WorldWideScience

Sample records for barite

  1. Barite

    Science.gov (United States)

    Miller, M.

    2011-01-01

    The article discusses the latest developments in the barite or baryte industry, particularly in the U.S., as of June 2011. It claims that the bulk of barites production in the country comes from four mines in Nevada, including the Big Ledge Mine, the Rossi Mine and the Greystone Mine. It cites that barite is mainly used as a weighting agent in natural gas and oil field drilling muds. Barite is also utilized as filler, extender or weighting agent in such products as paints, plastics and rubber.

  2. Barite (Barium)

    Science.gov (United States)

    Johnson, Craig A.; Piatak, Nadine M.; Miller, M. Michael; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    Barite (barium sulfate, BaSO4) is vital to the oil and gas industry because it is a key constituent of the mud used to drill oil and gas wells. Elemental barium is an additive in optical glass, ceramic glazes, and other products. Within the United States, barite is produced mainly from mines in Nevada. Imports in 2011 (the latest year for which complete data were available) accounted for 78 percent of domestic consumption and came mostly from China.Barite deposits can be divided into the following four main types: bedded-sedimentary; bedded-volcanic; vein, cavity-fill, and metasomatic; and residual. Bedded-sedimentary deposits, which are found in sedimentary rocks with characteristics of high biological productivity during sediment accumulation, are the major sources of barite production and account for the majority of reserves, both in the United States and worldwide. In 2013, China and India were the leading producers of barite, and they have large identified resources that position them to be significant producers for the foreseeable future. The potential for undiscovered barite resources in the United States and in many other countries is considerable, however. The expected tight supply and rising costs in the coming years will likely be met by increased production from such countries as Kazakhstan, Mexico, Morocco, and Vietnam.Barium has limited mobility in the environment and exposed barium in the vicinity of barite mines poses minimal risk to human or ecosystem health. Of greater concern is the potential for acidic metal-bearing drainage at sites where the barite ores or waste rocks contain abundant sulfide minerals. This risk is lessened naturally if the host rocks at the site are acid-neutralizing, and the risk can also be lessened by engineering measures.

  3. the chemical composition and industrial quality of barite ...

    African Journals Online (AJOL)

    PROF EKWUEME

    compares favourably with the Azara barite deposits of the Benue Trough. The quality of the barite meets American. Petroleum institute (API) requirements for use as drilling mud. KEYWORDS: Barite, mineralization, quality, chemical composition, southeastern Nigeria. INTRODUCTION. A typical barite sample is expected to ...

  4. Microbially mediated barite dissolution in anoxic brines

    International Nuclear Information System (INIS)

    Ouyang, Bingjie; Akob, Denise M.; Dunlap, Darren; Renock, Devon

    2017-01-01

    Fluids injected into shale formations during hydraulic fracturing of black shale return with extraordinarily high total-dissolved-solids (TDS) and high concentrations of barium (Ba) and radium (Ra). Barite, BaSO 4 , has been implicated as a possible source of Ba as well as a problematic mineral scale that forms on internal well surfaces, often in close association with radiobarite, (Ba,Ra)SO 4 . The dissolution of barite by abiotic processes is well quantified. However, the identification of microbial communities in flowback and produced water necessitates the need to understand barite dissolution in the presence of bacteria. Therefore, we evaluated the rates and mechanisms of abiotic and microbially-mediated barite dissolution under anoxic and hypersaline conditions in the laboratory. Barite dissolution experiments were conducted with bacterial enrichment cultures established from produced water from Marcellus Shale wells located in northcentral Pennsylvania. These cultures were dominated by anaerobic halophilic bacteria from the genus Halanaerobium. Dissolved Ba was determined by ICP-OES and barite surfaces were investigated by SEM and AFM. Our results reveal that: 1) higher amounts of barium (up to ∼5 × ) are released from barite in the presence of Halanaerobium cultures compared to brine controls after 30 days of reaction, 2) etch pits that develop on the barite (001) surface in the presence of Halanaerobium exhibit a morphology that is distinct from those that form during control experiments without bacteria, 3) etch pits that develop in the presence of Halanaerobium exhibit a morphology that is similar to the morphology of etch pits formed in the presence of strong organic chelators, EDTA and DTPA, and 4) experiments using dialysis membranes to separate barite from bacteria suggest that direct contact between the two is not required in order to promote dissolution. These results suggest that Halanaerobium increase the rate of barite dissolution in anoxic

  5. Durability of heavyweight concrete containing barite

    International Nuclear Information System (INIS)

    Binici, Hanifi

    2010-01-01

    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.)

  6. The chemical composition and industrial quality of Barite ...

    African Journals Online (AJOL)

    The chemical composition and industrial quality of Barite mineralization in Calabar flank, Oban Massif, Mamfe embayment and Obudu Plateau, southeastern Nigeria. ... The quality of the barite meets American Petroleum institute (API) requirements for use as drilling mud. KEYWORDS: Barite, mineralization, quality, ...

  7. Occurrence and distribution of barite mineralization in Cross River ...

    African Journals Online (AJOL)

    Shales and sandstones have the greatest occurrence of barite. The mineral occurs as veins trending NE-SW, N-S and NW-SE. They occur in a fracture system cross-cutting the lower Benue Trough axis suggesting a possible genetic relationship with the Azara barite mineralization of Benue Trough which is believed to be of ...

  8. Study on radioactive compounds in barites

    International Nuclear Information System (INIS)

    Cohen, I.M.; Mila, M.I.; Gomez, C.D.

    1981-01-01

    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.) [es

  9. 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.

  10. Properties of heavyweight concrete produced with barite

    International Nuclear Information System (INIS)

    Topcu, Ilker Bekir

    2003-01-01

    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/m 3

  11. 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.

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

    International Nuclear Information System (INIS)

    Campos, E.G.

    1984-01-01

    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) [pt

  13. 60Co γ-ray attenuation coefficient of barite concrete

    International Nuclear Information System (INIS)

    Bouzarjomehri, F.; Bayat, T.; Dashti, M. H.; Ghisari, J.; Abdoli, N.

    2006-01-01

    Recently, the use of medium and high energy X-rays has increased in Iran, and radiotherapy centers along with a variety of accelerators have been installed in some provinces. Hence, there is not sufficient skill in designing and installing radiotherapy treatment rooms. This study was conducted to evaluate the efficacy of different mixtures of barite concrete for shielding the radiotherapy rooms. This way, we have emphasized on determining the size and amount of barite aggregations to achieve the maximum radiation attenuation which leads to minimizing wall thickness in treatment room. Materials and Methods: To increase concrete density, the barite aggregation was added to concrete. Different size variations of barite aggregates mixed with different water/cement ratio were examined. The dimension of cubic concrete specimens for compression strength test was 15*15*15 cm. The rectangular barite concrete blocks with different compressions as used for strength test with cross section of 10*10 cm, and thicknesses from 5 to 40 cm were used for radiation attenuation test. To do so, concrete specimens were irradiated by gamma beam of 60 Co (Phoenix Theratron). The transmission radiation through the blocks was measured by a Farmer ionization chamber (Fc 65 P). Results: Our findings showed that in all specimens the highest mean compression strength was related to the specimens with equal ratio of fine to coarse barite aggregates, but the lowest half value layer was obtained from mixtures with fine to coarse ratio of 35/65. The concrete sample with a 0.45 water/cement ratio, 350 kg/m3 cement and equal amounts of fine and coarse barite sands had nearly minimum half value layer (half value layer), and maximum compression strength, so the sample was considered as the best barite concrete sample. Conclusion: Since half value layer of the barite concrete specimens with the same compression strength is markedly lower than the conventional concrete, and that there are quite a number

  14. Unlocking the Barite Paleoproductivity Proxy: Using a New Barite Extraction Method to Understand Productivity Trends During the Eocene Greenhouse

    Science.gov (United States)

    House, B. M.; Norris, R. D.

    2017-12-01

    The Early Eocene Climatic Optimum (EECO) around 50 Ma was a sustained period of extreme global warmth with ocean bottom water temperatures of up to 12° C. The marine biologic response to such climatic extremes is unclear, however, in part because proxies that integrate ecosystem-wide productivity signals are scarce. While the accumulation of marine barite (BaSO4) is one such proxy, its applicability has remained limited due to the difficulty in reliably quantifying barite. Discrete measurements of barite content in marine sediments are laborious, and indirect estimates provide unclear results. We have developed a fast, high-throughput method for reliable measurement of barite content that relies on selective extraction of barite rather than sample digestion and quantification of remaining barite. Tests of the new method reveal that it gives the expected results for a wide variety of sediment types and can quantitatively extract 10-100 times the amount of barite typically encountered in natural sediments. Altogether, our method provides an estimated ten-fold increase in analysis efficiency over current sample digestion methods and also works reliably on small ( 1 g or less) sediment samples. Furthermore, the instrumentation requirements of this method are minor, so samples can be analyzed in shipboard labs to generate real-time paleoproductivity records during coring expeditions. Because of the magnitude of throughput improvement, this new technique will permit the generation of large datasets needed to address previously intractable paleoclimate and paleoceanographic questions. One such question is how export productivity changes during climatic extremes. We used our new method to analyze globally distributed sediment cores to determine if the EECO represented a period of anomalous export productivity either due to higher rates of primary production or more vigorous heterotrophic metabolisms. An increase in export productivity could provide a mechanism for exiting

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

    International Nuclear Information System (INIS)

    Almeida Junior, Airton Tavares de

    2005-03-01

    Aiming to determine the barium sulphate (BaSO 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 2 and with an average thickness ranging from 1 to 5 cm, and three plates of crystal glass with 323 cm 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 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)

  16. Numerical Simulation of Barite Sag in Pipe and Annular Flow

    Directory of Open Access Journals (Sweden)

    Patrick Kabanda

    2017-01-01

    Full Text Available With the ever increasing global energy demand and diminishing petroleum reserves, current advances in drilling technology have resulted in numerous directional wells being drilled as operators strive to offset the ever-rising operating costs. In as much as deviated-well drilling allows drillers to exploit reservoir potential by penetrating the pay zone in a horizontal, rather than vertical, fashion, it also presents conditions under which the weighting agents can settle out of suspension. The present work is categorized into two parts. In the first part, governing equations were built inside a two-dimensional horizontal pipe geometry and the finite element method utilized to solve the equation-sets. In the second part, governing equations were built inside a three-dimensional horizontal annular geometry and the finite volume method utilized to solve the equation-sets. The results of the first part of the simulation are the solid concentration, mixture viscosity, and a prediction of the barite bed characteristics. For the second part, simulation results show that the highest occurrence of barite sag is at low annular velocities, nonrotating drill pipe, and eccentric drill pipe. The CFD approach in this study can be utilized as a research study tool in understanding and managing the barite sag problem.

