope geochemistry and geochronology of the Jinshachang carbonate-hosted Pb-Zn deposit, southwest China

    Science.gov (United States)

    Zhou, Jia-Xi; Bai, Jun-Hao; Huang, Zhi-Long; Zhu, Dan; Yan, Zai-Fei; Lv, Zhi-Cheng

    2015-02-01

    The Jinshachang Pb-Zn deposit, an exceptionally radiogenic Pb-enriched sulfide deposit, hosted by dolostone of the Upper Sinian (Neoproterozoic) Dengying Formation and the Lower Cambrian Meishucun Formation, is located in the western Yangtze Block, about 300 km northeast of Kunming city in southwest China. Ore bodies in this deposit are dominated by strata-bound type and steeply dipping vein type. Primary ores in these two types are composed of sphalerite, galena, fluorite, barite and quartz with massive, banded, veined and disseminated structures. Twenty-seven ore bodies in the Jinshachang deposit host 4.6 million tons of sulfide ores at average grades of 4.07 wt.% Pb and 5.03 wt.% Zn. Quartz separates from the sulfide ores have δDH2O values ranging from -137‰ to -86.2‰ with an average of -114‰ (n = 7), lower than those of magmatic, metamorphic and meteoric water, suggesting a contribution of organic water. δ34SCDT values of ninety-one sulfide separates range from +1.1‰ to +13.4‰ with an average of +5.7‰, lower than those of evaporites (δ34SCDT = +15‰ to +35‰) in the Cambrian to Triassic sedimentary strata in NE Yunnan province. δ34SCDT values of eight barite separates range from +32‰ to +35‰ (average +34‰), within the range of evaporites. These data suggest that S2- in the hydrothermal fluids derived from evaporites by thermo-chemical sulfate reduction (TSR), whereas SO42- directly originated from the evaporites. Six sulfide separates have highly radiogenic 206Pb/204Pb ratios ranging from 20.74 to 21.18 (average 20.92), 207Pb/204Pb ratios ranging from 15.85 to 15.89 (average 15.87), and 208Pb/204Pb ratios ranging from 40.89 to 41.42 (average 41.16). The Pb isotopes of the sulfides plot above the upper crust Pb average evolution curve and overlap the Cambrian sedimentary rocks, but are different from the Sinian dolostone. This indicates a crustal source of Pb most likely derived from the Cambrian sedimentary rocks. The initial 87Sr/86Sr

  5. A retrospective analysis of trace metals, C, N and diatom remnants in sediments from the Mississippi River delta shelf

    Energy Technology Data Exchange (ETDEWEB)

    Turner, R. Eugene; Milan, C.S.; Rabalais, N.N

    2004-10-01

    The development of oil and gas recovery offshore of the Mississippi River delta began in shallow water in the 1950s, expanded into deeper waters, and peaked in the 1990s. This area of the outer continental shelf (OCS) is the historical and present location of >90% of all US OCS oil and gas production and reserves. The juxtaposition of its 4000 producing platforms, recovering $10 billion yr{sup -1} of oil, gas and produced water in the same area where about 28% of the US fisheries catch (by weight) is made and near 40% of the US coastal wetlands, makes this an area worth monitoring for regional pollutant loading. This loading may come from several sources, including sources related to OCS development, but also from the Mississippi River watershed. In this context, any contaminant loading on this shelf may be neither detectable nor significant against a background of climatic or biological variability. We examined the sedimentary record for indicators of industrial byproducts from OCS oil and gas development and of industrial products entering via the Mississippi River, primarily using vanadium (V) and barium (Ba) concentrations normalized for aluminum (Al). Barium is primarily used in drilling muds in the form of barite, whereas V is an important strengthening component of metal alloys, including steel. The fluctuations in the accumulation of Ba, but not V, were coincidental with the presumed use of barite. The fluctuations in V concentration in the sediments were coincidental with the national consumption of V. Copper (Cu), cadmium (Cd) and zinc (Zn) concentrations in sediments fluctuate coincidentally with V, not Ba, thus indicating that the dominant source of these trace metals in offshore sediments were derived from riverine sources, and were not primarily from in situ industrial processes releasing them on the shelf. This is not to suggest that local site-specific contamination is not a significant management or health concern. The low oxygen (hypoxia; {<=}2 mg

  6. Updated model for radionuclide transport in the near-surface till at Forsmark - Implementation of decay chains and sensitivity analyses

    Energy Technology Data Exchange (ETDEWEB)

    Pique, Angels; Pekala, Marek; Molinero, Jorge; Duro, Lara; Trinchero, Paolo; Vries, Luis Manuel de [Amphos 21 Consulting S.L., Barcelona (Spain)

    2013-02-15

    tendency to overestimate radionuclide concentrations at the discharge zone). Specifically, examination of the modelling results indicates that: 1. The implementation of the revised till stratigraphy has an overall small impact on the modelling results: despite distinctly different groundwater flow patterns, tracer arrival at the discharge zone is similar between the previous and current till models. 2. Of the radionuclides studied only {sup 226}Ra is significantly affected by radioactive chain decay dynamics. 3. The values of geochemical parameters used in the Base Case reactive transport calculations produce conservative results. 4. The model is largely insensitive to significant variations in dispersivity of the till and an alternative definition of the shallow groundwater inflow, although the elimination of vertical stratification in hydraulic conductivity has the effect to speed up radionuclide transport. 5. Over saturation with barite is not reached under any of the considered scenarios hence Ra coprecipitation with barite does not contribute to {sup 226}Ra retardation under the assumptions of the model. In contrast, Sr co-precipitation with calcite is an important retention mechanism for {sup 90}Sr.

  7. Radioactive mineral spring precipitates, their analytical and statistical data and the uranium connection

    Science.gov (United States)

    Cadigan, R.A.; Felmlee, J.K.

    1982-01-01

    Major radioactive mineral springs are probably related to deep zones of active metamorphism in areas of orogenic tectonism. The most common precipitate is travertine, a chemically precipitated rock composed chiefly of calcium carbonate, but also containing other minerals. The mineral springs are surface manifestations of hydrothermal conduit systems which extend downward many kilometers to hot source rocks. Conduits are kept open by fluid pressure exerted by carbon dioxide-charged waters rising to the surface propelled by heat and gas (CO2 and steam) pressure. On reaching the surface, the dissolved carbon dioxide is released from solution, and calcium carbonate is precipitated. Springs also contain sulfur species (for example, H2S and HS-), and radon, helium and methane as entrained or dissolved gases. The HS- ion can react to form hydrogen sulfide gas, sulfate salts, and native sulfur. Chemical salts and native sulfur precipitate at the surface. The sulfur may partly oxidize to produce detectable sulfur dioxide gas. Radioactivity is due to the presence of radium-226, radon-222, radium-228, and radon-220, and other daughter products of uranium-238 and thorium-232. Uranium and thorium are not present in economically significant amounts in most radioactive spring precipitates. Most radium is coprecipitated at the surface with barite. Barite (barium sulfate) forms in the barium-containing spring water as a product of the oxidation of sulfur species to sulfate ions. The relatively insoluble barium sulfate precipitates and removes much of the radium from solution. Radium coprecipitates to a lesser extent with manganese-barium- and iron-oxy hydroxides. R-mode factor analysis of abundances of elements suggests that 65 percent of the variance of the different elements is affected by seven factors interpreted as follows: (1) Silica and silicate contamination and precipitation; (2) Carbonate travertine precipitation; (3) Radium coprecipitation; (4) Evaporite precipitation

  8. Geological Fluid Mapping in the Tongling Area: Implications for the Paleozoic Submarine Hydrothermal System in the Middle-Lower Yangtze Metallogenic Belt, East China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    that enveloped no economic stringerstockwork zones beneath massive sulfides. This transgressive zone likely marks an upflow path of highflux fluids from the hydrothermal aquifer. Lateral zonation of the sub-discordant alteration zones and their relationship to overlying massive sulfide lenses suggest lateral flows and diffusive discharging of the hydrothermal fluids in a permeable sandstone sequence. Three large-sized, 14 middle-small massive sulfide deposits, and 40 massive sulfide sites have been mapped in detail. They show regional stratabound characters and two major styles, i.e., the layered sheet plus strata-bound stringer-style and the mound-style. Associated exhalite and chemical sedimentary rock suites include (1) anhydrite-barite, (2) jasper-chert, (3) Mg-rich mudstone-pyrite shale, (4) barite lens, (5) siderite-Fe-bearing dolomite, and (6) Mn-rich shale-mudstone, which usually comprise three sulfide-exhalite cyclic units in the area.The spatial distribution of these alteration zones (minerals) and associated massive sulfides and exhalites, and regional variation in δ34S of hydrothermal pyrite and in δ18O-δ34C of hanging wall carbonates, suggest three WNW-extending domains of fluid flow, controlled by the basement faults and syn-depositional faults. Each fluid domain appears to have at least two upflow zones, with estimated even spacing of about 5-8 km in the mapped area. The repeated appearance of sulfide-sulfate or sulfide-carbonate rhythmic units in the area suggests episodically venting of fluids through the upflow conduits by breaking the overlying seals of the hydrothermal aquifer.

  9. Características geoquímicas de la mineralización epitermal del área El Dorado-Monserrat, Provincia de Santa Cruz, Argentina

    Directory of Open Access Journals (Sweden)

    Leandro E Echavarría

    1998-07-01

    metals show great variations as demonstrated by the coss-cut sections through the host rocks. An increase of contents was found in close relationship with the presence of narrow veinlets carrying ore minerals. The highest Au-Ag contents were found in the Monserrat area where quartz as well as barite veins were analyzed. The results allow to establish that the former ones are Au-enriched while the barite lodes have higher Ag grades. Most of the elements show a log normal distribution with long queues towards the highest values. Many samples with different quartz textures have also been studied, those with replacement and massive textures have higher Au-Ag contents that those with banded textures. The latter is possible due to the lower formation temperatures of the banded quartz. The geochemical and textural differences found between both areas suggest that they represent different exposition levels. Monserrat, where there are coarse-grained quartz textures and carbonate replacements intergrown with pyrite and adularia, is the deepest one, and it coincides with the precipitation level of the noble elements; El Dorado represents superficial levels, with massive chalcedony and recrystallization textures, with higher contents of Hg and lack of Au-Ag.

  10. Multi-isotope (C - O - S - H - B - Mg - Ca - Ba) and trace element variations along a vertical pore water profile across a brackish-fresh water transition, Baltic Sea

    Science.gov (United States)

    Böttcher, Michael E.; Lapham, Laura; Gussone, Nikolaus; Struck, Ulrich; Buhl, Dieter; Immenhauser, Adrian; Moeller, Kirsten; Pretet, Chloé; Nägler, Thomas F.; Dellwig, Olaf; Schnetger, Bernhard; Huckriede, Hermann; Halas, Stan; Samankassou, Elias

    2013-04-01

    downcore increase in pore water concentrations of earth alkaline ions and the formation of authigenic barites. Coupled S-34 and O-18 isotope signals in authigenic barites suggest that they were formed in pre-Yoldia sediments from pore waters strongly depleted in O-18 (as low as -20 per mil vs. VSMOW). In the present communication, we will discuss possible impacts of diagenetic processes on multi-isotope signals in pore waters and authigenic phases. A combination of mixing between brackish and fresh water, ion exchange, precipitation/dissolution, and transport reactions is considered to explain most of the observed isotope variations along the vertical pore water profile. This work was supported by the Leibniz IOW, BONUS+ program, the Universities of Bern, Geneva, Bochum, Münster, and Oldenburg, and the Natural Museum of History, Berlin.

  11. Manganese mineralization in andesites of Brestovačka Banja, Serbia: evidence of sea-floor exhalations in the Timok Magmatic Complex

    Science.gov (United States)

    Pačevski, Aleksandar; Cvetković, Vladica; Šarić, Kristina; Banješević, Miodrag; Hoefer, Heidi Eva; Kremenović, Aleksandar

    2016-08-01

    Andesites near Brestovačka Banja belong to the Late Cretaceous Timok Magmatic Complex (TMC), which hosts the world-class Bor metallogenic zone including numerous porphyry-copper and epithermal deposits. Two main volcanic phases are recognized in the TMC. The newly discovered Mn mineralization reported here is associated with the second volcanic phase of Turonian-Campanian age. Manganese mineralization containing 58 % MnO on average, occurs as black veins, lumps and nests filling cracks and cavities within an autoclastic andesite, which was deposited in a subaqueous environment. This rock also contains minor Fe mineralization, which is contemporaneous with the manganese mineralization. Manganese mineralization predominantly consists of Mn-Ca silicates (macfallite, pumpellyite-Mn, orientite, bustamite) and Mn oxides (pyrolusite, manganite). Micrometer-scale mineral intergrowths and locally preserved botryoidal and colloform textures are characteristic features of this uncommon mineral assemblage. The features could indicate that the mineralization was formed by deposition from a primary colloidal assemblage and is of sub-marine hydrothermal origin. Orientite is the only Mn mineral with grain size reaching several tenths of micrometers and showing prismatic crystal habit. Scarce to rare associated minerals are hollandite, crednerite, an unknown REE mineral, powellite, pyrite, barite and galena, in decreasing abundance. Trace element analyses of the Mn mineralization show different element contents and REE patterns compared to those of the volcanic host-rock. Manganese mineralization shows relatively high contents of Cu - 1784 ppm, Mo - 20 ppm and As - 268 ppm. These elements are commonly enriched in the Cu deposits of the Bor zone and their relatively high contents in the studied Mn crusts indicate sea-floor hydrothermal vents as a source of the metals.

  12. Characterization of acid river dilution and associated trace element behavior through hydrogeochemical modeling: A case study of the Banyu Pahit River in East Java, Indonesia

    International Nuclear Information System (INIS)

    elements including F, Al, Cd and Tl, which are transported downstream by the Banyu Pahit River, which is eventually used to irrigate farmland on the Asambagus Plain. The fate and behavior of major and trace elements are investigated, in the region of greatest change to the Banyu Pahit River, where thermal springs and the neutral Kali Sat and Kali Senggon Rivers increase its discharge 6-fold and pH increases from 1.9 to 4.5 with the development of abundant precipitates. The conservative behavior of Cl, F and SO4 allows determination of the proportions of the mixing constituents at each confluence. Comparing a mass balance model based on the resulting proportions with measured concentrations demonstrates conservative behavior for most cations, with the exception of Si, Zr, Sn and Ba, which precipitate as amorphous silica, barite, and Zr and Sn phases, respectively. Iron is added as particulate Fe-(oxy)hydroxide in mixing with thermal spring outflow, and dissolves in the lower pH water. This also contributes Co, Cd, Mn, Y, and the rare earth elements, which are desorbed from the Fe-(oxy)hydroxide upon entering the acid water. Subsequent saturation in Fe-(oxy)hydroxide after mixing with the neutral rivers leads to a reverse response. Still, element behavior is close to conservative, which means that the volcanogenic toxic element load is almost entirely transferred to the Asambagus Plain with ensuing environmental and health impacts. This study shows that compositions of these acid waters can be understood and reproduced in a thermodynamic model, but only when fine-tuned using measured compositions and field observations. Therefore, the model’s utility in assessing the fate of toxic elements and in planning the environmental mitigation is limited.

  13. Optimization of radiation protection in gamma radiography facilities; Otimizacao do sistema de radioprotecao nas instalacoes radiograficas de gamagrafia

    Energy Technology Data Exchange (ETDEWEB)

    Antonio Filho, Joao

    1999-07-01

    To determine optimized dose limits for workers, a study of optimization of radiation protection was undertaken in gamma radiography facilities closed, using the Technique Multiple Attributes Utility Analysis. A total of 217 protection options, distributed in 34 irradiation scenarios for tree facility types ( fixed open, moveable and closed (bunker) were analyzed. In the determination of the optimized limit dose, the following attributes were considered; costs of the protection barriers, costs attributed to the biological detriment for different alpha (the reference value of unit collective dose), size of the isolation area, constrained limits dose of annual individual equivalent doses and collective dose. The variables studied in the evaluation included: effective work load, type and activity of the sources of radiation ({sup 192}Ir and {sup 60}Co), source-operator distance related to the characteristic of the length of the command cable and the guide tube, type and thickness of the materials used in the protection barriers (concrete, barite, ceramic, lead, steel alloy and tungsten). The optimal analytic solutions obtained in the optimization process that resulted in the indication of the optimized dose limit were determined by means of a sensitivity analysis and by direct and logic evaluations, thus, independent of the values of the monetary coefficient attributed to the biological detriment, of the annual interest rate applied to the protection cost and of the type of installation studied, it was concluded that the primary limit of annual equivalent dose for workers (now 50 mSv) can be easily reduced to an optimized annual dose limit of 5 mSv. (author)

  14. The artists' materials of Fernando Melani: a precursor of the Poor Art artistic movement in Italy.

    Science.gov (United States)

    Carlesi, Serena; Bartolozzi, Giovanni; Cucci, Costanza; Marchiafava, Veronica; Picollo, Marcello

    2013-03-01

    A comprehensive understanding of both the chemical composition and physical behaviour of modern materials is an important consideration in devising correct conservation treatments for contemporary artworks. To this end, national and international research projects and networks have been established that deal mainly with the preservation, conservation, and understanding of materials used by contemporary artists. This paper focuses on the self-taught artist Fernando Melani (1907-1985), one of the precursors of the Poor Art artistic movement in Italy, and for the first time provides a scientific viewpoint on the artist's materials and works. The analyses, which mainly focus on the pigments/dyes found in his home-studio, were carried out primarily by using Fourier Transform Infrared Spectroscopy (FT-IR) and ultraviolet, visible, and near-infrared Fibre Optic Reflectance Spectroscopy (UV-Vis-NIR FORS). This paper emphasises the performance of FT-IR and FORS in the identification of contemporary artistic materials, since these two techniques have been found to produce highly complementary data. The use of both of these was required in order to obtain a comprehensive understanding of the composition of Melani's materials. Furthermore, one of his artworks, named by Melani himself with its inventory number N. Inv. 2625 (1981), was investigated in situ with the sole use of the FORS technique. The results showed that Melani used traditional inorganic pigments as well as modern organic dyes. Calcite and barite were used as fillers and extenders. Sulphur and abrasive powder were also found, thus confirming his use of a large variety of non-conventional artists' materials. PMID:23291192

  15. Radium and uranium concentrations and associated hydrogeochemistry in ground water in southwestern Pueblo County, Colorado

    Science.gov (United States)

    Felmlee, J. Karen; Cadigan, Robert Allen

    1979-01-01

    Radium and uranium concentrations in water from 37 wells tapping the aquifer system of the Dakota Sandstone and Purgatoire Formation in southwestern Pueblo County, Colorado, have a wide range of values and define several areas of high radioactivity in the ground water. Radium ranges from 0.3 to 420 picocuries per liter and has a median value of 8.8, and uranium ranges from 0.02 to 180 micrograms per liter and has a median value of 2.4. Radon concentrations, measured in 32 of the 37 wells, range from less than 100 picocuries per liter to as much as 27,000 and have a median value of 580. Relationships among the radioactive elements and 28 other geochemical parameters were studied by using correlation coefficients and R-mode factor analysis. Five factor groups were determined to represent major influences on water chemistry: (1) short-term solution reactions, (2) oxidation reactions, (3) hydrolysis reactions, (4) uranium distribution, and (5) long-term solution reactions. Uranium concentrations are most strongly influenced by oxidation reactions but also are affected by solution reactions and distribution of uranium in the rocks of the aquifer system. Radon and radium concentrations are mostly controlled by uranium distribution; radium also shows a moderate negative relationship with oxidation. To explain the statistical and spatial relationships among the parameters, a model was developed involving the selective leaching of uranium-bearing phases and metal sulfides which occur in discontinuous zones in sandstone and shale. When reducing conditions prevail, uranium is immobile, but radium can be taken into solution. When faults and associated fractured rocks allow oxidizing conditions to dominate, uranium can be taken into solution; radium can also be taken into solution, or it may become immobilized by coprecipitation with iron and manganese oxides or with barite. Several areas within the study area are discussed in terms of the model.

  16. Geochemistry of metalliferous, hydrothermal deposits in the Aeolian arc (Tyrrhenian Sea)

    Science.gov (United States)

    Savelli, C.; Marani, M.; Gamberi, F.

    1999-03-01

    In shallow-water areas of the submerged volcanic complex around the island of Panarea (Aeolian archipelago), hydrothermal precipitation of both low-temperature Fe-oxyhydroxide-rich red muds and crusts, and high-temperature, sediment-hosted massive sulfides was discovered during an integrated, high-resolution survey. Iron-rich crusts were also found on the bathymetric high of Secca del Capo, north of Salina island. The exhalative iron-rich sediments occur in small (closed) depressions or in proximity to faults and scarps at water depths ranging from 55 to 285 m. The principal chemical characteristics of these deposits are high, but variable, Fe content ranging from 12.2 to 45%, and low contents of the transition elements Mn, Cu, Zn, Ni and Co. The low contents of Cu, Ni and Co suggest a hydrothermal origin. The Fe-oxyhydroxide deposits are enriched in light rare earth element (REE) (35-110×chondrite) compared to heavy REE (10-25×chondrite). Their REE patterns are similar to those of associated calc-alkaline volcanics: negative slope of light REE and a horizontal distribution of the heavy ones. This contrasts with the pattern for iron and manganese oxides of hydrogenous origin, which have tilted trends of heavy REE paralleling that of seawater. The mineralogy of the polymetallic sulfide deposits consists of galena, sphalerite, pyrite and barite in the form of silt-sand grains and decimeter-sized fragments disseminated in clay, 30 cm below the seabed, at a waterdepth of 80 m. The chemistry of the Aeolian iron-rich, low-temperature deposits and of the high-temperature, Ba-rich Pb and Zn sulfides suggests that they are genetically analogous to, respectively, the kuroko-type iron formation (`tetsusekiei') and the black ore exposed in the Miocene Hokuroku district of Japan.

  17. Time distribution of the main Brazilian mineral deposits. 2: metallogenic epochs; Distribuicao no tempo geologico dos principais depositos minerais brasileiros. 2: epocas metalogeneticas

    Energy Technology Data Exchange (ETDEWEB)

    Biondi, Joao C. [Parana Univ., Curitiba, PR (Brazil). Dept. de Geologia]. E-mail: jcbiondi@setuva.geologia.ufpr.br

    1999-12-01

    The metallogenic epochs of the main mineral deposit groups were defined with base on the ore's of the 194 main Brazilian mineral deposits. Mineral deposits are rare on epochs that: precede the beginning of juvenile accretion peak periods, and/or of cooling of rocks formed during each of the main brazilian thermo-tectonic events. Deposits are more frequent on epochs that are coincident or immediately younger than these peak periods. The most important metallogenic epoch, with about 30% of the selected deposits, is between 50 Ma and the Recent, and corresponds to the formation of supergenic and/or residual and placer deposits. Brazilian's volcanogenic (VHMS), Mississippi Valley (MTV) and mesothermal gold-lode deposits have discordant ages as compared with their equivalents in other countries, while deposits believed to be SEDEX have concordant ages. With the exception of Urucum, the primary iron and manganese ores of brazilian deposits are Archean. Primary tin deposits from Amazonas, Amapa and Goias State cluster between 1500 and 2300 Ma. Tin deposits from Rondonia and Mato Grosso are more recent and most formed between 1000 and 1600 Ma, in sequence with the other groups of tin deposits. Uranium deposits vary on genetic model and ages, due to the mobility of the element in all geologic environments. Most part of Brazilian deposits of phosphate, titanium, niobium, Rare Earths, diamond in kimberlites and of amethyst formed during the Mesozoic, and arte genetically related to the alkaline and basaltic magmatism that affected the brazilian territory in this period. Gemstone (tourmaline and aquamarine), talc and magnesite deposits are more frequent in the Brasiliano period. Gipsite, silvite and barite occur in Senonian to Aptian evaporites. (author)

  18. FIRE-RESISTANT SHIELDING COATING BASED ON SHUNGITE-CONTAINING PAINT

    Directory of Open Access Journals (Sweden)

    BELOUSOVA Elena Sergeevna

    2013-08-01

    Full Text Available Today when specific shielded facilities are designed the construction materials and shields should meet a range of fire safety requirements. A composite coating on the basis of a water-based fire-resistant paint filled with shungite nanopowder can be applied onto walls, floors, ceilings and other surfaces in the shielded areas to reduce electromagnetic radiation and simultaneously to ensure fire safety. Shungit is a mineral with multilayer carbon fullerene globules which diameter is 10–30 nm. Due to the high conductivity shungite is able to weaken electromagnetic radiation. A coating made of schungite-containing paint on a cellulose substrate was subjected to the open flame under the temperature of 1700° C for 3 minutes and 40 seconds. That resulted in the formation of insulating foam layer without mechanical damage of the substrate. The XRD diffraction analysis of the powder obtained in the process of flame influence on the coating showed the formation of the such substances as orthoclase, barite, rutile, etc. Carbon contained in shungit and used as a filler for the fireproof paint wasn’t detected. This fact indicates carbon oxidation as the result of its burning out. The shielding efficiency of the composite coating after open flame exposure was measured for the frequency range 8…12 GHz with the use of the panoramic attenuation meter and voltage standing wave ratio meter YA2R-67-61 with a sweep generator and waveguides. After that the reflection and transmission coefficients were calculated. The results of measurements and calculations showed decrease of the reflection and transmission coefficients due to conductivity decrease and dielectric losses changes of the composite coating provided by silica content increase and carbon percentage decrease.

  19. Multielement X-ray radiometric analysis with application of semiconductor detectors and automatic processing of the results of measurements

    International Nuclear Information System (INIS)

    Problems of complex extraction of useful components from the ores with compound composition demand to ensure multielement analysis having the accuracy which is sufficient for practical purposes. Great possibilities has the X-ray-radiometric analysis with application of semiconductor detectors (SD) and with processing the results of measurements by means of mini- or micro-computers. Present state in the detection and computation techniques permits to introduce the said instruments into the practical use in the analytical laboratories of the mining enterprises. On the base of discussion of the practical tasks in analysis of different types of ores, in the paper basic principles of the multielement X-ray-radiometric analysis for industrial purposes have been formulated. First of all it is an installation with few channels. The main requirement in creation of such installations is to ensure high relaibility and stability of their performance. A variant is given of such analyzer, constructed with use of SiLi or Ge detecting blocks. Possibility for quick change of the excitation sources made of the set of iron-55, cadmium-109, americium-241 or cobalt-57 ensures effective excitation of elements in the range from calcium to uranium. Some practical methods of analysis have been discussed in the paper. They are based both on the methods of passive and active experiments at the calibration stages. Accuracy of these methods is enough for change of ordinary chemical analysis by the radiometric one. Problems are discussed of application of mini- and micro-computers, permitting processing of information according to the metods of analysis having been developed. Some examples are given of practical realization of the multielement X-ray-radiometric analysis of the lead-zinc, cppper-molybdenum, lead-barite and some other types of ores and also of the products of processing of ores

  20. Geochemistry and age of metamorphosed felsic igneous rocks with A-type affinities in the Willyama Supergroup, Olary Block, South Australia, and implications for mineral exploration

    Science.gov (United States)

    Ashley, P. M.; Cook, N. D. J.; Fanning, C. M.

    1996-09-01

    Leucocratic quartzofeldspathic gneisses form a significant proportion of the lower part of the Palaeoproterozoic Willyama Supergroup sequence in the Olary Block, South Australia and have correlatives in the adjacent Broken Hill Block. Field and geochemical data demonstrate that these rocks were originally rhyolitic volcanics and granite, with A-type affinities consistent with magma production during intracratonic rifting, supporting tectonic models proposed for the Willyama Supergroup in the Broken Hill Block. Although the rocks have characteristic high-field-strength element enrichment, many have undergone extensive pervasive pre- or syn-metamorphic sodic alteration and are typically rich in albite. Sensitive high resolution ion microprobe (SHRIMP) U-Pb zircon data tightly constrain the depositional and early intrusive history. Zircons from an interpreted metavolcanic rock containing relict quartz phenocrysts yield an age of 1699 ± 10 Ma, whereas a metagranitoid sample has an age of 1703 ± 6 Ma. These results are compatible with recent geochronological data on felsic metavolcanic rocks from the Broken Hill Block (Page and Laing, 1992) and are indicative of widespread magmatism during deposition of the Willyama Supergroup. Nd signatures for the two Olary Block samples imply the presence of a significant component from a depleted mantle source. The A-type metavolcanic rocks are locally associated with small iron formations, some of which grade into stratiform barite-rich horizons. Although potentially favourable for sediment-hosted exhalative PbZn mineralisation, the Fe- and Ba-rich units, along with transgressive vein and breccia occurrences of Fe oxides ± quartz ± pyrite cutting both the metavolcanic and metagranitoid rocks, may be more prospective for epigenetic Cu-Au mineralisation related to later metamorphic and/or magmatic events. Partial melting of the A-type suite during high grade regional metamorphism at ~ 1600 ± 20 Ma led to the formation of local

  1. Ironstone deposits hosted in Eocene carbonates from Bahariya (Egypt)-New perspective on cherty ironstone occurrences

    Science.gov (United States)

    Afify, A. M.; Sanz-Montero, M. E.; Calvo, J. P.

    2015-11-01

    This paper gives new insight into the genesis of cherty ironstone deposits. The research was centered on well-exposed, unique cherty ironstone mineralization associated with Eocene carbonates from the northern part of the Bahariya Depression (Egypt). The economically important ironstones occur in the Naqb Formation (Early Eocene), which is mainly formed of shallow marine carbonate deposits. Periods of lowstand sea-level caused extensive early dissolution (karstification) of the depositional carbonates and dolomitization associated with mixing zones of fresh and marine pore-water. In faulted areas, the Eocene carbonate deposits were transformed into cherty ironstone with preservation of the precursor carbonate sedimentary features, i.e. skeletal and non-skeletal grain types, thickness, bedding, lateral and vertical sequential arrangement, and karst profiles. The ore deposits are composed of iron oxyhydroxides, mainly hematite and goethite, chert in the form of micro- to macro-quartz and chalcedony, various manganese minerals, barite, and a number of subordinate sulfate and clay minerals. Detailed petrographic analysis shows that quartz and iron oxides were coetaneous and selectively replaced carbonates, the coarse dolomite crystals having been preferentially transformed into quartz whereas the micro-crystalline carbonates were replaced by the iron oxyhydroxides. A number of petrographic, sedimentological and structural features including the presence of hydrothermal-mediated minerals (e.g., jacobsite), the geochemistry of the ore minerals as well as the structure-controlled location of the mineralization suggest a hydrothermal source for the ore-bearing fluids circulating through major faults and reflect their proximity to centers of magmatism. The proposed formation model can contribute to better understanding of the genetic mechanisms of formation of banded iron formations (BIFs) that were abundant during the Precambrian.

  2. Defining an exposure-response relationship for suspended kaolin clay particulates and aquatic organisms: work toward defining a water quality guideline for suspended solids.

    Science.gov (United States)

    Gordon, Andrew K; Palmer, Carolyn G

    2015-04-01

    Water quality guidelines for suspended solids generally rely on the percentage departure from reference condition, an approach that has been criticized. Attempts to develop a biological effects-base guideline have, however, been confounded by low data availability. Furthermore, the high biological response variability to suspended solids exposure suggests that organisms are responding not only to exposure concentration and duration but also to other mechanisms of effect associated with suspended particles (e.g., size, shape, and geochemical composition). An alternative option is to develop more situation and site specific guidelines by generating biological effects data to suspended particles of a particular geochemistry and restricted size range. With this in mind, aquatic organism responses to kaolin clay particle exposure were collated from the literature and incorporated into 2 exposure-response relationship approaches. The species sensitivity distribution approach produced a hazardous concentration affecting 5% of species estimate of 58 mg/L for mortality responses, and 36 mg/L for sublethal data. The severity-of-ill-effect approach produced similar estimates for lethal and sublethal data. These results suggest that aquatic organisms are slightly more tolerant of kaolin clay particles than particles from barite or bentonite clays, based on results from previous studies on these clay types. This type of information can enable better estimates of the risk faced by aquatic organisms exposed to suspended solids. For example, when the sediments of a particular water body are dominated by a particular type of clay particle, then the most appropriate exposure-response relationship can be applied. PMID:25711545

  3. Cyclic magnetite dissolution in Pleistocene sediments of the abyssal northwest Pacific Ocean: Evidence for glacial oxygen depletion and carbon trapping

    Science.gov (United States)

    Korff, Lucia; Dobeneck, Tilo; Frederichs, Thomas; Kasten, Sabine; Kuhn, Gerhard; Gersonde, Rainer; Diekmann, Bernhard

    2016-05-01

    The carbonate-free abyss of the North Pacific defies most paleoceanographic proxy methods and hence remains a "blank spot" in ocean and climate history. Paleomagnetic and rock magnetic, geochemical, and sedimentological methods were combined to date and analyze seven middle to late Pleistocene northwest Pacific sediment cores from water depths of 5100 to 5700 m. Besides largely coherent tephra layers, the most striking features of these records are nearly magnetite-free zones corresponding to glacial marine isotope stages (MISs) 22, 12, 10, 8, 6, and 2. Magnetite depletion is correlated with organic carbon and quartz content and anticorrelated with biogenic barite and opal content. Within interglacial sections and mid-Pleistocene transition glacial stages MIS 20, 18, 16, and 14, magnetite fractions of detrital, volcanic, and bacterial origin are all well preserved. Such alternating successions of magnetic iron mineral preservation and depletion are known from sapropel-marl cycles, which accumulated under periodically changing bottom water oxygen and redox conditions. In the open central northwest Pacific Ocean, the only conceivable mechanism to cause such abrupt change is a modified glacial bottom water circulation. During all major glaciations since MIS 12, oxygen-depleted Antarctic Bottom Water (AABW)-sourced bottom water seems to have crept into the abyssal northwest Pacific below ~5000 m depth, thereby changing redox conditions in the sediment, trapping and preserving dissolved and particulate organic matter and, in consequence, reducing and dissolving both, biogenic and detrital magnetite. At deglaciation, a downward progressing oxidation front apparently remineralized and released these sedimentary carbon reservoirs without replenishing the magnetite losses.

  4. Diagenesis of Paleozoic playa-lake and ephemeral-stream deposits from the Pimenta Bueno Formation, Siluro-Devonian (?) of the Parecis Basin, central Brazil

    Science.gov (United States)

    Goldberg, K.; Morad, S.; Al-Aasm, I. S.; De Ros, L. F.

    2011-07-01

    The Parecis Basin is a large intracratonic rift located in central Brazil and filled with Paleozoic carbonate, evaporite and siliciclastic sediments. The occurrence of gas seeps has recently attracted significant exploration interest by the Brazilian petroleum agency and by Petrobras. The continuously cored PB-01-RO well provided the first opportunity to study the depositional environments, diagenetic evolution and hydrocarbon potential of the largely unknown sedimentary successions of the Parecis Basin. The cored lithologies, belonging to the Siluro-Devonian (?) Pimenta Bueno Formation, are interpreted as deposited in playa-lake and ephemeral-stream environments. The deposits display a strong facies control on the diagenetic mineral assemblages and evolution. Diagenetic minerals in the ephemeral-stream deposits include eogenetic hematite and smectitic clay coats and quartz cement, and the mesogenetic process includes precipitation of sulfates (anhydrite and barite) and carbonates (calcite, dolomite and kutnahorite-ankerite-huntite), followed by partial dissolution of these carbonates and sulfates, and of feldspar grains. Telogenetic processes include the precipitation of hematite and kaolinite within secondary pores, and the replacement of anhydrite by gypsum. A second burial phase and mesodiagenesis is indicated by the precipitation of discrete K-feldspar crystals within moldic pores after dissolved feldspars, and by the illitization of etched, telogenetic kaolinite. The playa-lake deposits show early diagenetic dolomitization of lime mud, precipitation of anhydrite nodules and extensive silicification. The anhydrite nodules were replaced by gypsum and chalcedony during telodiagenesis. Potential source rocks are locally represented by organic shales. The fluvial sandstones show fair reservoir quality and limited compaction, as indicated by their intergranular volume, suggesting that the succession has undergone moderate burial. Potential seals for hydrocarbon

  5. Production of a datolite-based heavy concrete for shielding nuclear reactors and megavoltage radiotherapy rooms

    International Nuclear Information System (INIS)

    Biological shielding of nuclear reactors has always been a great concern and decreasing the complexity and expense of these installations is of great interest. In this study, we used datolite and galena minerals for production of a high performance heavy concrete. Materials and Methods: Datolite and galena minerals which can be found in many parts of Iran were used in the concrete mix design. To measure the gamma radiation attenuation of the Datolite and galena concrete samples, they were exposed to both narrow and wide beams of gamma rays emitted from a cobalt-60 radiotherapy unit. An Am-Be neutron source was used for assessing the shielding properties of the samples against neutrons. To test the compression strengths, both types of concrete mixes (Datolite and galena and ordinary concrete) were investigated. Results: The concrete samples had a density of 4420-4650 kg/m3 compared to that of ordinary concrete (2300-2500 kg/m3) or barite high density concrete (up to 3500 kg/m3). The measured half value layer thickness of the Datolite and galena concrete samples for cobalt-60 gamma rays was much less than that of ordinary concrete (2.56 cm compared to 6.0 cm). Furthermore, the galena concrete samples had a significantly higher compressive strength as well as 20% more neutron absorption. Conclusion: The Datolite and galena concrete samples showed good shielding/engineering properties in comparison with other reported samples made, using high-density materials other than depleted uranium. It is also more economic than the high-density concretes. Datolite and galena concrete may be a suitable option for shielding nuclear reactors and megavoltage radiotherapy rooms.

  6. Determination of dominant biogeochemical processes in a contaminated aquifer-wetland system using multivariate statistical analysis

    Science.gov (United States)

    Baez-Cazull, S. E.; McGuire, J.T.; Cozzarelli, I.M.; Voytek, M.A.

    2008-01-01

    Determining the processes governing aqueous biogeochemistry in a wetland hydrologically linked to an underlying contaminated aquifer is challenging due to the complex exchange between the systems and their distinct responses to changes in precipitation, recharge, and biological activities. To evaluate temporal and spatial processes in the wetland-aquifer system, water samples were collected using cm-scale multichambered passive diffusion samplers (peepers) to span the wetland-aquifer interface over a period of 3 yr. Samples were analyzed for major cations and anions, methane, and a suite of organic acids resulting in a large dataset of over 8000 points, which was evaluated using multivariate statistics. Principal component analysis (PCA) was chosen with the purpose of exploring the sources of variation in the dataset to expose related variables and provide insight into the biogeochemical processes that control the water chemistry of the system. Factor scores computed from PCA were mapped by date and depth. Patterns observed suggest that (i) fermentation is the process controlling the greatest variability in the dataset and it peaks in May; (ii) iron and sulfate reduction were the dominant terminal electron-accepting processes in the system and were associated with fermentation but had more complex seasonal variability than fermentation; (iii) methanogenesis was also important and associated with bacterial utilization of minerals as a source of electron acceptors (e.g., barite BaSO4); and (iv) seasonal hydrological patterns (wet and dry periods) control the availability of electron acceptors through the reoxidation of reduced iron-sulfur species enhancing iron and sulfate reduction. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

  7. Exploring the high-pressure behavior of the three known polymorphs of BiPO{sub 4}: Discovery of a new polymorph

    Energy Technology Data Exchange (ETDEWEB)

    Errandonea, D., E-mail: daniel.errandonea@uv.es; García-Domene, B. [Departamento de Física Aplicada-ICMUV, MALTA Consolider Team, Universidad de Valencia, Edificio de Investigación, C/Dr. Moliner 50, Burjassot, 46100 Valencia (Spain); Gomis, O. [Centro de Tecnologías Físicas, MALTA Consolider Team, Universitat Politècnica de Valencia, 46022 Valencia (Spain); Santamaría-Perez, D. [Departamento de Física Aplicada-ICMUV, MALTA Consolider Team, Universidad de Valencia, Edificio de Investigación, C/Dr. Moliner 50, Burjassot, 46100 Valencia (Spain); Earth Sciences Department, University College London, London WC1E 6BT (United Kingdom); Muñoz, A.; Rodríguez-Hernández, P. [Departamento de Física, Instituto de Materiales y Nanotecnología, MALTA Consolider Team, Universidad de La Laguna, La Laguna 38205, Tenerife (Spain); Achary, S. N.; Tyagi, A. K. [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Popescu, C. [CELLS-ALBA Synchrotron Light Facility, Cerdanyola, 08290 Barcelona (Spain)

    2015-03-14

    We have studied the structural behavior of bismuth phosphate under compression. We performed x-ray powder diffraction measurements up to 31.5 GPa and ab initio calculations. Experiments were carried out on different polymorphs: trigonal (phase I) and monoclinic (phases II and III). Phases I and III, at low pressure (P < 0.2–0.8 GPa), transform into phase II, which has a monazite-type structure. At room temperature, this polymorph is stable up to 31.5 GPa. Calculations support these findings and predict the occurrence of an additional transition from the monoclinic monazite-type to a tetragonal scheelite-type structure (phase IV). This transition was experimentally found after the simultaneous application of pressure (28 GPa) and temperature (1500 K), suggesting that at room temperature the transition might by hindered by kinetic barriers. Calculations also predict an additional phase transition at 52 GPa, which exceeds the maximum pressure achieved in the experiments. This transition is from phase IV to an orthorhombic barite-type structure (phase V). We also studied the axial and bulk compressibility of BiPO{sub 4}. Room-temperature pressure-volume equations of state are reported. BiPO{sub 4} was found to be more compressible than isomorphic rare-earth phosphates. The discovered phase IV was determined to be the less compressible polymorph of BiPO{sub 4}. On the other hand, the theoretically predicted phase V has a bulk modulus comparable with that of monazite-type BiPO{sub 4}. Finally, the isothermal compressibility tensor for the monazite-type structure is reported at 2.4 GPa showing that the direction of maximum compressibility is in the (0 1 0) plane at approximately 15° (21°) to the a axis for the case of our experimental (theoretical) study.

  8. Formation of the Wiesloch Mississippi Valley-type Zn-Pb-Ag deposit in the extensional setting of the Upper Rhinegraben, SW Germany

    Science.gov (United States)

    Pfaff, Katharina; Hildebrandt, Ludwig H.; Leach, David L.; Jacob, Dorrit E.; Markl, Gregor

    2010-01-01

    The Mississippi Valley-type (MVT) Zn-Pb-Ag deposit in the Wiesloch area, Southwest Germany, is controlled by graben-related faults of the Upper Rhinegraben. Mineralization occurs as vein fillings and irregular replacement ore bodies consisting of sphalerite, banded sphalerite, galena, pyrite, sulfosalts (jordanite and geocronite), barite, and calcite in the Middle Triassic carbonate host rock. Combining paragenetic information, fluid inclusion investigations, stable isotope and mineral chemistry with thermodynamic modeling, we have derived a model for the formation of the Wiesloch deposit. This model involves fluid mixing between ascending hot brines (originating in the crystalline basement) with sedimentary formation waters. The ascending brines originally had a near-neutral pH (around 6) and intermediate oxidation state, reflecting equilibrium with granites and gneisses in the basement. During fluid ascent and cooling, the pH of the brine shifted towards more acidic (around 4) and the oxidation state increased to conditions above the hematite-magnetite buffer. These chemical characteristics contrast strongly with those of the pore and fracture fluid residing in the limestone aquifer, which had a pH between 8 and 9 in equilibrium with calcite and was rather reduced due to the presence of organic matter in the limestone. Mixing between these two fluids resulted in a strong decrease in the solubility of silver-bearing sphalerite and galena, and calcite. Besides Wiesloch, several Pb-Zn deposits are known along the Upper Rhinegraben, including hydrothermal vein-type deposits like Badenweiler and the Michael mine near Lahr. They all share the same fluid origin and formation process and only differ in details of their host rock and fluid cooling paths. The mechanism of fluid mixing also seems to be responsible for the formation of other MVT deposits in Europe (e.g., Reocin, Northern Spain; Treves, Southern France; and Cracow-Silesia, Poland), which show notable

  9. A Study on the Role of Pre-Gelatinized Starch (PGS in the Non Damaging Drilling Fluid (NDDF for the Tipam Sand of Geleki Oilfield of Upper Assam Basin

    Directory of Open Access Journals (Sweden)

    Prasenjit Talukdar

    2015-06-01

    Full Text Available The drilling of the wells from surface to target location with conventional drilling fluids may impair production and ultimate recovery by failing to adequately connect the reservoir with the wellbore by damaging the producing interval. One of the most common ways of damaging a formation is the filtration loss. Non Damaging Drilling Fluid (NDDF is a clay and barite free environmental friendly polymer mud system mostly used in pay zone sections of development wells and specifically in horizontal drilling to avoid formation damage. Starches [(C6H10O5 n] are an environment-friendly drilling mud additive for water-base drilling fluids used to control the filtration loss. This paper reports the effect and optimum composition of Pre-Gelatinized Starch (PGS as a filtration control component in the NDDF. PGS is a high-quality nonionic polysaccharide having the Chemical Formula: C27H48O20 and Molecular Weight: 692.658020 [g/mol] which controls the filtration loss by sealing the walls of the borehole due to its long chains of monosaccharide. Some clay specifically the montmorillonite a member of the smectite group that generally also found in the payzones of Geleki Oilfield of Upper Assam Basin absorb hydrogen ions into their structure when comes in contact with fresh water and causing swelling of the clay resulting in a reduction of the pore volume and possibly plug in the pore throats. Therefore the filtration loss should be as low as possible by forming high quality low permeable mud cake of as thin as possible. In this work, an attempt has been made to study the effect of varying composition of PGS on the different mud properties of laboratory formulated NDDF and to choose its optimum composition based on the required mud parameters of the study area.

  10. Exploring the high-pressure behavior of the three known polymorphs of BiPO4: Discovery of a new polymorph

    International Nuclear Information System (INIS)

    We have studied the structural behavior of bismuth phosphate under compression. We performed x-ray powder diffraction measurements up to 31.5 GPa and ab initio calculations. Experiments were carried out on different polymorphs: trigonal (phase I) and monoclinic (phases II and III). Phases I and III, at low pressure (P < 0.2–0.8 GPa), transform into phase II, which has a monazite-type structure. At room temperature, this polymorph is stable up to 31.5 GPa. Calculations support these findings and predict the occurrence of an additional transition from the monoclinic monazite-type to a tetragonal scheelite-type structure (phase IV). This transition was experimentally found after the simultaneous application of pressure (28 GPa) and temperature (1500 K), suggesting that at room temperature the transition might by hindered by kinetic barriers. Calculations also predict an additional phase transition at 52 GPa, which exceeds the maximum pressure achieved in the experiments. This transition is from phase IV to an orthorhombic barite-type structure (phase V). We also studied the axial and bulk compressibility of BiPO4. Room-temperature pressure-volume equations of state are reported. BiPO4 was found to be more compressible than isomorphic rare-earth phosphates. The discovered phase IV was determined to be the less compressible polymorph of BiPO4. On the other hand, the theoretically predicted phase V has a bulk modulus comparable with that of monazite-type BiPO4. Finally, the isothermal compressibility tensor for the monazite-type structure is reported at 2.4 GPa showing that the direction of maximum compressibility is in the (0 1 0) plane at approximately 15° (21°) to the a axis for the case of our experimental (theoretical) study

  11. A comparative study for different shielding material composition and beam geometry applied to PET facilities: simulated transmission curves

    Energy Technology Data Exchange (ETDEWEB)

    Hoff, Gabriela [Pontificia Univ. Catolica do Rio Grande do Sul (PUCRS), Porto Alegre, RS (Brazil). Grupo de Experimentacao e Simulacao Computacional em Fisica Medica; Costa, Paulo Roberto, E-mail: pcosta@if.usp.br [Universidade de Sao Paulo (IF/USP), SP (Brazil). Dept. de Fisica Nuclear. Lab. de Dosimetria das Radiacoes e Fisica Medica

    2013-03-15

    The aim of this work is to simulate transmission data for different beam geometry and material composition in order to evaluate the effect of these parameters on transmission curves. The simulations are focused on outgoing spectra for shielding barriers used in PET facilities. The behavior of the transmission was evaluated as a function of the shielding material composition and thickness using Geant4 Monte Carlo code, version 9.2 p 03.The application was benchmarked for barited mortar and compared to The American Association of Physicists in Medicine (AAPM) data for lead. Their influence on the transmission curves as well the study of the influence of the shielding material composition and beam geometry on the outgoing spectra were performed. Characteristics of transmitted spectra, such as shape, average energy and Half-Value Layer (HVL), were also evaluated. The Geant4 toolkit benchmark for the energy resulting from the positron annihilation phenomena and its application in transmission curves description shown good agreement between data published by American Association on Physicists in Medicine task group 108 and experimental data published by Brazil. The transmission properties for different material compositions were also studied and have shown low dependency with the considered thicknesses. The broad and narrow beams configuration presented significant differences on the result. The fitting parameter for determining the transmission curves equations, according to Archer model is presented for different material. As conclusion were defined that beam geometry has significant influence and the composition has low influence on transmission curves for shielding design for the range of energy applied to PET. (author)

  12. Vein mineralizations - record of paleo-fluid systems in the Thuringian basin (Germany)

    Science.gov (United States)

    Lepetit, Petra; Viereck, Lothar; Abratis, Michael; Fritsch, Stefanie

    2014-05-01

    Vein-related mineralizations within the Mesozoic sediments of the Thuringian basin (Germany) are investigated in analytical detail (petrography, XRD, XRF, EPMA, LA-ICP-MS, and isotope studies: O, C, S, Sr) in order to characterize paleo-fluid systems that intruded the basin and circulated within it millions of years ago. Samples from 55 outcrops, 34 quarries and 21 drill cores comprise mainly carbonates (calcite, dolomite, siderite, ankerite), additional sulfates (gypsum, celestine, barite,), and rarely sulfides. The mineralizations are almost exclusively restricted to WNW-ESE trending fault systems. First δ13C and δ18O isotope analyses of calcite mineralizations reveal differences between veins within Triassic sediments (Lower Muschelkalk: δ13C: 1.8 to 2.9 o, mean 2.3 o, δ18O: -7.3 to -10.4 o, mean -8.2 o) and Jurassic sediments (δ13C: -0.7 to -2.1 o, mean -1.4 o, δ18O: -9.3 to -10.6 o, mean -9.9 o), indicating intra-formational and extra-formational paleo-fluid transport. Also first δ34S and δ18O isotope analyses of gypsum mineralizations display differences between veins within Triassic and Permian sediments, respectively. These initial data are comparable with isotope analyses of vein-related host rocks and hydrochemical signatures of recent well waters in the Thuringian basin indicating intra-formational in addition to extra-formational paleo-fluid transport. Further isotope studies are in progress including high resolution in situ-Sr- isotope analysis. The present study is part of INFLUINS, a BMBF-funded project bundle, which is dedicated to the comprehensive description and understanding of the fluid systems within the Thuringian basin in time and space.

  13. Design and optimization of HPLWR high pressure Turbine gamma ray shield

    International Nuclear Information System (INIS)

    Highlights: • Shield around HPLWR high pressure turbine optimized by Monte Carlo method. • The occupancy period in the turbine building was considered in the optimization. • Shield thickness is significantly reduced when heavy concretes are used. • Shield thickness for BWRs is sufficient for HPWR if heavy concrete is used. - Abstract: This work proposes the optimum gamma ray shield thickness around the HPLWR high pressure turbine for different occupancy periods in the turbine building. Monte Carlo method was employed in the design process and only radioactive nitrogen-16 was considered as the source of radiation. Five grades of concrete (ordinary, magnetite, heavy magnetite, steel magnetite and barite) were used as shielding materials. The isotope source term in the high pressure turbine was estimated by modeling the HPLWR three pass core in MCNP and tracking the inventory using a simple algorithm. The high pressure turbine was thereafter modeled in MCNP with a concrete shield arrayed in layers around it. The surface flux tally and ICRP74 dose conversion coefficients were employed to estimate the dose profile across the shield. For some shielding materials, exponential functions were fitted on the calculated data to extrapolate dose values beyond the model thickness. The optimum shield thickness was determined by comparing the calculated dose profiles with dose limit proposals in the IAEA standard (NS-G-1.13) on radiation protection considerations during nuclear power plant design. It was observed that with a 120 cm thick heavy concrete shield, the turbine building would be safe for most occupancy periods. However for ordinary concrete the shield would require some extension to guarantee safety. For very long occupancy (more than 10 person hours per week), magnetite shield may also require slight extension. It can therefore be concluded that the shield thickness recommended for BWR turbines (which operate on a direct cycle like HPLWR) could be sufficient

  14. Discovery of new hydrothermal vent sites in Bransfield Strait, Antarctica

    Science.gov (United States)

    Klinkhammer, G. P.; Chin, C. S.; Keller, R. A.; Dählmann, A.; Sahling, H.; Sarthou, G.; Petersen, S.; Smith, F.; Wilson, C.

    2001-12-01

    We carried out a search for hydrothermal vents in the Central Basin of Bransfield Strait, Antarctica. The ZAPS (zero angle photon spectrometer) chemical sensor and instrument package (Oregon State University), OFOS (ocean-floor observation system) camera sled and TVG (TV-grab) (GEOMAR) were used to explore the water column and underlying seafloor. These operations were supplemented with a series of dredges. Hydrothermal plumes over Hook Ridge at the eastern end of the basin are confined to the E ridge crest and SE flank. The plumes are complex and sometimes contain two turbidity maxima one widespread feature centered at 1150 m and a smaller, more localized but broad maximum at 600-800 m. We traced the source of the shallower plume to a sunken crater near the ridge crest using sensors on the ZAPS instrument package. Subsequently two TV-grabs from the crater brought back hot, soupy sediment (42-49°C) overlain by hard, siliceous crusts and underlain by a thick layer of volcanic ash. We also recovered chimney fragments whose texture and mineralogy indicate venting temperatures in excess of 250°C. Native sulfur and Fe-sulfides occur in fractures and porous layers in sediment from throughout the area. Pore water data from the crater site are consistent with venting into a thin sediment layer and indicate phase separation of fluids beneath Hook Ridge. The source of the deeper plumes at Hook Ridge has yet to be located. We also explored a series of three parallel volcanic ridges west of Hook Ridge called Three Sisters. We detected water column anomalies indicative of venting with the ZAPS package and recovered hydrothermal barites and sulfides from Middle Sister. We spent considerable time photographing Middle Sister and Hook Ridge but did not identify classic vent fauna at either location. We either missed small areas with our photography or typical MOR vent fauna are absent at these sites.

  15. Petrological and geochemical features of the Jingtieshan banded iron formation (BIF): A unique type of BIF from the Northern Qilian Orogenic Belt, NW China

    Science.gov (United States)

    Yang, Xiu-Qing; Zhang, Zuo-Heng; Duan, Shi-Gang; Zhao, Xin-Min

    2015-12-01

    The Jingtieshan banded iron formation (BIF) is located in the Northern Qilian Orogenic Belt (NQOB) in NW China. The BIFs are hosted in Mesoproterozoic Jingtieshan Group, a dominantly clastic-carbonate sedimentary formation, and was metamorphosed to lower greenschist facies. The Jingtieshan BIFs include oxide-, carbonate- and mixed carbonate-oxide facies, and consist of alternating iron-rich and silica-rich bands. The BIFs are composed essentially of specularite and jasper, with minor carbonate minerals and barite. The SiO2 + Fe2O3 content is markedly high in the oxide facies BIF, followed by FeO, CO2 and Ba, with the other elements usually lower than 1%, suggesting that the original chemical sediments were composed of Fe, Si, CO32- and Ba. The positive correlation between Al2O3, TiO2 and Zr in the BIFs indicates that these chemical sediments incorporate minor detrital components. Oxide facies BIF shows low HFSE, low ∑REE and low Y/Ho. The Post Archean Australian Shale-normalized REE patterns for Jingtieshan BIFs are characterized slight LREE depletion, strong positive Eu anomalies and lack of significant negative Ce anomalies. Siderite in the carbonate- and mixed carbonate-oxide facies BIF shows negative δ13C values varying from -8.4‰ to -3.0‰, and δ18O values show a range of -16.6‰ to -11.7‰. The geochemical signatures and carbon-oxygen isotopes suggest origin from high-temperature hydrothermal fluids with weak seawater signature for the sediments of Jingtieshan BIFs. The absence of negative Ce anomalies and the high Fe3+/∑Fe ratios of the oxide facies BIF do not support ocean anoxia. In contrast to the three main types (Algoma-, Superior- and Rapitan-type) of global BIFs, the Jingtieshan BIFs represent a unique type with features similar to those of sedimentary-exhalative mineralization.

  16. Hydration effects on gypsum dissolution revealed by in situ nanoscale atomic force microscopy observations

    Science.gov (United States)

    Burgos-Cara, A.; Putnis, C. V.; Rodriguez-Navarro, C.; Ruiz-Agudo, E.

    2016-04-01

    Recent work has suggested that the rates of mineral dissolution in aqueous solutions are dependent on the kinetics of dehydration of the ions building the crystal. Dehydration kinetics will be ultimately determined by the competition between ion-water and water-water interactions, which can be significantly modified by the presence of background ions in solution. At low ionic strength, the effect of electrolytes on ion-water (electrostatic) interactions will dominate (Kowacz et al., 2007). By performing macroscopic and in situ, microscopic (atomic force microscopy) dissolution experiments, the effect of background electrolytes on the dissolution kinetics of gypsum (CaSO4·2H2O) {0 1 0} cleavage surfaces is tested at constant, low ionic strength (IS = 0.05) and undersaturation (saturation index, SI = -0.045). Dissolution rates are systematically lower in the presence of 1:1 background electrolytes than in an electrolyte-free solution, regardless of the nature of the electrolyte tested. We hypothesize that stabilization of the hydration shell of calcium by the presence of background ions can explain this result, based on the observed correlations in dissolution rates with the ionic surface tension increment of the background ion in solution. Stabilization of the cation hydration shell should favor dissolution. However, in the case of strongly hydrated ions such as Ca2+, this has a direct entropic effect that reduces the overall ΔG of the system, so that dissolution is energetically less favorable. Overall, these results provide new evidence that supports cation dehydration being the rate-controlling step for gypsum dissolution, as proposed for other minerals such as barite, dolomite and calcite.

  17. Carbonatite and alkaline intrusion-related rare earth element deposits–A deposit model

    Science.gov (United States)

    Verplanck, Philip L.; Van Gosen, Bradley S.

    2011-01-01

    The rare earth elements are not as rare in nature as their name implies, but economic deposits with these elements are not common and few deposits have been large producers. In the past 25 years, demand for rare earth elements has increased dramatically because of their wide and diverse use in high-technology applications. Yet, presently the global production and supply of rare earth elements come from only a few sources. China produces more than 95 percent of the world's supply of rare earth elements. Because of China's decision to restrict exports of these elements, the price of rare earth elements has increased and industrial countries are concerned about supply shortages. As a result, understanding the distribution and origin of rare earth elements deposits, and identifying and quantifying our nation's rare earth elements resources have become priorities. Carbonatite and alkaline intrusive complexes, as well as their weathering products, are the primary sources of rare earth elements. The general mineral deposit model summarized here is part of an effort by the U.S. Geological Survey's Mineral Resources Program to update existing models and develop new descriptive mineral deposit models to supplement previously published models for use in mineral-resource and mineral-environmental assessments. Carbonatite and alkaline intrusion-related REE deposits are discussed together because of their spatial association, common enrichment in incompatible elements, and similarities in genesis. A wide variety of commodities have been exploited from carbonatites and alkaline igneous rocks, such as rare earth elements, niobium, phosphate, titanium, vermiculite, barite, fluorite, copper, calcite, and zirconium. Other enrichments include manganese, strontium, tantalum, thorium, vanadium, and uranium.

  18. The petrogenesis of metamorphosed carbonatites in the Grenville Province, Ontario

    Energy Technology Data Exchange (ETDEWEB)

    Moecher, D.P.; Anderson, E.D.; Cook, C.A. [Univ. of Kentucky, Dept. of Geological Sciences, Lexington, Kentucky (United States)]. E-mail: moker@pop.uky.edu; Mezger, K. [Max-Planck-Institut fuer Chemie, Mainz (Germany)

    1997-09-15

    Veins and dikes of calcite-rich rocks within the Central Metasedimentary Belt boundary zone (CMBbz) in the Grenville Province of Ontario have been interpreted to be true carbonatites or to be pseudocarbonatites derived from interaction of pegmatite melts and regional Grenville marble. The putative carbonatites have been metamorphosed and consist mainly of calcite, biotite, and apatite with lesser amounts of clinopyroxene, magnetite, allanite, zircon, titanite, cerite, celestite, and barite. The rocks have high P and rare earth element (REE) contents, and calcite in carbonatite has elevated Sr, Fe, and Mn contents relative to Grenville Supergroup marble and marble melange. Values of {delta}{sup 18}O{sub SMOW} (9.9 - 13.3o/oo) and {delta}{sup 13}C{sub PDB} (-4.8 to -1.9o/oo) for calcite are also distinct from those for marble and most marble melange. Titanites extracted from clinopyroxene -calcite-scapolite skarns formed by metasomatic interaction of carbonatites and silicate lithologies yield U-Pb ages of 1085 to 1035 Ma. Zircon from one carbonatite body yields a U-Pb age of 1089 {+-} 5 Ma; zircon ages from two other bodies are 1170 {+-} 3 and 1143 {+-} 8 Ma, suggesting several carbonatite formation events or remobilization of carbonatite during deformation and metamorphism around 1080 Ma. Values of {epsilon}{sub Nd}(T) are 1.7 - 3.2 for carbonatites, -1.5 -1.0 for REE-rich granite dikes intruding the CMBbz, and 1.6 - 1.7 for marble. The mineralogy and geochemical data are consistent with derivation of the carbonatites from a depleted mantle source. Mixing calculations indicate that interaction of REE-rich pegmatites with regional marbles cannot reproduce selected major and minor element abundance, REE contents, and O and Nd isotope compositions of the carbonatites. (author)

  19. Mineralogy and Geochemistry of the Nižná Boca Sb-Au Hydrothermal Ore Deposit (Western Carpathians, Slovakia)

    Science.gov (United States)

    Smirnov, Alexander; Pršek, Jaroslav; Chovan, Martin

    2007-01-01

    Samples from hydrothermal Sb-Au mineralization in the area SE of Nižná Boca village in the N&iAzke Tatry Mountains were investigated using a variety of geochemical and mineralogical methods. Ore minerals typically occur in N-S striking quartz-carbonate veins hosted by an I-type biotite granodiorite to tonalite of Variscan Age (the Ďumbier Type). Paragenetic associations in the deposit are comparable to other mineralizations of the same type in the Ďumbierske Nízke Tatry Mountains. A quartz-arsenopyrite, pyrite stage of mineralization is the oldest with a calculated temperature of formation of about 445°C. It is followed by a quartz-carbonate-stibnite, zinkenite stage and, in turn, a quartz-carbonate-sphalerite-galena, boulangerite-gold stage. The gold typically contains between 9-18 wt.% Ag regardless of mineral association. No evidence for further generations of gold was found although it is possible that some gold was remobilized from the structure of the auriferous arsenopyrite. The Au and Ag content of the bulk ore ranges from 0.53 g.t-1 to 20.2 g.t-1 and from 0.9 g.t-1 to 31.2 g.t-1, respectively. A tetrahedrite-chalcopyrite stage is followed by a barite-hematite stage - the youngest assemblage in the deposit. Fluid inclusions from the first mineralization stage are usually less than 3 μm in size and contain less than 3.6 wt.% CO2; salinity, density and homogenization temperature range from 2.7-16.3 wt.% NaCl(eq), 0.85-1.03 g.cm-1 and 128-280°C, respectively.

  20. Preferential Treatment: Interaction Between Amino Acids and Minerals

    Science.gov (United States)

    Crapster-Pregont, E. J.; Cleaves, H. J.; Hazen, R. M.

    2008-12-01

    Amino acids are the building blocks of proteins and are important for some models of the origin of life. Polymerization of amino acids from dilute solution is unlikely without a scaffold or catalyst. The surfaces of early Earth minerals are the most likely candidates for this role. The surface adsorption behavior of 12 amino acids (L-alanine, L-serine, L-aspartic acid, L-proline, L- phenylalanine, L-valine, L-arginine, d-amino valeric acid, glycine, L-lysine, L-isoleucine, and B-alanine) on 21 minerals (quartz, calcite, enstatite, illite, olivine, pyrrhotite, pyrite, alkali basalt, albite, analcime, chlorite, barite, hydroxyl apatite, hematite, magnetite, aluminum hydroxide, kaolin, silica gel, corundum, rutile, and montmorillonite) was determined via batch adsorption experiments. Absorption was determined for concentrations between 10-4M and 10-6M in the presence of 0.1M NaCl, and between pH values of 3 and 9 at 25 degrees C. The equilibrated solutions were centrifuged, filtered, derivatized using a fluorescent amino group tag (dansyl-chloride) and analyzed by HPLC. Adsorption was standardized using BET surface area measurements for each mineral to give the number of mols of each amino acid adsorbed per square meter for each mineral. The results indicate an enormous difference in the adsorption of amino acids between minerals, along with major differences in the adsorption of individual amino acids on the same mineral surface. There is also a change in the absorbance of amino acids as the pH changes. Many previous studies of amino acid concentration and catalysis by minerals have used clay minerals because of their high surface areas, however, this data suggests that the surfaces of minerals such as calcite, quartz and pyrite have even higher affinities for amino acids. The results suggest mineral surfaces that could be optimal locations for the polymerization of molecules linked to the origin of life.