  17. Diagenetic behavior of barite in a coastal upwelling setting

    Science.gov (United States)

    Hendy, I. L.

    2010-12-01

    Multiproxy data from ODP Hole 1017E (Point Conception, California) provide an excellent opportunity to examine the behavior of barium, within a well-characterized sedimentary system. Bariumexcess is generally considered to be a productivity proxy; however, in nearshore environments, Baexcess records can be compromised by both sediment provenance and barite remobilization. For the last 60 kyr, ODP Hole 1017E exhibits significant changes both in primary productivity driven by coastal upwelling and in the sediment redox chemistry of underlying sediments. Significant barite enrichment occurs at an active diagenetic front that marks the boundary between sulfate-rich and sulfate-poor pore waters. This boundary also intersects a sediment facies change from deposition of relatively coarse-grained sediment before 35 ka to an interval of fine-grained, organic-rich sediment after (i.e., Interstadial Event 8). Changes in diffusion rates associated with the sediment facies change cause a strong but misleading correlation between a mobile zone of barite enrichment and rapid climate change. Thus, within the Baexcess record at ODP Hole 1017E is a history of redox chemistry that has corrupted the paleoproductivity record of Babiogenic.

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

    International Nuclear Information System (INIS)

    Toyoda, Shin; Sato, Fumihiro; Nishido, Hirotsugu; Kayama, Masahiro; Ishibashi, Jun-Ichiro

    2012-01-01

    The alpha effectiveness was investigated for an ESR signal due to SO 3 − 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 SO 3 − 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.

  19. 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.

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

    International Nuclear Information System (INIS)

    Kilinçarslan, Ş.; Akkurt, İ.; Molla, T.; Akarslan, F.

    2012-01-01

    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.

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

    Science.gov (United States)

    Kilinçarslan, Ş.; Akkurt, İ.; Molla, T.; Akarslan, F.

    2012-09-01

    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.

  2. Subtask 1.23 - Mercury Removal from Barite the Oil Industry

    Energy Technology Data Exchange (ETDEWEB)

    Michael Holmes; Carolyn Nyberg; Katie Brandt; Kurt Eylands; Nathan Fiala; Grant Dunham

    2008-09-01

    Drilling muds are used by the oil and gas industry to provide a seal and to float rock chips to the surface during the drilling process. Barite (naturally occurring barium sulfate ore) is commonly used as a weighting agent additive in drilling muds because it is chemically nonreactive and has a high specific gravity (between 4.2 and 4.25 at 20 C). Because of environmental concerns, barite used by the oil and gas industry in the Gulf of Mexico must be certified to contain less than 1 mg/kg of mercury. Faced with these regulations, the U.S. Gulf Coast oil industry has looked to foreign sources of low-mercury barite, primarily India and China. These sources tend to have high-grade barite deposits and relatively inexpensive domestic transportation costs; as of late, however, U.S. purchasers have been forced to pay increasing costs for shipping to U.S. grinding plants. The objective of this project was to demonstrate two mercury removal techniques for high-mercury barite sources. Two barite samples of unique origins underwent processing to reduce mercury to required levels. The chemical treatment with dilute acid removed a portion of the mercury in both barite samples. The desired concentration of 1 mg/kg was achieved in both barite samples. An economic analysis indicates that thermal removal of mercury would not significantly add to the cost of barite processing, making higher-mercury barite a viable alternative to more expensive barite sources that contain lower concentrations of mercury.

  3. Study on Mechanical Properties of Barite Concrete under Impact Load

    Science.gov (United States)

    Chen, Z. F.; Cheng, K.; Wu, D.; Gan, Y. C.; Tao, Q. W.

    2018-03-01

    In order to research the mechanical properties of Barite concrete under impact load, a group of concrete compression tests was carried out under the impact load by using the drop test machine. A high-speed camera was used to record the failure process of the specimen during the impact process. The test results show that:with the increase of drop height, the loading rate, the peak load, the strain under peak load, the strain rate and the dynamic increase factor (DIF) all increase gradually. The ultimate tensile strain is close to each other, and the time of impact force decreases significantly, showing significant strain rate effect.

  4. Role of bacteria in marine barite precipitation : A case study using Mediterranean seawater

    NARCIS (Netherlands)

    Torres-Crespo, N.; Martínez-Ruiz, F.; González-Muñoz, M. T.; Bedmar, E. J.; De Lange, G. J.; Jroundi, F.

    2015-01-01

    Marine bacteria isolated from natural seawater were used to test their capacity to promote barite precipitation under laboratory conditions. Seawater samples were collected in the western and eastern Mediterranean at 250. m and 200. m depths, respectively, since marine barite formation is thought to

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

    DEFF Research Database (Denmark)

    Zhen Wu, Bi Yun

    dependence of Pitzer parameters for NaCl, Na2SO4 and BaCl2 were derived from published osmotic coefficient data (PhD Study 2). Furthermore, barite solubility was determined experimentally at 90 °C and pressures of 150 and 250 bar. Comparison of barite solubilities calculated with the Pitzer model...... of this 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 90 C at 1 bar of pressure. Resulting thermodynamic and kinetic parameters were combined and coupled with PHREEQC to predict precipitation scaling rates in three oil production wells, where barite has been observed. Average linear growth rates of 3, 2.5 and 2 mm of barite per year were estimated...

  6. Fundamental insights into the radium uptake into barite by atom probe tomography and electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Juliane

    2017-10-01

    Recently, the Ba{sub x}Ra{sub 1-x}SO{sub 4} solid solution has been investigated with regard to its applicability to the long-term safety of spent nuclear fuel (SNF) disposal. As {sup 226}Ra originates from the U decay chain, its concentration in SNF builds up with time. In some scenarios for the direct disposal of SNF taken from the Swedish license application for a final SNF repository, {sup 226}Ra dominates the dose after 100,000 years. Currently, the solubility of {sup 226}Ra is considered to be controlled by the formation of Ra-SO{sub 4} in the Swedish license application as the Ba{sub x}Ra{sub 1-x}SO{sub 4} solid solution characteristics were not sufficiently investigated at the point of submission. The Ba{sub x}Ra{sub 1-x}SO{sub 4} solid solution could be considered as solubility controlling phase for Ra if the uptake mechanism of Ra into barite was understood in more detail. Barite can occur as a primary phase in the surrounding of the future repository or as a secondary phase within nuclear waste due to the different positions of Ba and Ra within SNF. In the case of SNF corrosion, Ba would come in contact with water first. Sulfate-containing water would lead to barite precipitation. Therefore, a system is most likely where pre-existing barite is in equilibrium with an aqueous solution into which Ra then enters. Recent studies comprising long-term batch recrystallization experiments propose a kinetically influenced uptake of Ra into barite that equilibrates into a thermodynamically controlled situation within 800 days. This thesis provides the first detailed four-dimensional characterization of the Ra uptake into barite by combining three-dimensional sample characterization with the temporal evolution. To understand the mechanism of Ra uptake into barite, two types of barites (SL and AL barite) obtained from batch recrystallization experiments of previous studies were characterized prior to, during and after the Ra uptake. A combination of different state

  7. Fundamental insights into the radium uptake into barite by atom probe tomography and electron microscopy

    International Nuclear Information System (INIS)

    Weber, Juliane

    2017-01-01

    Recently, the Ba x Ra 1-x SO 4 solid solution has been investigated with regard to its applicability to the long-term safety of spent nuclear fuel (SNF) disposal. As 226 Ra originates from the U decay chain, its concentration in SNF builds up with time. In some scenarios for the direct disposal of SNF taken from the Swedish license application for a final SNF repository, 226 Ra dominates the dose after 100,000 years. Currently, the solubility of 226 Ra is considered to be controlled by the formation of Ra-SO 4 in the Swedish license application as the Ba x Ra 1-x SO 4 solid solution characteristics were not sufficiently investigated at the point of submission. The Ba x Ra 1-x SO 4 solid solution could be considered as solubility controlling phase for Ra if the uptake mechanism of Ra into barite was understood in more detail. Barite can occur as a primary phase in the surrounding of the future repository or as a secondary phase within nuclear waste due to the different positions of Ba and Ra within SNF. In the case of SNF corrosion, Ba would come in contact with water first. Sulfate-containing water would lead to barite precipitation. Therefore, a system is most likely where pre-existing barite is in equilibrium with an aqueous solution into which Ra then enters. Recent studies comprising long-term batch recrystallization experiments propose a kinetically influenced uptake of Ra into barite that equilibrates into a thermodynamically controlled situation within 800 days. This thesis provides the first detailed four-dimensional characterization of the Ra uptake into barite by combining three-dimensional sample characterization with the temporal evolution. To understand the mechanism of Ra uptake into barite, two types of barites (SL and AL barite) obtained from batch recrystallization experiments of previous studies were characterized prior to, during and after the Ra uptake. A combination of different state-of-the-art high-resolution microscopy techniques was used to

  8. Bioaccessibility of barium from barite contaminated soils based on gastric phase in vitro data and plant uptake.

    Science.gov (United States)

    Abbasi, Sedigheh; Lamb, Dane T; Palanisami, Thavamani; Kader, Mohammed; Matanitobua, Vitukawalu; Megharaj, Mallavarapu; Naidu, Ravi

    2016-02-01

    Barite contamination of soil commonly occurs from either barite mining or explorative drilling operations. This work reported in vitro data for barite contaminated soils using the physiologically based extraction test (PBET) methodology. The existence of barite in plant tissue and the possibility of 'biomineralised' zones was also investigated using Scanning Electron Microscopy. Soils with low barium (Ba) concentrations showed a higher proportion of Ba extractability than barite rich samples. Barium uptake to spinach from soil was different between short term spiking studies and field weathered soils. Furthermore, Ba crystals were not evident in spinach tissue or acid digest solutions grown in barium nitrate spiked soils despite high accumulation. Barite was found in the plant digest solutions from barite contaminated soils only. Results indicate that under the conservative assumptions made, a child would need to consume extreme quantities of soil over an extended period to cause chronic health problems. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Spectroscopic study of barite from the Kremikovtsi Deposit (Bulgaria with implication for its origin

    Directory of Open Access Journals (Sweden)

    Dimova Maya

    2006-01-01

    Full Text Available Different genetic types (endogene and supergene of barite from the Kremikovtsi deposit (Bulgaria were studied by Laser-induced time-resolved luminescence (LITRL, Infrared (IR and Raman spectroscopy. The IR spectra of the endogene barites are quite similar to those reported in the literature and do not show appreciable differences among them. The IR spectra of the supergene barites are almost identical to those of the endogene ones in respect to the positions of the vibrational modes ν1, ν2 and ν4 of SO4 2 except for a shift of 3 cm-1 for the ν 3 band. They displayed a presence of additional bands, which are close to the ν3 and ν1 modes of CO3 2- in calcite. The Raman studies support the suggestion that the supergene barite contains traces of calcite. The modern LITRL technique allowed the detection of several luminescent centers in the endogene barite. Eu3+ luminescence was identified for the first time in barite. The different emission spectra at 266 and 532 nm excitations suggest there are at least 2 structural positions for Eu3+ in the barite crystal lattice. The luminescent spectra also revealed a rather unusual violet-blue Nd3+ emission, which usually occurs in the IR spectral range, as well as emissions of Ce3+, Eu2+, Tb3+, Ag+, Sn2+(? and UO2 2+. The oxidation state of cations isomorphically present in the barite crystal lattice suggests the endogene barite in the Kremikovtsi deposit precipitated from reduced fluids supposedly subjected to cooling (conductive/convective and oxidation (mixing with seawater.

  10. 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

  11. Barite mineralization in Kalana speleothems, Central Estonia: Sr, S and O isotope characterization

    Directory of Open Access Journals (Sweden)

    Mikk Gaškov

    2017-06-01

    Full Text Available Barite mineralization in association with calcitic speleothem precipitates in cave structures in Silurian Aeronian carbonate rocks in Kalana quarry, Central Estonia, was studied. Barite mineralization in Kalana occurs in two generations – euhedral bladed-tabular barite zonal crystals from a few to 10 cm in size, growing on the limestone-dolomite wall-rock (generation I, and sparsely placed thin tabular crystals a few millimetres thick and up to 1 cm in size, growing on calcitic crusts (generation II. The barite crystals of generation I are frequently found embedded by paragenetically later calcitic botryoidal crusts. The Sr and S isotopic composition of barite crystals shows a trend of increasing Sr isotope ratios (from 0.7114 to 0.7120 and δ34S values (from 13‰ to 33‰ from the central parts towards the edges of zonal crystals. This suggests barite precipitation by mixing of two endmember fluids at varying ratios during barite formation: warm (up to 70 °C reducing fluid bearing Ba, characterized by an elevated radiogenic Sr- and 34S-enriched isotopic signal, and a cooler ambient fluid bearing an isotopically lighter dissolved sulphate, characterized by lower Sr isotope ratios. The excess of radiogenic 87Sr in barite compared to Phanerozoic seawater values suggests Sr derived from a continental source, whereas sulphate was derived either from oxidized H2S or a modified seawater source. Gradual increase in δ34S values towards the outer zones could also indicate the 34S enrichment due to bacterial sulphate reduction, even though there is no paired 34S and 18O enrichment of sulphate, characteristic of bacterial reworking. This can be interpreted as indicating an open system with limited sulphate resupply where the δ18O composition of sulphate was equilibrated with warm ascending hydrothermal fluid.

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

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    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

  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.

    2007-01-01

    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% BaSO4, 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. Selective Separation of Fluorite, Barite and Calcite with Valonea Extract and Sodium Fluosilicate as Depressants

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    Zijie Ren

    2017-02-01

    Full Text Available Fluorite, barite and calcite are important industry minerals. However, they often co-exist, presenting difficulty in selectively separating them due to their similar surface properties. In this study, valonea extract and sodium fluosilicate were used as depressants to selectively separate them by flotation, with sodium oleate as the collector. The single mineral flotation results showed that valonea extract displayed the strongest depression on calcite, while sodium fluosilicate displayed the strongest depression on barite. These two depressants allowed selective separation of the three minerals through sequential flotation. The flotation of mixed minerals showed that 94% of the calcite was successfully depressed by the valonea extract, and 95% recovery of the fluorite was achieved in the subsequent flotation with sodium fluosilicate depressing barite. The different depressant–mineral interactions were investigated via electro-kinetic studies and molecular dynamics (MD simulations using the Materials Studio 6.0 program. The valonea extract exhibited the strongest adsorption on the calcite surface, and sodium fluosilicate exhibited the strongest adsorption on the barite surface, which prevented oleate species from reacting with Ca2+ or Ba2+ surface sites. This study provides useful guidance for how to process fluorite, barite and calcite resources.

  15. Comparison of some sediment-hosted, stratiform barite deposits in China, the United States, and India

    Science.gov (United States)

    Clark, S.H.B.; Poole, F.G.; Wang, Z.

    2004-01-01

    Shifts in world barite production since the 1980s have resulted in China becoming the world's largest barite-producing country followed by the US and India. Most barite produced for use in drilling fluids is derived from black shale- and chert-hosted, stratiform marine deposits. In China, Late Proterozoic to Early Cambrian marine barite deposits occur on the oceanic margins of the Yangtze platform, in the Qinling region in the north and the Jiangnan region in the south. Most US ore-grade deposits are in the Nevada barite belt; most commercial deposits occur in Ordovician and Devonian marine rocks along the western margin of the early Paleozoic North American continent. Production in India is predominantly from a single Middle Proterozoic deposit in a sedimentary basin located on Archean basement in Andrah Pradesh.The geologic and geochemical characteristics of the deposits are consistent with origins from a variety of sedimentary-exhalative processes, with biogenic processes contributing to the concentration of some seafloor barite. Linear distributions of clusters of lenticular deposits suggest a geographic relationship to syndepositional seafloor fault zones. Sulfur isotope data of the barite deposits range from values that are similar to coeval seawater sulfate to significantly higher ??34S values. Strontium isotope values of continental-margin-type deposits in Nevada and China are less radiogenic than those of cratonic-rift deposits (e.g. Meggen and Rammelsberg). Comparison of Lan/ Cen ratios of barite in the Qinling region of China with marine chert ratios suggests a relationship to hydrothermal fluids, whereas ratios from the Jiangnan region and Nevada can be interpreted as reflecting a biogenic influence.The California Borderland provides a potential modern analog where hydrothermal barium is being deposited on the seafloor in fault-block-bounded basins. Anoxic to dysaerobic conditions on some marine basin floors result from upwelling, nutrient-rich currents

  16. Influence of the barite tenors of the Jaicos, Piaui, Brazil, clays on the ceramic properties of electric insulator porcelains

    International Nuclear Information System (INIS)

    Correa, W.L.P.; Lima, M.B.; Carvalho, F.M.S.

    2009-01-01

    The clays of the Municipality of Jaicos, Piaui, has been used as raw materials for the manufacture of insulators for company located in the municipality of Pedreira - Sao Paulo. It can be noticed in the clay blocks and consolidated, 'lenses' of barite. The mineralogical composition of clay and the nature of these 'lenses' were studied by chemical analysis, X-ray diffraction for mineralogical characterization. The clays are composed primarily by kaolinite, quartz, and some amount of illite and orthoclase. The presence of orthoclase does believe in a recent deposition of these clays. The 'lenses' were characterized as barite, BaSO 4 . To check the influence of barite in the composition of bodies of porcelain to insulators made up six compositions with different levels of barite, obtained their own clay. It applies, then the tests of ceramic fracture to bending, water absorption, apparent porosity to determine the effect of the introduction of barite in the compositions. (author)

  17. Bioavailability of barium to plants and invertebrates in soils contaminated by barite.

    Science.gov (United States)

    Lamb, Dane T; Matanitobua, Vitukawalu P; Palanisami, Thavamani; Megharaj, Mallavarapu; Naidu, Ravi

    2013-05-07

    Barium (Ba) is a nonessential element to terrestrial organisms and is known to be toxic at elevated concentrations. In this study, the bioavailability and toxicity of Ba in barite (BaSO4) contaminated soils was studied using standard test organisms (Lactuca sativa L. "Great Lakes", Eisenia fetida). Contamination resulted from barite mining activities. Barium concentrations in contaminated soils determined by X-ray fluorescence were in the range 0.13-29.2%. Barite contaminated soils were shown to negatively impact both E. fetida and L. sativa relative to control soil. For E. fetida, pore-water concentrations and acid extractable Ba were linearly related to % body weight loss. In L. sativa, pore-water Ba and exchangeable Ba were both strongly related to shoot Ba and shoot biomass production. A negative linear relationship was observed between shoot Ba content and shoot weight (P Barium concentrations in pore-water were lower than predicted from barite solubility estimates but strongly related to exchangeable Ba, indicating an influence of ion exchange on Ba solubility and toxicity to E. fetida and L. sativa.

  18. The appraisal of a proposed barite quarry in Akpet Area, Cross River ...

    African Journals Online (AJOL)

    Electrical resistivity survey was done at a site at Akpet area, Cross River State to evaluate the subsurface for barite mineralization. Both vertical electrical sounding (VES) and horizontal resistivity profiling (HRP) were performed in conjunction with surface geological mapping in the area. In both VES and HRP, the ...

  19. Comparative study among hydrostatic reduction of invagination with barited enema and saline solution, under echography

    International Nuclear Information System (INIS)

    Ortiz de Neira, Clara Lucia; Jutchenko, Carlos Andres

    1993-01-01

    In this study it is compared the treatment of the intestinal invagination using barited enema and enema with a saline solution under echographic vision, it was found that this last method has a high reliance and lacks of inherent complications to the myosis

  20. Uptake of Ra during the recrystallization of barite: a microscopic and time of flight-secondary ion mass spectrometry study.

    Science.gov (United States)

    Klinkenberg, Martina; Brandt, Felix; Breuer, Uwe; Bosbach, Dirk

    2014-06-17

    A combined macroscopic and microanalytical approach was applied on two distinct barite samples from Ra uptake batch experiments using time of flight-secondary ion mass spectrometry (ToF-SIMS) and detailed scanning electron microscopy (SEM) investigations. The experiments were set up at near to equilibrium conditions to distinguish between two possible scenarios for the uptake of Ra by already existent barite: (1) formation of a Ba1-xRaxSO4 solid solution surface layer on the barite or (2) a complete recrystallization, leading to homogeneous Ba1-xRaxSO4 crystals. It could be clearly shown that Ra uptake in all barite particles analyzed within this study is not limited to the surface but extends to the entire solid. For most grains a homogeneous distribution of Ra could be determined, indicating a complete recrystallization of barite into a Ba1-xRaxSO4 solid solution. The maxima of the Ra/Ba intensity ratio distribution histograms calculated from ToF-SIMS are identical with the expected Ra/Ba ratios calculated from mass balance assuming a complete recrystallization. In addition, the role of Ra during the recrystallization of barite was examined via detailed SEM investigations. Depending on the type of barite used, an additional coarsening effect or a strong formation of oriented aggregates was observed compared to blank samples without Ra. In conclusion, the addition of Ra to a barite at close to equilibrium conditions has a major impact on the system leading to a fast re-equilibration of the solid to a Ba1-xRaxSO4 solid solution and visible effects on the particle size distribution, even at room temperature.