  1. Origin of the Mariano Lake uranium deposit, McKinley County, New Mexico

    International Nuclear Information System (INIS)

    The Mariano Lake uranium deposit, hosted by the Brushy Basin Member of the Jurassic Morrison Formation, occurs in the Smith Lake district of the Grants uranium region, New Mexico. The orebody, contains abundant amorphous organic material, which suggests that it represents a primary-type deposit; however, the orebody is close to a regional reduction-oxidation interface, which suggests that uranium was secondarily redistributed by oxidative processes. Uranium contents correlate positively with organic carbon contents. Petrographic evidence points to uranium residence in amorphous organic material that was postdepositionally introduced in the diagenetic history of the host sandstone. Uranium mineralization was preceded by precipitation of pyrite (δ/sup 34/S values of -11.0 to -38.2 per mil), mixed-layer smectite-illite clays, and quartz and potassium feldspar overgrowths; and also partial dissolution of some detrital feldspars. Alterations associated with uranium mineralization include precipitation of the organic material, microcrystalline quartz, and pyrite and marcasite (δ/sup 34/S values of -29.4 to -41.6 per mil), and the destruction of detrital Fe-Ti oxide grains. Following mineralization, calcite, dolomite, barite, and kaolinite were precipitated, and some iron disulfides were replaced by ferric oxides. Geochemical data and petrographic observations both indicate that the Mariano Lake orebody is a primary-type deposit. Oxidative processes have not noticeably redistributed uranium in the immediate vicinity of the deposit, nor have they greatly modified geochemical characteristics in the ore. Impedance of ground-water flow by local folds and the lower porosity characteristics of ore zones may have helped to preserve the deposit

  2. Comparative investigation of laser ablation plumes in air and argon by analysis of spectral line shapes: Insights on calibration-free laser-induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    We investigate the characteristic features of plume expansion in air and argon resulting from ultraviolet laser ablation of solid matter in conditions typically applied in material analysis via laser-induced breakdown spectroscopy (LIBS). Barite crown glass is chosen as a target material for the characteristic emission spectrum suitable for plasma diagnostics. The space-integrated plasma emission spectrum recorded with an echelle spectrometer coupled to a gated detector is compared to the computed spectral radiance of a nonuniform plasma in local thermodynamic equilibrium. In particular, resonance lines of neutral sodium atoms and barium ions are observed to probe gradients of temperature and density within the plume. It is shown that laser ablation in argon leads to an almost uniform plasma whereas gradients of temperature and density are evidenced in ambient air. The discrepancy is attributed to the different physical properties of both gases leading to a stronger vapor–gas energy exchange in the case of air. However, strong gradients occur only in a thin peripheral zone, close to the vapor–gas contact front. The larger plasma core appears almost uniform. The peripheral zone of low temperature mostly contributes to the plasma emission spectrum by absorption and material analysis via calibration-free LIBS in air may ignore the nonuniform character of the plasma if only transitions of small optical thickness are considered. - Highlights: • Investigation of laser ablation plumes by analysis of spectral line shapes • Simulation of emission spectra from nonuniform laser-produced plasma • Plasma is more uniform for ablation in argon. • Plasma nonuniformity mostly affects optically thick lines. • Calibration-free LIBS may ignore gradients if optically thin lines are chosen

  3. Update on environmental site assessment requirements at drilling waste sites

    International Nuclear Information System (INIS)

    Details of recent changes to environmental site assessment (ESA) requirements at drilling waste sites were presented. Drilling wastes are typically disposed of into soil on the well site or adjacent forested or agricultural land. Wastes can become a source of contamination if the disposal is improperly conducted. Drilling fluids are often saline and contain other additives such as heavy metals and hydrocarbons. Alberta Environment's reclamation certification program has instituted changes representing an increased focus on ensuring that well sites are free of contamination. ESAs must focus on potential areas of contamination, including drilling waste disposal areas. Three compliance options were presented in a guidance document for assessing drilling waste disposal areas. Option 1 was to be used to complete a Phase 1 ESA for disposal areas that have Alberta Energy and Utility Board (EUB) Guide 50 notification information available. Option 2 provides Phase 1 ESA requirements for sites that do not have Guide 50 notification information. Option 3 provided specific Phase 2 ESA requirements for drilling waste disposal areas. Consultants, members of industry and regulators have identified a number of additions and clarifications that could improve the document. Methods for assessing the impact of drill stem test returns under Options 1 and 2 are now being considered. It was observed that lime and gypsum have caused confusion as research now suggests they have less influence on waste salinity than has been assumed in the salt calculations. It was concluded that members of the Canadian Association of Petroleum Producers (CAPP) intend to gather data to further assess the influences of lime and gypsum, as well as data to evaluate the relationships between barium analytical data and barite calculations. Other amendments will include: the ability to use actual mix ratios in the calculations; improved guidance for sampling sumps; and general revisions to improve clarity

  4. Distribution of uranium and thorium in dolomitic gravel fill and shale saprolite.

    Science.gov (United States)

    Phillips, D H; Watson, D B

    2015-03-21

    The objectives of this study were to examine (1) the distribution of U and Th in dolomitic gravel fill and shale saprolite, and (2) the removal of uranium from acidic groundwater by dolomitic gravel through precipitation with amorphous basaluminite at the U.S. DOE Oak Ridge Integrated Field Research Challenge (ORIFRC) field site west of the Oak Ridge Y-12 National Security Complex in East Tennessee. Media reactivity and sustainability are a technical concern with the deployment of any subsurface reactive media. Because the gravel was placed in the subsurface and exposed to contaminated groundwater for over 20 years, it provided a unique opportunity to study the solid and water phase geochemical conditions within the media after this length of exposure. This study illustrates that dolomite gravel can remove U from acidic contaminated groundwater with high levels of Al(3+), Ca(2+), NO(3-), and SO4(2-) over the long term. As the groundwater flows through high pH carbonate gravel, U containing amorphous basaluminite precipitates as the pH increases. This is due to an increase in groundwater pH from 3.2 to ∼6.5 as it comes in contact with the gravel. Therefore, carbonate gravel could be considered as a possible treatment medium for removal and sequestration of U and other pH sensitive metals from acidic contaminated groundwater. Thorium concentrations are also high in the carbonate gravel. Thorium generally shows an inverse relationship with U from the surface down into the deeper saprolite. Barite precipitated in the shallow saprolite directly below the dolomitic gravel from barium present in the acidic contaminated groundwater. PMID:25544493

  5. Geochemistry and potential environmental impact of the mine tailings at Rosh Pinah, southern Namibia

    Science.gov (United States)

    Nejeschlebová, L.; Sracek, O.; Mihaljevič, M.; Ettler, V.; Kříbek, B.; Knésl, I.; Vaněk, A.; Penížek, V.; Dolníček, Z.; Mapani, B.

    2015-05-01

    Mine tailings at Rosh Pinah located in semiarid southern Namibia were investigated by the combination of mineralogical methods and leaching using water and simulated gastric solution. They are well-neutralized with leachate pH > 7 and neutralization potential ratios (NPR) up to 4. Neutralization is mainly due to abundant Mn-rich dolomite in the matrix. Concentrations of released contaminants in water leachate follow the order Zn > Pb > Cu > As. Relatively high leached concentrations of Zn and partly also of Pb are caused by their link to relatively soluble carbonates and Mn-oxyhydroxides. In contrast, As is almost immobile by binding into Fe-oxyhydroxides, which are resistant to dissolution. Barium is released by the dissolution of Ba-carbonate (norsethite) and precipitates in sulfate-rich pore water as barite. Dissolved concentrations in neutral mine drainage water collected in the southern pond are low, but when total concentrations including colloidal fraction are taken into account, more than 70% of Zn is in colloidal form. Groundwater upgradient of the mine tailings is of poor quality and there seems to be no negative impact on groundwater downgradient from mine tailings. Contaminant concentrations in simulated gastric leachates are in the order Ba > Pb > Zn > Cu > As with a maximum gastric bioaccessibility of 86.6% for Ba and a minimum of 3.3% for As. These results demonstrate that total contaminant content and toxicity in the solid phase are poor predictors of risk, and therefore mineralogical and bioavailability/bioaccessibility studies are necessary for evaluation of contaminant environmental impact.

  6. Investigation on radiation shielding parameters of bismuth borosilicate glass from 1 keV to 100 GeV

    International Nuclear Information System (INIS)

    Highlights: ► Radiation shielding parameters of bismuth borosilicate glasses have been investigated. ► The energy variation of effective atomic number was observed. ► Shielding properties of glasses are better than some standard shielding materials. - Abstract: The radiation shielding parameters of (50 − x)SiO2: 15B2O3: 2Al2O3: 10CaO: 23Na2O: xBi2O3 glass systems (where x = 0, 5, 10, 15 and 20 mol%) were theoretically calculated using WinXCom program. The characteristics of radiation shielding parameters for the glass systems of different bismuth compositions were found to be dependent on energy regions. At low-energy region, the radiation shielding parameters show several discontinuous jumps correspond to photoelectric absorption edges. At medium-energy region, the radiation shielding parameters are almost constant and the effective atomic number is close to the mean atomic number, dominated by Compton scattering process. In high-energy regions, pair production becomes the main interaction process and tends to be constant over energy. The mean free paths of the glasses were compared with several standard shielding concretes and it had been shown with lower values of MFP (from 10 MeV to 100 GeV) than serpentite, odinary, chromite, ferrite and barite except for the glass systems with 0 and 5 mol% of Bi2O3. The investigation was carried out to explore the advantages of the glass systems in radiation shielding applications

  7. Hydrogeochemical modelling of fluid–rock interactions triggered by seawater injection into oil reservoirs: Case study Miller field (UK North Sea)

    International Nuclear Information System (INIS)

    A hydrogeochemical model is presented and applied to quantitatively elucidate interdependent reactions among minerals and formation water–seawater mixtures at elevated levels of CO2 partial pressure. These hydrogeochemical reactions (including scale formation) occur within reservoir aquifers and wells and are driven by seawater injection. The model relies on chemical equilibrium thermodynamics and reproduces the compositional development of the produced water (formation water–seawater mixtures) of the Miller field, UK North Sea. This composition of the produced water deviates from its calculated composition, which could result solely from mixing of both the end members (formation water and seawater). This indicates the effect of hydrogeochemical reactions leading to the formation and/or the dissolution of mineral phases. A fairly good match between the modelled and measured chemical composition of produced water indicates that hydrogeochemical interactions achieve near-equilibrium conditions within the residence time of formation water–seawater mixtures at reservoir conditions. Hence the model enables identification of minerals (including scale minerals), to quantitatively reproduce and to predict their dissolution and/or formation. The modelling results indicate that admixing of seawater into formation water triggers the precipitation of Sr–Barite solid solution, CaSO4 phases and dolomite. In contrast, calcite and microcrystalline quartz are dissolved along the seawater flow path from the injection well towards the production well. Depending on the fraction of seawater admixed, interdependent reactions induce profound modifications to the aquifer mineral phase assemblage. At low levels of seawater admixture, Ba–Sr sulfate solid solution is precipitated and coupled to concurrent dissolution of calcite and microcrystalline quartz. Massive dissolution of calcite and the formation of CaSO4 phases and dolomite are triggered by intense seawater admixture

  8. Microbial colonization of basaltic glasses in hydrothermal organic-rich sediments at Guaymas Basin

    Directory of Open Access Journals (Sweden)

    Nolwenn eCallac

    2013-08-01

    Full Text Available Oceanic basalts host diverse microbial communities with various metabolisms involved in C, N, S and Fe biogeochemical cycles which may contribute to mineral and glass alteration processes at, and below the seafloor. In order to study the microbial colonization on basaltic glasses and their potential biotic/abiotic weathering products, two colonization modules called AISICS (Autonomous In Situ Instrumented Colonization System were deployed in hydrothermal deep-sea sediments at the Guaymas Basin for 8 days and 22 days. Each AISICS module contained 18 colonizers (including sterile controls filled with basaltic glasses of contrasting composition. Chemical analyses of ambient fluids sampled through the colonizers showed a greater contribution of hydrothermal fluids (maximum temperature 57.6°C for the module deployed during the longer time period. For each colonizer, the phylogenetic diversity and metabolic function of bacterial and archaeal communities were explored using a molecular approach by cloning and sequencing. Results showed large microbial diversity in all colonizers. The bacterial distribution is primarily linked to the deployment duration, as well as the depth for the short deployment time module. Some 16s rRNA sequences form a new cluster of Epsilonproteobacteria. Within the Archaea the retrieved diversity could not be linked to either duration, depth or substrata. However, mcrA gene sequences belonging to the ANME-1 mcrA-guaymas cluster were found sometimes associated with their putative sulfate-reducers syntrophs depending on the colonizers. Although no specific glass alteration texture was identified, nano-crystals of barite and pyrite were observed in close association with organic matter, suggesting a possible biological mediation. This study gives new insights into the colonization steps of volcanic rock substrates and the capability of microbial communities to exploit new environmental conditions.

  9. The artists' materials of Fernando Melani: A precursor of the Poor Art artistic movement in Italy

    Science.gov (United States)

    Carlesi, Serena; Bartolozzi, Giovanni; Cucci, Costanza; Marchiafava, Veronica; Picollo, Marcello

    2013-03-01

    A comprehensive understanding of both the chemical composition and physical behaviour of modern materials is an important consideration in devising correct conservation treatments for contemporary artworks. To this end, national and international research projects and networks have been established that deal mainly with the preservation, conservation, and understanding of materials used by contemporary artists. This paper focuses on the self-taught artist Fernando Melani (1907-1985), one of the precursors of the Poor Art artistic movement in Italy, and for the first time provides a scientific viewpoint on the artist's materials and works. The analyses, which mainly focus on the pigments/dyes found in his home-studio, were carried out primarily by using Fourier Transform Infrared Spectroscopy (FT-IR) and ultraviolet, visible, and near-infrared Fibre Optic Reflectance Spectroscopy (UV-Vis-NIR FORS). This paper emphasises the performance of FT-IR and FORS in the identification of contemporary artistic materials, since these two techniques have been found to produce highly complementary data. The use of both of these was required in order to obtain a comprehensive understanding of the composition of Melani's materials. Furthermore, one of his artworks, named by Melani himself with its inventory number N. Inv. 2625 (1981), was investigated in situ with the sole use of the FORS technique. The results showed that Melani used traditional inorganic pigments as well as modern organic dyes. Calcite and barite were used as fillers and extenders. Sulphur and abrasive powder were also found, thus confirming his use of a large variety of non-conventional artists' materials.

  10. Manganese mineralization in andesites of Brestovačka Banja, Serbia: evidence of sea-floor exhalations in the Timok Magmatic Complex

    Science.gov (United States)

    Pačevski, Aleksandar; Cvetković, Vladica; Šarić, Kristina; Banješević, Miodrag; Hoefer, Heidi Eva; Kremenović, Aleksandar

    2016-01-01

    Andesites near Brestovačka Banja belong to the Late Cretaceous Timok Magmatic Complex (TMC), which hosts the world-class Bor metallogenic zone including numerous porphyry-copper and epithermal deposits. Two main volcanic phases are recognized in the TMC. The newly discovered Mn mineralization reported here is associated with the second volcanic phase of Turonian-Campanian age. Manganese mineralization containing 58 % MnO on average, occurs as black veins, lumps and nests filling cracks and cavities within an autoclastic andesite, which was deposited in a subaqueous environment. This rock also contains minor Fe mineralization, which is contemporaneous with the manganese mineralization. Manganese mineralization predominantly consists of Mn-Ca silicates (macfallite, pumpellyite-Mn, orientite, bustamite) and Mn oxides (pyrolusite, manganite). Micrometer-scale mineral intergrowths and locally preserved botryoidal and colloform textures are characteristic features of this uncommon mineral assemblage. The features could indicate that the mineralization was formed by deposition from a primary colloidal assemblage and is of sub-marine hydrothermal origin. Orientite is the only Mn mineral with grain size reaching several tenths of micrometers and showing prismatic crystal habit. Scarce to rare associated minerals are hollandite, crednerite, an unknown REE mineral, powellite, pyrite, barite and galena, in decreasing abundance. Trace element analyses of the Mn mineralization show different element contents and REE patterns compared to those of the volcanic host-rock. Manganese mineralization shows relatively high contents of Cu - 1784 ppm, Mo - 20 ppm and As - 268 ppm. These elements are commonly enriched in the Cu deposits of the Bor zone and their relatively high contents in the studied Mn crusts indicate sea-floor hydrothermal vents as a source of the metals.

  11. Diagenetic and oil migration history of the Kimmeridgian Ascla Formation, Maestrat Basin, Spain

    Energy Technology Data Exchange (ETDEWEB)

    Rossi, C.; Marfil, R.; Pena, J.A. de la; Caja, M.A. [Universidad Complutense, Madrid (Spain). Departamento de Petrologia y Geoquimica; Goldstein, R.H. [University of Kansas, Lawrence, KS (United States). Dept. of Geology; Salas, R.; Permanyer, A. [Universidad de Barcelona (Spain). Departamento de Geoquimica; Benito, M.I. [Universidad Complutense, Madrid (Spain). Departamento de Estratigrafia

    2001-03-01

    The marine limestones of the Kimmeridgian Ascla Formation in the Maestrat Basin reached more than 3500 m in burial depth during the Cretaceous era. Despite containing organic-rich intervals, mature in parts of the basin, its potential as oil source-rock has been either overlooked or questioned. A petrographic, geochemical and fluid-inclusion (Fl) study of the cements of the Ascla was performed in order to unravel its diagenetic and thermal evolution. We particularly sought evidence of oil migration and its timing. Three sequences of cement were distinguished. Sequence 1 fills the primary porosity and began with Fe-poor calcites with geochemistry and FIs consistent with precipitation from marine-derived waters during shallow burial. These calcites were followed by burial cements, including ferroan calcite, dolomite, and minor celestite and barite. Sequence 2 consists of Mg-rich, fracture-filling calcite cement zones. The earlier ones are ferroan and contain primary aqueous and oil FIs with homogenization temperatures suggesting precipitation at temperatures as high as 117{sup o}C. Sequence 3 is dominated by fracture-filling calcites with geochemistry and FIs indicating precipitation at low temperatures (less than {approx} 50{sup o}C) from meteoric waters. Cross-cutting relationships with compressional microstructures indicate that Sequence 3 formed after the Eocene Oligocene tectonic inversion of the basin. Oil FIs in Sequence 2 provide evidence that light oils migrated through the Ascla Formation via fractures and microfractures. These oils were likely generated in the organic-rich marls of the basal part of the Ascla. The paragenetic sequence and burial history are consistent with oil generation when the Ascla was at or close to maximum burial depth, but before the Eocene Alpine tectonism, which likely formed the structural traps in the basin. Oil generation and migration occurred long before this event. Therefore, it is probable that early traps were breached by

  12. Paragenesis and conditions of formation of ore minerals from metalliferous breccia pipes, N. Arizona

    International Nuclear Information System (INIS)

    Ore deposits within N. Arizona breccia pipes are currently being exploited for U, but at various times during the past century Cu, Pb, Zn, and Ag were mined. These pipes formed as solution-collapses within the Mississippian Redwall Ls and stopped upward through overlying strata. The principal ore minerals are: uraninite, chalcopyrite, chalcocite, tennantite-tetrahedrite, galena, sphalerite, millerite, gersdorffite, siegenite, and molybdenite. Common gangue minerals are marcasite, pyrite, barite, dolomite, calcite and quartz. Marcasite and pyrite appear to have formed prior to the ore minerals, followed closely by chalcopyrite. The Ni and Co phases also appear to be early: gersdorffite crystals are rimmed by later galena. Tennantite-tetrahedrite formed later than both galena and sphalerite; uraninite, the latest ore mineral, consisting fills interstices. Primary fluid inclusions in dolomite, quartz, and sphalerite show filling temperatures from 80 to 145 degree C and high salinities, averaging 15 wt% NaCl (eq). Secondary inclusions in sphalerite have consistently higher filling temperatures from 105 to 173 degree C, but similar salinities. Rock-Eval pyrolysis of pyrobitumen yields little or no volatile hydrocarbons (S1=0-0.2 mg/gm), but large amounts of pyrolytic hydrocarbons (S2=105-216 mg/gm). Temperatures of maximum pyrolytic yield are relatively low (424-430 degree C), suggesting temperatures did not exceed 150 degree C following pyrobitumen emplacement. Except for uraninite, the breccia pipes are similar to Mississippi Valley-type (MVT) deposits in mineralogy, fluid-inclusion filling temperatures and salinities, and associated organic material. Because MVT deposits do not host U minerals, a possible two-stage mineralization history of the pipes is suggested, the first by a MVT brine and perhaps a second forming the uraninite

  13. Multi-stage Ag-Bi-Co-Ni-U and Cu-Bi vein mineralization at Wittichen, Schwarzwald, SW Germany: geological setting, ore mineralogy, and fluid evolution

    Science.gov (United States)

    Staude, Sebastian; Werner, Wolfgang; Mordhorst, Teresa; Wemmer, Klaus; Jacob, Dorrit E.; Markl, Gregor

    2012-03-01

    The Wittichen Co-Ag-Bi-U mining area (Schwarzwald ore district, SW Germany) hosts several unconformity-related vein-type mineralizations within Variscan leucogranite and Permian to Triassic redbeds. The multistage mineralization formed at the intersection of two fault systems in the last 250 Ma. A Permo-Triassic ore stage I with minor U-Bi-quartz-fluorite mineralization is followed by a Jurassic to Cretaceous ore stage II with the main Ag and Co mineralization consisting of several generations of gangue minerals that host the sub-stages of U-Bi, Bi-Ag, Ni-As-Bi and Co-As-Bi. Important ore minerals are native elements, Co and Ni arsenides, and pitchblende; sulphides are absent. The Miocene ore stage III comprises barite with the Cu-Bi sulfosalts emplectite, wittichenite and aikinite, and the sulphides anilite and djurleite besides native Bi, chalcopyrite, sphalerite, galena and tennantite. The mineral-forming fluid system changed from low salinity (<5 wt.% NaCl) at high temperature (around 300°C) in Permian to highly saline (around 25 wt.% NaCl + CaCl2) at lower temperatures (50-150°C) in Triassic to Cretaceous times. Thermodynamic calculations and comparison with similar mineralizations worldwide show that the Mesozoic ore-forming fluid was alkaline with redox conditions above the hematite-magnetite buffer. We suggest that the precipitation mechanism for native elements, pitchblende and arsenides is a decrease in pH during fluid mixing processes. REE patterns in fluorite and the occurrence of Bi in all stages suggest a granitic source of some ore-forming elements, whereas, e.g. Ag, Co and Ni probably have been leached from the redbeds. The greater importance of Cu and isotope data indicates that the Miocene ore stage III is more influenced by fluids from the overlying redbeds and limestones than the earlier mineralization stages.

  14. Origin and K/Ar age of cryptomelane-bearing Sn placers on silcretes, SE Germany

    Science.gov (United States)

    Dill, H. G.; Wemmer, K.

    2012-11-01

    During the early Miocene (Aquitanian-Burdigalian) an alluvial-fluvial drainage system evolved along the boundary fault of the Münchberg Gneiss Complex in SE Germany. The resultant NE-SW trending channel system collected debris from the enclosing Paleozoic country rocks and from gossans of cassiterite-bearing veins exposed to denudation in the roof rocks of the adjacent Late Variscan Sparnberg-Pottiga Granite. Three different types of placer minerals occur: (1) isolated grains of cassiterite, (2) armored relics of cassiterite and barite, (3) remobilized and redeposited silica aggregates. Silica is present in a zone of silcretes, in mechanically redeposited pebbles within this depression and in cobbles of quartz gangue derived from the nearby vein-type deposits. These silcretes developed from alkaline fluids and were redeposited under semiarid conditions with dryer (period of solution) and wetter seasons (period of redeposition) at ≥ 23 Ma. Cryptomelane I formed under dry conditions around 23 Ma when the pore space of the channel lag deposits was incompletely filled with water, whereas goethite points to more humid climatic conditions between 23 and 17 Ma as the fluids were more acidic. Cryptomelane II filled the pore space of the clastic sediments to completeness on increasing humidity at ≤ 17 Ma. The mineral association under study pertains to the group of supergene Fe-Mn deposits (Hunsrück-type) whose ore-forming processes span a wide range from pedological/ground water-related Fe-Mn concentration in hydromorphic soils to alluvial-fluvial pebble or placer-type concentrations. The current investigations involved geological mapping and geoelectrical DC deep sounding in the field and optical microscopy, SEM-EDX, and K/Ar age dating of cryptomelane in the laboratory.

  15. Heavy metal behaviour in peat - A mineralogical perspective

    International Nuclear Information System (INIS)

    The mineralogical composition of a 40 cm subsurface layer of transitional mire 'Bagno Bruch' (southern Poland) polluted with atmospheric dust was studied using scanning electron microscopy. The mire is located 9 km to the east of a zinc smelter on the northern limit of industrial Upper Silesia in southern Poland. Concentrations of zinc, lead and cadmium reach values of 494, 238 and 16 mg kg-1, respectively, in the peat layer. Inorganic particles in the peat were grouped into two main categories based on their origin: air dust particles of anthropogenic- and natural sources, and authigenic minerals that originated within the mire. Anthropogenic particles comprise an important part of the inorganic particles in the peat. As they are typically enriched in heavy metals, their stability is critical to controlling metal mobilities. Spheroidal aluminosilicate fly-ash particles are the most common- and most stable anthropogenic pollutants. Partially dissolved Pb-bearing particles (sulphides, chlorides and oxides) and ZnS occur as trace components throughout the peat profile. The prolonged existence of the particles made them susceptible to gravitational relocation in the peat and limits the biogeochemical cycling of the constituent elements. The least resistant Fe (hydro)oxides release Zn and minor amounts of Mn, Mg and Sn due to reductive dissolution. The released Zn is immobilized in the form of ZnS spherules, 1-3 μm in diameter, approximately 10 cm further down in the profile. The investigation shows that the behaviour of trace elements in polluted peatland is controlled by mineral dissolution/precipitation processes. The formation of authigenic minerals (ZnS, barite, gypsum) indicates complex redox conditions and element redistribution in the transitional mire.

  16. Mineralogical Characterization of The Alteration Facies at Gabal El-Missikat Area, Central Eastern Desert, Egypt

    International Nuclear Information System (INIS)

    The present study deals with the petrographical, mineralogical and geochemical characteristics of the alteration facies zones recognized around the shear zone at Gabal El-Missikat area, Central Eastern Desert, Egypt. Petrographically, the fresh granitic samples are composed mainly of quartz, K-feldspars (microcline and microcline perthite), plagioclase, biotite. The secondary minerals are sericite, kaolinite, muscovite, chlorite and epidote as well as zircon, apatite, fluorite, titanite and iron oxides as accessory minerals. Two alteration facies zones are recognized and namely as propylitic and advanced argillic. The propylitic facies zone is composed mainly of sericite with minor kaolinite, muscovite, quartz, relics of plagioclases, chlorite and rare epidote as well as zircon, hematite, goethite, magnetite, ilmenite, ilmenorutile, rutile, titanite, apatite, columbite and fluorite and secondary uranium minerals, the advanced argillic facies zone is composed mainly of kaolinite with minor sericite, quartz, muscovite, chlorite and rare epidote as well as zircon, hematite, goethite, magnetite, ilmenite, ilmenorutile, rutile, titanite, apatite and garnet of spessartine type as accessory minerals. The identified minerals in the studied two alteration facies zones can be grouped into three mineral groups which are: the primary minerals (pyrite, magnetite, galena, columbite and gold), the secondary minerals (uranophane, kasolite and wulfenite) and the gangue minerals (anhydrite, barite, celestine, hematite, goethite and fluorite). The identified mineral assemblage of the studied propylitic alteration facies zone may be attributed to strongly alkaline hydrothermal solutions at ph value of more than 7 with temperature varying between 350 and 450°C, while the advanced argillic alteration facies zone is essentially associated with strongly acidic hydrothermal solutions at ph value less than 7 with temperature varying between 150 and 400°C

  17. Optimization of radiation protection in gamma radiography facilities

    International Nuclear Information System (INIS)

    To determine optimized dose limits for workers, a study of optimization of radiation protection was undertaken in gamma radiography facilities closed, using the Technique Multiple Attributes Utility Analysis. A total of 217 protection options, distributed in 34 irradiation scenarios for tree facility types ( fixed open, moveable and closed (bunker) were analyzed. In the determination of the optimized limit dose, the following attributes were considered; costs of the protection barriers, costs attributed to the biological detriment for different alpha (the reference value of unit collective dose), size of the isolation area, constrained limits dose of annual individual equivalent doses and collective dose. The variables studied in the evaluation included: effective work load, type and activity of the sources of radiation (192Ir and 60Co), source-operator distance related to the characteristic of the length of the command cable and the guide tube, type and thickness of the materials used in the protection barriers (concrete, barite, ceramic, lead, steel alloy and tungsten). The optimal analytic solutions obtained in the optimization process that resulted in the indication of the optimized dose limit were determined by means of a sensitivity analysis and by direct and logic evaluations, thus, independent of the values of the monetary coefficient attributed to the biological detriment, of the annual interest rate applied to the protection cost and of the type of installation studied, it was concluded that the primary limit of annual equivalent dose for workers (now 50 mSv) can be easily reduced to an optimized annual dose limit of 5 mSv. (author)

  18. Hydrogeochemical characteristics of the Tinto and Odiel Rivers (SW Spain). Factors controlling metal contents.

    Science.gov (United States)

    Cánovas, C R; Olías, M; Nieto, J M; Sarmiento, A M; Cerón, J C

    2007-02-01

    The Tinto and Odiel Rivers are strongly affected by acid mine drainage (AMD) due to the intense sulphide mining developed in their basins over the past 5000 years. In this study the results obtained from a weekly sampling in both rivers, before their mouth in the Ría of Huelva, over three and a half years of control are analysed. In the Tinto River, the concentrations of sulphates, Al, Cd, Co, Li and Zn are double to those of the Odiel as a consequence of lower dilution. However, the concentration of Fe in the Odiel River is 20 times lower, since the precipitation of Fe oxyhydroxysulphates caused by neutralisation processes is more intense. Lower As, Cr, Cu and Pb concentrations are also found in the Odiel River as, to a greater or lesser extent, they are sorbed and/or coprecipitated with Fe. Other elements such as Be, Mn, Ni and Mg show similar values in both systems, which is ascribed to lithological factors. The seasonal evolution of contaminants is typical of rivers affected by AMD, reaching a maximum in autumn due to the dissolution of evaporitic salts precipitated during the summer. Nevertheless, in the Tinto River, Ca, Na and Sr show a strong increase during the summer, probably due to a greater water interaction with marly materials, through which the last reach of the river flows. Barium has a different behaviour from the rest of the metals and its concentration seems to be controlled by the solubility of barite. Iron, As and Pb show different behaviours in both rivers, those for Fe and As possibly linked to the prevalence of different dissolved species of Fe. The different Pb pattern is probably due to the control of Pb solubility by anglesite or other minerals rich in Pb in the Tinto River. PMID:17207846

  19. Exploring Archean seawater sulfate via triple S isotopes in carbonate associated sulfate.

    Science.gov (United States)

    Paris, G.; Fischer, W. W.; Sessions, A. L.; Adkins, J. F.

    2015-12-01

    Multiple sulfur isotope ratios in Archean sedimentary rocks provide powerful insights into the behavior of the ancient sulfur cycle, the redox state of fluid Earth, and the timing of the rise of atmospheric oxygen [1]. The Archean sulfur isotope record is marked by pronounced mass-independent fractionation (Δ33S≠0)—signatures widely interpreted as the result of SO2 photolysis from "short-wavelength" UV light resulting in a reduced phase carrying positive Δ33S values (ultimately recorded in pyrite) and an oxidized phase carrying negative Δ33S values carried by sulfate [2]. Support for this hypothesis rests on early laboratory experiments and observations of negative Δ33S from barite occurrences in mixed volcanic sedimentary strata in Mesoarchean greenstone terrains. Despite forming the framework for understanding Archean sulfur cycle processes, this hypothesis is still largely untested, notably due to the lack of sulfate minerals in Archean strata. Using a new MC-ICP-MS approach combined with petrography and X-ray spectroscopy we have generated a growing S isotope dataset from CAS extracted from Archean carbonates from a range of sedimentary successions, including: the 2.6 to 2.521 Ga Campbellrand-Malmani carbonate platform (Transvaal Supergroup, South Africa), 2.7 Ga Cheshire Formation (Zimbabwe), and 2.9 Ga Steep Rock Formation (Canada). Importantly, we observe positive δ34S and Δ33S values across a range of different lithologies and depositional environments. These results demonstrate that dissolved sulfate in seawater was characterized by positive Δ33S values—a result that receives additional support from recent laboratory and theoretical experiments [e.g. 4, 5]. [1] Farquhar et al., 2000, Science [2] Farquhar et al., 2001, Journal of Geophysical Research: Planets [3] Paris et al., 2014, Science. [4] Whitehill et al., 2013, Proceedings of the National Academy of Sciences. [5] Claire et al., 2014 Geochimica et Cosmochimica Acta

  20. Study of chemical composition of sludges and scales from the oil production activities and correlation with natural radioactivity - case study: Campos Basin, Brazil

    International Nuclear Information System (INIS)

    This work intended to study general aspects related to natural radioactivity, focusing on its occurrence in the oil industry and on sludge and scales samples taken from the Oil E and P region from Campos's Basin. The physical and chemical analysis and the statistical treatment were carried out with the objective of determine the samples composition checking the differences between the sludges and the scales. Third six representative samples were obtained from the Radioprotection and Dosimetry Institute (IRD/CNEN), Brazil, taking into account factors such as activity concentration, physical and chemical aspects and origin. After the oil extraction, samples were classified by aspects as color and granulometry. Ali the studied samples were analyzed by X-rays diffraction being identified the presence of barite, calcite, quartz among others. The results supplied a base for the elaboration of a successive determination scheme which comprehended residual organic material, carbonate, sulfate, silica, chloride and metals as the alkaline, earthy alkaline, aluminum, etc. The sludges presented a highly variable chemical composition, being rich in silica and carbonates. The main components analysis showed a statistical valid relationship among the radium isotopes and the carbonates presence. On the other hand, the scales are made of barium and strontium sulfates (75%), presenting a minor variation on its chemical composition and in the existing radium content. Due to this low variability of the barium, sulfate and radium contents, it has not been possible to consider valid a relationship that could exist among them in the application of the main component analysis. (author)

  1. The project of El Berrocal: preliminary synthesis

    International Nuclear Information System (INIS)

    El Berrocal is an international research project on the natural radionuclide migration in a fissured granitic environment. This project is being carried out in the El Berrocal zone, north of the village of Nombela (Toledo). The geological formation studied is a granitic pluton with an epithermal vein-type mineralization comprising quartz, sphalerite, pyrite and chalcopyrite; and pitchblende, pyrite, carbonates and barite. The activities of the project are focused on the structural, lithological, geochemical, hydrochemical and hydrogeological aspects of the granite-U mineralization system, in order to establish a migration model of the natural radionuclides of the environment. The concurrence of the tectonic, hydrothermal and supergenic processes has originated several U remobilizations during the deuteric, hydrothermal and supergenic alteration phases which affected the system. These phases are responsible of the mineralogical species and present distribution of this element within the system. The Th remobilization is much more limited, due to its different geochemical behavior. The present water-rock interaction processes account for the different types of water existing in the system, which are sulphatic, in the shallowest zones, and calcium bicarbonated in the deepest. The U contents in these waters vary from 1 to 100 ppb. The hydrogeology of the zone is controlled, at a local scale, by the topography and the fracture network, and the mineralized quartz dyke plays a major role on the groundwater flow. The isotopic analyses of the U and Th series in the infill materials seem to indicate recent sorption- desorption U processes and coprecipitation with carbonates. (Author) 21 refs

  2. Methodological aspects and development of techniques for neutron activation analysis of microcomponents in materials of geologic origin

    International Nuclear Information System (INIS)

    Some aspects of the activation analysis methodology applied to geological samples activated in nuclear reactors were studied, and techniques were developed for the determination of various elements in different types of matrixes, using gamma spectrometry for the measurement of the products. The consideration of the methodological aspects includes the study of the working conditions, the preparation of samples and standards, irradiations, treatment of the irradiated material, radiochemical separation and measurement. Experiments were carried out on reproducibility and errors in relation to the behaviour of the measurement equipment and that of the methods of area calculation (total area, Covell and Wasson), as well as on the effects of geometry variations on the results of the measurements, the RA-3 reactors's flux variations, and the homogeneity of the samples and standards. Also studied were: the selection of the conditions of determination, including the irradiation and decay times; the irradiation with thermal and epithermal neutrons; the measurement with the use of absorbers, and the resolution of complex peaks. Both non-destructive and radiochemical separation techniques were developed for the analysis of 5 types of geological materials. These methods were applied to the following determinations: a) In, Cd, Mn, Ga and Co in blende; b) La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu in fluorites; c) La, Ca, Eu, Tb, Yb, Se and Th in barites and celestites; d) Cu and Zn in soils. The spectral interferences or those due to nuclear reactions were studied and evaluated by mathematical calculation. (M.E.L.)

  3. Alteration and petrology of Intrusive Rocks associated with Gold Mineralization at Kuh-E-Zar Gold Deposit, Torbat-e-Heydaryeh

    Directory of Open Access Journals (Sweden)

    Alireza Mazloumi Bajestani

    2009-09-01

    Full Text Available Kuh- e -Zar gold deposit located 35 km west of Torbat-e-Heydaryeh, (Khorassan e- Razavi province, East of Iran. This deposit is a specularite-rich Iron oxide type (IOCG. This mine is situated within Khaf-Bardascan volcanic plutonic belt. Based on recent exploration along this belt, several IOCG type system plus Kuh-e-Zar deposit are discovered. In the study area, several type of tuff and lava having acid to intermediate composition are identified (upper Eocene. Oligo-Miocene granite, granodiorite, synogranite and monzonite intruded upper Eocene andesite-dacite-rhyolite. Intrusive rocks are meta-aluminous, medium to high-K series I-type. Based on spider diagram, intrusive rocks show enrichment in LILE = K, Th, Rb and depletion in HFSE = Nb, Sr, Ti. Based geochemistry of igneous rock, they formed in continental margin subduction zone. Propylitic (chlorite alteration is dominated and covers large area. Silicification is restricted only to mineralized zones. Argillic and albitization is found in certain location and cover small areas. The style of mineralization was controlled by the type and geometry of fault zones. Mineralization is found as vein, stockwork and breccias. Hypogene mineral Paragenesis include: specularite-quartz-gold-chlorite ± chalcopyrite ± pyrite ± galena ± barite. Secondary minerals formed due to oxidation are: goethite, limonite, lepidocrucite, Malachite, Azurite, Covelite, Cerucite, hydrocerucite, Pyrolusite and Smitsonite. In a few localities, chalcopyrite and minor pyrite and galena are found. Based on SEM analysis gold is present as electrum. Mineralization appeared in different type such as vein, stockwork and Hydrothermal breccia in strike sleep fault zone which are hidden inside volcano plutonic rocks. The average gold grade is between 3.02 ppm and ore reserve is estimated more than 3 million tons (cut off grade = 0.7 ppm.

  4. Quantitative assessment of radionuclide retention in the Quaternary sediments/granite interface of the Fennoscandian shield (Sweden)

    Energy Technology Data Exchange (ETDEWEB)

    Grandia, Fidel [Amphos XXI Consulting S.L., Passeig de Garcia i Faria, 49-51, 1o-1a - E08019, Barcelona (Spain); Sena, Clara, E-mail: csena@ua.pt [Amphos XXI Consulting S.L., Passeig de Garcia i Faria, 49-51, 1o-1a - E08019, Barcelona (Spain)] [I and DGeoBioTec, Geosciences Dept., University of Aveiro, 3810-193 Aveiro (Portugal); Arcos, David; Molinero, Jorge; Duro, Lara; Bruno, Jordi [Amphos XXI Consulting S.L., Passeig de Garcia i Faria, 49-51, 1o-1a - E08019, Barcelona (Spain)

    2011-05-15

    Highlights: > The release of radionuclides from a deep geological repository is investigated. > We simulate the transport of radionuclides in a Quaternary sediment. > The Quaternary sediment's geochemistry is studied to select the reactive minerals. > U, Sr, Cs and Ra were selected due to their contribution for the radioactive dose. > The retention capacity of the Quaternary sediments was quantitatively evaluated. - Abstract: The Quaternary sediments representing the interface between the granite host rock and the Earth surface are of paramount importance when determining the potential cycling of anthropogenic and natural radionuclides in near-surface systems. This is particularly true in the case of high-level nuclear waste (HLNW) repositories placed in granite. In this work a modelling procedure is presented to quantitatively determine the retention capacity of a Quaternary till in the Forsmark area, which has been recently selected to host the deep geologic storage of HLNW in Sweden. Reactive transport numerical models have been used to simulate the intrusion of a deep groundwater carrying radionuclides potentially released from a repository into a Quaternary till. Four radionuclides ({sup 235}U, {sup 135}Cs, {sup 226}Ra and {sup 90}Sr) have been selected according to their different geochemical behaviour and potential dose relevance to surface ecosystems. Numerical results indicate that repository-derived: (i) U will have a minor impact in the till, mainly due to the high natural concentration of U and its adsorption on ferrihydrite; (ii) Cs will be efficiently retained by cation exchange on illite; (iii) Ra will be retained via co-precipitation with barite; and although (iv) Sr will be retained via co-precipitation with calcite and cation exchange on illite, the retention capacity of the Quaternary till for Sr is limited.

  5. Fish scales in sediments from off Callao, central Peru

    Science.gov (United States)

    Díaz-Ochoa, J. A.; Lange, C. B.; Pantoja, S.; De Lange, G. J.; Gutiérrez, D.; Muñoz, P.; Salamanca, M.

    2009-07-01

    We study fish scales as a proxy of fish abundance and preservation biases together with phosphorus from fish remains (P fish) in a sediment core retrieved off Callao, Peru (12°1'S, 77°42'W; water depth=179 m; core length=52 cm). We interpret our results as a function of changing redox conditions based on ratios of redox-sensitive trace elements (Cu/Al, Mo/Al, Ni/Al, Zn/Al, V/Al), terrigenous indicators (Fe in clays, Ti, Al), and biogenic proxies (CaCO 3, biogenic opal, total nitrogen, organic carbon, barite Ba). The core covers roughly 700 years of deposition, based on 210Pb activities extrapolated downcore and 14C dating at selected intervals. Our fish-scale record is dominated by anchovy ( Engraulis ringens) scales followed by hake ( Merluccius gayii) scales. The core presented an abrupt lithological change at 17 cm (corresponding to the early 19th century). Above that depth, it was laminated and was more organic-rich (10-15% organic carbon) than below, where the core was partly laminated and less organic-rich (<10%). The lithological shift coincides with abrupt changes in dry bulk density and in the contents of terrigenous and redox-sensitive trace elements, biogenic proxies, and fish scales. The remarkable increase in redox-sensitive trace elements in the upper 17 cm of the core suggests more reducing conditions when compared with deeper and older horizons, and is interpreted as an intensification of the oxygen minimum zone off Peru beginning in the early 19th century. Higher fish-scale contents and higher P fish/P total ratios were also observed within the upper 17 cm of the core. The behavior of biogenic proxies and redox-sensitive trace elements was similar; more reduced conditions corresponded to higher contents of CaCO 3, C org, total nitrogen and fish scales, suggesting that these proxies might convey an important preservation signal.

  6. Gateways, Supergyre, and proto-Antarctic Circumpolar Current in the middle to late Eocene

    Science.gov (United States)

    Katz, M. E.; Cramer, B. S.; Toggweiler, J.

    2013-12-01

    The (proto-)Antarctic Circumpolar Current (ACC) began to develop in the middle Eocene through a shallow Drake Passage and Tasman Gateway. Progressive deepening of these gateways and northward migration of Australia through the Eocene impacted global ocean circulation. We present middle to late Eocene (~36-40 Ma) benthic foraminiferal stable isotope (δ18O, δ13C) records from ODP Site 1090 that extend published late Eocene-early Oligocene records (Pusz et al. 2011). Comparisons with published isotope records highlight that the deep (~3000m) eastern and western South Atlantic (Sites 699 (Mead et al. 1993) and 1090) was warmer than the shallower (~1500-2500m) Southern Ocean Sites 689 (Diester-Haass and Zahn, 1996; Bohaty et al., 2012). The divergence in the δ18O records began in the late middle Eocene and continued through the late Eocene, as the Drake and Tasman gateways progressively deepened, and Australia moved northward. We speculate that these paleogeographic changes resulted in the development of circulation analogous to the modern Supergyre, which transported warm Indian and Pacific water westward into the South Atlantic and cooler South Atlantic water eastward into the Pacific Ocean via the Tasman Seaway, and acted as a barrier that prevented subtropical water from flowing to high southern latitudes. At the same time, a significant carbon isotopic (δ13C) offset developed between Site 1090 (values ~ 0.7‰ lower) and other sites from ~37.5 to 34 Ma, coinciding with onset of elevated opaline silica (Diekmann et al. 2004), barite, carbonate, and phosphorous (Anderson and Delaney 2005) deposition at Site 1090; these changes are consistent with enhanced primary productivity at the northern edge of the developing polar front, consistent with model predictions for the effects of proto-ACC development (Heinze and Crowley, 1997; Toggweiler and Bjornsson, 2000).

  7. Chemical Considerations for an Updated National Assessment of Brackish Groundwater Resources.

    Science.gov (United States)

    McMahon, P B; Böhlke, J K; Dahm, K G; Parkhurst, D L; Anning, D W; Stanton, J S

    2016-07-01

    Brackish groundwater (BGW) is increasingly used for water supplies where fresh water is scarce, but the distribution and availability of such resources have not been characterized at the national scale in the United States since the 1960s. Apart from its distribution and accessibility, BGW usability is a function of the chemical requirements of the intended use, chemical characteristics of the resource, and treatment options to make the resource compatible with the use. Here, we discuss relations between these three chemical factors using national-scale examples and local case studies. In a preliminary compilation of BGW data in the United States, five water types accounted for the major-ion composition of 70% of samples. PHREEQC calculations indicate that 57-77% of samples were oversaturated with respect to barite, calcite, or chalcedony. In the study, 5-14% of samples had concentrations of arsenic, fluoride, nitrate, or uranium that exceeded drinking-water standards. In case studies of the potential use of BGW for drinking water, irrigation, and hydraulic fracturing, PHREEQC simulations of a hypothetical treatment process resembling reverse osmosis (RO) showed that BGW had the potential to form various assemblages of mineral deposits (scale) during treatment that could adversely affect RO membranes. Speciation calculations showed that most boron in the irrigation example occurred as boric acid, which has relatively low removal efficiency by RO. Results of this preliminary study indicate that effective national or regional assessments of BGW resources should include geochemical characterizations that are guided in part by specific use and treatment requirements. PMID:26312379

  8. Mineralogical, geochemical and isotopic characterization of authigenic carbonates from the methane-bearing sediments of the Bering Sea continental margin (IODP Expedition 323, Sites U1343-U1345)

    Science.gov (United States)

    Pierre, C.; Blanc-Valleron, M.-M.; Caquineau, S.; März, C.; Ravelo, A. C.; Takahashi, K.; Alvarez Zarikian, C.

    2016-03-01

    During Expedition 323 of the Integrated Ocean Drilling Program to the Bering Sea (July 5-September 4, 2009), three sites were drilled along the Bering Sea northeastern continental margin [U1343 down to 745 meters below sea floor (mbsf), U1344 (745 mbsf), U1345 (150 mbsf)]. Diagenetic carbonates are present at all sites within the clayey, diatom-rich oozes of the Bering Sea, where pore waters are also characterized by extremely high methane concentrations. We here present mineralogical, elemental and isotopic data obtained from the authigenic carbonate-rich intercalations within the clay-rich Pleistocene sediments deposited along the Bering Sea continental margin. The mineralogy of the authigenic carbonates is generally represented by composite mixtures of very small crystals of magnesian calcite, dolomite, and iron-rich carbonates, with the latter phases occurring below 260 mbsf at Site U1343, below 200 mbsf at Site U1344, and below 130 mbsf at Site U1345. Element geochemistry shows that Ca, Mg, Fe, Ba, Mn, Sr and U are enriched in the carbonate-rich intercalations relative to the background sediments due to their incorporation into the carbonates and into other authigenic phases (e.g., barite and pyrite). The oxygen and carbon isotopic compositions of the authigenic carbonate minerals show that they were sequentially precipitated from pore waters at different temperatures (i.e., different burial depths) and with different isotopic compositions of dissolved inorganic carbon (DIC). The authigenic Mg-calcite precipitated early during diagenesis and shallow burial from a 13C-depleted DIC pool, whereas dolomite and Fe-rich carbonates formed during later diagenesis and deeper burial from a 13C-enriched DIC pool. These authigenic carbonate occurrences are interpreted as resulting from microbial sulfate reduction combined with anaerobic oxidation of methane, and methanogenesis that was intimately linked to the alteration of silicates, especially iron-rich clay minerals.

  9. Thermodynamic model for the solubility of Ba(SeO4, SO4) precipitates

    International Nuclear Information System (INIS)

    The solubility of Ba(SeO4, SO4) precipitates was determined as a function of the BaSeO4 mole fractions, ranging from 0.0015 to 0.3830, and time with an equilibration period extending to as long as 302 days. Equilibrium/steady state conditions in this system are reached in ≤ 65 days. Pitzer's ion interaction model was used to calculate solid and aqueous phase activity coefficients. Thermodynamic analyses showed that the data do not satisfy Gibbs-Duhem equation, thereby demonstrating that a single-solid solution phase does not control both the selenate and sulfate concentrations. Our extensive data with log10 [Ba] ranging from -3.6 to -5.9 mol kg-1, log10 [SeO4] ranging from -3.6 to -5.2 mol kg-1, and log10 [SO4] ranging from -4.0 to -5.3 mol kg-1 can be explained with the formation of an ideal BaSeO4 solid solution phase that controls the selenium concentrations and a slightly disordered/less-crystalline BaSO4(s) (log10 Kspcircle = -9.5 instead of -10.05 for barite) that controls the sulfate concentrations. In these experiments the BaSO4 component of the solid solution phase never reaches thermodynamic equilibrium with the aqueous phase. Thermodynamic interpretations of the data show that both the ideal BaSeO4 solid solution phase and less-crystalline BaSO4(s) phase are in equilibrium with each other in the entire range of BaSeO4 mole fractions investigated in this study.

  10. Geologic mapping of the Semipalatinsk region, Eastern Kazakstan, using Landsat Thematic Mapper and spot panchromatic data

    Energy Technology Data Exchange (ETDEWEB)

    Davis, P.A. [Geological Survey, Flagstaff, AZ (United States); Berlin, G.L. [Northern Arizona Univ., Flagstaff, AZ (United States)

    1992-12-31

    This geologic reconnaissance study centers on a 90 by 140 km area about 100 km southwest of Semipalatinsk near the east border of the Kazakstan Republic of the USSR. Semipalatinsk, a regional center for grain growing, and several other cities along the Irtysh River were originally established as fortified outposts by the Russians during the 18th and 19th centuries to contain the indigenous, nomadic Kazak herdsmen. The Kazakstan region remained largely undeveloped until after the 1917 Russian Revolution, when exploration geologists began discovering many large mineral deposits. Today, known resources include coal, copper, iron ore, lead, zinc, and barite; most of these are of national significance. These vast mineral resources have prompted development of many metallurgical and chemical industries in the republic. Despite the extensive exploration for mineral resources in this region, published geologic maps (Nalivkin, 1960; Esenov, 1971; Borovikov, 1972) are all at scales of 1:1,100,000 or smaller, and there are no detailed descriptions of the geology around Semipalatinsk in the open literature. Our preliminary examination of commercial remote-sensing, data indicated that the lithology and structure of this area are extremely varied and complex at all scales -- much more so than that portrayed on the published geologic maps. Therefore, the main objective of this study was to use commercially available remotely sensed data for the area and remotely sensed data obtained for analog study sites, as well as the sparse, sketchy information in the published literature, to better define and map the geologic units (Sheet 1), structure (Sheet 2), and drainage features (Sheet 3) of this area.

  11. Heterogeneous Nucleation and Growth of Barium Sulfate at Organic–Water Interfaces: Interplay between Surface Hydrophobicity and Ba 2+ Adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Chong; Stack, Andrew G.; Koishi, Ayumi; Fernandez-Martinez, Alejandro; Lee, Sang Soo; Hu, Yandi

    2016-05-31

    Barium sulfate (BaSO4) is a common scale-forming mineral in natural and engineered systems, yet the rates and mechanisms of heterogeneous BaSO4 nucleation are not understood. To address these, we created idealized interfaces on which to study heterogeneous nucleation rates and mechanisms, which also are good models for organic–water interfaces: self-assembled thin films terminated with different functional groups (i.e., -COOH, -SH, or mixed -SH & COOH) coated on glass slides. BaSO4 precipitation on coatings from Barite-supersaturated solutions (saturation index, SI, = 1.1) was investigated using grazing-incidence small-angle X-ray scattering. After reaction for 1 h, a little amount of BaSO4 formed on hydrophilic bare and -COOH coated glasses. Meanwhile, BaSO4 nucleation was significantly promoted on hydrophobic -SH and mixed -SH & COOH coatings. This is because substrate hydrophobicity likely affected the interfacial energy and hence thermodynamic favorability of heterogeneous nucleation. The heterogeneous BaSO4 nucleation and growth kinetics were found to be affected by the amount of Ba2+ adsorption onto the substrate and incipient BaSO4 nuclei. The importance of Ba2+ adsorption was further corroborated by the finding that precipitation rate increased under [Ba2+]/[SO42–] concentration ratios >1. These observations suggest that thermodynamic favorability for nucleation is governed by substrate–water interfacial energy, while given favorable thermodynamics, the rate is governed by ion attachment to substrates and incipient nuclei.

  12. Evaluation of the concrete shield compositions from the 2010 criticality accident alarm system benchmark experiments at the CEA Valduc SILENE facility

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Thomas Martin [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Celik, Cihangir [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dunn, Michael E [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wagner, John C [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); McMahan, Kimberly L [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Authier, Nicolas [French Atomic Energy Commission (CEA), Centre de Valduc, Is-sur-Tille (France); Jacquet, Xavier [French Atomic Energy Commission (CEA), Centre de Valduc, Is-sur-Tille (France); Rousseau, Guillaume [French Atomic Energy Commission (CEA), Centre de Valduc, Is-sur-Tille (France); Wolff, Herve [French Atomic Energy Commission (CEA), Centre de Valduc, Is-sur-Tille (France); Savanier, Laurence [French Atomic Energy Commission (CEA), Centre de Valduc, Is-sur-Tille (France); Baclet, Nathalie [French Atomic Energy Commission (CEA), Centre de Valduc, Is-sur-Tille (France); Lee, Yi-kang [French Atomic Energy Commission (CEA), Centre de Saclay, Gif sur Yvette (France); Trama, Jean-Christophe [French Atomic Energy Commission (CEA), Centre de Saclay, Gif sur Yvette (France); Masse, Veronique [French Atomic Energy Commission (CEA), Centre de Saclay, Gif sur Yvette (France); Gagnier, Emmanuel [French Atomic Energy Commission (CEA), Centre de Saclay, Gif sur Yvette (France); Naury, Sylvie [French Atomic Energy Commission (CEA), Centre de Saclay, Gif sur Yvette (France); Blanc-Tranchant, Patrick [French Atomic Energy Commission (CEA), Centre de Saclay, Gif sur Yvette (France); Hunter, Richard [Babcock International Group (United Kingdom); Kim, Soon [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Dulik, George Michael [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Reynolds, Kevin H. [Y-12 National Security Complex, Oak Ridge, TN (United States)

    2015-01-01

    In October 2010, a series of benchmark experiments were conducted at the French Commissariat a l'Energie Atomique et aux Energies Alternatives (CEA) Valduc SILENE facility. These experiments were a joint effort between the United States Department of Energy Nuclear Criticality Safety Program and the CEA. The purpose of these experiments was to create three benchmarks for the verification and validation of radiation transport codes and evaluated nuclear data used in the analysis of criticality accident alarm systems. This series of experiments consisted of three single-pulsed experiments with the SILENE reactor. For the first experiment, the reactor was bare (unshielded), whereas in the second and third experiments, it was shielded by lead and polyethylene, respectively. The polyethylene shield of the third experiment had a cadmium liner on its internal and external surfaces, which vertically was located near the fuel region of SILENE. During each experiment, several neutron activation foils and thermoluminescent dosimeters (TLDs) were placed around the reactor. Nearly half of the foils and TLDs had additional high-density magnetite concrete, high-density barite concrete, standard concrete, and/or BoroBond shields. CEA Saclay provided all the concrete, and the US Y-12 National Security Complex provided the BoroBond. Measurement data from the experiments were published at the 2011 International Conference on Nuclear Criticality (ICNC 2011) and the 2013 Nuclear Criticality Safety Division (NCSD 2013) topical meeting. Preliminary computational results for the first experiment were presented in the ICNC 2011 paper, which showed poor agreement between the computational results and the measured values of the foils shielded by concrete. Recently the hydrogen content, boron content, and density of these concrete shields were further investigated within the constraints of the previously available data. New computational results for the first experiment are now available

  13. Quantitative analyses of glass via laser-induced breakdown spectroscopy in argon

    International Nuclear Information System (INIS)

    We demonstrate that elemental analysis of glass with a measurement precision of about 10% can be performed via calibration-free laser-induced breakdown spectroscopy. Therefore, plasma emission spectra recorded during ultraviolet laser ablation of different glasses are compared to the spectral radiance computed for a plasma in local thermodynamic equilibrium. Using an iterative calculation algorithm, we deduce the relative elemental fractions and the plasma properties from the best agreement between measured and computed spectra. The measurement method is validated in two ways. First, the LIBS measurements are performed on fused silica composed of more than 99.9% of SiO2. Second, the oxygen fractions measured for heavy flint and barite crown glasses are compared to the values expected from the glass composing oxides. The measured compositions are furthermore compared with those obtained by X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy. It is shown that accurate LIBS analyses require spectra recording with short enough delays between laser pulse and detector gate, when the electron density is larger than 1017 cm−3. The results show that laser-induced breakdown spectroscopy based on accurate plasma modeling is suitable for elemental analysis of complex materials such as glasses, with an analytical performance comparable or even better than that obtained with standard techniques. - Highlights: • Plasma modeling including the calculation of the plasma pressure • Calibration-free LIBS based on accurate modeling of the plasma emission spectrum • Quantitative LIBS analysis of multicomponent optical glasses including oxygen • Good measurement accuracy obtained only for small delays between laser pulse and detector gate

  14. Quantitative analyses of glass via laser-induced breakdown spectroscopy in argon

    Energy Technology Data Exchange (ETDEWEB)

    Gerhard, C. [Laboratory of Laser and Plasma Technologies, University of Applied Sciences and Arts, Von-Ossietzky-Straße 99, 37085 Göttingen (Germany); Hermann, J., E-mail: Hermann@lp3.univ-mrs.fr [LP3, CNRS – Aix–Marseille University, 163 Av. de Luminy, 13288 Marseille (France); Mercadier, L. [LP3, CNRS – Aix–Marseille University, 163 Av. de Luminy, 13288 Marseille (France); Loewenthal, L. [Laboratory of Laser and Plasma Technologies, University of Applied Sciences and Arts, Von-Ossietzky-Straße 99, 37085 Göttingen (Germany); Axente, E.; Luculescu, C.R. [Laser–Surface–Plasma Interactions Laboratory, Lasers Department, National Institute for Lasers, Plasma and Radiation Physics, Măgurele (Romania); Sarnet, T.; Sentis, M. [LP3, CNRS – Aix–Marseille University, 163 Av. de Luminy, 13288 Marseille (France); Viöl, W. [Laboratory of Laser and Plasma Technologies, University of Applied Sciences and Arts, Von-Ossietzky-Straße 99, 37085 Göttingen (Germany)

    2014-11-01

    We demonstrate that elemental analysis of glass with a measurement precision of about 10% can be performed via calibration-free laser-induced breakdown spectroscopy. Therefore, plasma emission spectra recorded during ultraviolet laser ablation of different glasses are compared to the spectral radiance computed for a plasma in local thermodynamic equilibrium. Using an iterative calculation algorithm, we deduce the relative elemental fractions and the plasma properties from the best agreement between measured and computed spectra. The measurement method is validated in two ways. First, the LIBS measurements are performed on fused silica composed of more than 99.9% of SiO{sub 2}. Second, the oxygen fractions measured for heavy flint and barite crown glasses are compared to the values expected from the glass composing oxides. The measured compositions are furthermore compared with those obtained by X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy. It is shown that accurate LIBS analyses require spectra recording with short enough delays between laser pulse and detector gate, when the electron density is larger than 10{sup 17} cm{sup −3}. The results show that laser-induced breakdown spectroscopy based on accurate plasma modeling is suitable for elemental analysis of complex materials such as glasses, with an analytical performance comparable or even better than that obtained with standard techniques. - Highlights: • Plasma modeling including the calculation of the plasma pressure • Calibration-free LIBS based on accurate modeling of the plasma emission spectrum • Quantitative LIBS analysis of multicomponent optical glasses including oxygen • Good measurement accuracy obtained only for small delays between laser pulse and detector gate.

  15. Nanoparticulate mineral matter from basalt dust wastes.

    Science.gov (United States)

    Dalmora, Adilson C; Ramos, Claudete G; Querol, Xavier; Kautzmann, Rubens M; Oliveira, Marcos L S; Taffarel, Silvio R; Moreno, Teresa; Silva, Luis F O

    2016-02-01

    Ultra-fine and nano-particles derived from basalt dust wastes (BDW) during "stonemeal" soil fertilizer application have been the subject of some concern recently around the world for their possible adverse effects on human health and environmental pollution. Samples of BDW utilized were obtained from companies in the mining district of Nova Prata in southern Brazil for chemical characterization and nano-mineralogy investigation, using an integrated application of advanced characterization techniques such as X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/(Energy Dispersive Spectroscopy) EDS/(selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM)/EDS and granulometric distribution analysis. The investigation has revealed that BDW materials are dominated by SiO2, Al2O3 and Fe2O3, with a complex micromineralogy including alkali feldspar, augite, barite, labradorite, hematite, heulandrite, gypsum, kaolinite, quartz, and smectite. In addition we have identified a number of trace metals such as Cd, Cu, Cr, Zn that are preferentially concentrated into the finer, inhalable, dust fraction and could so present a health hazard in the urban areas around the basalt mining zone. The implication of this observation is that use of these nanometric-sized particulates as soil fertilizer may present different health challenges to those of conventional fertilizers, inviting future work regarding the relative toxicities of these materials. Our investigation on the particle size distribution, nano-particle mineralogy and chemical composition in typical BDW samples highlights the need to develop cleaning procedures to minimise exposure to these natural fertilizing basalt dust wastes and is thus of direct relevance to both the industrial sector of basalt mining and to agriculture in the region. PMID:26551199

  16. The petrogenesis of metamorphosed carbonatites in the Grenville Province, Ontario

    International Nuclear Information System (INIS)

    Veins and dikes of calcite-rich rocks within the Central Metasedimentary Belt boundary zone (CMBbz) in the Grenville Province of Ontario have been interpreted to be true carbonatites or to be pseudocarbonatites derived from interaction of pegmatite melts and regional Grenville marble. The putative carbonatites have been metamorphosed and consist mainly of calcite, biotite, and apatite with lesser amounts of clinopyroxene, magnetite, allanite, zircon, titanite, cerite, celestite, and barite. The rocks have high P and rare earth element (REE) contents, and calcite in carbonatite has elevated Sr, Fe, and Mn contents relative to Grenville Supergroup marble and marble melange. Values of δ18OSMOW (9.9 - 13.3o/oo) and δ13CPDB (-4.8 to -1.9o/oo) for calcite are also distinct from those for marble and most marble melange. Titanites extracted from clinopyroxene -calcite-scapolite skarns formed by metasomatic interaction of carbonatites and silicate lithologies yield U-Pb ages of 1085 to 1035 Ma. Zircon from one carbonatite body yields a U-Pb age of 1089 ± 5 Ma; zircon ages from two other bodies are 1170 ± 3 and 1143 ± 8 Ma, suggesting several carbonatite formation events or remobilization of carbonatite during deformation and metamorphism around 1080 Ma. Values of εNd(T) are 1.7 - 3.2 for carbonatites, -1.5 -1.0 for REE-rich granite dikes intruding the CMBbz, and 1.6 - 1.7 for marble. The mineralogy and geochemical data are consistent with derivation of the carbonatites from a depleted mantle source. Mixing calculations indicate that interaction of REE-rich pegmatites with regional marbles cannot reproduce selected major and minor element abundance, REE contents, and O and Nd isotope compositions of the carbonatites. (author)

  17. Ions, vapors and/or nanoparticles penetrating volcanic edifices?

    Science.gov (United States)

    Obenholzner, Johannes; Edwards, Marc; Parks, J. L.; Fulingati, Paolo

    2010-05-01

    A top-sealed plastic tube with a diameter of ca. 15 cm had been buried ca. 70 cm deep vertically at the base of La Fossa volcano, Vulcano island, Italy, next to the front of the obsidian flow. The tube had been filled with layered rock and quartz wool to condense vapors emanating from the soil. At ca. 75 cm below the surface the sample had been exposed to vapors from Sept. 2005 to April 2006. The leached sample had not been in touch with the ground. 2 other glass wool cushions (ca. 10 cm thick, uncompacted) had been underneath to minimize capillary effects. A rock wool layer not touching ground revealed nucleated sylvite (KCl ~10 µm in size) and barite (BaSO4 ~5-10 µm in size) crystals by SEM/EDS in its basal portion. Other very small (metal compounds. The nucleation of sylvite and barite documents the presence of ions. Leaching of the quartz wool at room temperature with deionized H2O and ICP-MS analysis documented positive values for: Mg, Al, Si, P, K, Ca, Cr, Mn, Ni, Cu, Zn, Cd, Sn, Pb and partially W. Leaching with nitric acid documented also V and Fe. Acid leaching produced higher values for all elements, except K and Sn. Negative values had been obtained for As, Se, Mo. Influence from soil breathing can be excluded as the active fumaroles contain As and Se. This experiment documents for the first time an unknown element transport by vapors/gases through a volcanic edifice interacting with hydrothermal and magmatic gases. In comparison with blank data, 4 groups of elements can be distinguished: . positive signal: Mg, K, Ca, Cr, Mn, Ni, (Ba); low to moderate volatility at magmatic conditions. 2. unclear signal: Al, Si, P, Fe; low volatility at magmatic conditions. 3. no signal: V, As, Se, Mo, Co. As, Se, Mo, V are considered to be highly volatile, Co got a low volatiliy. 4. positive signal: Cu, Zn, Cd, Sn, Pb, W; high volatility at magmatic conditions. Charging, and to a lesser degree ions, in volcanic environments had been documented after fracture

  18. Hydrothermal vents near a mantle hot spot: the Lucky Strike vent field at 37°N on the Mid-Atlantic Ridge

    Science.gov (United States)

    Langmuir, C.; Humphris, S.; Fornari, D.; Van Dover, C.; Von Damm, K.; Tivey, M. K.; Colodner, D.; Charlou, J.-L.; Desonie, D.; Wilson, C.; Fouquet, Y.; Klinkhammer, G.; Bougault, H.

    1997-04-01

    The Lucky Strike hydrothermal field occurs in the summit basin of a large seamount that forms the shallow center of a 65 km long ridge segment near 37°N on the Mid-Atlantic Ridge. The depth and chemistry of the ridge segment are influenced by the Azores hot spot, and this hydrothermal field is the first Atlantic site found on crust that is dominated by a hot spot signature. Multiple hydrothermal vents occur over an area of at least 300 m by 700 m. Vent morphologies range from flanges and chimneys with temperatures of 200-212°C, to black smoker chimneys with temperatures up to 333°C. Cooler fluids from northern vents have higher chlorinities and lower gas volumes, while hotter, southern fluids have chlorinities 20% below seawater with higher gas volumes, suggesting phase separation has influenced their compositions. All gas volumes in fluids are higher than those at TAG and Snake Pit hydrothermal fields. Black smokers exhibit their typical mineralogy, except that barite is a major mineral, particularly at lower-temperature sites, which contrasts with previously investigated Atlantic sites. The fluid chemistry, distribution of the relict sulfide deposits on the seamount summit in the areas investigated using DSV Alvin, and contact relationships between active vent sites and surrounding basaltic and sulfide substrate suggest that the hydrothermal system has a long history and may have recently been rejuvenated. Fauna at the Lucky Strike vent sites are dominated by a new species of mussel, and include the first reported sea urchins. The Lucky Strike biological community differs considerably from other vent fauna at the species level and appears to be a new biogeographic province. The Lucky Strike field helps to constrain how variations in the basaltic substrate influence the composition of hydrothermal fluids and solids, because basalt compositions at Lucky Strike are 10-30 times enriched in incompatible elements compared to other Atlantic hydrothermal sites such as

  19. Igneous geology of the Carlin trend, Nevada: The importance of Eocene magmatism in gold mineralization

    Science.gov (United States)

    Ressel, Michael Walter, Jr.