  1. Preparation of TiO2-coated barite composite pigments by the hydrophobic aggregation method and their structure and properties.

    Science.gov (United States)

    Sun, Sijia; Ding, Hao; Zhou, Hong

    2017-08-30

    We obtained hydrophobic barite (BaSO 4 ) and rutile titanium dioxide (TiO 2 ) particles (as raw materials) by organic surface modification. Subsequently, TiO 2 -coated barite composite pigments were prepared via the hydrophobic aggregation of heterogeneous particles in a water medium. The pigment properties of the TiO 2 -coated barite composite pigments were characterized and evaluated by determining their hiding power, oil absorption value and whiteness. The optical properties were determined by obtaining their UV-vis diffuse reflectance spectra and using the CIE-L*a*b* method. The morphology and bonding properties were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and infrared spectroscopy (IR). The results show the similarity between the composite pigment and pure rutile TiO 2 : when the mass ratio of rutile TiO 2 in the composite pigment was 60%, the hiding power of the TiO 2 -coated barite composite pigment was 90.81% of that of pure rutile TiO 2 . Moreover, the surfaces of the barite particles were uniformly and firmly coated by TiO 2 , with a hydrophobic association occurring between the hydrophobic carbon chains on the surfaces of barite and TiO 2 particles.

  2. Structure and Dynamics of Water on Aqueous Barium Ion and the {001} Barite Surface

    International Nuclear Information System (INIS)

    Stack, Andrew G.; Rustad, James R.

    2007-01-01

    The structure of water and its dynamics affect a number of fundamental properties of an interface. Yet, these properties are often inaccessible experimentally and computational studies including solvent are comparatively few. Here, we estimate the structure and kinetics of water exchange of aqueous barium ions and barium ions within the {001} barite surface using molecular dynamics and the reactive flux method. For the aqueous ion, the Ba-O distance to water in the first hydration shell was found to be 280 pm with a coordination number of 8.3, and the best estimate of the exchange rate constant is 4.8 x 10 9 s -1 , closely matching experimental estimates. For the barite surface, the first shell water distance was 282 pm, with a coordination number of 0.9 and the best estimate of the rate constant for exchange is 1.7 x 10 10 s -1 , 3.5 times faster than that of the aqueous ion.

  3. Measurement of properties and of the resistance to segregation in heavyweight, self-compacting barite concrete

    OpenAIRE

    Navarro, D.; Barona, A.; Revuelta, D.

    2009-01-01

    Heavyweight concrete is used for shielding in structures requiring protection against radiation. The addition of superplasticizers to mixes yields workable, high density materials with low water/cement ratios. This paper discusses the results of adding a polycarboxylate-based superplasticizer to heavyweight barite concrete to obtain a self-compacting mix. The fresh properties were characterized with trials suitable for self-compacting concrete. Since the large differences in constituent densi...

  4. X-ray shielding behaviour of kaolin derived mullite-barites ceramic

    Science.gov (United States)

    Ripin, A.; Mohamed, F.; Choo, T. F.; Yusof, M. R.; Hashim, S.; Ghoshal, S. K.

    2018-03-01

    Mullite-barite ceramic (MBC) is an emergent material for effective shielding of redundant ionizing radiation exposure. The composition dependent mechanical, thermal, and microstructure properties of MBC that makes MBC a high performing novel radiation shielding candidate remained unexplored. This paper examines the possibility of exploiting Malaysian kaolin (AKIM-35) and barite (BaSO4) derived ceramic (MBC) system for X-ray shielding operation. Using conventional pressing and sintering method six ceramic samples are prepared by mixing AKIM-35 with barite at varying contents (0, 10, 20, 30, 40 and 50 wt%). Synthesized pressed mixtures are calcined at 400 °C for 30 min and then sintered to 1300 °C for 120 min at a heating rate of 10 °C/min. Sintered samples are characterized via X-ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), lead equivalent (LE), uniformity and dose reduction analyses. XRD pattern of prepared ceramics revealed the presence of monoclinic barium alumino-silicate (BAS) and orthorhombic mullite as major shielding phases together with other minor phase of barite and hexagonal quartz (SiO2) structures. Furthermore, FESEM images of ceramics (between 0 and 30 wt%) displayed the existence of compacted monoclinic plate of BAS and acicular mullite morphology (ceramics at 40 and 50 wt%). Radiation tests displayed the capacity of ceramics (at 0 and 10 wt%) to shield the X-ray radiation emanated at tube potential range of 50-120 kV. The highest radiation attenuation is ascertained at 70 kV where the dose is reduced remarkably between 99.11% and 97.42%. Ceramics at 0 and 10 wt% demonstrated the highest lead (Pb) equivalent thickness (LE) of 0.44 mm and 0.34 mm, respectively. It is established that such MBC may contribute towards the development of shielding material against ionizing radiation in diagnostic radiology (X-ray) dose range.

  5. Selective Separation of Fluorite, Barite and Calcite with Valonea Extract and Sodium Fluosilicate as Depressants

    OpenAIRE

    Zijie Ren; Futao Yu; Huimin Gao; Zhijie Chen; Yongjun Peng; Lingyun Liu

    2017-01-01

    Fluorite, barite and calcite are important industry minerals. However, they often co-exist, presenting difficulty in selectively separating them due to their similar surface properties. In this study, valonea extract and sodium fluosilicate were used as depressants to selectively separate them by flotation, with sodium oleate as the collector. The single mineral flotation results showed that valonea extract displayed the strongest depression on calcite, while sodium fluosilicate displayed the...

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

    Science.gov (United States)

    Almeida Junior, T. Airton; Nogueira, M. S.; Vivolo, V.; Potiens, M. P. A.; Campos, L. L.

    2017-11-01

    The probability of a photon interacting in a particular way with a given material, per unit path length, is usually called the linear attenuation coefficient (μ), and it is of great importance in radiation shielding. Plates of barite concrete with different thickness were fabricated in order to determining their mass attenuation coefficients at different energies. The plates were irradiated with ISO X-ray beams (N60, N80, N110 and N150), generated by Pantak HF320 X-ray equipment, at the IPEN laboratory. The mass attenuation coefficients of barite concrete have been measured using X-ray attenuation for different thicknesses of barite concrete qualities of the ISO. The attenuator material issued from different regions of Brazil. The experimental procedure in this research was validated by comparison between the experimental measurements of mass attenuation coefficients and coefficients determined by the same atomic composition, using as a tool to XCOM. The highest value of (μ/ρ) found experimentally was in the energy of 48 keV, in ISO 60 N quality, being 1.32(±0.49) for purple barite; 1.47(±0.41) for white barite and 1.75(±0.41) for cream barite. The determination of the chemical composition of the barite samples was of fundamental importance for the characterization of these materials. It can be seen that both calculated and measured data for the linear attenuation coefficients increase with the increasing materials density, as it is expected. It can be concluded that the photon attenuation coefficients depends on the photon energy and the materials density is the main contribution to the photon attenuation coefficients, which is important for radiation shielding.

  7. 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.

  8. 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)

  9. Fluid Evolution During Mineralization of Atashkuh Fluorite-Barite (±Sulfide Deposit, South of Delijan

    Directory of Open Access Journals (Sweden)

    Seyed Javad Moghaddasi

    2016-07-01

    Full Text Available Introduction More than 30 fluorite occurrences with approximately 1.35 million tons of reserves have been recognized in Iran (Ghorbani, 2013. The Atashkuh fluorite-barite (±sulfide deposit is one of four occurrences located south of the city of Delijan in Markazi province, about 80 km SE of Arak city. The Atashkuh deposit occurs between the central Iran structural zone on the north and the Sanandaj-Sirjan structural zone on the south. The geology of the area is dominated by folded and faulted Jurassic carbonates and shales (Thiele et al., 1968. The lower Jurassic shale and calcareous sandstone of the Shemshak Formation and the Middle to Upper Jurassic dolomite of the Badamu Formation are the main host rocks for the fluorite veins. In this study, 40 samples from fluorite veins and host rocks were collected, from which 25 thin sections and 8 doubly-polished thin sections were prepared. Micro-thermometric studies were conducted on primary fluid inclusions using the Linkam THM600 heating-freezing stage. In addition, 10 samples were analyzed by XRD. Results Fluid inclusion data indicate that the Atashkuh fluorite-barite (±sulfides veins were deposited as a result of mixing a primary multi-component Na-K(-Mg-Ca high-salinity brine (SH type inclusions with less saline calcium-rich connate water (LVHH type inclusions and pressure reduction of ore bearing fluids. Fluid inclusions containing halite in high-salinity brine, and hydrohalite in connate water show suggest a high-salinity brine and connate water before mixing. The main mineralization stage was followed by circulation of low temperature meteoric water, responsible for the late stage mineralization. The micro-thermometry results suggest that the main fluorite mineralization occurred at 250 °C and 150 Mpa pressure. Dolomitization and silicification are the main alteration types associated with the Atashkuh mineralization. The occurrence of chlorite, talc, illite and dolomitized host rock all

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

    International Nuclear Information System (INIS)

    Ruiz Cruces, R.; Perez Martinez, M.; Diez de los Rios Delgado, A.

    1997-01-01

    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

  11. Thermal and chemical variations of the Nigerian Benue trough lead-zinc-barite-fluorite deposits

    Science.gov (United States)

    Ogundipe, Ibukun Emmanuel

    2017-08-01

    The Benue trough is an intra-continental rift initiated in the Cretaceous during the opening of the South Atlantic Ocean. Lead-zinc-barite-fluorite mineralization occurs along the 600 km axis of the trough in three discrete sub-basins which coincide with the lower, middle and upper mineral districts of the Benue Valley. Lithologically these sub-basins are dominated by black carbonaceous shale in the Lower Benue, platform carbonates in the Middle Benue and sandstones in the Upper Benue. Micro-thermometric analysis of fluid inclusions in sphalerite, fluorite, barite and quartz have shown that each mineral district has its own unique thermal and chemical imprint. For example, the temperature can be bracketed between 109 °C and 160 °C for lower Benue, 89 °C-144 °C for the Middle Benue and 176 °C-254 °C for the Upper Benue. Chemical differentiation also exists between each mineral district with the Lower Benue having 22 wt % equivalent NaCl while the Middle and Upper Benue have 18 and 16 wt % equivalent NaCl respectively. This study shows that inter-district thermal and chemical variations exist between the ore-stage sulfide and post-sulfide gangue minerals of the entire Benue Valley. Similarly, intra-district thermal and chemical variations have also been observed among all the paragenetic minerals of each district. The thermal variations may be as a result of variations in the geothermal gradient accompanying continental rifting from one district to the other. The variations in the chemistry between the Lower Benue and the Upper Benue paragenic minerals may be as a result of the distinct lithological differences across the Benue Trough.