    Igneous rocks of five ages are present in the Carlin trend, Nevada, and include: (1) Paleozoic basalt of the Roberts Mountains allochthon, (2) the Jurassic (˜158 Ma) Goldstrike intrusive complex, which includes the Goldstrike diorite laccolith and abundant dikes and sills, (3) a Cretaceous (112 Ma) granite stock, (4) lavas and intrusions of the Emigrant Pass volcanic field and widespread epizonal plugs and dikes of Eocene (˜40-36 Ma) age that range from rhyolite through basalt, and (5) Miocene (15 Ma) rhyolite lava and tuff. Jurassic and Eocene igneous rocks are by far the most important volumetrically and are spatially associated with nearly all ore deposits of the Carlin trend. This study focuses on the field relations, isotopic dating, and geochemistry of Eocene dikes that intrude sedimentary rocks in many deposits of the Carlin trend, because they are the youngest pre-mineral rocks and have simpler alteration histories than other host rocks. In the Beast, Genesis, Deep Star, Betze-Post, Rodeo-Goldbug, Meikle-Griffin, and Dee-Storm deposits, Eocene dikes are altered, commonly mineralized, and locally constitute ore. Gold-bearing dikes and sedimentary rocks have similar ore mineralogy, including arsenian pyrite, marcasite, and arsenopyrite, with late barite and stibnite. At Beast, as much as half the ore is hosted in a 37.3 Ma rhyolite dike. Post-gold alunite is ˜18.6 Ma. At Meikle and Griffin, porphyritic dacite dikes yield concordant U/Pb zircon and 40Ar/39Ar biotite emplacement ages of ˜39.2 Ma, and illite from the same QSP-altered dacite, with as much 9 ppm Au, yields similar, although imprecise 40Ar/39Ar ages. Thus, gold mineralization at these deposits closely followed emplacement of Eocene dikes. Carlin-type gold deposits in northeastern Nevada have been variously interpreted as partly syngenetic with Paleozoic carbonate rocks, products of Mesozoic contraction and metamorphism with or without significant magmatism, and of Tertiary age and related or

  20. Distribution of uranium and thorium in dolomitic gravel fill and shale saprolite

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, D.H. [Environmental Engineering Research Centre, School of Planning, Architecture, and Civil Engineering, Queen’s University of Belfast, Belfast BT9 5AG, Northern Ireland (United Kingdom); Watson, D.B., E-mail: watsondb@ornl.gov [Environmental Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, 37831 TN (United States)

    2015-03-21

    Highlights: • Dolomite gravel can remove U from acidic groundwater with high Al{sup 3+} and SO{sub 4}{sup 2−}. • U containing amorphous basaluminite precipitates as the pH increases. • Dolomite gravel maybe a possible treatment medium for U acidic groundwater. • Dolomite gravel has been removing U from ground over a 20 year period. • Thorium is also high in the dolomitic gravel and has an inverse relationship with U. - Abstract: The objectives of this study were to examine (1) the distribution of U and Th in dolomitic gravel fill and shale saprolite, and (2) the removal of uranium from acidic groundwater by dolomitic gravel through precipitation with amorphous basaluminite at the U.S. DOE Oak Ridge Integrated Field Research Challenge (ORIFRC) field site west of the Oak Ridge Y-12 National Security Complex in East Tennessee. Media reactivity and sustainability are a technical concern with the deployment of any subsurface reactive media. Because the gravel was placed in the subsurface and exposed to contaminated groundwater for over 20 years, it provided a unique opportunity to study the solid and water phase geochemical conditions within the media after this length of exposure. This study illustrates that dolomite gravel can remove U from acidic contaminated groundwater with high levels of Al{sup 3+}, Ca{sup 2+}, NO{sup 3−}, and SO{sub 4}{sup 2−} over the long term. As the groundwater flows through high pH carbonate gravel, U containing amorphous basaluminite precipitates as the pH increases. This is due to an increase in groundwater pH from 3.2 to ∼6.5 as it comes in contact with the gravel. Therefore, carbonate gravel could be considered as a possible treatment medium for removal and sequestration of U and other pH sensitive metals from acidic contaminated groundwater. Thorium concentrations are also high in the carbonate gravel. Thorium generally shows an inverse relationship with U from the surface down into the deeper saprolite. Barite

  1. Chemical composition of modern and fossil hippopotamid teeth and implications for paleoenvironmental reconstructions and enamel formation - Part 2: Alkaline earth elements as tracers of watershed hydrochemistry and provenance

    Science.gov (United States)

    Brügmann, G.; Krause, J.; Brachert, T. C.; Stoll, B.; Weis, U.; Kullmer, O.; Ssemmanda, I.; Mertz, D. F.

    2012-11-01

    . The most plausible explanation is that Ba mobility decreased with increasing aridification due to preferential deposition with clay and Fe-oxide-hydroxide or barite on the watershed of Lake Albert.

  2. Methane-derived authigenic carbonates along the North Anatolian fault system in the Sea of Marmara (Turkey)

    Science.gov (United States)

    Crémière, Antoine; Pierre, Catherine; Blanc-Valleron, Marie-Madeleine; Zitter, Tiphaine; Çağatay, M. Namik; Henry, Pierre

    2012-08-01

    The Marnaut cruise (May-June 2007) investigated the submerged part of the North Anatolian fault system, an active tectonic area in the Sea of Marmara. Already known and new fluid venting sites along the fault system were visited by submersible diving. Cold seeps present a considerable diversity of geochemical background associated with occurrences of authigenic carbonate crusts outcropping at the seafloor. Buried carbonate concretions were also recovered by coring within the sediments of the Tekirdağ Basin and of the Western-High ridge that separates the Tekirdağ and Central Basins. Interestingly, numerous of these early diagenetic carbonates were found within the transitional sediments from lacustrine to marine environment deposited after the late glacial maximum. The authigenic carbonates are mainly composed of aragonite, Mg-calcite and minor amounts of dolomite, and are often associated with pyrite and barite. The carbon isotopic compositions of carbonates present a wide range of values from -50.6‰ to +14.2‰ V-PDB indicating different diagenetic settings and complex mixtures of dissolved inorganic carbon from different sources. The low δ13C values of the seafloor crusts and of most buried concretions indicate that the carbon source was a mixture of microbial and thermogenic methane and possibly other hydrocarbons that were oxidized by anaerobic microbial processes. The positive δ13C values of a few buried concretions from the Western-High ridge reflect the mineralization of heavy CO2, which is thought to represent the residual by-product of oil biodegradation in a subsurface petroleum reservoir that migrated up with brines. Most of the oxygen isotopic compositions of seafloor carbonates are close to the isotopic equilibrium with the present-day bottom water conditions but a few values as low as -1.9‰ V-PDB indicate precipitation from brackish waters. In buried carbonate concretions, δ18O values as high as +4.9‰ V-PDB reflect the contribution of

  3. Remote Raman - laser induced breakdown spectroscopy (LIBS) geochemical investigation under Venus atmospheric conditions

    Energy Technology Data Exchange (ETDEWEB)

    Clegg, Sanuel M [Los Alamos National Laboratory; Barefield, James E [Los Alamos National Laboratory; Humphries, Seth D [Los Alamos National Laboratory; Wiens, Roger C [Los Alamos National Laboratory; Vaniman, D. T. [Los Alamos National Laboratory; Sharma, S. K. [UNIV OF HAWAII; Misra, A. K. [UNIV OF HAWAII; Dyar, M. D. [MT. HOLYOKE COLLEGE; Smrekar, S. E. [JET PROPULSION LAB.

    2010-12-13

    quantitatively determine the major elemental abundance of the remaining samples. PLS analysis suggests that the major element compositions can be determined with root mean square errors ca. 5% (absolute) for SiO{sub 2}, Al{sub 2}O{sub 3}, Fe{sub 2}O{sub 3}(total), MgO, and CaO, and ca. 2% or less for TiO{sub 2}, Cr{sub 2}O{sub 3}, MnO, K{sub 2}O, and Na{sub 2}O. Finally, the Raman experiments have been conducted under supercritical CO{sub 2} involving single-mineral and mixed-mineral samples containing talc, olivine, pyroxenes, feldspars, anhydrite, barite, and siderite. The Raman data have shown that the individual minerals can easily be identified individually or in mixtures.

  4. 160 Ma of magmatic/hydrothermal and metamorphic activity in the Gällivare area: Re-Os dating of molybdenite and U-Pb dating of titanite from the Aitik Cu-Au-Ag deposit, northern Sweden

    Science.gov (United States)

    Wanhainen, Christina; Billström, Kjell; Martinsson, Olof; Stein, Holly; Nordin, Roger

    2005-12-01

    Host rocks to the Aitik Cu-Au-Ag deposit in northern Sweden are strongly altered and deformed Early Proterozoic mica(-amphibole) schists and gneisses. The deposit is characterised by numerous mineralisation styles, vein and alteration types. Four samples were selected for Re-Os molybdenite dating and 12 samples for U-Pb titanite dating in order to elucidate the magmatic/hydrothermal and metamorphic history following primary ore deposition in the Aitik Cu-Au-Ag deposit. Samples represent dyke, vein and alteration assemblages from the ore zone, hanging wall and footwall to the deposit. Re-Os dating of molybdenite from deformed barite and quartz veins yielded ages of 1,876±10 Ma and 1,848±8 Ma, respectively. A deformed pegmatite dyke yielded a Re-Os age of 1,848±6 Ma, and an undeformed pegmatite dyke an age of 1,728±7 Ma. U-Pb dating of titanite from a diversity of alteration mineral associations defines a range in ages between 1,750 and 1,805 Ma with a peak at ca. 1,780 Ma. The ages obtained, together with previous data, bracket a 160-Ma (1,890-1,730 Ma) time span encompassing several generations of magmatism, prograde to peak metamorphism, and post-peak cooling; events resulting in the redistribution and addition of metals to the deposit. This multi-stage evolution of the Aitik ore body suggests that the deposit was affected by several thermal events that ultimately produced a complex ore body. The Re-Os and U-Pb ages correlate well with published regional Re-Os and U-Pb age clusters, which have been tied to major magmatic, hydrothermal, and metamorphic events. Primary ore deposition at ca. 1,890 Ma in connection with intrusion of Haparanda granitoids was followed by at least four subsequent episodes of metamorphism and magmatism. Early metamorphism at 1,888-1,872 Ma overlapping with Haparanda (1,890-1,880 Ma) and Perthite-monzonite (1,880-1,870 Ma) magmatism clearly affected the Aitik area, as well as late metamorphism and Lina magmatism at 1,810-1,774 Ma and

  5. Investigations of a novel fauna from hydrothermal vents along the Arctic Mid-Ocean Ridge (AMOR) (Invited)

    Science.gov (United States)

    Rapp, H.; Schander, C.; Halanych, K. M.; Levin, L. A.; Sweetman, A.; Tverberg, J.; Hoem, S.; Steen, I.; Thorseth, I. H.; Pedersen, R.

    2010-12-01

    The Arctic deep ocean hosts a variety of habitats ranging from fairly uniform sedimentary abyssal plains to highly variable hard bottoms on mid ocean ridges, including biodiversity hotspots like seamounts and hydrothermal vents. Deep-sea hydrothermal vents are usually associated with a highly specialized fauna, and since their discovery in 1977 more than 400 species of animals have been described. This fauna includes various animal groups of which the most conspicuous and well known are annelids, mollusks and crustaceans. The newly discovered deep sea hydrothermal vents on the Mohns-Knipovich ridge north of Iceland harbour unique biodiversity. The Jan Mayen field consists of two main areas with high-temperature white smoker venting and wide areas with low-temperature seepage, located at 5-700 m, while the deeper Loki Castle vent field at 2400 m depth consists of a large area with high temperature black smokers surrounded by a sedimentary area with more diffuse low-temperature venting and barite chimneys. The Jan Mayen sites show low abundance of specialized hydrothermal vent fauna. Single groups have a few specialized representatives but groups otherwise common in hydrothermal vent areas are absent. Slightly more than 200 macrofaunal species have been identified from this vent area, comprising mainly an assortment of bathyal species known from the surrounding area. Analysis of stable isotope data also indicates that the majority of the species present are feeding on phytodetritus and/or phytoplankton. However, the deeper Loki Castle vent field contains a much more diverse vent endemic fauna with high abundances of specialized polychaetes, gastropods and amphipods. These specializations also include symbioses with a range of chemosynthetic microorganisms. Our data show that the fauna composition is a result of high degree of local specialization with some similarities to the fauna of cold seeps along the Norwegian margin and wood-falls in the abyssal Norwegian Sea

  6. Health and environmental concerns on the radioactivity of phosphogypsum storage in Israel

    Energy Technology Data Exchange (ETDEWEB)

    Godfrey-Smith, D. [Defence R and D Canada, 101 Colonel By Drive (Canada); Nassar, H.; Steiner, V. [Ministry of Environmental Protection (Israel); Moinester, M.; Malki, A. [School of Physics and Astronomy (Israel); Kronfeld, J. [Dept Geophysics and Planetary Sci. (Israel)

    2014-07-01

    the banks of the Kishon River. The chemistry of the fluids in the stacks prevents potential releases and mobilization of the radio-nuclides before they can affect the groundwater. For example, there may be nuclide incorporation within in situ formed barite minerals, or the acid soluble nuclides may be immobilized as they encounter the clays and (basic pH) carbonate material underlying the stacks. Document available in abstract form only. (authors)

  7. Chemical Equilibrium and Mineral Saturation in Waters from Oil Wells of the Activo Luna Field, Tabasco, Mexico; Equilibrio quimico y grado de saturacion de minerales en aguas de pozos petroleros de Activo Luna, Tabasco, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Barragan R, Rosa Maria; Arellano G, Victor M.; Portugal M, Enrique; Torres R, Vicente [Instituto de Investigaciones Electricas (Mexico); Torres Alvarado, Ignacio [Universidad Nacional Autonoma de Mexico (Mexico); Ascencio C, Fernando; Martinez A; Ana E [Petroleos Mexicanos (Mexico)

    2001-09-01

    Chemical equilibrium of formation waters from seven oil wells of the Activo Luna field (Tabasco, Mexico) was modelled. Saturation indices of characteristic hydrothermal minerals were calculated at ambient and reservoir conditions in order to predict scaling potential of deep and surface installations. The salinity of waters was found to be in the range from 43,000 (well Escuintle 2) to 250,000 (well Lune 3B) mg/kg as total dissolved solids. The water samples were classified as sodium-chioride type. Ionic strength for the solutions was found to be between 0.75 and 6.5. Activity coefficients were estimated by virial (Pitzer equations) methods using the GEOCHEMIST WORKENCH (GWB) software. Minerals such as anhydrite, halite, alunite, fluorite and barite were found to be supersaturated at reservoir conditions. A solid scale sample obtained from well Luna-3B was analysed. Analysis indicate the presence of calcite, anhydrite, fluorite and sphalerite which suggest the occurrence of temperatures of at least 180 Celcius degrees with acidic conditions and high chemical corrosion potential. [Spanish] Se modelo el equilibrio quimico de aguas de formacion producidas por siete pozos petroleros pertenecientes al Activo Luna, en el estado de Tabasco, Mexico, se calcularon los indices de saturacion de minerales caracteristicos tanto en las condiciones ambiente como en las de yacimiento, con el proposito de apoyar el control de incrustaciones en las instalaciones superficiales y profundas. La salinidad de las salmueras se encontro en el rango de 43,000 (pozos Escuintle 2) a 250,000 (pozos Luna 3B) mg/kg de solidos disueltos totales y las muestras se clasificaron como del tipo clorurado-sodico. La fuerza ionica de las soluciones varia entre 0.75 y 6.5 molar, por lo que los coeficientes de actividad de la modelacion de equilibrio quimico se estimaron por metodos viriales empleando las ecuaciones de Pitzer mediante el programa GEOCHEMIST WORKBENCH (GWB). Minerales como anhidrita, halita

  8. TOXIC SUBSTANCES FROM COAL COMBUSTION A COMPREHENSIVE ASSESSMENT

    Energy Technology Data Exchange (ETDEWEB)

    A KOLKER; AF SAROFIM; CA PALMER; FE HUGGINS; GP HUFFMAN; J LIGHTY; JJ HELBLE; JOL WENDT; MR AMES; N YAP; R FINKELMAN; R. MAMANI-PACO; SJ MROCZKOWSKY; T PANAGIOTOU; W SEAMES

    1999-01-28

    The technical objectives of this project are: (a) To identify the effect of the mode-of-occurrence of toxic elements in coal on the partitioning of these elements among vapor, submicron fume, and fly ash during the combustion of pulverized coal, (b) To identify the mechanisms governing the post-vaporization interaction of toxic elements and major minerals or unburnt char, (c) To determine the effect of combustion environment (i.e., fuel rich or fuel lean) on the partitioning of trace elements among vapor, submicron fume, and fly ash during the combustion of pulverized coal, (d) To model the partitioning of toxic elements among various chemical species in the vapor phase and between the vapor phase and complex aluminosilicate melts, (e) To develop the new Toxics Partitioning Engineering Model (ToPEM), applicable to all combustion conditions including new fuels and coal blends, low-NO{sub x} combustion systems, and new power generation plants. A description of the work plan for accomplishing these objectives is presented in Section 2.1 of this report. The work discussed in this report covers the reporting period from 1 October 1998 to 31 December 1998. During this quarter, basic coal testing at USGS was completed. Total sulfur contents range from 0.43 wt-% in the Wyodak to 2.68 wt-% in the Ohio sample. In the North Dakota and Ohio samples, about half of the total sulfur is pyritic and half is organic. The North Dakota sample also contains a minor amount of sulfate, consistent with the presence of barite in this sample. In the Wyodak sample, the majority of the sulfur is organic. Preliminary mineralogy of the three Phase II coals was determined by SEM/EDX. The Ohio coal contains all of the five most common major phases: quartz, illitic clay, kaolinitic clay, pyrite and calcite. Based on this preliminary work, the North Dakota sample appears to lack both kaolinite and calcite, and the Wyodak sample appears to lack calcite. Subsequent SEM work will attempt to reconfirm

  9. Xenon Fractionation, Hydrogen Escape, and the Oxidation of the Earth

    Science.gov (United States)

    Zahnle, K. J.; Catling, D. C.

    2014-12-01

    Xenon in Earth's atmosphere is severely mass fractionated and depleted compared to any plausible solar system source material, yet Kr is unfractionated. These observations seem to imply that Xe has escaped from Earth. Vigorous hydrodynamic hydrogen escape can produce mass fractionation in heavy gases. The required hydrogen flux is very high but within the range permitted by solar EUV heating when Earth was 100 Myrs old or younger. However this model cannot explain why Xe escapes but Kr does not. Recently, what appears to be ancient atmospheric xenon has been recovered from several very ancient (3-3.5 Ga) terrestrial hydrothermal barites and cherts (Pujol 2011, 2013). What is eye-catching about this ancient Xe is that it is less fractionated that Xe in modern air. In other words, it appears that a process was active on Earth some 3 to 3.5 billion years ago that caused xenon to fractionate. By this time the Sun was no longer the EUV source that it used to be. If xenon was being fractionated by escape — currently the only viable hypothesis — it had to be in Earth's Archean atmosphere and under rather modest levels of EUV forcing. It should be possible for Xe, but not Kr, to escape from Earth as an ion. In a hydrodynamically escaping hydrogen wind the hydrogen is partially ionized. The key concepts are that ions are much more strongly coupled to the escaping flow than are neutrals (so that a relatively modest flow of H and H+ to space could carry Xe+ along with it, the flux can be small enough to be consistent with diffusion-limited flux), and that Xe alone among the noble gases is more easily ionized than hydrogen. This sort of escape is possible along the polar field lines, although a weak or absent magnetic field would likely work as well. The extended history of hydrogen escape implicit in Xe escape in the Archean is consistent with other suggestions that hydrogen escape in the Archean was considerable. Hydrogen escape plausibly played the key role in creating

  10. Compilation of Mineral Resource Data for Mississippi Valley-Type and Clastic-Dominated Sediment-Hosted Lead-Zinc Deposits

    Science.gov (United States)

    Taylor, Ryan D.; Leach, David L.; Bradley, Dwight C.; Pisarevsky, Sergei A.

    2009-01-01

    This report contains a global compilation of the mineral resource data for sediment-hosted lead-zinc (SH Pb-Zn) deposits. Sediment-hosted lead-zinc deposits are historically the most significant sources of lead and zinc, and are mined throughout the world. The most important SH Pb-Zn deposits are hosted in clastic-dominated sedimentary rock sequences (CD Pb-Zn) that are traditionally called sedimentary exhalative (SEDEX) deposits, and those in carbonate-dominated sequences that are known as Mississippi Valley-type (MVT) Pb-Zn deposits. In this report, we do not include sandstone-Pb, sandstone-hosted Pb, or Pb-Zn vein districts such as those in Freiberg, Germany, or Coeur d'Alene, Idaho, because these deposits probably represent different deposit types (Leach and others, 2005). We do not include fracture-controlled deposits in which fluorite is dominant and barite typically abundant (for example, Central Kentucky; Hansonburg, N. Mex.) or the stratabound fluorite-rich, but also lead- and zinc-bearing deposits, such as those in southern Illinois, which are considered a genetic variant of carbonate-hosted Pb-Zn deposits (Leach and Sangster, 1993). This report updates the Pb, Zn, copper (Cu), and silver (Ag) grade and tonnage data in Leach and others (2005), which itself was based on efforts in the Canadian Geological Survey World Minerals Geoscience Database Project (contributions of D.F. Sangster to Sinclair and others, 1999). New geological or geochronological data, classifications of the tectonic environment in which the deposits formed, and key references to the geology of the deposits are presented in our report. Data for 121 CD deposits, 113 MVT deposits, and 6 unclassified deposits that were previously classified as either SEDEX or MVT in the Leach and others (2005) compilation, are given in appendix table A1. In some cases, mineral resource data were available only for total district resources, but not for individual mines within the district. For these

  11. A reappraisal of the age, origin and structural setting of sulphide mineralisation in the UK North Pennines Orefield

    Science.gov (United States)

    Holdsworth, Bob; Dempsey, Eddie; Selby, David; Le Cornu, Chris; Young, Brian

    2015-04-01

    The North Pennines Orefield (NPO) is centred on the Alston block, a structural high of fractured Carboniferous sedimentary rocks that unconformably overlie a Devonian age (ca. 399 Ma) granite pluton buried at shallow depths (leaching of the host sedimentary (carbonate-rich) rocks. The vein-hosted part of the orefield consists of linked systems of shear and tensile fractures with a variety of regionally recognised orientations (ESE-WNW Quarter Point, NE-SW, NW-SE Cross Veins). These are associated with lead (galena), iron (pyrite, pyrrhotite, marcasite), copper (chalcopyrite), zinc (sphalerite), fluorite, barite and quartz mineralization. New Rhenium-Osmium (Re-Os) isotope geochemical analysis of the vein-hosted pyrite mineralization suggests that: (i) the metalliferous ores of the NPO formed ca. 294Ma (earliest Permian); and (ii) that they carry an initial Os ratio indicative of a mantle source similar to that indicated by the initial Os ratio of the Whin Sill dolerite suite (emplacement ages ca. 297-294 Ma). New field observations and stress inversion analyses show that at least two regional deformation events are recognised in the Carboniferous host rocks of the NPO. A initial phase of Late Carboniferous ('Variscan') N-S compression pre-dates mineralisation and leads to formation of the NW-SE fractures, initiation of the Burtreeford Disturbance as a N-S fault and compressional reactivation of the previously extensional E-W Lunedale Fault. A later phase of dextral transtension (NNE-SSW extension, ESE-WNW compression) leads to the formation of the ESE-WNW and NE-SW veins, together with compressional reactivation of the Burtreeford Disturbance and Lunedale Fault. Field and microstructural analyses show that the transtensional deformation is synchronous with the main phases of NPO mineralisation and also with emplacement of the Whin Sill and associated intrusions. We conclude that: (i) the main phase of NPO mineralization occurred synchronously with regional dextral

  12. The early Cambrian Chahmir shale-hosted Zn-Pb deposit, Central Iran: an example of vent-proximal SEDEX mineralization

    Science.gov (United States)

    Rajabi, Abdorrahman; Rastad, Ebrahim; Canet, Carles; Alfonso, Pura

    2015-06-01

    The Chahmir zinc-lead deposit (1.5 Mt @ 6 % Zn + 2 % Pb) in Central Iran is one among several sedimentary-exhalative Zn-Pb deposits in the Early Cambrian Zarigan-Chahmir basin (e.g., Koushk, Darreh-Dehu, and Zarigan). The deposit is hosted by carbonaceous, fine-grained black siltstones, and shales interlayered with volcaniclastic sandstone beds. It corresponds to the upper part of the Early Cambrian volcano-sedimentary sequence (ECVSS), which was deposited on the Posht-e-Badam Block during back-arc rifting of the continental margin of Central Iran. Based on crosscutting relationships, mineralogy, and texture of sulfide mineralization, four different facies can be distinguished: stockwork (feeder zone), massive ore, bedded ore, and distal facies (exhalites with barite). Silicification, carbonatization, sericitization, and chloritization are the main wall-rock alteration styles; alteration intensity increases toward the proximal feeder zone. Fluid inclusion microthermometry was carried out on quartz associated with sulfides of the massive ore. Homogenization temperatures are in the range of 170-226 °C, and salinity is around 9 wt% NaCl eq. The size distribution of pyrite framboids of the bedded ore facies suggests anoxic to locally suboxic event for the host basin. δ34S(V-CDT) values of pyrite, sphalerite, and galena range from +10.9 to +29.8 ‰. The highest δ34S values correspond to the bedded ore (+28.6 to +29.8 ‰), and the lowest to the massive ore (+10.9 to +14.7 ‰) and the feeder zone (+11.3 and +12.1 ‰). The overall range of δ34S is consistent with a sedimentary environment where sulfide sulfur was derived from two sources. One of them was corresponding to early ore-stage sulfides in bedded ore and distal facies, consistent with bacterial reduction from coeval seawater sulfate in a closed or semiclosed basin. However, the δ34S values of late ore-stage sulfides, observed mainly in massive ore, interpreted as a hydrothermal sulfur component, leached

  13. Geologic Map of the Kings Mountain and Grover Quadrangles, Cleveland and Gaston Counties, North Carolina, and Cherokee and York Counties, South Carolina

    Science.gov (United States)

    Horton, J. Wright, Jr.

    2008-01-01

    sequence show a westward decrease from upper amphibolite facies (sillimanite zone) near the High Shoals Granite in the eastern side of the map area to upper greenschist (epidote-amphibolite) facies in the south-central part of the area near the Kings Mountain shear zone. Amphibolite-facies mineral assemblages in the Inner Piedmont terrane increase in grade from the kyanite zone near the Kings Mountain shear zone to the sillimanite zone in the northwestern part of the map area. Surficial deposits include alluvium in the stream valleys and colluvium along ridges and steep slopes. These quadrangles are unusual in the richness and variety of the mineral deposits that they contain, which include spodumene (lithium), cassiterite (tin), mica, feldspar, silica, clay, marble, kyanite and sillimanite, barite, manganese, sand and gravel, gold, pyrite, and iron.

  14. Mineralogical characterization of tailing dams: incidence of abandoned mining works on soil pollution (Linares, Jaén)

    Science.gov (United States)

    de la Torre, M. J.; Hidalgo, C.; Rey, J.; Martínez, J.

    2012-04-01

    The metallogenic district of Linares-La Carolina (Jaén, Spain) consists of dyke mineralizations mainly of galena, accompanied by blende, chalcopyrite and barite. Associated to these abandoned mines, relatively extensive areas occupied by spoil heaps and tailing impoundments exist and constitute potential sources of soil pollution by metals and semimetals. In order to analyze the pollution potential of these mining wastes, we have carried out a mineralogical and geochemical study of seven tailing dams and surrounding soils in the area. The mineralogy of the samples was studied by x-ray diffraction (XRD) and scanning electron microscope (SEM). In addition, the total metal content of samples was determined by inductively coupled plasma mass spectrometry (ICP-MS) analysis. Samples were taken from the first 30 cm of the waste piles and soil deposits and white efflorescences were also obtained from the surface of the tailings. In all analyzed heaps, high to very high total contents in Pb (1220-22890 mg/kg), Zn (150-51280 mg/kg), Mn (2658-4160 mg/kg), Ba (1026-19610 mg/kg) and Fe (19400-138000 mg/kg) were observed. The concentrations for these same elements in the studied soils range from 527-9900 mg/kg for Pb, 27-1700 mg/kg for Zn, 506-2464 mg/kg for Mn, 2832-4306 for Ba and 8642-29753 mg/kg for Fe, and these figures indicate a contamination of the soils, according to the guidelines established by the Spanish law. The XRD and SEM results indicate that the tailings are primarily constituted by gangue of the exploited mineralization: quartz, calcite, ankerite, feldspars and phyllosilicates. They are inherited, primary mineral phases. Galena, also primary, appears in low proportion, as well as lepidocrocite, melanterite and cerussite, being these three last secondary minerals and indicating a certain remobilization of metal cations, especially lead and iron. On the other hand, quartz and phyllosilicates predominate in the soils, in which, in addition, is identified a

  15. 40 Ar/39 Ar Ages of Auriferous Quartz Veins from the Fengyang and Zhangbaling Regions and Their Geological Significance

    Institute of Scientific and Technical Information of China (English)

    应汉龙; 赵利清

    2003-01-01

    Geotectonically the Fengyang and Zhangbaling regions belong to the North China craton and the Dabie-Sulu orogene, respectively. Neo-Archean gneiss and amphibolite and metamor-phosed sea-facies sodic volcanic rocks are the main outcrops in the two regions, respectively. The Zhangbaling terrane strike-skipped along the Tancheng-Lujiang fault zone in Mesozoic and Cenozo-ic eras and got close to the Fengyang terrane. Mesozoic Yanshanian intrusions occur broadly in the two regions. Gold-bearing quartz veins occur in the metamorphic rocks in the Fengyang region and in the granodiorite and metamorphosed sea-facies sodic volcanic rocks in the Zhangbaling region.Generally, the formation of the auriferous quartz veins involved three stages. At the first stage, gold-poor sulfide quartz veins were formed; at the second stage gold-rich quartz sulfide veins were formed; and at the third stage gold-poor barite and/or carbonate veins were formed. The 40Ar/39Ar step-heating plateau ages of the first-stage and the second-stage quartz aggregates from the Zhuding, Maoshan and Shangcheng gold deposits range between 116.1 + 0.6 Ma and 118.3 + 0.5 Ma and are pretty close to their least apparent ages and isochronal ages, respectively. All plat-eau, least apparent and isochronal ages range between 113.4 ± 0.4 Ma and 118.3 ± 0.5 Ma,which are considered as the formation age range of the quartz. It is reasonable and reliable to take the 40Ar/39Ar age range of the quartz as the formation age range of gold-bearing quartz veins on the basis of spatial relationship between gold-bearing quartz veins and their country rocks. The gold deposits in the two regions were formed in Aptian, Cretaceous, when the Tancheng-Lujiang fault zone moved as a normal fault with slightly right-lateral strike-skip, was extensional and expe-rienced very strong magmatic process. It is shown that the magmatic hydrothermal fluid is a very important part of the gold ore-forming hydrothermal fluid in the Fengyang and

  16. Sulfur, carbon, and oxygen isotope variations in submarine hydrothermal deposits of Guaymas Basin, Gulf of California, USA

    Science.gov (United States)

    Peter, J.M.; Shanks, Wayne C., III

    1992-01-01

    Sulfur, carbon, and oxygen isotope values were measured in sulfide, sulfate, and carbonate from hydrothermal chimney, spire, and mound samples in the southern trough of Guaymas Basin, Gulf of California, USA. ??34S values of sulfides range from -3.7 to 4.5%. and indicate that sulfur originated from several sources: 1. (1) dissolution of 0??? sulfide contained within basaltic rocks, 2. (2) thermal reduction of seawater sulfate during sediment alteration reactions in feeder zones to give sulfide with positive ??34S, and 3. (3) entrainment or leaching of isotopically light (negative-??34S) bacteriogenic sulfide from sediments underlying the deposits. ??34S of barite and anhydrite indicate sulfur derivation mainly from unfractionated seawater sulfate, although some samples show evidence of sulfate reduction and sulfide oxidation reactions during mixing within chimneys. Oxygen isotope temperatures calculated for chimney calcites are in reasonable agreement with measured vent fluid temperatures and fluid inclusion trapping temperatures. Hydrothermal fluids that formed calcite-rich chimneys in the southern trough of Guaymas Basin were enriched in 18O with respect to seawater by about 2.4??? due to isotopic exchange with sedimentary and/or basaltic rocks. Carbon isotope values of calcite range from -9.6 to -14.0??? ??34CpDB, indicating that carbon was derived in approximately equal quantities from the dissolution of marine carbonate minerals and the oxidation of organic matter during migration of hydrothermal fluid through the underlying sediment column. Statistically significant positive, linear correlations of ??34S, ??34C, and ??18O of sulfides and calcites with geographic location within the southern trough of Guaymas Basin are best explained by variations in water/rock ( w r) ratios or sediment reactivity within subsurface alteration zones. Low w r ratios and the leaching of detrital carbonates and bacteriogenic sulfides at the southern vent sites result in relatively

  17. The Modern Marine Ca-isotope Budget and its Application to the Phanerozoic Ca-isotope Record

    Science.gov (United States)

    Blattler, C. L.; Jenkyns, H. C.; Henderson, G. M.

    2011-12-01

    Variations in the calcium-isotope ratio (δ44/40Ca) of ancient seawater have been recorded in several studies using marine carbonate, barite, or apatite, but the causes of these variations have not been explored quantitatively. Seawater Ca-isotope ratios are affected by the average fractionation factor between seawater and the carbonate that precipitates from it, which is defined by the composition of the marine carbonate sink. To investigate possible changes in the fractionation factor of marine carbonate over the Phanerozoic, a Ca-isotope budget has been constructed for the modern oceans. Over 250 Ca-isotope measurements have been compiled from a wide variety of carbonate sources to describe the modern marine Ca-isotope budget. This dataset includes over 50 new measurements to characterize several components of the carbonate system, such as coral reefs, which are quantitatively important but have been undersampled, for example, relative to planktic foraminifera. δ44/40Ca values have been temperature-normalized using the relationship of +0.02% per °C, which permits observations and comparisons based on mineralogy, taxonomy, and locus of carbonate precipitation. A general offset of ~0.25%, increasing up to ~0.8% for certain taxa, is observed between subsets of aragonite and calcite samples; no statistical difference is observed between high-Mg calcite and low-Mg calcite. Additionally, within the data for calcite skeletons, two broad groups appear based on taxonomic patterns. Taxa with generally weak control over their biomineralization, such as sclerosponges, brachiopods, and calcareous red algae, are 0.4-0.5% heavier than organisms with more controlled calcification mechanisms, such as coccolithophores and planktic foraminifera. The patterns that emerge from this dataset for different clades demonstrate the usefulness of fossil carbonate for reconstructing the Ca-isotope ratio of ancient seawater. The composition of the modern Ca-isotope budget provides a basis

  18. 污泥防辐射功能集料的制备及性能%Preparation and Properties of Radiation Shielding Functional Aggregate Based on Sludge

    Institute of Scientific and Technical Information of China (English)

    丁庆军; 杨堃; 黄修林; 孙华; 胡曙光

    2011-01-01

    基于重金属元素对高能射线具有优良屏蔽性能的特点,以含10%(质量分数,下同)钡元素的某化工厂污泥为原材料,辅以高岭土、分析纯化学物质为校正材料,通过对生料的配合比优化设计,在一定的煅烧制度下制备出了重金属离子溶出率小、射线屏蔽性能较好的功能集料.试验结果表明:该集料的表观密度达2.95×103 kg/m3,吸水率达1.57%,抗压强度达82 MPa,Ba离子浸出率低至1 mg/L,线性衰减系数达0.243 9 cm-1,可作为集料替代天然重晶石集料制备防辐射混凝土.%Considering that heavy metal elements possess the characteristic of high-energy radiation shielding, chemical sludge containing 10%(by mass) barium was used as raw material. Meanwhile, kaolin and analytically pure chemicals were supplemented as correction materials. Through optimization design of the mix proportion of raw material, the functional aggregate with low heavy metal release rate and excellent performance of radiation shielding was prepared in proper calcination system. The results show that, the functional aggregate bulk density reaches 2. 95×103 kg/m3, water absorption is as low as 1. 57%, com pressive strength is as high as 82 Mpa, barium ion leaching rate is 1 mg/L, and the linear attenuation coef ficient is as low as 0. 243 9 cm-1. Therefore, the functional aggregate is expected to be able to replace bar-ite ore in the radiation shielding concrete.

  19. ALVIN-SeaBeam studies of the Sumisu Rift, Izu-Bonin arc

    Science.gov (United States)

    Taylor, B.; Brown, G.; Fryer, P.; Gill, J. B.; Hochstaedter, A. G.; Hotta, H.; Langmuir, C. H.; Leinen, M.; Nishimura, A.; Urabe, T.

    1990-10-01

    Bimodal volcanism, normal faulting, rapid sedimentation, and hydrothermal circulation characterize the rifting of the Izu-Bonin arc at 31°N. Analysis of the zigzag pattern, in plan view, of the normal faults that bound Sumisu Rift indicates that the extension direction (080° ± 10°) is orthogonal to the regional trend of the volcanic front. Normal faults divide the rift into an inner rift on the arc side, which is the locus for maximum subsidence and sedimentation, and an outer rift further west. Transfer zones that link opposing master faults and/or rift flank uplifts further subdivide the rift into three segments along strike. Volcanism is concentrated along the ENE-trending transfer zone which separates the northern and central rift segments. The differential motion across the zone is accommodated by interdigitating north-trending normal faults rather than by ENE-trending oblique-slip faults. Volcanism in the outer rift has built 50-700 m high edifices without summit craters whereas in the inner rift it has formed two multi-vent en echelon ridges (the largest is 600 m high and 16 km long). The volcanism is dominantly basaltic, with compositions reflecting mantle sources little influenced by arc components. An elongate rhyolite dome and low-temperature hydrothermal deposits occur at the en echelon step in the larger ridge, which is located at the intersection of the transfer zone with the inner rift. The chimneys, veins, and crusts are composed of silica, barite and iron oxide, and are of similar composition to the ferruginous chert that mantles the Kuroko deposits. A 1.2-km transect of seven ALVIN heat flow measurements at 30°48.5'N showed that the inner-rift-bounding faults may serve as water recharge zones, but that they are not necessarily areas of focussed hydrothermal outflow, which instead occurs through the thick basin sediments. The rift basin and arc margin sediments are probably dominated by permeable rhyolitic pumice and ash erupted from submarine

  20. The collision that changed the world

    Directory of Open Access Journals (Sweden)

    Wally Broecker

    2015-07-01

    Full Text Available Abstract In connection with the Anthropocene, one might ask how climate is likely to evolve in the absence of man’s intervention and whether humans will be able to purposefully alter this course. In this commentary, I deal with the situation for very long time scales. I make a case that fifty million years ago, the collision between the northward drifting Indian land mass and Asia set the Earth’s climate on a new course. Ever since then, it has cooled. In the absence of some other dramatic disruption in the movement of the plates which make up our planet’s crust, on the time scale of tens of millions of years, this drift would cause the Earth to freeze over as it did during the late Precambrian. Evidence for this change in course comes from records of oxygen and lithium isotopic composition of foraminifer shells. It is reinforced by records of Mg to Ca in halite-hosted fluid inclusions and in marine CaCO3. In addition, the collision appears to have created abrupt changes in the sulfur isotope composition of marine barite and the carbon isotope composition of amber. Not only did this collision create the Himalaya, but more important, it led to a reorganization of the crustal plate motions. Through some combination of the building of mountains and lowering of sea level, these changes generated a mismatch between the supply of CO2 by planetary outgassing and that of calcium by the weathering of silicate rock. The tendency toward an oversupply of calcium has been compensated by a drawdown of the atmosphere’s CO2 content. This drawdown cooled the Earth, slowing down the supply of calcium. Although we are currently inadvertently compensating for this cooling by burning fossil fuels, the impacts of this CO2 on Earth climate will last no more than a tenth of a million years. So, if humans succeed in avoiding extinction, there will likely be a long-term effort to warm the planet.

  1. Massive sulfides in a sedimented rift valley, northern Juan de Fuca Ridge

    Science.gov (United States)

    Davis, Earl E.; Goodfellow, Wayne D.; Bornhold, Brian D.; Adshead, John; Blaise, Bertrand; Villinger, Heiner; Le Cheminant, Gina M.

    1987-03-01

    A number of mounds each several hundred meters across and up to sixty meters high have been observed with SeaMARC II acoustic imagery and Seabeam bathymetry in the sediment-filled axial valley at the northern end of the Juan de Fuca Ridge. The mounds are located a few kilometers west of the eastern valley-bounding normal fault scarp where the local sediment fill is approximately 300 m thick. All of the mounds are believed to be of hydrothermal origin, and one is associated with anomalously high heat flow in excess of 1 W m -2. A piston core collected from that mound comprises coarse clastic sulfide units interbedded with sulfidic muds. Hydrothermal minerals present in the 2.3 m section include pyrrhotite, pyrite, marcasite, sphalerite, chalcopyrite, iss (intermediate solid solution in the Cu sbnd Fe sbnd Zn sbnd S system), chalcopyrrhotite, galena, talc, barite, and amorphous silica. Mineral fabrics of the clasts indicate that the material was precipitated at or near the sea floor by mixing of hot hydrothermal fluids with cold seawater. Low concentrations of Zn, Cu, Cd, and Ag relative to those found in unsedimented ridge hydrothermal deposits, and the presence of pyrrhotite as an early phase mineral indicates that the vent fluids have been modified by reaction with sediments beneath the mound. Rapid sedimentation in a rift valley is clearly conducive to the formation of large hydrothermal mineral deposits like those believed to be present within and beneath these mounds. The relatively impermeable sediment cover insulates the crust, inhibits groundwater recharge, promotes long-lived discharge at a restricted number of sites, provides a substrate for the efficient subsurface precipitation of minerals, and through continued sedimentation, protects surficial deposits from the corrosive effects of seawater. No reliable estimate of the bulk composition of the mounds can be made with existing data, but their size is comparable to major hydrothermal mineral deposits

  2. 1D Thermal-Hydraulic-Chemical (THC) Reactive transport modeling for deep geothermal systems: A case study of Groß Schönebeck reservoir, Germany

    Science.gov (United States)

    Driba, D. L.; De Lucia, M.; Peiffer, S.

    2014-12-01

    Fluid-rock interactions in geothermal reservoirs are driven by the state of disequilibrium that persists among solid and solutes due to changing temperature and pressure. During operation of enhanced geothermal systems, injection of cooled water back into the reservoir disturbs the initial thermodynamic equilibrium between the reservoir and its geothermal fluid, which may induce modifications in permeability through changes in porosity and pore space geometry, consequently bringing about several impairments to the overall system.Modeling of fluid-rock interactions induced by injection of cold brine into Groß Schönebeck geothermal reservoir system situated in the Rotliegend sandstone at 4200m depth have been done by coupling geochemical modeling Code Phreeqc with OpenGeoSys. Through batch modeling the re-evaluation of the measured hydrochemical composition of the brine has been done using Quintessa databases, the results from the calculation indicate that a mineral phases comprising of K-feldspar, hematite, Barite, Calcite and Dolomite was found to match the hypothesis of equilibrium with the formation fluid, Reducing conditions are presumed in the model (pe = -3.5) in order to match the amount of observed dissolved Fe and thus considered as initial state for the reactive transport modeling. based on a measured composition of formation fluids and the predominant mineralogical assemblage of the host rock, a preliminary 1D Reactive transport modeling (RTM) was run with total time set to 30 years; results obtained for the initial simulation revealed that during this period, no significant change is evident for K-feldspar. Furthermore, the precipitation of calcite along the flow path in the brine results in a drop of pH from 6.2 to a value of 5.2 noticed over the simulated period. The circulation of cooled fluid in the reservoir is predicted to affect the temperature of the reservoir within the first 100 -150m from the injection well. Examination of porosity change in

  3. La porosidad en las areniscas triásicas (Rama Aragonesa de la Cordillera Ibérica

    Directory of Open Access Journals (Sweden)

    Arribas, J.

    1984-12-01

    Full Text Available Triassic sandstone's porosity (Buntsandstein and Muschelkalk facies from the Aragonesa Branch of the Iberian Range are studied, firstly at the sediment primary porosity calculation and secondly the porosity-reducing processes are analyzed. Processes creating secondary sandstone porosity can be established (dissolution and fracturing by the textural and genetic caracterization of the sandstone's voids. The dissolution of potassium feldspar, carbonate cement and barite cement, is related with meteoric pore-water flow alloys to intramesozoic unconformities, Fracturing porosity is related to Iberian Range tertiary structuration. Finally, we concluded that the amount of the sandstone's secondary porosity depends mainly on the original composition of the sediments and also on the geochemical sedimentary environments that control the first diagenetic stages (eodiagenesis, This fact manifests itself in the amount and types of variating porosities along the stratigraphic section.

    Se estudia la porosidad en las areniscas triásicas (facies Buntsandstein y Muschelkalk de la Rama Aragonesa de la Cordillera Ibérica, partiendo del cálculo estimativo de la porosidad primaria del sedimento, para posteriormente analizar los distintos procesos diagenéticos que han intervenido en su destrucción (compactación mecánica, compactación química y cementación. La caracterización textural y genética de los poros en dichas areniscas permite establecer la existencia de procesos generadores de porosidad secundaria (disolución y fractura. La disolución del feldespato potásico, cemento carbonático y de baritina se relaciona con flujos de aguas meteóricas ligadas a discordancias intramesozoicas, mientras que la porosidad de fractura se asocia a la estructuración terciaria de la Cordillera Ibérica. Por ú1timo se concluye que la cantidad de porosidad secundaria en las areniscas estudiadas depende fundamentalmente de la composición original de los dep

  4. Development of a ceramic material to cover walls to be applied in diagnostic radiological protection

    International Nuclear Information System (INIS)

    This study aims to formulate a ceramic composition for wall coating seeking to contribute to the optimization of diagnosis rooms' shielding. The work was based on experimental measures of X-radiation attenuation (80 and 100 kV) using ceramic coating materials containing different ceramic bases (red, white, gres, stoneware porcelain tiles, etc). Among the appraised ceramic bases, the white gres presented better attenuation properties and it was considered the most suitable material for the targets of this work. Different formulations of white gres were studied and altered in order to obtain better attenuation properties. Simulations of ceramic compositions using gres coating were made maintaining the percentages of 12-20% clay; 6-18% kaolin; 12-25% phyllite; 8-14% quartz; 1018% feldspar; 32-40% pegmatite and 6-8% talc in the composition of the necessary raw-material. The quantitative and qualitative chemical compositions of these materials were also evaluated and the most common representative elements are SiO2, Fe2O3, Al2O3, CaO and Ti2O3. Formulations containing Pb and Ba oxides were studied, considering that CaO can be replaced by PbO or BaO. The attenuation properties for X-radiation were investigated by computer simulations considering the incident and transmitted X-ray spectra for the different studied compositions and they were compared to the properties of the reference materials Pb, Ba and BaSO4 (barite). The results obtained with the simulations indicated the formulated composition of gres ceramic base that presented better attenuation properties considering the X-ray energies used in diagnosis (80, 100 and 150 kV). Ceramic plates based on the formulated compositions that presented lower percentage differences related to Pb were experimentally produced and physically tested as wall coating and protecting barrier. Properties as flexion resistance module, density, load rupture, water absorption and X radiation attenuation were evaluated for all produced

  5. Early Archaean collapse basins, a habitat for early bacterial life.

    Science.gov (United States)

    Nijman, W.

    case of the North Pole Chert huge barite growths, are juxtaposed with the otherwise generally low-energy sediments. Such localities are interpreted as sites of hydrothermal vents. Within this large-scale geological context, many environments on the micro-scale were habitable for life, such as hydrothermal vents and their vicinities, volcanic rock surfaces, subsurface sediments and sediment surfaces. These early collapse basins, hosting this bacterial life, are only partially comparable to Earthly analogues. A resemblance with Venus' coronae and the chaos terranes on Mars is suggested. This study forms part of an international project on Earth's Earliest Sedimentary Basins, supported by the Dutch Foundation Dr. Schürmannfonds. 2

  6. CHEMICAL AND GEOCHEMICAL CHARACTERISTICS OF THE ČEMERNICA ANTIMONITE DEPOSIT IN THE MID-BOSNIAN SCHIST MOUNTAINS

    Directory of Open Access Journals (Sweden)

    Ivan Jurković

    1999-12-01

    Full Text Available The Čemernica Sb-Zn-Hg-W quartz vein system is situated in Lower Palaeozoic metasediments formed under 3-5 kbars and 350° to 450 °C, intruded by Upper Palaeozoic rhyolites. K-Ar dating indicated three metamorphic phases. The first, 343 Ma old affected phyllite rocks, the second 120-90 Ma metamorphosed rhyolites and the third one, 46 to 37 Ma caused formation of ottrelite schist, host rocks of ore deposit. The Čemernica vein (NW-SE, 1,5 km long, and over 350 m deep, on average 0,67 m thick, is faulted in four separated parts: »Southern vein«: »Erbstollcn vein«; »Main vein* and »NW-vein«. Structures of the veins are massive, banded, rarely brecciated. Par-agenesis: quartz I (50-95% of ore mass as the main gangue mineral; antimonite I, II, sphalerite I, II. cinnabar as the main ore minerals; subordinate are chalcedony, siderite, ferberite, jamesonite.berthierite, boulangerile, plagionite, arsenopyrite, scarce arc pyrite I, II, marcasite, pyrrhotite, barite, chalcopyrite I, II, tetrahedrite and enargite, whereas accessories are galena, quartz II, realgar, gold and mineral »X«. Chemical analysis of 177 ore samples taken from old Saxon and Austrian mining works gave 4.33% Zn, 2,22% Sb and 137 gr/t Ag. Fifteen samples gave trace to 0.1% Hg and eight samples trace to 0.l gr/t Au. Untouched part ol the »Main vein« gave5.9(1% Zn, 8.93%Sb and 126 g/t Ag. Remnant ore gave 2.60-3.28% Zn, 0.69-0.73% Sb and 161 to 190 gr/t Ag. Entire proved, probable and posssible ore reserves (306.000 t have 5.9% Zn, 4.0% Sb and 114 gr/t Ag. The 34 S of antimonite is +2.6 ‰ and of sphalerite +3.7‰ indi¬cating juvenile origin of sulphur, Fluid inclusion study of quartz iden-tified three types of fluids: Variscan NaCI-KCI-H2O type related to the Late Palaeozoic granite (rhyolite megmatism, post-Variscan NaCl-CaCl2 + MgCl2-H2O type formed by admixing of hot saline connate waters originated from the Late Permian evaporite complex and meta

  7. Proximal and distal styles of pegmatite-related metasomatic emerald mineralization at Ianapera, southern Madagascar

    Science.gov (United States)

    Andrianjakavah, Prosper Rakotovao; Salvi, Stefano; Béziat, Didier; Rakotondrazafy, Michel; Giuliani, Gaston

    2009-10-01

    The Ianapera emerald deposit is located in the Neoproterozoic Vohibory Block of southern Madagascar. The local geology consists of intercalated migmatitic gneissic units and calcareous metasedimentary rocks, containing boudinaged metamorphosed mafic/ultramafic lenses, all intruded by pegmatite veins. These units occur near the hinge of the tightly folded Ianapera antiform, within a few kilometers of the Ampanihy shear zone. Emerald mineralization is hosted by metasomatic phlogopite veins, and bodies developed within the mafic/ultramafic rocks. Based on field and textural relationships, we distinguish proximal and distal styles of mineralization. Proximal mineralization occurs at the contact of pegmatite veins with mafic/ultramafic units; in the distal style, pegmatites are not observed. Three types of emeralds could be distinguished, mainly on the basis of color and mineral zoning. Some of these emeralds have the most Al-depleted and Cr-rich composition ever recorded. Another characteristic feature to the Ianapera deposit and, to our knowledge, yet unreported, is the association of some emeralds with scapolite in metasomatised mafic rocks. Mineral inclusions are common in most emeralds and include phlogopite, carbonates, barite, K-feldspar, quartz, pyrite, zircon, monazite, bastnaesite, phenakite, plus Fe and Cr oxides. However, feldspar and rare earth element-bearing minerals occur predominantly in proximal emeralds, which also have a more incompatible trace-element signature than distal emeralds. We propose a model related to syn- to post-tectonic magmatic-hydrothermal activity. Pegmatitic bodies intruded units of the Ianapera antiform probably during tectonic relaxation. Exsolution of fluids rich in halogens and incompatible elements from the cooling pegmatites caused hydrothermal metasomatism of Cr-bearing mafic/ultramafic rocks in direct contact with the pegmatites. Local fracturing favored fluid infiltration, permitting the formation of distal mineralization

  8. Géométrie et dynamique sur les surfaces algébriques réelles [Geometry and dynamics on real algebraic surfaces

    Science.gov (United States)

    McLin, Kristie S.

    The study of fluid-rock interactions provides insight into subsurface geologic processes, such as diagenesis, hydrothermal alteration and metamorphism. Understanding and predicting these interactions also helps us assess the geologic impact of hydrocarbon recovery and geothermal production and injection. Therefore, the study of fluid-rock interactions has both geologic and economic impact. At the Dixie Valley geothermal field, NV, precipitated calcite and aragonite within a production well trapped boiling fluids in fluid inclusions. The trapped gases were analyzed and shown to be compositionally different than those sampled at the well head. The inclusions trapped a greater ratio of light gases CH 4 and H2 to CO2 than those sampled at the well head. This result indicates that the fluid inclusions trapped the initial steam fraction during boiling. Declining performance of injection wells at the Coso and Salton Sea geothermal fields, CA, were found to result from mineral deposition in the near-wellbore environment during fluid injection. At Coso, opal-A and minor calcite scale mineral precipitates were found in cuttings from wells drilled near previously operating injection wells. At the Salton Sea, cuttings from a deepened injection well contained banded barite, fluorite, amorphous silica, and minor anhydrite scales. Mineral precipitation was modeled and predicted with the non-isothermal reactive transport modeling code TOUGHREACT. Geochemical simulations were also performed to predict the consequences of injecting H2SO 4 modified fluid for mitigating silica precipitation at Coso using TOUGHREACT. The models predict that silica precipitation will be reduced significantly by maintaining pH of 5 or less. This can be accommodated in the models by reducing the kinetic rate constant for silica precipitation. TOUGHREACT simulations also predict that corundum proppants will be chemically stable under geothermal conditions. The formation of talc in the outer aureole of the

  9. Radionuclide solubility control by solid solutions

    International Nuclear Information System (INIS)

    The migration of radionuclides in the geosphere is to a large extend controlled by sorption processes onto minerals and colloids. On a molecular level, sorption phenomena involve surface complexation, ion exchange as well as solid solution formation. The formation of solid solutions leads to the structural incorporation of radionuclides in a host structure. Such solid solutions are ubiquitous in natural systems - most minerals in nature are atomistic mixtures of elements rather than pure compounds because their formation leads to a thermodynamically more stable situation compared to the formation of pure compounds. However, due to a lack of reliable data for the expected scenario at close-to equilibrium conditions, solid solution systems have so far not been considered in long-term safety assessments for nuclear waste repositories. In recent years, various solid-solution aqueous solution systems have been studied. Here we present state-of-the art results regarding the formation of (Ra,Ba)SO4 solid solutions. In some scenarios describing a waste repository system for spent nuclear fuel in crystalline rocks 226Ra dominates the radiological impact to the environment associated with the potential release of radionuclides from the repository in the future. The solubility of Ra in equilibrium with (Ra,Ba)SO4 is much lower than the one calculated with RaSO4 as solubility limiting phase. Especially, the available literature data for the interaction parameter WBaRa, which describes the non-ideality of the solid solution, vary by about one order of magnitude (Zhu, 2004; Curti et al., 2010). The final 226Ra concentration in this system is extremely sensitive to the amount of barite, the difference in the solubility products of the end-member phases, and the degree of non-ideality of the solid solution phase. Here, we have enhanced the fundamental understanding regarding (1) the thermodynamics of (Ra,Ba)SO4 solid solutions and (2) the kinetics of Ra uptake. A novel approach

  10. Development of a ceramic material to cover walls to be applied in diagnostic radiological protection; Desenvolvimento de um material ceramico para utilizacao em protecao radiologica diagnostica

    Energy Technology Data Exchange (ETDEWEB)

    Frimaio, Audrew

    2006-07-01

    This study aims to formulate a ceramic composition for wall coating seeking to contribute to the optimization of diagnosis rooms' shielding. The work was based on experimental measures of X-radiation attenuation (80 and 100 kV) using ceramic coating materials containing different ceramic bases (red, white, gres, stoneware porcelain tiles, etc). Among the appraised ceramic bases, the white gres presented better attenuation properties and it was considered the most suitable material for the targets of this work. Different formulations of white gres were studied and altered in order to obtain better attenuation properties. Simulations of ceramic compositions using gres coating were made maintaining the percentages of 12-20% clay; 6-18% kaolin; 12-25% phyllite; 8-14% quartz; 1018% feldspar; 32-40% pegmatite and 6-8% talc in the composition of the necessary raw-material. The quantitative and qualitative chemical compositions of these materials were also evaluated and the most common representative elements are SiO{sub 2}, Fe{sub 2}O{sub 3}, Al{sub 2}O{sub 3}, CaO and Ti{sub 2}O{sub 3}. Formulations containing Pb and Ba oxides were studied, considering that CaO can be replaced by PbO or BaO. The attenuation properties for X-radiation were investigated by computer simulations considering the incident and transmitted X-ray spectra for the different studied compositions and they were compared to the properties of the reference materials Pb, Ba and BaSO{sub 4} (barite). The results obtained with the simulations indicated the formulated composition of gres ceramic base that presented better attenuation properties considering the X-ray energies used in diagnosis (80, 100 and 150 kV). Ceramic plates based on the formulated compositions that presented lower percentage differences related to Pb were experimentally produced and physically tested as wall coating and protecting barrier. Properties as flexion resistance module, density, load rupture, water absorption and X

  11. 华阳川铀多金属矿床碳酸岩脉矿化特征%Mineralization Characteristic of Carbonatite Veins in Huayangchuan U-polymetal Deposit,Shanxi Province

    Institute of Scientific and Technical Information of China (English)

    惠小朝; 何升

    2016-01-01

    Huayangchuan U-polymetal deposit is quite unique in Xiaoqinling metallogenetic belt,the frac-trure in the carbonatite vein is an important storing space for the deposit. Carbonatite extensively distrib-ute in deposit and intruded into metamorphic rock,pegmatite as vein and stockwork vein along NW-tren-ding tensional fracture,tensional-shear fracture and the subsidiary crack. The gangue mineral in mineral-ized vein carbonatite is mainly calcite and some hornblende,quartz,magnetite,K-feldspar and the ore minerals include betafite,monazite,allanite,barite and celestine. Betafite is the main uranium mineral, the average contents of U,Nb,Ba,Sr,REE are respectively 2554.20×10 6 ,1836.80×10 6 ,4145.78 ×10 6 ,4412.80×10 6 ,7348.44×10 6 which can be comprehensive utilized.%华阳川铀多金属矿床是小秦岭成矿带中成矿特征最为独特的矿床,其碳酸岩脉破碎带是重要的成矿空间.区内碳酸岩分布很广泛,沿 NW 向张性和张扭性断裂及其伴生的次级裂隙充填,呈单脉状和网脉状穿插于变质岩、伟晶岩中.矿化碳酸岩脉中,脉石矿物大部分为方解石,少量为角闪石、石英、磁铁矿、碱性长石等;矿石矿物为铌钛铀矿、独居石、褐帘石、重晶石、天青石.铌钛铀矿是最主要的赋铀矿物,矿化元素铀、铌、钡、锶、稀土等平均含量分别为2554.20×106、1836.80×106、4145.78×106、4412.80×106、7348.44×106,可以综合开发利用.

  12. Evaluation of the particle size of aggregates used in high density micro-concretes on the gamma-ray linear attenuation coefficient

    International Nuclear Information System (INIS)

    three concrete families were analyzed: Family 1 - magnetite sand micro concretes; Family 2 - barite sand micro concretes; Family 3 - silica sand micro concretes. The samples were analyzed by applying a narrow beam with two millimeters (2 mm) of collimation, on a automated acquisition table that allowed millimeter steps whose variation was of five millimeters (5 mm) horizontally and ten millimeters (10 mm) vertically, which allows to sweep the entire useful area of the samples. (author)

  13. Ultrasound Propagation in Colloidal Dispersions.

    Science.gov (United States)

    Sherman, Nigel E.

    Available from UMI in association with The British Library. This thesis describes apparatus and techniques for making ultrasonic measurements in fluids and applications of them to measurements of ultrasonic parameters in colloidal dispersions. A brief description of the properties and uses of ultrasound propagation in dispersions is followed by an extensive review of theories which relate the particulate properties of the dispersions to the measurable ultrasonic parameters, velocity (c) and attenuation (alpha ). Measurement principles are outlined related to the design of near-field measurement methods and the development of three techniques is described. These are shown to give results which are both highly self-consistent and in excellent agreement with a far-field method. Measurements of alpha and c for model dispersions of glass spheres in Newtonian liquids are shown to be in good agreement with the relevant theory when particle polydispersity is taken into account. For structured fluids as the continuous phase, the alpha and c data for suspensions of spheres are used to obtain the continuous phase viscosity ( eta). The alpha data agree approximately with the macroscopic viscosity, but the velocity data requires the introduction of a shear elastic term and the revision of theory in order to obtain agreement. Attenuation as a function of barite concentration in Newtonian liquids was investigated and the ultrasonic particle radius was found to be systematically larger than expected. This is attributed to particle rugosity. Measurements of alpha and c using non-gelling aqueous kaolinite suspensions are shown to agree well with theory when the eccentricity and the interactions of particles are taken into account. For gelling aqueous bentonite suspensions, alpha and c were found to be time-dependent over a period of several days following initial dispersion. The observed increases in both alpha and c are interpreted in terms of a growth in gel fraction and shear

  14. Origin of the Mariano Lake uranium deposit, McKinley County, New Mexico

    Science.gov (United States)

    Fishman, Neil S.; Reynolds, Richard L.

    1982-01-01

    The Mariano Lake uranium deposit, hosted by the Brushy Basin Member of the Jurassic Morrison Formation, occurs in the trough of an east-west trending syncline at the western end of the Smith Lake-Mariano Lake group of uranium deposits near Crownpoint, New Mexico. The orebody, which contains abundant amorphous organic material, is situated on the reduced side of a regional reduction-oxidation (redox) interface. The presence of amorphous organic material suggests the orebody may represent a tabular (primary) deposit, whereas the close proximity of the orebody to the redox interface is suggestive that uranium was secondarily redistributed by oxidative processes from pre-existing tabular orebodies. Uranium contents correlate positively with both organic carbon and vanadium contents. Petrographic evidence and scanning electron microscope-energy dispersive analyses point to uranium residence in the epigentically introduced amorphous organic material, which coats detrital grains and fills voids. Uranium mineralization was preceded by the following diagenetic alterations: precipitation of pyrite (d34S values ranging from-11.0 to-38.2 per mil); precipitation of mixed-layer smectite-illite clays; partial dissolution of some of the detrital feldspar population; and precipitation of quartz and adularia overgrowths. Alterations associated with uranium mineralization include emplacement of amorphous organic material (possibly uranium bearing); destruction of detrital iron-titanium oxide grains; coprecipitation of chlorite and microcrystalline quartz, and precipitation of pyrite and marcasite (d34S values for these sulfides ranging from -29.4 to -41.6 per mil). After mineralization, calcite, dolomite, barite, and kaolinite precipitated, and authigenic iron disulfides were replaced by ferric oxides and hydroxides. Geochemical data (primarily the positive correlation of uranium content to both organic carbon and vanadium contents) and petrographic observations (epigentically

  15. Health and environmental concerns on the radioactivity of phosphogypsum storage in Israel

    International Nuclear Information System (INIS)

    the Kishon River. The chemistry of the fluids in the stacks prevents potential releases and mobilization of the radio-nuclides before they can affect the groundwater. For example, there may be nuclide incorporation within in situ formed barite minerals, or the acid soluble nuclides may be immobilized as they encounter the clays and (basic pH) carbonate material underlying the stacks. Document available in abstract form only. (authors)

  16. Distribution of uranium and thorium in dolomitic gravel fill and shale saprolite

    International Nuclear Information System (INIS)

    Highlights: • Dolomite gravel can remove U from acidic groundwater with high Al3+ and SO42−. • U containing amorphous basaluminite precipitates as the pH increases. • Dolomite gravel maybe a possible treatment medium for U acidic groundwater. • Dolomite gravel has been removing U from ground over a 20 year period. • Thorium is also high in the dolomitic gravel and has an inverse relationship with U. - Abstract: The objectives of this study were to examine (1) the distribution of U and Th in dolomitic gravel fill and shale saprolite, and (2) the removal of uranium from acidic groundwater by dolomitic gravel through precipitation with amorphous basaluminite at the U.S. DOE Oak Ridge Integrated Field Research Challenge (ORIFRC) field site west of the Oak Ridge Y-12 National Security Complex in East Tennessee. Media reactivity and sustainability are a technical concern with the deployment of any subsurface reactive media. Because the gravel was placed in the subsurface and exposed to contaminated groundwater for over 20 years, it provided a unique opportunity to study the solid and water phase geochemical conditions within the media after this length of exposure. This study illustrates that dolomite gravel can remove U from acidic contaminated groundwater with high levels of Al3+, Ca2+, NO3−, and SO42− over the long term. As the groundwater flows through high pH carbonate gravel, U containing amorphous basaluminite precipitates as the pH increases. This is due to an increase in groundwater pH from 3.2 to ∼6.5 as it comes in contact with the gravel. Therefore, carbonate gravel could be considered as a possible treatment medium for removal and sequestration of U and other pH sensitive metals from acidic contaminated groundwater. Thorium concentrations are also high in the carbonate gravel. Thorium generally shows an inverse relationship with U from the surface down into the deeper saprolite. Barite precipitated in the shallow saprolite directly below

  17. The Gifford Creek Ferrocarbonatite Complex, Gascoyne Province, Western Australia: Associated fenitic alteration and a putative link with the ~ 1075 Ma Warakurna LIP

    Science.gov (United States)

    Pirajno, Franco; González-Álvarez, Ignacio; Chen, Wei; Kyser, Kurt T.; Simonetti, Antonio; Leduc, Evelyne; leGras, Monica

    2014-08-01

    The Gifford Creek Ferrocarbonatite Complex (GFC), located in the Neoarchean-Palaeoproterozoic Gascoyne Province, Western Australia, comprises sills, dykes, and veins of ferrocarbonatite intruding the Pimbyana Granite and Yangibana Granite of the Durlacher Supersuite and metasedimentary rocks of the Pooranoo Metamorphics. The ferrocarbonatites are associated with complex and irregularly distributed zones of fenitic alteration. These ferrocarbonatites and fenites are also associated with a swarm of ironstone veins, containing magnetite, hematite and goethite. The GFC and associated fenite outcrops are distributed within a ~ 700 km2 area, north of the Lyons River Fault. Ferrocarbonatite sills and dykes are predominant in a northwest-trending belt, along the southern margin of the complex; whereas ferrocarbonatite veins tend to be distributed in a series of sub-parallel west-northwest-trending linear belts, generally associated with the Fe oxide veins with sinuous trends. These veins have margins of Fe-rich carbonates associated with zones of alteration that have a fenitic character. The fenitic haloes are characterised by the presence of Na-K-feldspars and/or Na-amphiboles and magnetite. In some cases monomineralic feldspar zones (orthoclasite) are present. Fenitic alteration is spatially associated with the carbonatites, but it can also form discrete veins and veinlets in basement granitic rocks (Pimbyana and Yangibana Granites). Petrographic, XRD and SEM analyses show that the ferrocarbonatites are dominantly composed of ankerite-dolomite, magnetite, arfvedsonite-riebeckite, and lesser calcite. Alkali amphibole has compositions ranging from potassian magnesio-arfvedsonite to magnesio-riebeckite. Sills and dykes north of the Lyons River, are characterised by a carbonate-rich matrix, containing > 50 vol.% ankerite-dolomite, with accessory quantities of apatite, barite, monazite, and phlogopite. In-situ U-Pb age determination of apatite grains by LA-ICP-MS on a sample

  18. Very heavy iron-punching concretes; Betons tres lourds a base de riblons

    Energy Technology Data Exchange (ETDEWEB)

    Dubois, F. [Commissariat a l' Energie Atomique, Saclay(France). Centre d' Etudes Nucleaires

    1966-07-01

    The present report deals with all the heavy iron-punching concretes, metallic wastes produced by the transformation industry. After a detailed description of the physical properties of metallic aggregates, a classification of heavy mortars is given, into three main categories: steel-shot grouts d = 5,3 - 6; steel-shot grouts mixed with a mineral d = 3,7 - 4,2; injection heavy grouts d = 3,5 - 4. The following chapter describes iron-punching concretes the most used in the atomic industry: iron-punching concretes mixed with cast-iron - iron-punching concretes mixed with magnetite; iron-punching concretes mixed with barite; iron-punching concretes mixed with limonite; iron-punching concretes mixed with boron. The compositions of these concretes are given together with their physical and mechanical characteristics. Numerous diagrams make it possible to find rapidly the proportions of the constituents of these concretes as a function of the required density. Technical advice and specifications are given in an appendix together with a bibliography of these heavy concretes. (author) [French] Le present rapport traite de l'ensemble des betons lourds realises a l'aide de riblons, dechets metalliques fournis par l'industrie de transformation. Apres une description detaillee des proprietes physiques des agregats metalliques, les mortiers lourds sont d'abord presentes en les classant en trois grandes categories: les mortiers a base de grenailles d 5,3 a 6; les mortiers a base de grenailles avec addition d'un mineral d 3,7 a 4,2; les mortiers lourds injectables d = 3,5 a 4. Le chapitre suivant decrit les betons a base de riblons les plus utilises, dans l'industrie atomique: les betons de riblons avec addition de fonte; les betons de riblons avec addition de magnetite; les betons de riblons avec addition de barytine; les betons de riblons avec addition de limonite; les betons de riblons avec addition de bore. Les compositions de ces betons ainsi que

  19. Study on Drill Pipe with Mud Membrane Corrosion Mechanics Under Atmospheric Environment%泥浆膜在大气环境下对钻杆的腐蚀机理研究

    Institute of Scientific and Technical Information of China (English)

    刘婉颖; 施太和; 曾德智; 朱泽华; 贾华明; 卢强; 刘鹏

    2011-01-01

    High temperatures and pressures autoclave were used to simulate the field environment of Tarim oil deposit. And corrosion behavior and mechanism of S135 drill pipe in lignosulfonate mud were studied. Topographic features of mud cake adhereing to the drill pipe and the corrosion product of drill pipe were analyzed by XRD and SEM. The results showed that S135 drill pipe emerged local oxidation corrosion. Features were ulcer-like corrosion and local contiguous corrosion and pit corrosion. Main corrosion products were orthorhombic crystal system's allcharite. The main reason of drill pipe corrosion was unscraped mud while hoisting. Moisture from mud membrane volatilized on the air and formed mud cake shell. Then iron hematite, barite, bentonite powder,and calcium powder were left as the framework for solid phase substrates. That was called scale buildup. It contacted drill pipe's surface and three interrelated local corrosions,which were differential oxygen concentration, bimetallic corrosion and crevice corrosion, were produced.%采用高温高压釜模拟研究塔里木油田现场环境所用聚磺体系钻井液对S135钻杆的腐蚀行为及腐蚀机理.通过对表面黏附有泥饼的挂片进行XRD和SEM观察,分析钻杆表面黏附的泥饼形貌特征及腐蚀行为.结果表明:S135钻杆发生了局部氧腐蚀,特征为溃疡状腐蚀、局部连片腐蚀和深坑蚀.腐蚀产物主要是正交(斜方)晶系的针铁矿.钻杆腐蚀的主要原因是起钻时未刮泥浆,黏附在钻杆外壁的泥浆膜在空气中因水分挥发而形成泥饼壳后,留下铁矿粉、重晶石、土粉、碳酸钙粉等作为骨架的固相物,该固相物称为垢层.垢层与钻杆表面接触,产生三种相互关联的局部腐蚀,即供氧差异微电池腐蚀、电偶腐蚀和缝隙腐蚀.