  12. Chapter H: Stratiform Barite Deposits in the Roberts Mountains Allochthon, Nevada: A Review of Potential Analogs in Modern Sea-Floor Environments

    Science.gov (United States)

    Koski, Randolph A.; Hein, James R.

    2004-01-01

    The United States is a net importer of barite, a critical mineral for the oil and gas industry; more than 80 percent of current domestic consumption of barite is imported from China. Nearly all of the domestic production of barite comes from stratiform deposits in Nevada. The 'modern analogs' approach adopted in this review can contribute to improving deposit models and the long-term resource picture in the United States. Massive barite deposits in Nevada are interlayered with deep-water siliceous sedimentary strata of Paleozoic age within the Roberts Mountains Allochthon. Although the barite deposits formed along the long-lived, tectonically active margin of western North America before the Antler orogeny, uncertainty still exists regarding key aspects of their genesis, especially with respect to tectonic setting and depositional processes. Proposed tectonic settings include a continental slope adjacent to an ocean basin, and a rifted basin formed on continental crust. A margin dominated by other stress configurations and strike-slip faulting may also have been present during the Paleozoic. Hypotheses for the genesis of sediment-hosted, stratiform barite deposits in Nevada can be grouped into two categories: (1) a synsedimentary hydrothermal model and (2) an ocean-circulation/productivity-zone model. Both models include a stage involving bacterial reduction of seawater sulfate. Disseminated, diagenetic, and hydrothermal barite deposits are widespread features of the modern ocean. In the Pacific Ocean, disseminated barite deposits (max 9 weight percent BaSO4) are forming below high-productivity zones (for example, in equatorial belts) and on the flanks of ocean ridges (as fallout of 'black smoker' particles). Massive barite deposits of diagenetic (in the subsea floor and at cold seeps) and hydrothermal origins are present in several sediment-covered tectonic settings, including ocean ridges (Escanaba Trough and Guaymas Basin), oceanic transform faults (Blanco

  13. 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)

  14. Controls on the precipitation of barite (BaSO 4) crystals in calcite travertine at Twitya Spring, a warm sulphur spring in Canada's Northwest Territories

    Science.gov (United States)

    Bonny, Sandy M.; Jones, Brian

    2008-01-01

    Twitya Spring discharges warm (24 °C), anoxic, sulphide-, calcium- (65 ppm) and barium- (≥ 0.78 ppm) rich spring water to a steep flow path that is inhabited by streamer and mat-forming microbes ( Thiothrix, Beggiatoa, Oscillatoria, Spirulina, diatoms, rod shaped bacteria). Oxidation and CO 2 degassing drive precipitation of elemental sulphur, barite, opaline silica, and calcite. A mound of travertine at the base of the flow path, dominantly composed of bedded barium-enriched crystallographic and noncrystallographic dendritic calcite crystals and calcite cements, hosts three types of barite crystals: type 1 (T1) intergrown tabular crystals that formed in solution, type 2 (T2) tabular and rhombic crystals that nucleated on calcite, and type 3 (T3) subhedral and anhedral microcrystals that nucleated on microbial cell surfaces and in microbial extracellular polymeric substances. The formation and distribution of T1, T2, and T3 barite in the Twitya Spring flow path are controlled by physiochemical gradients, calcite precipitation rates, and adsorption of barium to microbial biomass, all of which vary seasonally and episodically at Twitya Spring. The complex physiochemical and biological controls on barite formation at Twitya Spring both suggest that the classification of biogenic or inorganic sedimentary barite on the basis of crystal size and morphology may be oversimplified. There is also the potential that primary and authigenic barite crystals hosted in carbonates may yield information about the microbial ecology and ambient physiochemistry of their depositional environments.

  15. 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

  16. 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.

  17. In Situ Raman Spectroscopic Study of Barite as a Pressure Gauge Using a Hydrothermal Diamond Anvil Cell.

    Science.gov (United States)

    Liu, Chuanjiang; Wang, Duojun; Zheng, Haifei

    2016-02-01

    In situ Raman measurements of barite were performed at temperatures in the range of 298-673 K and pressures in the range of 105-1217 MPa using a hydrothermal diamond anvil cell combined with laser Raman spectroscopy. The Raman frequency and the full width at half maximum (FWHM) of the most intense ν1 Raman peak for barite as a function of pressure and temperature were obtained. In the experimental P-T ranges, the ν1Raman band systematically shifted toward low wavenumbers with increasing pressure and temperature. The positive pressure dependence of ν1Raman frequency indicates stress-induced shortening of the S-O bond, whereas the negative temperature dependence shows temperature-induced expansion of the S-O bond. In contrast, the observed ν1Raman band became broadened, which should be attributed to the reduced ordering of molecular structure. Based on the obtained data, the established relationships among the Raman shift or the FWHM, pressure and temperature can be used to obtain good estimates of the internal pressure in natural barite-bearing fluid inclusions or hydrothermal diamond anvil cell. This is a sensitive and reliable approach to the accurate determination of geological pressure. © The Author(s) 2015.

  18. Mineral Reactions in Shale Gas Reservoirs: Barite Scale Formation from Reusing Produced Water As Hydraulic Fracturing Fluid.

    Science.gov (United States)

    Paukert Vankeuren, Amelia N; Hakala, J Alexandra; Jarvis, Karl; Moore, Johnathan E

    2017-08-15

    Hydraulic fracturing for gas production is now ubiquitous in shale plays, but relatively little is known about shale-hydraulic fracturing fluid (HFF) reactions within the reservoir. To investigate reactions during the shut-in period of hydraulic fracturing, experiments were conducted flowing different HFFs through fractured Marcellus shale cores at reservoir temperature and pressure (66 °C, 20 MPa) for one week. Results indicate HFFs with hydrochloric acid cause substantial dissolution of carbonate minerals, as expected, increasing effective fracture volume (fracture volume + near-fracture matrix porosity) by 56-65%. HFFs with reused produced water composition cause precipitation of secondary minerals, particularly barite, decreasing effective fracture volume by 1-3%. Barite precipitation occurs despite the presence of antiscalants in experiments with and without shale contact and is driven in part by addition of dissolved sulfate from the decomposition of persulfate breakers in HFF at reservoir conditions. The overall effect of mineral changes on the reservoir has yet to be quantified, but the significant amount of barite scale formed by HFFs with reused produced water composition could reduce effective fracture volume. Further study is required to extrapolate experimental results to reservoir-scale and to explore the effect that mineral changes from HFF interaction with shale might have on gas production.

  19. 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.

  20. Geology and mining history of the Southeast Missouri Barite District and the Valles Mines, Washington, Jefferson, and St. Francois Counties, Missouri

    Science.gov (United States)

    Mugel, Douglas N.

    2017-03-09

    The Southeast Missouri Barite District and the Valles Mines are located in Washington, Jefferson, and St. Francois Counties, Missouri, where barite and lead ore are present together in surficial and near-surface deposits. Lead mining in the area began in the early 1700’s and extended into the early 1900’s. Hand mining of lead in the residuum resulted in widespread pits (also called shafts or diggings), and there was some underground mining of lead in bedrock. By the 1860’s barite was recovered from the residuum by hand mining, also resulting in widespread diggings, but generally not underground mines in bedrock. Mechanized open-pit mining of the residuum for barite began in the 1920’s. Barite production slowed by the 1980’s, and there has not been any barite mining since 1998. Mechanized barite mining resulted in large mined areas and tailings ponds containing waste from barite mills.The U.S. Environmental Protection Agency (EPA) has determined that lead is present in surface soils in Washington and Jefferson Counties at concentrations exceeding health-based screening levels. Also, elevated concentrations of barium, arsenic, and cadmium have been identified in surface soils, and lead concentrations exceeding the Federal drinking-water standard of 15 micrograms per liter have been identified in private drinking-water wells. Potential sources of these contaminants are wastes associated with barite mining, wastes associated with lead mining, or unmined natural deposits of barium, lead, and other metals. As a first step in helping EPA determine the source of soil and groundwater contamination, the U.S. Geological Survey (USGS), in cooperation with the EPA, investigated the geology and mining history of the Southeast Missouri Barite District and the Valles Mines.Ore minerals are barite (barium sulfate), galena (lead sulfide), cerussite (lead carbonate), anglesite (lead sulfate), sphalerite (zinc sulfide), smithsonite (zinc carbonate), and chalcopyrite (copper

  1. Genetic aspects of barite mineralization related to rocks of the teschenite association in the Silesian Unit, Outer Western Carpathians, Czech Republic

    Directory of Open Access Journals (Sweden)

    Jirásek Jakub

    2017-04-01

    Full Text Available Barite is a relatively uncommon phase in vein and amygdule mineralizations hosted by igneous rocks of the teschenite association in the Silesian Unit (Western Carpathians. In macroscopically observable sizes, it has been reported from 10 sites situated only in the Czech part of the Silesian Unit. Microscopic barite produced by the hydrothermal alteration of rock matrix and also by the supergene processes is more abundant. We examined four samples of barite by mineralogical and geochemical methods. Electron microprobe analyses proved pure barites with up to 0.038 apfu Sr and without remarkable internal zonation. Fluid inclusion and sulphur isotope data suggests that multiple sources of fluid components have been involved during barite crystallization. Barite contains primary and secondary aqueous all-liquid (L or less frequent two-phase (L+V aqueous fluid inclusions with variable salinity (0.4-2.9 wt. % NaCl eq. and homogenization temperatures between 77 and 152 °C. The higher-salinity fluid endmember was probably Cretaceous seawater and the lower-salinity one was probably diagenetic water derived from surrounding flysch sediments during compaction and thermal alteration of clay minerals. The δ34S values of barite samples range between -1.0 ‰ and +16.4 ‰ CDT suggesting participation of two sources of sulphate, one with a near-zero δ34S values probably derived from wall rocks and another with high δ34S values being most probably sulphate from the Cretaceous seawater. All results underline the role of externally derived fluids during post-magmatic alteration of bodies of rock of the teschenite association.