  20. 一种石油钻杆的腐蚀机理%Corrosion Mechanism of a Drill Pipe

    Institute of Scientific and Technical Information of China (English)

    刘婉颖; 施太和; 曾德智; 朱泽华; 贾华明; 卢强; 刘鹏

    2011-01-01

    A high temperature and pressure autoclave was used to simulate the drill pipe corrosion in situ field environment of Tarim oil field. The corrosion products and corrosion mechanisms of 8135 drill pipe working in lignosulfonate mud were studied. The corrosion product film on the outside of the drill pipe was analyzed by XRD and SEM. The results showed that localized oxidation corrosion occurred on S135 drill pipe, the features were the ulcerlike corrosion, localized contiguous corrosion and pit corrosion. The main corrosion products were orthorhombic crystal system's allcharite. The corrosion took place while the drill pipe standed on the derrick, where moisture in the mud cake clinging to the outside of drill pipe volatilized to the air and produced iron hematite, barite, bentonite powders and calcium powders. Three kinds of interrelated localized corrosion induding differential oxygen concentration corrosion, bimetallic corrosion and crevice corrosion oecured.%采用高温高压釜,模拟研究了塔里木油田现场环境所用聚磺体系钻井液对S135钻杆的腐蚀行为及腐蚀机理。通过对表面黏附有泥饼的挂片进行X射线衍射(XRD)和扫描电镜(SEM)分析,对腐蚀形貌和腐蚀产物进行了研究。结果表明,S135钻杆发生了局部氧腐蚀,特征为溃疡状腐蚀、连片局部腐蚀和深坑腐蚀,腐蚀产物主要是正交(斜方)晶系的针铁矿。钻杆腐蚀的主要原因是起钻时未刮泥浆,粘附在钻杆外壁的泥浆膜在空气中水分挥发过程和形成泥饼壳后便留下铁矿粉、重晶石、土粉、碳酸钙粉等作为骨架的固相物,称为垢层。垢层与钻杆表面接触,产生三种相互关联的局部腐蚀,即供氧差异微电池腐蚀、电偶腐蚀和缝隙腐蚀。

  1. Effect of Oxygen Co-Injected with Carbon Dioxide on Gothic Shale Caprock-CO2-Brine Interaction during Geologic Carbon Sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Hun Bok; Um, Wooyong; Cantrell, Kirk J.

    2013-09-16

    Co-injection of oxygen, a significant component in CO2 streams produced by the oxyfuel combustion process, can cause a significant alteration of the redox state in deep geologic formations during geologic carbon sequestration. The potential impact of co-injected oxygen on the interaction between synthetic CO2-brine (0.1 M NaCl) and shale caprock (Gothic shale from the Aneth Unit in Utah) and mobilization of trace metals was investigated at ~10 MPa and ~75 °C. A range of relative volume percentages of O2 to CO2 (0, 1, 4 and 8%) were used in these experiments to address the effect of oxygen on shale-CO2-brine interaction under various conditions. Major mineral phases in Gothic shale are quartz, calcite, dolomite, montmorillonite, and pyrite. During Gothic shale-CO2-brine interaction in the presence of oxygen, pyrite oxidation occurred extensively and caused enhanced dissolution of calcite and dolomite. Pyrite oxidation and calcite dissolution subsequently resulted in the precipitation of Fe(III) oxides and gypsum (CaSO4•2H2O). In the presence of oxygen, dissolved Mn and Ni were elevated because of oxidative dissolution of pyrite. The mobility of dissolved Ba was controlled by barite (BaSO4) precipitation in the presence of oxygen. Dissolved U in the experimental brines increased to ~8–14 g/L, with concentrations being slightly higher in the absence of oxygen than in the presence of oxygen. Experimental and modeling results indicate the interaction between shale caprock and oxygen co-injected with CO2 during geologic carbon sequestration can exert significant impacts on brine pH, solubility of carbonate minerals, stability of sulfide minerals, and mobility of trace metals. The major impact of oxygen is most likely to occur in the zone near CO2 injection wells where impurity gases can accumulate. Oxygen in CO2-brine migrating away from the injection well will be continually consumed through the reactions with sulfide minerals in deep geologic formations.

  2. Biogenic gas in the Cambrian-Ordovcian Alum Shale (Denmark and Sweden)

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, H.M.; Wirth, R.; Biermann, S.; Arning, E.T. [Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ, Potsdam (Germany); Krueger, M.; Straaten, N. [BGR Hannover (Germany); Bechtel, A. [Montanuniv. Leoben (Austria); Berk, W. van [Technical Univ. of Clausthal (Germany); Schovsbo, N.H. [Geological Survey of Denmark and Greenland - GEUS, Copenhagen (Denmark); Crabtree, Stephen [Gripen Gas (Sweden)

    2013-08-01

    . This local geological phenomenon leads to the fact that microbes with the potential to form biogenic methane flourish in such aqueous realms with low contents of total dissolved solids. Similar systems may have developed during the Quaternary in the Alum Shale. In contrast, the overmature Alum Shale which was recovered during drilling in the framework of the GASH project on Bornholm island (Denmark, Baltic Sea), showed no methane production potential in incubation experiments. However, ancient biogenic methane production can be retraced from the occurrence of layered, repeating barite precipitations.

  3. High-pressure crystal chemistry of zircon, monazite, scheelite and related minerals

    International Nuclear Information System (INIS)

    Full text: Many crystal structures of ABO4 compounds consists AO8 bisdisphenoids and BO4 tetrahedra. They include important mineral structures, e.g. zircon (ZrSiO4), anhydrite (CaSO4), silver perchlorate (AgClO4), and scheelite (CaWO4). These oxides, because of their compositional diversity and structural simplicity, played a key role in developing comparative crystal chemistry. In addition, zircon-type oxides exist in Nature being important minerals in the Earth mantle. Due to their incorporation of rare-earth (RE) elements they control the RE distribution in igneous rocks. Thus, the knowledge of their high-pressure (HP) structural behavior is relevant for mineral physics and chemistry (also for petrology). On the other hand, last decade RE phosphates and vanadates gained attention due to their optical and luminescent properties. Furthermore, given the crystal-chemical similarity between RE and actinides, phosphates were investigated for their use as solid-state repository for radioactive waste. The study of the HP mechanical and structural properties of ABO4 oxides is relevant for all these subjects. In this presentation different HP pressure studies performed in zircon-, monazite-, and scheelite-type oxides and related minerals (e.g. wolframite, barite, and anhydrite) are reviewed. The studies include XRD, EXAFS, and Raman experiments using a diamond-anvil cell up to 50 GPa as well as ab initio calculations. The combination of the experiments and calculations reveals the existence of complex HP phase-diagrams. In particular, the occurrence of pressure-induced phase transitions is discussed in detail. The differential bond compressibility of different polyhedra is also commented and related to the anisotropic compressibility of the structures. Results for tungstates, molybdates, vanadates, phosphates, chromates, arsenates, silicates, and germanates are shown. Finally, a systematic for the HP structural sequence of the studied oxides is present and discussed (e

  4. Diagenetic origin of ironstone crusts in the Lower Cenomanian Bahariya Formation, Bahariya Depression, Western Desert, Egypt

    Science.gov (United States)

    Afify, A. M.; Sanz-Montero, M. E.; Calvo, J. P.; Wanas, H. A.

    2015-01-01

    In this paper, a new interpretation of the ironstone crusts of the Bahariya Formation as late diagenetic products is provided. The siliciclastic Lower Cenomanian Bahariya Formation outcropping in the northern part of the Bahariya Depression (Western Desert, Egypt) is subdivided into three informal units that are mainly composed of thinly laminated siltstone, cross-bedded and massive sandstone, fossiliferous sandstone/sandy limestone and variegated shale. Abundant ironstone crusts occur preferentially within its lower and upper units but are absent in the middle unit. The ironstone crusts show selective replacement of carbonate components, including calcretes, by iron oxyhydroxides. More permeable parts of the terrigenous beds such as burrow traces, subaerial exposure surfaces, concretionary features and soft-sediment deformation structures led to heterogeneous distribution of the iron oxyhydroxides. A variety of diagenetic minerals, where goethite and hematite are the main end-products, were characterized by mineralogical analysis (XRD), petrography and SEM observation, and geochemical determinations (EMPA). Other diagenetic minerals include Fe-dolomite/ankerite, siderite, manganese minerals, barite, silica, illite/smectite mixed-layer, and bitumen. These minerals are interpreted to be formed in different diagenetic stages. Some minerals, especially those formed during eodiagenesis, show features indicative of biogenic activity. During burial, dolomite and ankerite replaced preferentially the depositional carbonates and infilled secondary porosity as well. Also during mesodiagenesis, the decomposition of organic matter resulted in the formation of bitumen and created reducing conditions favorable for the mobilization of iron-rich fluids in divalent stage. Telodiagenesis of the Cenomanian Bahariya deposits took place during the Turonian-Santonian uplift of the region. This resulted in partial or total dissolution of Fe-dolomite and ankerite which was concomitant to

  5. Hot-pressed barium sulphate ceramic waste forms for direct immobilization of medium level Magnox waste

    International Nuclear Information System (INIS)

    A possible method of treatment for Magnox cladding waste is by dissolution in nitric acid and precipitation of barium sulphate-based floc with which radioactive ions are co-precipitated. The floc could then be immobilized in a matrix material such as cement or bitumen to give the waste form, or alternatively can be converted directly into a waste form by hot pressing. This paper describes the direct conversion of barium sulphate floc, containing simulated radwaste, into a synthetic, ceramic version of the natural mineral barite by a hot-pressing route. By variation of the parameters pressure, temperature and time, optimum conditions for consolidation of the floc to > 90% theoretical density on a laboratory scale are found to be 22.5 MPa, 9000C for 10 minutes. Using a pressure of 15 MPa, at 9000C for 30 min., hot-pressed billets of BaSO4 have been made on a 5 kg scale. In going from the magnox waste to the hot-pressed barium sulphate a volume reduction factor approx. 18 is achieved. The principal phases in the product are found to be BaSO4, MgO and Fe3O4, and the degree of consolidation achieved depends on the MgO content. The leaching behaviour of the hot-pressed materials in 1000C, 3 day Soxhlet tests also depends on the MgO content, and on the consequent level of open porosity. If there is porosity accessible to the leach water, MgO at the internal surfaces is converted to Mg(OH)2, which deposits within the pores, and a weight gain is registered in the Soxhlet test. If, however, there is no open porosity, a weight loss occurs, and leach rates approx. 4 x 10-7 kg/m2/sec are found. In contrast, pure BaSO4, hot-pressed to similar densities, shows no variation in leaching behaviour over a wide range of open porosities, and gives Soxhlet leach rates approx. 8 x 10-8 kg/m2/sec. 6 figures, 2 tables

  6. Procedures for the determination of stable elements in construction materials from the nuclear reactors at Risoe National Laboratory

    International Nuclear Information System (INIS)

    Methods for the accurate determination of stable isotopes of elements in construction materials with relevance to the work of the Danish Decommissioning have been developed. Prior to the analysis the elements of interest must be released from the construction materials and this is done with several different digestion methods. For the analysis of aluminium, lead, graphite and steels the samples are digested with mineral acids and microwave heating at increased pressures in a sealed teflon vessel. The aluminium, lead and steel are fully dissolved after the digestion procedure whereas graphite is chemically inert to the acid treatment used, but the elements of interest are extracted from the graphite quite efficiently. Concrete is digested with open-vessel heating in a ModblockTM digesting unit in a two step procedure involving 40% HF followed by 32% HNO3. The heavy barite concrete is first treated as the concrete samples but a large residue of poorly soluble sulphates (mainly BaSO4) is left. The residue is fused with NaOH/Na2CO3 at 575 deg. C and after some work up the product from the fusion is dissolved in dilute HNO3. After the release of the elements from the materials, the samples are analysed by ICP-OES and ICP-MS multi-element analysis. In general the following elements are of interest to DD; Ag, Ba, Ca, Co, Eu, Fe, Li, Mo, Nb, Ni, Sm, Th and U. For graphite, steel, concrete and heavy concrete, analytical methods for the determination of all 13 elements have been developed (except Ca in steel). For aluminium and lead methods for the determination of Ag, Co, Li, Nb, Ni and U, as well as Ba in the lead have been developed. When possible the methods have been verified against certified reference materials and calibration with standards additions and internal standard corrections have been used to correct for matrix effects most efficiently. The accuracy has also been checked with spikes when reference materials are not available. For the aluminium, lead

  7. Actinide speciation bound to hydrous ferric oxide colloids in the near-field conditions of the waste pond at 'Mayak' facility (Russia)

    International Nuclear Information System (INIS)

    Full text of publication follows: 'Mayak' facility is a nuclear waste and spent nuclear fuel reprocessing plant located in Ural Mountains, Russia. The opened pond, Karachay Lake, was used for several decades for the discharge of low- and intermediate level waste solutions containing fission products and traces of actinides. Due to high salt concentration and high density of waste solutions, they are penetrating into the groundwater system that is represented by oxic Eh conditions. The speciation of actinides in groundwater samples collected close to Karachay Lake was studied by successive micro- and ultra-filtrations with subsequent SEM, TEM, nano-SIMS, membrane extraction and other techniques. It was established that U and Np were found in soluble fraction (pass through 10 kD ultra-filter) in the form of their bi- and tri-carbonate complexes that was supported by chemical thermodynamic calculations. In contrast, Pu and Am were bound to nano-colloids 10 kD - 50 nm in size. The SEM and TEM data indicate the presence of variety of different colloidal particles which relative concentration decrease in the row: hydrous ferric oxides (HFO) >> clays ≅ calcite > rutile ≅ hematite ≅ barite ≅ MnO2 > monazite > other phases. The SIMS with submicron resolution (Cameca nanoSIMS-50) was used to study local concentration of actinides. According to the obtained data among different colloids detected in the sample actinides were preferentially bound to HFO and MnO2 while other phases did not sorb actinides. In order to determine actinide speciation bound to HFO colloids XPS and An L3 edge XAFS measurements were done at Siberian Synchrotron Radiation Centre. The storage ring VEPP-3 with electron beam energy of 2 GeV and an average stored current of 80 mA was used as the source of radiation. Since the concentration of actinides in actual samples was too low for XAFS, the samples for measurements were prepared by contacting about 10-5 M solutions of Np(V) and Pu(V) with UFO

  8. Development and Applications of the Solid Emulsifier Used to Improve the Performance of Oil-in-water Drilling Fluids

    Institute of Scientific and Technical Information of China (English)

    YanJienian; WangFuhua

    2004-01-01

    The oil-in-water emulsion drilling fluids, prepared by adding 5-12% (by volume) of mineral oil (or diesel) to water-based muds, have been widely used for stuck-pipe prevention in the Shengli Oilfield. In some cases, the emulsion stability of this kind of mud system is not strong enough to meet the requirements of drilling operations. To overcome this drawback, a solid emulsifer, which is characterized by its very small particle size and special wetting behavior (slightly water-wet), has been developed and successfully applied to improve the emulsion stability and other performances of these drilling fluids. Prior to the development of this technology, an extensive study was conducted to deal with the influence of various kinds of finely divided insoluble solid particles on oil/water emulsification. The substances used include bentonite, organophilic clay, kaolinite, barite, two kinds of calcium carbonate with different particle sizes, two kinds of silica with different wetting behaviors, and a newly developed solid emulsifier. Both the emulsion stability experiments and the drop coalescence experiments are performed to evaluate the contribution of these particles to emulsification. The measured final emulsion volume disappears after 12 hours and the half-life for water and oil drops are used as the measures of emulsion stability. The experimental data show that the type, size, concentration and wettability of the particles, and the presence of some surfactants control the type and stability of emulsions for a given oil/water system, and the fine particles of the solids emulsifier provide the most effective stabilization for water-continuous emulsions compared with other kinds of particles. Meanwhile, it can be observed that these particles also stabilize oil-continuous emulsions effectively in some cases since their wetting behavior is close to neutral. The O/W emulsion mud stabilized by the newly developed solid emulsifier has become one of the major mud systems

  9. Mineralogía y aspectos genéticos del depósito volcanogénico submarino de Manganeso "La Casualidad", Cerro atraves, Neuquén

    Directory of Open Access Journals (Sweden)

    Eduardo O Zappettini

    2012-12-01

    Full Text Available El depósito La Casualidad está constituido por capas manganesíferas intercaladas en calizas y tobas de la Formación Chachil (Pliensbachiano. La mineralización identificada comprende carbonatos (rodocrosita, calcita, sulfatos (baritina, jarosita, silicatos (tefroíta, granate manganesífero, pennantita, serpentina -caryopilita-, nontronita, bementita, óxidos (pirolusita, espinelos de la serie jacobsita-franklinita, pirofanita, hetaerolita, akhtenskita, nsutita, criptomelano, coronadita, hematita, magnetita, jaspe, sulfuros (gersdorffita, esfalerita, galena, pirita, calcopirita, greigita y posible alabandita y sulfosales (de la serie tennantita-tetraedrita, algunos de ellos reconocidos por primera vez en Argentina. La mineralogía y geoquímica del depósito sugieren que éste se formó en condiciones hidrotermales submarinas en un paleomargen extensional a través de fallas sinsedimentarias en un ambiente hemipelágico con desarrollo de plataforma calcárea. Su génesis se vincula con la etapa de rift tardío del depocentro Chachil, definido como un pequeño hemigraben extensional activo durante el rifting inicial de la Cuenca Neuquina. La presencia de sulfuros y de niveles de granates manganesíferos, así como la asociación de los niveles de Mn con calizas, sugiere la posibilidad de hallazgo de cuerpos de sulfuros masivos en las proximidades.La Casualidad ore deposit is characterized by manganiferous layers interbedded with limestones and tuffs of the Chachil formation (Pliensbachian. The identified mineralogy comprises carbonates (rhodochrosite, calcite, sulfates (barite, jarosite, silicates (tefroite, manganoan garnet, pennatite, serpentine -caryopillite-, nontronite, bementite, oxides (pyrolusite, spinels from the jacobsite-franklinite series, pyrophanite, hetaerolite, akhtenskite, nsutite, cryptomelane, coronadite, hematite, magnetite, jasper, sulfides (gersdorffite, sphalerite, galena, pyrite, chalcopyrite, greigite y possible

  10. Laboratory quantification of permeability-porosity relationships for seafloor vent deposits: anisotropy in flange, slab, and crust samples

    Science.gov (United States)

    Gribbin, J. L.; Zhu, W.; Tivey, M. K.

    2010-12-01

    Seafloor hydrothermal vents accommodate the convective transfer of material from Earth’s interior to the oceans. A variety of seafloor deposits form at vent fields, including flanges, slabs, and crust. Flanges recovered from Guaymas Basin and the Main Endeavour Field (MEF) are horizontal ledges that protrude from the sides of larger structures. Fluid pools under and can percolate upwards through the flanges. Slabs taken from the Lucky Strike Vent Field are layered silicified deposits rich in sulfides, barite, and volcanic fragments; fluids can percolate upward through the cracked slab layers. Crust samples recovered from the Trans-Atlantic Geotraverse (TAG) active mound are composed of re-cemented older vent debris, and, again, fluids can percolate upward through the crust layers. Permeability and porosity measurements were made on a suite of flange, slab, and crust samples to determine evolution of permeability-porosity relationships (EPPRs). EPPRs are power-law relationships relating permeability and porosity through an exponent, α, that varies with changes in pore geometry - the higher the α value, the greater the change in permeability with respect to changes in porosity. Two trends were identified for the measured permeability and porosity data. First, measurements made on cores taken parallel to flange/slab/crust layers had consistently higher permeabilities (≈ 10-12 m2) and porosities (30-40%), and followed a trend of α ≈ 2. This trend differs significantly from the trend determined for measurements made on cores taken perpendicular to layering (representing most of the sample measurements): permeabilities ranged from 10-16-10-12 m2 and porosities from 20-45%, with a trend of α ≈ 4. The two distinct trends are consistent with the primary fluid flow direction having been parallel to layering (the α ≈ 2 trend), with flow perpendicular to layering (the α ≈ 4 trend) having been restricted to serial pathways that intersected the various layers

  11. Age, Episodicity and Migration of Hydrothermal Activity within the Axial Valley, Endeavour Segment, Juan de Fuca Ridge

    Science.gov (United States)

    Jamieson, J. W.; Hannington, M. D.; Kelley, D. S.; Clague, D. A.; Holden, J. F.; Tivey, M. K.; Delaney, J. R.

    2011-12-01

    Hydrothermal sulfide deposits record the history of high-temperature venting along the Endeavour Segment. Active venting is currently located within five discreet vent fields, with minor diffuse venting occurring between the fields. However, inactive and/or extinct sulfide structures are found throughout the entire axial valley of the ridge segment, suggesting that hydrothermal activity has been more vigorous in the past or focused venting has migrated with time. Here, we present age constraints from U-series dating of 44 sulfide samples collected by manned submersible from between the Mothra Field in the south to Sasquatch in the north. Samples are dated using 226Ra/Ba ratios from hydrothermal barite that precipitates along with the sulfide minerals. Most samples have been collected from within or near the active vent fields. Fifteen samples from the Main Endeavour Field (MEF) show a spectrum of ages from present to 2,430 years old, indicating that this field has been continuously active for at least ~2,400 years. MEF appears to be oldest currently active field. This minimum value for the age of hydrothermal activity also provides a minimum age of the axial valley itself. Ages from thirteen samples from the High-Rise Field indicate continuous venting for at least the past ~1,250 years. These age data are used in conjunction with age constraints of the volcanic flows to develop an integrated volcanic, hydrothermal and tectonic history of the Endeavour Segment. The total volume of hydrothermal sulfide within the axial valley, determined from high-resolution bathymetry, is used in conjunction with the age constraints of the sulfide material to determine the mass accumulation rates of sulfide along the Endeavour Segment. These data can be used to calibrate the efficiency of sulfide deposition from the hydrothermal vents, and provide a time-integrated history of heat, fluid and chemical fluxes at the ridge-segment scale. The comparison of time-integrated rates with

  12. El Rombohorst mineralizado de Las Herrerias: un caso de «doming» e hidrotermalismo submarino mioceno en el SE ibérico

    Directory of Open Access Journals (Sweden)

    López Gutiérrez, J.

    1993-04-01

    Full Text Available The present contribution offers new data on the Miocene, seafloor, hydrothermal deposit of Herrerías, in relation with its geotectonic setting. This deposit consists of a simple paragenesis of Fe-Mn oxides, base metal sulphides, native silver, barite, siderite, jasper, calcedony and gypsum (scarce; these minerals are forming part of: 1 beds of mineralized exhalites, 2 veins and pipes, 3 Fe-Mn crusts and 4 dissemination zones. The main mineralized outcrops are controlled by three fracturation systems: a sinistral, wreoch faults NNE-SSW, b inverse faults WNW-ESE and c normal faults N-S, N190E and N150E. Basically, its geotectonic setting corresponds to a positive «flower structure», of Upper Miocene age, within which the N-S and N150E faults were the main channels for the emplacement of the ore fluids. This mineralized structure has been formed according to a subvolcanic doming in a shear zone.En este trabajo, se ofrecen nuevos datos sobre el encuadre geotectónico del yacimiento hidrotermal submarino, mioceno de Herrerías. Este depósito posee una paragénesis simple de óxidos e hidróxidos de Fe-Mn, sulfuros de metales base, plata nativa, barita, siderita, jasperoides, calcedonia y yeso (escaso; la investigación detallada de las secuencias deposicionales indica que estos minerales se encuentran, invariablemente, formando parte de: 1 lechos de exhalitas mineralizadas, 2 filones y chimeneas; 3 costras ferromanganesíferas y 4 zonas diseminadas. Los principales afloramientos mineralizados están controlados por tres sistemas de fracturación: a desgarres senestrales NNE-SSO, b fallas inversas aNO-ESE y c fallas normales N-S, N190E YN150E. De acuerdo con esta estructuración, el encuadre de la mineralización corresponde a una estructura en flor positiva, de edad Mioceno superior, dentro de la cual las fallas correspondientes al tercer sistema habrían servido como las vías principales de emplazamiento de los fluidos mineralizadores. La

  13. Formation and evolution stages of gold rich Barika massive sulfide deposit, east of Sardasht, northern Sanandaj-Sirjan zone: based on structural, textural and fluid inclusion studies

    Directory of Open Access Journals (Sweden)

    Hossein Ali Tajeddin

    2010-05-01

    Full Text Available Barika gold (and silver rich massive sulfide deposit is located 18 km east of Sardasht, north western part of Sanandaj-Sirjan metamorphic zone. Rock units outcropped in this area are Cretaceous metamorphosed volcano-sedimentary rocks in green schist facies, and include association of meta-andesite, meta-tuffite, phyllite and slate rocks, where the meta-andesitic unit (Kmv1 is host rock to the deposit. Barika deposit is composed of stratiform ore and stringer zone. Stratiform part contains massive and banded sulfide and barite associated with subordinary silica bands underlain by stringer silicic zone. The massive and banded ore is surrounded by an extensive zone of silicic stringer veins and disseminated mineralization within strongly altered and deformed andesitic volcanic rocks. Ore mineral assemblages in stratiform part of the deposit are quite variable and consist of pyrite, sphalerite, galena, stibnite, a variety of sulfosalt minerals and gold (electrum. Ore mineral assemblages in silicic veins in the stringer zone are simpler and consist of pyrite, galena, sphalerite, tetrahedrrite and trace chalcopyrite. Average gold and silver grades in stratiform ore are 8.3 and 420 g/t respectively and in silicic stringer veins are 0.7 and 30 g/t. Base metal content in both parts of the deposit are less than 1%. Based on our research, Barika is an immature Kuroko type massive sulfide deposit, which contains only black ore. The Barika deposit underwent low-grade metamorphism and high grade deformation after the ore deposition event. Geologic processes appear to control the mode of occurrence of gold in the deposit. In synvolcanism stage, deposition of a gold–bearing low temperature (140-200°C and low salinity (1-9.6 wt% NaCl hydrothermal fluid formed a Kuroko black ore type deposit. In the stage of mineralization, invisible gold was concentrated in framboidal pyrite and other sulfide minerals. The main effect of progressive metamorphism (D1 on gold

  14. Chemical characterization, nano-particle mineralogy and particle size distribution of basalt dust wastes.

    Science.gov (United States)

    Dalmora, Adilson C; Ramos, Claudete G; Oliveira, Marcos L S; Teixeira, Elba C; Kautzmann, Rubens M; Taffarel, Silvio R; de Brum, Irineu A S; Silva, Luis F O

    2016-01-01

    Understanding the geochemistry of basalt alteration is central to the study of agriculture systems. Various nano-minerals play an important role in the mobilization of contaminants and their subsequent uptake by plants. We present a new analytical experimental approach in combination with an integrated analytical protocol designed to study basalt alteration processes. Recently, throughout the world, ultra-fine and nano-particles derived from basalt dust wastes (BDW) during "stonemeal" soil fertilizer application have been of great concern for their possible adverse effects on human health and environmental pollution. Samples of BDW utilized were obtained from companies in the Nova Prata mining district in southern Brazil for chemical characterization and nano-mineralogy investigation, using an integrated application of advanced characterization techniques such as X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/Energy Dispersive Spectroscopy (EDS)/(selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM/EDS), and granulometric distribution analysis. The investigation has revealed that BDW materials are dominated by SiO2, Al2O3, and Fe2O3, with a complex micromineralogy including alkali feldspar, augite, barite, labradorite, hematite, heulandrite, gypsum, kaolinite, quartz, and smectite. In addition, we have identified a number of trace metals such as Cd, Cu, Cr, and Zn, that are preferentially concentrated into the finer, inhalable, dust fraction and, thus, could present a health hazard in the urban areas around the basalt mining zone. The implication of this observation is that use of these nanometric-sized particulates as soil fertilizer may present different health challenges to those of conventional fertilizers, inviting future work regarding the relative toxicities of these materials. Our investigation on the particle size distribution, nano-particle mineralogy and chemical composition in

  15. Non-river flood barium signals in the skeletons of corals from coastal Queensland, Australia

    Science.gov (United States)

    Sinclair, Daniel J.