  2. Measurement of properties and of the resistance to segregation in heavyweight, self-compacting barite concrete

    Directory of Open Access Journals (Sweden)

    Navarro, D.

    2009-07-01

    Full Text Available Heavyweight concrete is used for shielding in structures requiring protection against radiation. The addition of superplasticizers to mixes yields workable, high density materials with low water/cement ratios. This paper discusses the results of adding a polycarboxylate-based superplasticizer to heavyweight barite concrete to obtain a self-compacting mix. The fresh properties were characterized with trials suitable for self-compacting concrete. Since the large differences in constituent densities make segregation a key issue in this type of concrete, a specific trial was designed to check for homogeneity. The flowability, passing ability and resistance to segregation findings showed that the product obtained was a self-compacting concrete.El hormigón de alta densidad se emplea en estructuras en las que se necesita protección frente a radiaciones. El empleo de superplastificantes permite obtener mezclas trabajables con bajas relaciones agua/cemento y alta densidad. Este trabajo muestra los resultados obtenidos con el empleo de un superplastificante basado en policarboxilatos en un hormigón pesado de barita, que condujo a la obtención de un hormigón autocompactante. Las propiedades en el estado fresco se caracterizaron mediante ensayos adecuados para el hormigón autocompactante. Puesto que la segregación puede ser un aspecto clave en este tipo de hormigón, por las grandes diferencias entre las densidades de los componentes, se diseñó un ensayo específico para comprobar la homogeneidad del mismo. Los resultados permitieron comprobar que el hormigón fabricado poseía propiedades de autocompactabilidad, puesto que poseía la fluidez, la capacidad de paso a través de armaduras y la resistencia a la segregación adecuadas.

  3. Barite-polymetallic mineralization of Zmeinogorsk ore district and some genetic aspects of its formation

    Science.gov (United States)

    Bestemianova, K. V.; Grinev, O. M.

    2017-12-01

    Zmeinogorsky ore district is located in the northwest part of Ore Altai megatrough, which has long-lasting history of its development and complicated geological structure. Within the ore district, which is the northwest part of the devonian Zmeinogorsk-Bystrushinsky trough, ore mineralization is associated with the system of northwest border faults and cross branch faults. There were four main stages and five phases of minerogenesis. The first stage is the stage of oregenesis beginning and quartz-chlorite-sericite wall-rock alteration rocks formation. Ore deposition and intense tectonics took place during the second stage. The third stage is the most longstanding and productive ore formation stage. There are five distinct minerogenesis phases within this stage. The fourth stage expressed in erosion development and supergene alteration of already formed ore bodies with oxidation zone formation. Main ore minerals are pyrite, chalcopyrite, sphalerite and galena. Minor minerals are tetrahedrite, bornite, tennantite and chalcocite. Precious metals minerals are acanthite, gold, electrum, gold and silver amalgams. Barren minerals are barite, quartz, calcite, gypsum. According to obtained data average isotopic composition of third stage sulphides is: pyrite -0,2‰, chalcopyrite 0‰, galena +0,5‰, sphalerite -1,2‰ for the first complex; chalcopyrite -1,9‰, galena -3,4‰, sphalerite -2,3‰, tetrahedrite -3,7‰ for the second complex; tennantite -12,8‰, bornite -8,9‰ for the third complex. Sulfur isotopic compoisiton variations indicate source inhomogeneity. Thus, there was dominant source change from mantle one in the beginning to crustal one in the end. Main oregenesis stages took place in the range of temperatures between 170 and 210°С and in the mineral-forming solutions salinity range between 3 and 10 wt % NaCl equiv.

  4. Gas hydrate decomposition recorded by authigenic barite at pockmark sites of the northern Congo Fan

    Science.gov (United States)

    Kasten, Sabine; Nöthen, Kerstin; Hensen, Christian; Spieß, Volkhard; Blumenberg, Martin; Schneider, Ralph R.

    2012-12-01

    The geochemical cycling of barium was investigated in sediments of pockmarks of the northern Congo Fan, characterized by surface and subsurface gas hydrates, chemosynthetic fauna, and authigenic carbonates. Two gravity cores retrieved from the so-called Hydrate Hole and Worm Hole pockmarks were examined using high-resolution pore-water and solid-phase analyses. The results indicate that, although gas hydrates in the study area are stable with respect to pressure and temperature, they are and have been subject to dissolution due to methane-undersaturated pore waters. The process significantly driving dissolution is the anaerobic oxidation of methane (AOM) above the shallowest hydrate-bearing sediment layer. It is suggested that episodic seep events temporarily increase the upward flux of methane, and induce hydrate formation close to the sediment surface. AOM establishes at a sediment depth where the upward flux of methane from the uppermost hydrate layer counterbalances the downward flux of seawater sulfate. After seepage ceases, AOM continues to consume methane at the sulfate/methane transition (SMT) above the hydrates, thereby driving the progressive dissolution of the hydrates "from above". As a result the SMT migrates downward, leaving behind enrichments of authigenic barite and carbonates that typically precipitate at this biogeochemical reaction front. Calculation of the time needed to produce the observed solid-phase barium enrichments above the present-day depths of the SMT served to track the net downward migration of the SMT and to estimate the total time of hydrate dissolution in the recovered sediments. Methane fluxes were higher, and the SMT was located closer to the sediment surface in the past at both sites. Active seepage and hydrate formation are inferred to have occurred only a few thousands of years ago at the Hydrate Hole site. By contrast, AOM-driven hydrate dissolution as a consequence of an overall net decrease in upward methane flux seems to

  5. Measurement of the leaching rate of radionuclide 134Cs from the solidified radioactive sources in Portland cement mixed with microsilica and barite matrixes

    International Nuclear Information System (INIS)

    Shaaban, Ismail; Assi, Nasim

    2011-01-01

    Portland cement was mixed with radionuclide 134 Cs to produce low-level radioactive sources. These sources were surrounded with cement mixed with different materials like microsilica and barite. The leaching rate of 134 Cs from the solidified radioactive source in Portland cement alone was found to be 4.481 x 10 -4 g/cm 2 per day. Mixing this Portland cement with microsilica and with barite reduced significantly the leaching rate to 1.091 x 10 -4 g/cm 2 per day and 3.153 x 10 -4 g/cm 2 per day for 1 wt.% mixing, and to 1.401 x 10 -5 g/cm 2 per day and 1.703 x 10 -4 g/cm 2 per day for 3 wt.% mixing, respectively. It was also found that the application of a latex paint reduced these leaching rates by about 6.5%, 20.3% and 13.3% for Portland cement, cement mixed with microsilica and with barite, respectively. The leaching data were also analyzed using the polynomial method. The obtained results showed that cement mixed with microsilica and with barite can be effectively used for radioactive sources solidification.

  6. Hydrothermal Atomic Force Microscopy Investigation of Barite Growth: Role of Spectator Ions in Elementary Step Edge Growth Kinetics and Hillock Morphology [Supporting Information Only

    Energy Technology Data Exchange (ETDEWEB)

    Jindra, Sarah A. [Wright State Univ., Dayton, OH (United States); Bertagni, Angela L. [Wright State Univ., Dayton, OH (United States); Bracco, Jacquelyn N. [Wright State Univ., Dayton, OH (United States); Argonne National Lab. (ANL), Argonne, IL (United States); Higgins, Steven R. [Wright State Univ., Dayton, OH (United States)

    2017-09-25

    Here, to better understand the role of spectator ions in barite growth, the kinetics of step edge growth on barite (001) surfaces were studied under various salt solutions. Hydrothermal atomic force microscopy (HAFM) was used to investigate the effect of background electrolytes (NaCl, NaBr, and NaNO3) as a function of saturation index and ionic strength (I) on barite growth sourced at dislocations at 108 °C. Results demonstrate that hillock morphology is affected by I, as well as type of anion, where the prevalence of steps aligned on the [010] direction is highest under Cl. There is a modest increase in kinetic coefficient of 55–130% with a 10-fold increase in I for each salt. In comparing the kinetic coefficients of the salts at low ionic strength (0.01 M), there is a moderate difference, suggesting that the anion may play a role in barium attachment.

  7. 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)

  8. Influence of the barite tenors of the Jaicos, Piaui, Brazil, clays on the ceramic properties of electric insulator porcelains; Influencia dos teores de barita das argilas de Jaicos, Piaui, Brasil nas propriedades ceramicas de porcelana de isoladores eletricos

    Energy Technology Data Exchange (ETDEWEB)

    Correa, W.L.P. [Escola SENAI Mario Amato, Sao Bernardo do Campo, SP (Brazil); Lima, M.B. [Faculdade Sao Bernardo, SP (Brazil); Carvalho, F.M.S. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Geociencias

    2009-07-01

    The clays of the Municipality of Jaicos, Piaui, has been used as raw materials for the manufacture of insulators for company located in the municipality of Pedreira - Sao Paulo. It can be noticed in the clay blocks and consolidated, 'lenses' of barite. The mineralogical composition of clay and the nature of these 'lenses' were studied by chemical analysis, X-ray diffraction for mineralogical characterization. The clays are composed primarily by kaolinite, quartz, and some amount of illite and orthoclase. The presence of orthoclase does believe in a recent deposition of these clays. The 'lenses' were characterized as barite, BaSO{sub 4}. To check the influence of barite in the composition of bodies of porcelain to insulators made up six compositions with different levels of barite, obtained their own clay. It applies, then the tests of ceramic fracture to bending, water absorption, apparent porosity to determine the effect of the introduction of barite in the compositions. (author)

  9. Depositional conditions for the Kuna Formation, Red Dog Zn-PB-Ag-Barite District, Alaska, inferred from isotopic and chemical proxies

    Science.gov (United States)

    Johnson, Craig A.; Dumoulin, Julie A.; Burruss, Robert A.; Slack, John F.

    2015-01-01

    Water column redox conditions, degree of restriction of the depositional basin, and other paleoenvironmental parameters have been determined for the Mississippian Kuna Formation of northwestern Alaska from stratigraphic profiles of Mo, Fe/Al, and S isotopes in pyrite, C isotopes in organic matter, and N isotopes in bulk rock. This unit is important because it hosts the Red Dog and Anarraaq Zn-Pb-Ag ± barite deposits, which together constitute one of the largest zinc resources in the world. The isotopic and chemical proxies record a deep basin environment that became isolated from the open ocean, became increasingly reducing, and ultimately became euxinic. The basin was ventilated briefly and then became isolated again just prior to its demise as a discrete depocenter with the transition to the overlying Siksikpuk Formation. Ventilation corresponded approximately to the initiation of bedded barite deposition in the district, whereas the demise of the basin corresponded approximately to the formation of the massive sulfide deposits. The changes in basin circulation during deposition of the upper Kuna Formation may have had multiple immediate causes, but the underlying driver was probably extensional tectonic activity that also facilitated fluid flow beneath the basin floor. Although the formation of sediment-hosted sulfide deposits is generally favored by highly reducing conditions, the Zn-Pb deposits of the Red Dog district are not found in the major euxinic facies of the Kuna basin, nor did they form during the main period of euxinia. Rather, the deposits occur where strata were permeable to migrating fluids and where excess H2S was available beyond what was produced in situ by decomposition of local sedimentary organic matter. The known deposits formed mainly by replacement of calcareous strata that gained H2S from nearby highly carbonaceous beds (Anarraaq deposit) or by fracturing and vein formation in strata that produced excess H2S by reductive dissolution of

  10. Iron and sulfur isotope constraints on redox conditions associated with the 3.2 Ga barite deposits of the Mapepe Formation (Barberton Greenstone Belt, South Africa)

    Science.gov (United States)

    Busigny, Vincent; Marin-Carbonne, Johanna; Muller, Elodie; Cartigny, Pierre; Rollion-Bard, Claire; Assayag, Nelly; Philippot, Pascal

    2017-08-01

    The occurrence of Early Archean barite deposits is intriguing since this type of sediment requires high availability of dissolved sulfate (SO42-), the oxidized form of sulfur, although most authors argued that the Archean eon was dominated by reducing conditions, with low oceanic sulfate concentration (state of the paleo-atmosphere and -oceans, we examined Fe and S isotope compositions in a sedimentary sequence from the 3.2 Ga-old Mendon and Mapepe formations (Kaapvaal craton, South Africa), recovered from the drill-core BBDP2 of the Barberton Barite Drilling Project. Major elements were also analyzed to constrain the respective imprints of detrital vs metasomatic processes, in particular using Al, Ti and K interrelations. Bulk rock Fe isotope compositions are linked to mineralogy, with δ56Fe values varying between -2.04‰ in Fe sulfide-dominated barite beds, to +2.14‰ in Fe oxide-bearing cherts. δ34S values of sulfides vary between -10.84 and +3.56‰, with Δ33S in a range comprised between -0.35 and +2.55‰, thus supporting an O2-depleted atmosphere (<10-5 PAL). Iron isotope variations together with major element correlations show that, although the sediments experienced a pervasive stage of hydrothermal alteration, the rocks preserved a primary/authigenic signature predating subsequent hydrothermal stage. Highly positive δ56Fe values recorded in primary Fe-oxides from ferruginous cherts support partial Fe oxidation in a reducing oceanic environment (O2 < 10-4 μM), but are incompatible with a model of complete oxidation at the redox boundary of a stratified water column. Iron oxide precipitation under low O2 levels was likely mediated by anoxygenic photosynthesis, and/or abiotic photo-oxidation processes. Our results are consistent with global anoxic conditions in the 3.2 Ga-old sediments, implying that the barite deposits were most likely sourced by atmospheric photolysis of S gases produced by large subaerial volcanic events, and possibly SO42

  11. A SIMS Study of Sulfur Isotopes of Accessory Pyrites Associated with Barites from Methane Cold Seeps in the Gulf of Mexico

    Science.gov (United States)

    Morelli, E. C.; Aharon, P.

    2017-12-01

    Bacteria and archaea associated with seeps can fix methane from sublimating gas hydrates through coupled bacterial sulfate reduction/ anaerobic methane oxidation (BSR/AMO) and prevent outgassing to the atmosphere. The occurrence of such microbial processes has been established on the basis of the sulfur isotope compositions of microbial byproducts (pyrites; FeS2) that reflect the degree of fractionation between SO4 and FeS2 via the production of the H2S intermediate phase. BSR/AMO coupling has been discerned in accessory sulfides associated with carbonates from gas hydrate sites. Whether BSR/AMO coupling is also active in barites, another ubiquitous product of gas hydrate sublimation, has so far been overlooked. Here we present results of a new sulfur isotope study of accessory sulfides in barites associated with gas hydrates at the threshold of stability occurring on the Gulf of Mexico slope. Using a fractionation factor of 1.009 and a seawater δ34SSO4 value of 20.3‰ and assuming a Rayleigh distillation closed system model for marine sulfide precipitation, pyrites from barite gas seeps are predicted to exhibit a range of δ34S values (about -1‰ to 20‰ CDT) as the pool of sulfate is continuously depleted. Actual δ34S values could fall outside of the predicted range because the system in question is likely only partially closed and kinetic fractionations are likely. δ34S of accessory pyrites from three Garden Banks Lease Block 382 (510 - 640m water depth) and one Mississippi Canyon Lease Block 929 (590m) barite samples have been determined using an ims-1290 Secondary Ion Mass Spectrometer (SIMS). Two Garden Banks samples and one Mississippi Canyon sample reveal a spread of values from 5.30 ± 0.04 to 25.90 ± 0.09 (‰ CDT), which follow the predicted trend for gas seeps and indicate the source of fractionation is likely from the coupled BSR/AMO process. One Garden Banks sample yields a wide spread of values from -26.2 ± 0.05 to 20.5 ± 0.4 (‰ CDT). The

  12. 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

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

    Science.gov (United States)

    Majzlan, Juraj; Brey-Funke, Maria; Malz, Alexander; Donndorf, Stefan; Milovský, Rastislav

    2016-02-01

    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 deposited as massive barite

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

    International Nuclear Information System (INIS)

    Lopes, G.A.; Aragao Filho, G.L.; Almeida Junior, A.T.; Santos, M.A.P.; Araujo, F.G.S.; Nogueira, M.S.

    2013-01-01

    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

  15. Influence study of the barite mortar composition on shielding thickness for diagnostic radiology energies;Estudo da influencia da composicao da argamassa baritada na espessura da blindagem para energias do radiodiagnostico

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Wedla P. de; Hoff, Gabriela [Pontificia Univ. Catolica do Rio Grande do Sul (PUC/RS), Porto Alegre, RS (Brazil). Faculdade de Fisica

    2009-07-01

    The photons transmission is one of the used parameters for calculate the shielding material thickness. Using the computational simulation method purposed in this work was generated transmission curves for different energies for monoenergetic beams, on diagnostic radiology range, for values between 60 and 150 keV, in steps of 10 keV, to verify this way the sensitivity of the beam radiation to the differences on barite mortar composition. The computational universe generated simulated a primary beam radiation irradiating directly the shielding wall, and the barite composition was defined base on an sample analyzed using the energy dispersion spectroscopy (EDS) measurements in a Philips XL 30 Scanning Electron Microscope (SEM). The composition was analyzed for different sample areas, four different compositions for the same sample: one on open field view and three using focused field view. Was possible verify significant differences on transmission curves for the different studied energies and different compositions of barite mortar. We suggest futures works to study realistic spectra for different barite mortar compositions commercialized in Brazil. (author)

  16. Novel barite chimneys at the Loki´s Castle Vent Field shed light on key factors shaping microbial communities and functions in hydrothermal systems

    Directory of Open Access Journals (Sweden)

    Ida Helene eSteen

    2016-01-01

    Full Text Available 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 (≤ 1m 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

  17. 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.

  18. A record of barite accumulation rate for marine export productivity changes in the tropical Indian Ocean during the Mid-Pliocene--Early-Pleistocene transition

    Science.gov (United States)

    Zhou, Liping; Ma, Zhongwu; Ding, Xuan

    2016-04-01

    One of the most interesting features in the marine oxygen isotope records is the gradual shift towards heavier 18O from the Mid-Pliocene, which ends with the initiation of Northern Hemisphere glaciation (NHG) around 2.7 Ma. The lack of significant change in sea surface temperature in the tropical Indian Ocean as revealed in the previous studies does not rule out their possible contributions to this dramatic climate change during the Mid-Pliocene transition. Changing circulation systems in the region will control the supply of nutrients for the water masses which in turn determine the marine productivity. In the areas of high productivity, ocean export productivity may potentially provide a mechanism of CO2 draw-down into the deep ocean, through which contributing to the lowering of the global temperature. In this study, we present a record of barite accumulation rate (BAR) for DSDP Site 214 drilled on the Ninetyeast Ridge. Here we use the marine barite, which is formed during the decay of organism in the twilight zone, as a proxy for ocean export productivity. Our results show that the BAR of Site 214 varies between 0.25 and 1.25 mg/cm2/kyr during the period between 4 Ma and 2 Ma. Five intervals of increased BAR from 3.6 Ma to 2.4 Ma are identified with the most distinct peak centred around 3 Ma. The overall pattern does not follow either the oxygen isotope record for the Site or the sea surface temperature and subsurface temperature reconstructed with the Mg/Ca of foraminifera. This suggests that regional changes in ocean circulation and water masses may have played more important role than temperature in controlling the productivity change in the tropical Indian Ocean. The relative higher productivity around 3 Ma may imply a biogenetic process towards the intensification of NHGs.

  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)

    Duong Van Su; Truong Thi Ai; Bui Ba Duy; Bui Thi Bay; Nguyen Hong Ha; Le Thi Hong Ha; Doan Thi Mo; Doan Dac Ban; Nguyen Hoang Son

    2014-01-01

    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% TR 2 O 3 ; 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 TR 2 O 3 content archive 42.07% with recovery is 69.70%; (2) product plan B-rare-earth fine ore has TR 2 O 3 content archive 29.64% with recovery is 80.01%. (author)

  20. S- and Sr-isotopic compositions in barite-silica chimney from the Franklin Seamount, Woodlark Basin, Papua New Guinea: constraints on genesis and temporal variability of hydrothermal fluid

    Science.gov (United States)

    Ray, Durbar; Banerjee, Ranadip; Balakrishnan, S.; Paropkari, Anil L.; Mukhopadhyay, Subir

    2017-07-01

    Isotopic ratios of strontium and sulfur in six layers across a horizontal section of a hydrothermal barite-silica chimney from Franklin Seamount of western Woodlark Basin have been investigated. Sr-isotopic ratios in barite samples (87Sr/86Sr = 0.70478-0.70493) are less radiogenic than seawater (87Sr/86Sr = 0.70917) indicating that substantial leaching of sub-seafloor magma was involved in the genesis of hydrothermal fluid. The SO2 of magma likely contributed a considerable amount of lighter S-isotope in fluid and responsible for the formation of barite, which is isotopically lighter (δ34S = 19.4-20.5 ‰) than modern seawater (δ34S 21 ‰). The systematic changes in isotopic compositions across the chimney wall suggest temporal changes in the mode of mineral formation during the growth of the chimney. Enrichment of heavy S- and Sr-isotopes (δ34S = 20.58 ‰; 87Sr/86Sr = 0.70493) in the outermost periphery of the chimney indicates that, at the initial stage of chimney development, there was a significant contribution of seawater sulfate during barite mineralization. Thereafter, thickening of chimney wall occurred due to precipitation of fluid carrying more magmatic components relative to seawater. This led to a gradual enrichment of lighter isotopes (δ34S = 20.42-19.48 ‰; 87Sr/86Sr = 0.70491-0.704787) toward the inner portion of the chimney wall. In contrast, the innermost layer surrounding the fluid conduit is characterized by heavier and more radiogenic isotopes (δ34S = 20.3 ‰; 87Sr/86Sr = 0.7049). This suggests there was increasing influence of percolating seawater on the mineral paragenesis at the waning phase of the chimney development.