    2005-09-01

    Two corals from coastal Queensland (Cow and Calf Islands, and Orpheus Island) have been analysed for a suite of trace elements by laser-ablation ICP-MS (LA-ICP-MS). Barium signals in these two corals are 'anomalous' in comparison with Ba behaviour seen in other near-shore corals from this region. The two corals display large sharp peaks in spring which do not correlate with markers of river discharge (Y/Ca and fluorescence). This Ba pattern contrasts with 'normal' behaviour—characterised here by the patterns previously published for two other coastal Queensland corals (King Reef and Pandora Reef), which display Ba peaks in summer associated with flooding of nearby rivers [1] [D.J. Sinclair, M.T. McCulloch, Corals record low mobile barium concentrations in the Burdekin River during the 1974 flood: evidence for limited Ba supply to rivers?, Palaeogeogr. Palaeoclimatol. Palaeoecol. 214 (1-2) (2004) 155-174]. Similarities are observed between the anomalous Ba in the Queensland corals and other published patterns of Ba behaviour in corals from South Africa and the Arabian Sea. This non-river flood Ba behaviour is characterized by large sharp spikes of Ba which are resistant to oxidative cleaning and form a continuous horizon within the coral. Curiously, not all corals from a region display anomalous Ba behaviour despite being in similar environments. The timing of anomalous Ba is consistent within a coral, but may vary from one location to the next. Anomalous Ba spikes are too large to be caused by Ba-rich upwelling, and no single environmental forcing function seems to be able to account for their timing. This combination of observations argues against an exogenous abiotic source for the anomalous Ba signal; instead, it may result from a biological event triggered by a combination of environmental parameters. Three hypotheses are presented, and critically tested against the observations: barite inclusion following phytoplankton blooms, decaying blooms of the blue

  16. Site investigation SFR. Fracture mineralogy including identification of uranium phases and hydrochemical characterisation of groundwater in borehole KFR106

    International Nuclear Information System (INIS)

    This report presents the fracture mineralogy and hydrochemistry of borehole KFR106. The most abundant fracture minerals in the examined drill core samples are clay minerals, calcite, quartz and adularia; chlorite is also common but is mostly altered and found interlayered with corrensite. The most common clay mineral is a mixed layer clay consisting of illite-smectite. Pyrite, galena, chalcopyrite, barite (-celestine) and hematite are also commonly found in the fractures, but usually in trace amounts. Other minerals identified in the examined fractures are U-phosphate, pitchblende, U(Ca)-silicate, asphaltite, biotite, monazite, fluorite, titanite, sericite, xenotime, rutile and (Ca, REEs)-carbonate. Uranium has been introduced, mobilised and reprecipitated during at least four different episodes: 1) Originally, during emplacement of U-rich pegmatites, probably as uraninite. 2) At a second event, uranium was mobilised under brittle conditions during formation of breccia/cataclasite. Uraninite was altered to pitchblende and partly coffinitised. Mobilised uranium precipitated as pitchblende closely associated with hematite and chlorite in cataclasite and fracture sealings prior to 1,000 Ma. 3) During the Palaeozoic U was remobilised and precipitated as U-phosphate on open fracture surfaces. 4) An amorphous U-silicate has also been found in open fractures; the age of this precipitation is not known but it is inferred to be Palaeozoic or younger. Groundwater was sampled in two sections in borehole KFR106 with pumping sequences of about 6 days for each section. The samples from sections KFR106:1 and KFR106:2 (260-300 m and 143-259 m borehole length, i.e. -261 and -187 m.a.s.l. mid elevation of the section, respectively) were taken in November 2009 and yielded groundwater chemistry data in accordance with SKB chemistry class 3 and 5. In section KFR106:1 and KFR106:2, the chloride contents were 850 and 1,150 mg/L and the drilling water content 6 and 4%, respectively

  17. Radionuclide solubility control by solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, F.; Klinkenberg, M.; Rozov, K.; Bosbach, D. [Forschungszentrum Juelich GmbH (Germany). Inst. of Energy and Climate Research - Nuclear Waste Management and Reactor Safety (IEK-6); Vinograd, V. [Frankfurt Univ. (Germany). Inst. of Geosciences

    2015-07-01

    The migration of radionuclides in the geosphere is to a large extend controlled by sorption processes onto minerals and colloids. On a molecular level, sorption phenomena involve surface complexation, ion exchange as well as solid solution formation. The formation of solid solutions leads to the structural incorporation of radionuclides in a host structure. Such solid solutions are ubiquitous in natural systems - most minerals in nature are atomistic mixtures of elements rather than pure compounds because their formation leads to a thermodynamically more stable situation compared to the formation of pure compounds. However, due to a lack of reliable data for the expected scenario at close-to equilibrium conditions, solid solution systems have so far not been considered in long-term safety assessments for nuclear waste repositories. In recent years, various solid-solution aqueous solution systems have been studied. Here we present state-of-the art results regarding the formation of (Ra,Ba)SO{sub 4} solid solutions. In some scenarios describing a waste repository system for spent nuclear fuel in crystalline rocks {sup 226}Ra dominates the radiological impact to the environment associated with the potential release of radionuclides from the repository in the future. The solubility of Ra in equilibrium with (Ra,Ba)SO{sub 4} is much lower than the one calculated with RaSO{sub 4} as solubility limiting phase. Especially, the available literature data for the interaction parameter W{sub BaRa}, which describes the non-ideality of the solid solution, vary by about one order of magnitude (Zhu, 2004; Curti et al., 2010). The final {sup 226}Ra concentration in this system is extremely sensitive to the amount of barite, the difference in the solubility products of the end-member phases, and the degree of non-ideality of the solid solution phase. Here, we have enhanced the fundamental understanding regarding (1) the thermodynamics of (Ra,Ba)SO{sub 4} solid solutions and (2) the

  18. Site investigation SFR. Fracture mineralogy including identification of uranium phases and hydrochemical characterisation of groundwater in borehole KFR106

    Energy Technology Data Exchange (ETDEWEB)

    Sandstroem, Bjoern [WSP Sverige AB, Goeteborg (Sweden); Nilsson, Kersti [Geosigma AB, Uppsala (Sweden); Tullborg, Eva-Lena [Terralogica AB, Graabo (Sweden)

    2011-12-15

    This report presents the fracture mineralogy and hydrochemistry of borehole KFR106. The most abundant fracture minerals in the examined drill core samples are clay minerals, calcite, quartz and adularia; chlorite is also common but is mostly altered and found interlayered with corrensite. The most common clay mineral is a mixed layer clay consisting of illite-smectite. Pyrite, galena, chalcopyrite, barite (-celestine) and hematite are also commonly found in the fractures, but usually in trace amounts. Other minerals identified in the examined fractures are U-phosphate, pitchblende, U(Ca)-silicate, asphaltite, biotite, monazite, fluorite, titanite, sericite, xenotime, rutile and (Ca, REEs)-carbonate. Uranium has been introduced, mobilised and reprecipitated during at least four different episodes: 1) Originally, during emplacement of U-rich pegmatites, probably as uraninite. 2) At a second event, uranium was mobilised under brittle conditions during formation of breccia/cataclasite. Uraninite was altered to pitchblende and partly coffinitised. Mobilised uranium precipitated as pitchblende closely associated with hematite and chlorite in cataclasite and fracture sealings prior to 1,000 Ma. 3) During the Palaeozoic U was remobilised and precipitated as U-phosphate on open fracture surfaces. 4) An amorphous U-silicate has also been found in open fractures; the age of this precipitation is not known but it is inferred to be Palaeozoic or younger. Groundwater was sampled in two sections in borehole KFR106 with pumping sequences of about 6 days for each section. The samples from sections KFR106:1 and KFR106:2 (260-300 m and 143-259 m borehole length, i.e. -261 and -187 m.a.s.l. mid elevation of the section, respectively) were taken in November 2009 and yielded groundwater chemistry data in accordance with SKB chemistry class 3 and 5. In section KFR106:1 and KFR106:2, the chloride contents were 850 and 1,150 mg/L and the drilling water content 6 and 4%, respectively

  19. Evolution of the magmatic-hydrothermal acid-sulfate system at Summitville, Colorado: Integration of geological, stable-isotope, and fluid-inclusion evidence

    Science.gov (United States)

    Bethke, P.M.; Rye, R.O.; Stoffregen, R.E.; Vikre, P.G.

    2005-01-01

    The Summitville Au-Ag-Cu deposit is a classic volcanic dome-hosted high-sulfidation deposit. It occurs in the Quartz Latite of South Mountain, a composite volcanic dome that was emplaced along the coincident margins of the Platoro and Summitville calderas at 22.5??0.5 Ma, penecontemporaneous with alteration and mineralization. A penecontemporaneous quartz monzonite porphyry intrusion underlies the district and is cut and overlain by pyrite-quartz stockwork veins with traces of chalcopyrite and molybdenite. Alteration and mineralization proceeded through three hypogene stages and a supergene stage, punctuated by at least three periods of hydrothermal brecciation. Intense acid leaching along fractures in the quartz latite produced irregular pipes and lenticular pods of vuggy silica enclosed sequentially by alteration zones of quartz-alunite, quartz-kaolinite, and clay. The acid-sulfate-altered rocks host subsequent covellite+enargite/luzonite+chalcopyrite mineralization accompanied by kaolinite, and later barite-base-metal veins, some containing high Au values and kaolinite. The presence of both liquid- and vapor-rich fluid inclusions indicates the episodic presence of a low-density fluid at all levels of the system. In the mineralized zone, liquid-rich fluid inclusions in healed fractures in quartz phenocrysts and in quartz associated with mineralization homogenize to temperatures between 160 and 390 ??C (90% between 190 and 310 ??C), consistent with the range (200-250 ??C) estimated from the fractionation of sulfur isotopes between coexisting alunite and pyrite. A deep alunite-pyrite pair yielded a sulfur-isotope temperature of 390 ??C, marking a transition from hydrostatic to lithostatic pressure at a depth of about 1.5 km. Two salinity populations dominate the liquid-rich fluid inclusions. One has salinities between 0 and 5 wt.% NaCl equivalent; the other has salinities of up to 43 wt.% NaCl equivalent. The occurrence of high-salinity fluid inclusions in vein

  20. Complementary modelling of radionuclide retention in the near-surface system at Forsmark. Development of a reactive transport model using Forsmark 1.2 data

    Energy Technology Data Exchange (ETDEWEB)

    Sena, Clara; Grandia, Fidel; Arcos, David; Molinero, Jorge; Duro, Lara (Amphos XXI Consulting S.L., Barcelona (Spain))

    2008-10-15

    sensitivity analysis of the more relevant parameters considered in the reactive transport numerical models is also presented here. From the main report of the SR-Can project it is stated that Ra is one of the radionuclides with greater contribution to the radioactive doses that might be transferred to the biosphere in the context of repository release. For this reason, Ra was added to the set of radionuclides (Sr, Cs, and U). Another improvement in the numerical simulations presented here is the calculation of the hydrogeochemical steady state of the near-surface system, prior to repository release. This is done to approach the present-day conditions at Forsmark. In addition, radionuclides derived from repository release have been discriminated from those of natural origin, already present in the groundwaters. Radionuclides coming from repository were labelled as RDCs, RDSr, and RDU (RD stands for repository-derived). Ra was not labelled since the presence of this radionuclide in the modelled domain is exclusively attributed to repository release due to the extremely low concentrations observed in the natural waters of Forsmark. The results attained in the reactive transport models built in this work show that the near-surface systems at Forsmark constitute a geochemical reactive barrier able to retain radionuclides by several key processes, namely cation exchange, adsorption on mineral surfaces and precipitation of pure phases and solid solutions. The reactive transport simulations predict that repository-derived Sr, U, and Cs are retained in the solid phase of both Quaternary deposits under study, while Ra is effectively retained in the till deposit only. Ra is not retained in the glacial clay deposit since saturation of barite, which is the only retention mechanism considered in the simulations for this radionuclide, is not reached in this system. The simulations indicate that, in the till deposit, Sr is retained via cation exchange and coprecipitation with calcite, U is

  1. Geochemical and mineralogical characterization of a neutral, low-sulfide/high-carbonate tailings impoundment, Markušovce, eastern Slovakia.

    Science.gov (United States)

    Hiller, Edgar; Petrák, Marián; Tóth, Roman; Lalinská-Voleková, Bronislava; Jurkovič, L'ubomír; Kučerová, Gabriela; Radková, Anežka; Sottník, Peter; Vozár, Jaroslav

    2013-11-01

    Tailings deposits generated from mining activities represent a potential risk for the aquatic environment through the release of potentially toxic metals and metalloids occurring in a variety of minerals present in the tailings. Physicochemical and mineralogical characteristics of tailings such as total concentrations of chemical elements, pH, ratio of acid-producing to acid-neutralizing minerals, and primary and secondary mineral phases are very important factors that control the actual release of potentially toxic metals and metalloids from the tailings to the environment. The aims of this study are the determination of geochemical and mineralogical characteristics of tailings deposited in voluminous impoundment situated near the village of Markušovce (eastern Slovakia) and identification of the processes controlling the mobility of selected toxic metals (Cu, Hg) and metalloids (As, Sb). The studied tailings have unique features in comparison with the other tailings investigated previously because of the specific mineral assemblage primarily consisting of barite, siderite, quartz, and minor sulfides. To meet the aims, samples of the tailings were collected from 3 boreholes and 15 excavated pits and subjected to bulk geochemical analyses (i.e., determination of chemical composition, pH, Eh, acid generation, and neutralization potentials) combined with detailed mineralogical characterization using optical microscopy, X-ray diffraction (XRD), electron microprobe analysis (EMPA), and micro-X-ray diffraction (μ-XRD). Additionally, the geochemical and mineralogical factors controlling the transfer of potentially toxic elements from tailings to waters were also determined using short-term batch test (European norm EN 12457), sampling of drainage waters and speciation-equilibrium calculations performed with PHREEQC. The tailings mineral assemblage consists of siderite, barite, quartz, and dolomite. Sulfide minerals constitute only a minor proportion of the tailings

  2. Complementary modelling of radionuclide retention in the near-surface system at Forsmark. Development of a reactive transport model using Forsmark 1.2 data

    International Nuclear Information System (INIS)

    sensitivity analysis of the more relevant parameters considered in the reactive transport numerical models is also presented here. From the main report of the SR-Can project it is stated that Ra is one of the radionuclides with greater contribution to the radioactive doses that might be transferred to the biosphere in the context of repository release. For this reason, Ra was added to the set of radionuclides (Sr, Cs, and U). Another improvement in the numerical simulations presented here is the calculation of the hydrogeochemical steady state of the near-surface system, prior to repository release. This is done to approach the present-day conditions at Forsmark. In addition, radionuclides derived from repository release have been discriminated from those of natural origin, already present in the groundwaters. Radionuclides coming from repository were labelled as RDCs, RDSr, and RDU (RD stands for repository-derived). Ra was not labelled since the presence of this radionuclide in the modelled domain is exclusively attributed to repository release due to the extremely low concentrations observed in the natural waters of Forsmark. The results attained in the reactive transport models built in this work show that the near-surface systems at Forsmark constitute a geochemical reactive barrier able to retain radionuclides by several key processes, namely cation exchange, adsorption on mineral surfaces and precipitation of pure phases and solid solutions. The reactive transport simulations predict that repository-derived Sr, U, and Cs are retained in the solid phase of both Quaternary deposits under study, while Ra is effectively retained in the till deposit only. Ra is not retained in the glacial clay deposit since saturation of barite, which is the only retention mechanism considered in the simulations for this radionuclide, is not reached in this system. The simulations indicate that, in the till deposit, Sr is retained via cation exchange and coprecipitation with calcite, U is

  3. DUSEL Facility Cooling Water Scaling Issues

    Energy Technology Data Exchange (ETDEWEB)

    Daily, W D

    2011-04-05

    oilfield include calcium carbonates (CaCO3, mainly calcite) and alkaline-earth metal sulfates (barite BaSO4, celestite SrSO4, anhydrite CaSO4, hemihydrate CaSO4 1/2H2O, and gypsum CaSO4 2H2O or calcium sulfate). The cause of scaling can be difficult to identify in real oil and gas wells. However, pressure and temperature changes during the flow of fluids are primary reasons for the formation of carbonate scales, because the escape of CO2 and/or H2S gases out of the brine solution, as pressure is lowered, tends to elevate the pH of the brine and result in super-saturation with respect to carbonates. Concerning sulfate scales, the common cause is commingling of different sources of brines either due to breakthrough of injected incompatible waters or mixing of two different brines from different zones of the reservoir formation. A decrease in temperature tends to cause barite to precipitate, opposite of calcite. In addition, pressure drops tend to cause all scale minerals to precipitate due to the pressure dependence of the solubility product. And we can expect that there will be a pressure drop across the heat exchanger. Weather or not this will be offset by the rise in pressure remains to be seen. It's typically left to field testing to prove out. Progress has been made toward the control and treatment of the scale deposits, although most of the reaction mechanisms are still not well understood. Often the most efficient and economic treatment for scale formation is to apply threshold chemical inhibitors. Threshold scale inhibitors are like catalysts and have inhibition efficiency at very low concentrations (commonly less than a few mg/L), far below the stoichiometric concentrations of the crystal lattice ions in solution. There are many chemical classes of inhibitors and even more brands on the market. Based on the water chemistry it is anticipated that there is a high likelihood for sulfate compound precipitation and scaling. This may be dependent on the temperature

  4. Chronology of metal pollution offshore Coruh Mouth, Eastern Black Sea

    International Nuclear Information System (INIS)

    Among the areas investigated during two international cruises organised by the IAEA in the Black Sea in 1998 and 2000, two areas were singled out, on the NW Shelf and offshore the Coruh mouth, as having the highest levels of heavy metals in sediment. The River Coruh drains mountainous regions of Turkey and Georgia, having a high transport energy. Offshore its mouth, Cu reaches up to 340 μg/g and Ba up to 2350 μg/g in sediment. These maximum levels are about 7, respectively 10 times higher than 'background' values measured in Black Sea sediments. It can be noted that at two of the four locations in the studied area Cu exceeded the ERL concentration for marine sediments (270 μg/g), indicating a likely impact on marine biota at the respective sites. Most of the other heavy metals (Co, Ni, Pb, Zn, Cd, Cr and V), the major component Fe2O3 and the minor component TiO2 were also enriched, to a lesser degree, in the area offshore the Coruh mouth. Ba and Cu were related here by a significant linear correlation (rBa-Cu=0.905), indicating a common origin for both metals. At the same time both metals were significantly correlated (a≤0.01) with Pb, Cd and Zn, Ba being also significantly correlated with Cr. All these metals have no significant correlations with any potential normalizing component. The general enrichment of these elements points to a substantial input from a region characterized by the presence of polymetallic and barite mineralizations, the paragenesis being specific for porphyry copper deposits. Deposits of this type are present in both Georgia and Turkey and both countries are mining them. Both natural erosion and transport and anthropic activities can contribute to the measured enrichment and it is of interest to identify and characterize the sources and the processes and timescales involved in transport and deposition as well as the post-depositional processes. The spatial distribution of Cu and Ba surface sediment concentrations offshore the Coruh

  5. Chronology of metal pollution offshore Coruh mouth, eastern Black Sea

    International Nuclear Information System (INIS)

    Among the areas investigated during two international cruises organised by the IAEA in the Black Sea in 1998 and 2000, two areas were singled out, on the NW Shelf and offshore the Coruh mouth, as having the highest levels of heavy metals in sediment. The River Coruh drains mountainous regions of Turkey and Georgia, having a high transport energy. Offshore its mouth, Cu reaches up to 340 μg/g and Ba up to 2350 μg/g in sediment. These maximum levels are about 7, respectively 10 times higher than 'background' values measured in Black Sea sediments. It can be noted that at two of the four locations in the studied area Cu exceeded the ERL concentration for marine sediments (270 μg/g), indicating a likely impact on marine bio ta at the respective sites. Most of the other heavy metals (Co, Ni, Pb, Zn, Cd, Cr and V), the major component Fe2O3 and the minor component TiO2 were also enriched, to a lesser degree, in the area offshore the Coruh mouth. Ba and Cu were related here by a significant linear correlation (rBa-Cu=0.905), indicating a common origin for both metals. At the same time both metals were significantly correlated (α≤0.01) with Pb, Cd and Zn, Ba being also significantly correlated with Cr. All these metals have no significant correlations with any potential normalizing component. The general enrichment of these elements points to a substantial input from a region characterized by the presence of polymetallic and barite mineralizations, the paragenesis being specific for porphyry copper deposits. Deposits of this type are present in both Georgia and Turkey and both countries are mining them. Both natural erosion and transport and anthropic activities can contribute to the measured enrichment and it is of interest to identify and characterize the sources and the processes and timescales involved in transport and deposition as well as the post-depositional processes. The spatial distribution of Cu and Ba surface sediment concentrations offshore the Coruh

  6. Rediscovery and Exploration of Magic Mountain, Explorer Ridge, NE Pacific

    Science.gov (United States)

    Embley, R. W.

    2002-12-01

    either centered within the neovolcanic zone or associated with a boundary fault. The active venting occurs over at least 400 m along axis and is mostly concentrated in clusters of high temperature chimneys, each about 50 m in diameter. Two of these clusters have a basal sulfide mound. There is obvious structural control of many of the vents - many lie along or in line with distinct fissures or small faults and the entire field appears to have developed within a shallow graben formed on the ridge flank. Most of the chimneys consist of relatively friable sulfates (barite/anhydrite) that vent clear fluid at up to about 290°C. Several larger active chimneys consist primarily of sulfide minerals that emit gray smoke with temperatures as high as 312§ C. Biologic communities were primarily associated with the more stable sulfide structures. The mixture of proven technology used from a capable surface vessel during the 2002 Explorer Ridge program, including a cutting edge deep AUV and a large ROV, provided the tools to explore a little-known site at a full range of scales in a short amount of time and collect invaluable samples for research. These initial data sets from the 2002 exploration program set the stage for more detailed studies of this unique hydrothermal system in the future.

  7. Reconstitution of fluid paleo-circulations and element migrations in the environments of Oklo's natural nuclear reactors (Gabon) and of Tournemire's argillites (France)

    International Nuclear Information System (INIS)

    low to moderately saline (3-18 wt% NaCl) fluids with higher temperatures (200-550 deg. C), containing traces of O2, CH4 and CO2 are related to the reactors functioning and cooling with local silicification events. During the last compressional phase, the fluid paleo-circulations are mainly responsible of barren calcite crystallization (δ13C= 0 to -5 0/00 vs. PDB). (2) The Toarcian shales from experimental IPSN site in the Tournemire tunnel (Aveyron, France). Four mineral parageneses (calcite, calcite and framboidal pyrite, calcite and cubic pyrite, and calcite and barite) have been distinguished in fractures induced by compressional Pyrenean tectonic activities. The major- and trace-element contents, and the 87Sr/86Sr isotopic ratios (0.70847-0.70852) of the vein calcite are buffered by the surrounding shales, strongly suggesting short-distance migrations of the elements considered. Low uranium and high iron contents of the vein calcite suggest circulation of reducing fluids. However, an external origin for the carbonate fillings of the main fault, obtained with 87Sr/86Sr isotopic ratios (0.70841 and 0.70858), and of positive Eu anomalies in the REE patterns, cannot be excluded. This study shows that the competition between chemical aggressiveness of diagenetic fluids and buffering from surrounding rocks, with P-T conditions control determine or regulate the scale of element migration which has been important at Oklo and moderate at Tournemire. (author)

  8. Geology and geochemistry of jasperoids from the Gold Bar district, Nevada

    Science.gov (United States)

    Yigit, Ozcan; Hofstra, Albert H.; Hitzman, Murray W.; Nelson, Eric P.

    2006-09-01

    composition of jasperoids indicates that gold was introduced by the 18O-enriched fluid. The lowest calculated δ18O value for water in equilibrium with late-ore-stage quartz at 200°C (-15‰) and the measured δD value of fluid inclusion water extracted from late-ore-stage orpiment and realgar (-116‰) indicate that the 18O-depleted fluid was composed of relatively unexchanged meteoric water. The source of the 18O-enriched ore fluid is not constrained. The δ34S values of late-ore-stage realgar, orpiment, and stibnite (5.7-15.5‰) and barite (31.5-40.9‰) suggest that H2S and sulfate were derived from sedimentary sources. Likewise, the δ13C and δ18O values of late-stage calcite (-4.8 to 1.5‰ and 11.5 to 17.4‰, respectively) suggest that CO2 was derived from marine limestones. Based on these data and the apparent absence of any Eocene intrusions in the district, Gold Bar may be the product of a nonmagmatic hydrothermal system.

  9. Chemical composition of modern and fossil Hippopotamid teeth and implications for paleoenvironmental reconstructions and enamel formation - Part 2: Alkaline earth elements as tracers of watershed hydrochemistry and provenance

    Science.gov (United States)

    Brügmann, G.; Krause, J.; Brachert, T. C.; Stoll, B.; Weis, U.; Kullmer, O.; Ssemmanda, I.; Mertz, D. F.

    2012-03-01

    /Sr ranging from 0.1 to 3. This ratio varies on spatial and temporal scales and traces provenance signals as well as the fractionation of the elements in the hydrological cycle. Thus, Sr concentrations and Ba/Sr in enamel differentiate between habitats having basaltic or Archean crustal rocks as the ultimate sources of Sr and Ba. The provenance signal is modulated by climate change. In Miocene to Pleistocene enamel from the Lake Albert region, Ba/Sr decreases systematically with time from about 2 to 0.5. This trend can be correlated with changes in climate from humid to arid in vegetation from C3 to C4 biomass as well as with increasing evaporation of the lake water. The most plausible explanation is that with time, Ba mobility decreased relative to that of Sr. This can arise if preferential adsorption of Ba to clay and Fe-oxide-hydroxide is related to increasing aridification. Additionally, weathering solutions and lake water can become increasingly alkaline and barite becomes stable. In this case, Ba will be preferentially deposited on the watershed of Lake Albert and rivers with low Ba/Sr will feed the habitats of the Hippopotamids.

  10. Characterization and modes of occurrence of elements in feed coal and coal combustion products from a power plant utilizing low-sulfur coal from the Powder River Basin, Wyoming

    Science.gov (United States)

    Brownfield, Michael E.; Cathcart, James D.; Affolter, Ronald H.; Brownfield, Isabelle K.; Rice, Cynthia A.; O'Connor, Joseph T.; Zielinski, Robert A.; Bullock, John H., Jr.; Hower, James C.; Meeker, Gregory P.

    2005-01-01

    The U.S. Geological Survey and the University of Kentucky Center for Applied Energy Research are collaborating with an Indiana utility company to determine the physical and chemical properties of feed coal and coal combustion products from a coal-fired power plant. The Indiana power plant utilizes a low-sulfur (0.23 to 0.47 weight percent S) and lowash (4.9 to 6.3 weight percent ash) subbituminous coal from the Wyodak-Anderson coal zone in the Tongue River Member of the Paleocene Fort Union Formation, Powder River Basin, Wyoming. Based on scanning electron microscope and X-ray diffraction analyses of feed coal samples, two mineral suites were identified: (1) a primary or detrital suite consisting of quartz (including beta-form grains), biotite, feldspar, and minor zircon; and (2) a secondary authigenic mineral suite containing alumino-phosphates (crandallite and gorceixite), kaolinite, carbonates (calcite and dolomite), quartz, anatase, barite, and pyrite. The primary mineral suite is interpreted, in part, to be of volcanic origin, whereas the authigenic mineral suite is interpreted, in part, to be the result of the alteration of the volcanic minerals. The mineral suites have contributed to the higher amounts of barium, calcium, magnesium, phosphorus, sodium, strontium, and titanium in the Powder River Basin feed coals in comparison to eastern coals. X-ray diffraction analysis indicates that (1) fly ash is mostly aluminate glass, perovskite, lime, gehlenite, quartz, and phosphates with minor amounts of periclase, anhydrite, hematite, and spinel group minerals; and (2) bottom ash is predominantly quartz, plagioclase (albite and anorthite), pyroxene (augite and fassaite), rhodonite, and akermanite, and spinel group minerals. Microprobe and scanning electron microscope analyses of fly ash samples revealed quartz, zircon, and monazite, euhedral laths of corundum with merrillite, hematite, dendritic spinels/ferrites, wollastonite, and periclase. The abundant calcium and

  11. Caracterización hidroquímica y análisis de los estados de equilibrio termodinámico en aguas termominerales de Alhama de Murcia (Murcia, Espana

    Directory of Open Access Journals (Sweden)

    Padilla Benítez, A.

    1993-04-01

    Full Text Available The principal physico-chemical characteristics of sorne thermomineral waters of Alhama de Murcia detrital aquifer are studied. The waters show a temperature between 26-41 °C and they are calcium-magnesium chloride-sulphate type. The origin of ions has a direct relationship with the dissolution of evaporitic sulphate-chloride salts, carbonatic and silica rocks, agricultural contamination processes and possibly ore-deposits. Mixing processes with cold waters possibly also occur. By SOLMINEQ.88 program the thermodinamic equilibrium conditions in surface are studied; the samples are saturated in quartz, chalcedony and albite. A great part of the waters are also saturated in calcite, aragonite, dolomite, gypsum, barite and magnesite. Finally, the waters are undersaturated in cristobalite, anhydrite and fluorite. Conventional chemical geothermometers yield a broad range of temperatures. Both, calcite-dolomite and anhydrite-fluorite geothermometers was applied to two samples with anomalous results. The saturation index modeling, at a series of growing temperatures, shows an approach equilibrium with quartz, chalcedony, albite, sanidine, gipsum, anhydrite, gibbsite and halloisite between 80-110 °C. A spread in the apparent equilibration temperatures deduced from two metodology, should be a consequence of dilution by surface waters, effects of re-equilibration of minerals with waters and CO2 loss. Temperature and chemical composition of the waters shows a thermal anomaly directly related with the tectonic activity in the area.Se estudian las principales características físico-químicas de algunas aguas termominerales del acuífero detrítico de Alhama de Murcia cuya temperatura está comprendida entre 26 y 41 °C y son de facies clorurada-sulfatada cálcico-magnésica. El origen de los iones encontrados está relacionado con la disolución de materiales evaporíticos, sales sulfatadas y cloruradas, carbonatados y silicatados, procesos de

  12. El proyecto de El Berrocal: síntesis preliminar

    Directory of Open Access Journals (Sweden)

    Pardillo, J.

    1993-08-01

    Full Text Available El Berrocal is an international research project on the natural radionuclide migration in a fissured granitic environment. This project is being carried out in the El Berrocal zone, north of the village of Nombela (Toledo. The gelogical formation studied is a granitic pluton with an epithermal vein-type mineralization comprising quartz, sphalerite, pyrite and chalcopyrite; and pitchblende, pyrite, carbonates and barite. The activities of the project are focused on the structural, lithological, geochemical, hydrochemical and hydrogeological aspects of the granite-U mineralization system, in order to establish a migration model of the natural radionuclides of the environment. The concurrence of the tectonic, hydrothermal and supergenic processes has originated several U remobilizations during the deuteric, hydrothermal and supergenic alteration phases, which affected the system. These phases are responsible of the mineralogical species and present distribution of this element within the system. The Th remobilization is much more limited, due to its different geochemical behavior. The present water-rock interaction processes account for the different types of water existing in the system, which are sulphatic, in the shallowest zones, and calcium bicarbonated in the deepest. The U contents in these waters vary from 1 to 100 ppb. The hydrogeology of the zone is controlled, at a local scale, by the topography and the fracture network, and the mineralized quartz dyke plays a major role on the groundwater flow. The isotopic analyses of the U and Th series in the infill materials seem to indicate recent sorption-desorption U processes and coprecipitation with carbonates.«El Berrocal», es un proyecto internacional de investigación sobre la migración de radionucleidos naturales en un medio granítico fisurado. Este proyecto se está desarrollando en la zona de El Berrocal, situada al norte de Nombela (Toledo, en un plutón granítico con una

  13. Site investigation SFR. Water-rock interaction and mixing modelling in the SFR

    Energy Technology Data Exchange (ETDEWEB)

    Gimeno, Maria J.; Auque, Luis F.; Gomez, Javier B.; Acero, Patricia (University of Zaragoza (Spain))

    2011-10-15

    the major geochemical processes controlling the behaviour of variables such as pH and Eh and, in general, all the parameters controlled by microbial or water-rock interaction processes. Thus, an integration of the mineralogical and microbiological data has also been performed. The other aim is to characterise the mixing processes that have affected the groundwaters over time. Thus, a statistical analysis has been performed with M3 in order to obtain a more quantitative approach to the mixing processes in the system, as well as to provide a mathematical basis to take into account all the variability of the system and to evaluate the reliability of the categorised groundwater types which are based on expert judgement (Nilsson et al. 2010). Therefore, this report should be considered as a supporting document to the final hydrogeochemical site description version 1.0 (Nilsson et al. 2011). Most of the main geochemical characters and trends observed in the SFR groundwaters are similar to those observed at Forsmark, especially if only groundwaters with marine contributions are compared. This applies to the carbonate, sulphate, silica and fluoride systems. No clear pH trend with depth has been found in these waters which may reflect the lateral heterogeneity of the groundwater system. The high and variable HCO{sub 3}{sup -} values found in groundwaters with a marine signature seem to be the result of the biological activity during infiltration of marine waters through seabed sediments. Calcite equilibrium is the main pH controlling process, and its presence has been detected at all depths. Marine waters are the main source of sulphur, and neither heterogeneous reactions with sulphate minerals (undersaturated, in the case of gypsum or in equilibrium in the case of barite), nor sulphate reducing microbial activity have played an important role on the control of dissolved sulphate concentrations (conditioned, therefore, mainly by mixing). Dissolved silica and fluoride

  14. Contribución al conocimiento de las mineralizaciones Pb-Zn del tipo Reocín en el sector oeste de Cantabria

    Directory of Open Access Journals (Sweden)

    Bustillo Revuelta, M.

    1985-08-01

    Full Text Available The lead-zinc mineralizations from Western Cantabria are studied in this paper, mainly from a petrological and geochemical point of view. The host rocks are mesozoic dolomites which present some outstanding evidences: cavernous aspect, irregular distribution, coarsegrained, relict texture with ghosts and cloudy centers, and low geochemical content in Sr (50 ppm and high in Mn and Fe (1200 ppm and 4%. respectively, These characteristics aIlow classify them as originated by late diagenetic dolomitization processes.
    The primary ores are sphalerite, galena, pyrite, marcasite , and sometimes barite. These minerals fill cavities and other open spaces, being the most important texture composed by altemating bands of sphalerite of different colour ("colloform texture" with scattered crystals of galena, pyrite, and marcasite, The general morphology is tipically stratabound and not stratiform. The secondary minerals, product of weathering, inelude smithsonite from sphalerite, cerussite from galena, and goethite from pyrite and marcasite.
    The characteristics of the host rocks and mineralizations show they were formed epigenetically, with existence of a source rock, migration of mineralizating solutions and deposition of them in a host rock of dolomitic character.

    En este trabajo se hace un estudio de las mineralizaciones Pb-Zn del tipo Reocín en Cantabria, principalmente desde un punto de vista petrológico y geoquímico. Las rocas encajantes de las mineralizaciones son dolomías mesozoicas que poseen algunas características remarcables: aspecto cavernoso, estratificación difusa, distribución irregular, cristales de gran tamaño, 'textura relicta con existencia de fantasmas y "cloudy centers" y un bajo con tenido en estroncio (50 ppm. y alto en hierro y manganeso (4% y 1.200 ppm ., respectivamente. Estas características permiten clasificarlas como originadas por procesos de dolomitización diagenéticos tardíos.
    Las

  15. Ultra-oxidized redox conditions in subduction mélanges? Decoupling between oxygen fugacity and oxygen availability in a metasomatic environment

    Science.gov (United States)

    Tumiati, Simone; Poli, Stefano; Godard, Gaston; Martin, Silvana; Malaspina, Nadia

    2014-05-01

    The manganese ore of Praborna (Italian Western Alps) is embedded within a metasedimentary sequence belonging to a subduction mélange equilibrated