  1. In Situ AFM Study of Crystal Growth on a Barite (001 Surface in BaSO4 Solutions at 30 °C

    Directory of Open Access Journals (Sweden)

    Yoshihiro Kuwahara

    2016-11-01

    Full Text Available The growth behavior and kinetics of the barite (001 surface in supersaturated BaSO4 solutions (supersaturation index (SI = 1.1–4.1 at 30 °C were investigated using in situ atomic force microscopy (AFM. At the lowest supersaturation, the growth behavior was mainly the advancement of the initial step edges and filling in of the etch pits formed in the water before the BaSO4 solution was injected. For solutions with higher supersaturation, the growth behavior was characterized by the advance of the and [010] half-layer steps with two different advance rates and the formation of growth spirals with a rhombic to bow-shaped form and sector-shaped two-dimensional (2D nuclei. The advance rates of the initial steps and the two steps of 2D nuclei were proportional to the SI. In contrast, the advance rates of the parallel steps with extremely short step spacing on growth spirals were proportional to SI2, indicating that the lateral growth rates of growth spirals were directly proportional to the step separations. This dependence of the advance rate of every step on the growth spirals on the step separations predicts that the growth rates along the [001] direction of the growth spirals were proportional to SI2 for lower supersaturations and to SI for higher supersaturations. The nucleation and growth rates of the 2D nuclei increased sharply for higher supersaturations using exponential functions. Using these kinetic equations, we predicted a critical supersaturation (SI ≈ 4.3 at which the main growth mechanism of the (001 face would change from a spiral growth to a 2D nucleation growth mechanism: therefore, the morphology of bulk crystals would change.

  2. Experimental study on Ra2+ uptake by barite (BaSO{sub 4}). Kinetics of solid solution formation via BaSO{sub 4} dissolution and Ra{sub x}Ba{sub 1-x}SO{sub 4} (re) precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Bosbach, Dirk; Boettle, Melanie; Metz, Volker (Karlsruher Inst. fuer Technologie, Inst fuer Nukleare Entsorgung (INE), Karlsruhe (Germany))

    2010-03-15

    226Ra2+ and 133Ba2+ uptake by barite in aqueous solution is studied on the basis of batch type experiments with two different barite powders with different specific surface area (0.5 m2/g and 3.2 m2/g, respectively). The uptake of 226Ra2+ and 133Ba2+ is not only limited to adsorption reactions but proceeds significantly into the bulk of the barite crystals. 133Ba2+ uptake kinetics is affected by various parameters, such as amount of sample, specific surface area, sample type and solution composition. In the case of 133Ba2+, complete isotopic equilibration of the 133Ba2+ spiked solution with the barite powder occurs within 50 to 600 days. This information is derived by monitoring the aqueous 133Ba2+ concentration combined with simple mass balance calculations. In the case of 226Ra2+ a Ra{sub x}Ba{sub 1-x}SO{sub 4} solid solution forms and the uptake rate drops significantly within 400 days. The observed 226Ra2+ concentration in solution is controlled by the solubility of a Ra{sub x}Ba{sub 1-x}SO{sub 4} solid solution and several orders of magnitude below the Ra2+ solubility with respect to a pure RaSO{sub 4}(s) end member. It cannot be demonstrated unambiguously that a zero exchange rate and therefore thermodynamic equilibrium has been established within the observation period. The observed concentrations may be interpreted either as (1) a partial equilibration of 20 to 50% of the barite crystals with 226Ra2+ or (2) as complete equilibration of a Ra{sub 0.000128}Ba{sub 0.999872}SO{sub 4} solid solution with 226Ra2+ with no pure barite left. In both cases it is concluded that equilibration between aqueous Ra2+ and barite involves the replacement of a substantial fraction of the initial barite and proceeds significantly beyond pure surface adsorption processes

  3. Shocking Path of Least Resistance Shines Light on Subsurface by Revealing the Paths of Water and the Presence of Faults: Stacked EM Case Studies over Barite Hills Superfund Site in South Carolina

    Science.gov (United States)

    Haggar, K. S.; Nelson, H. R., Jr.; Berent, L. J.

    2017-12-01

    The Barite Hills/Nevada Gold Fields mines are in Late Proterozoic and early Paleozoic rocks of the gold and iron sulfides rich Carolina slate belt. The mines were active from 1989 to1995. EPA and USGS site investigations in 2003 resulted in the declaration of the waste pit areas as a superfund site. The USGS and private consulting firms have evaluated subsurface water flow paths, faults & other groundwater-related features at this superfund site utilizing 2-D conductivity & 3-D electromagnetic (EM) surveys. The USGS employed conductivity to generate instantaneous 2-D profiles to evaluate shallow groundwater patterns. Porous regolith sediments, contaminated water & mine debris have high conductivity whereas bedrock is identified by its characteristic low conductivity readings. Consulting contractors integrated EM technology, magnetic & shallow well data to generate 3-D images of groundwater flow paths at given depths across the superfund site. In so doing several previously undetected faults were identified. Lighting strike data was integrated with the previously evaluated electrical and EM data to determine whether this form of natural-sourced EM data could complement and supplement the more traditional geophysical data described above. Several lightning attributes derived from 3-D lightning volumes were found to correlate to various features identified in the previous geophysical studies. Specifically, the attributes Apparent Resistivity, Apparent Permittivity, Peak Current & Tidal Gravity provided the deepest structural geological framework & provided insights into rock properties & earth tides. Most significantly, Peak Current showed remarkable coincidence with the preferred groundwater flow map identified by one of the contractors utilizing EM technology. This study demonstrates the utility of robust integrated EM technology applications for projects focused on hydrology, geohazards to dams, levees, and structures, as well as mineral and hydrocarbon exploration.

  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.

  5. Determination of half-value layers and tenth-value layer to barite as shielding against X radiation in radiological protection; Determinacao de camadas semi-redutoras e deci-redutoras para barita como blindagem contra radiacao x em protecao radiologica

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, G.A.; Aragao Filho, G.L., E-mail: lopesgideon@gmail.com, E-mail: geraldo_lemos10@hotmail.com [Instituto Federal de Pernambuco (IFPE), Recife, PE (Brazil); Almeida Junior, A.T., E-mail: airton.almeilda@fundacentro.gov.br [Fundacao Jorge Duprat Figueiredo de Seguranca e Medicina do Trabalho (FUNDACENTRO), Belo Horizonte, MG (Brazil); Santos, M.A.P., E-mail: masantos@cnen.gov.br [Centro Regional de Ciencias Nucleares (CRCN-NE/CNEN-PE), Recife, PE (Brazil); Araujo, F.G.S., E-mail: fgabrielaraujo@uol.com.br [Universidade Federal de Ouro Preto (UFOP /REDEMAT), MG (Brazil); Nogueira, M.S., E-mail: mnogue@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2013-07-01

    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.

  6. 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

    2015-07-16

    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.

  7. occurrence and distribution of barite mineralization in cross river ...

    African Journals Online (AJOL)

    BARTH

    Structural features of southern. Obudu Plateau, Bamenda massif, southeastern. Nigeria. Preliminary Interpretations. J. Min. Geol. 30 (1): 45-59. Ekwueme, B. N., 2003. The Precambrian Geology and. Evolution of Southern Nigerian Basement. Complex. Univ. Calabar Press, 135. Ekwueme, B. N. and Kroener, A., 1997. Zircon.

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

    International Nuclear Information System (INIS)

    Ruiz Cruces, R.; Perez Martinez, M.; Martinez Morillo, M.; Diez de los Rios Delgado, A.; Ruiz del Pino, M.F.; Lopez Hidalgo, J.

    1997-01-01

    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

  9. Spectra transmitted by mortar barite in X-Ray qualities applied in diagnostic radiology as shielding

    Energy Technology Data Exchange (ETDEWEB)

    Almeida Junior, Airton T., E-mail: airton.almeida@fundacentro.gov.br [Fundacaoo Jorge Duprat Figueiredo de Seguranca e Medicina do Trabalho (FUNDACENTRO), Belo Horizonte, MG (Brazil); Araujo, F.G.S. [Universidade Federal de Ouro Preto (REDEMAT/UFOP), MG (Brazil); Nogueira, M.S., E-mail: mnogue@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Santos, M.A.P. [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil)

    2015-07-01

    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. (author)

  10. Stable and Radiogenic Sr Isotopes in Barite - Clues on the Links Between Weathering, Climate and the C Cycle

    Science.gov (United States)

    Paytan, A.; Eisenhauer, A.; Wallmann, K. J. G.; Griffith, E. M.; Ridgwell, A.

    2017-12-01

    The radiogenic Sr-isotopic signature (87Sr/86Sr) of seawater fluctuates primarily in response to changes in the inputs of Sr from weathering and hydrothermal activity, which have distinct 87Sr/86Sr values. Changes in the isotopic ratio of the weathered terrain also contribute to observed changes in 87Sr/86Sr. The stable Sr-isotope ratios in seawater (mass dependent isotopic fractionation; δ88/86Sr) fluctuate primarily in response to the rate of calcium carbonate (CaCO3) accumulation at the seafloor. Together the radiogenic and stable Sr can constrain the coupling between weathering and sedimentation and shed light on the relation between weathering, CaCO3 deposition, the global carbon (C) cycle and climate. Reconstruction of the coupled stable and radiogenic Sr seawater curves over the past 35 Ma of Earth history indicates that the location and rate of CaCO3 burial in the ocean fluctuated considerably over the past 35 Ma. Between 35 to 18 Ma a reduction in neritic CaCO3 burial and increased burial in pelagic settings is observed. The trend was reversed between 20 and 3 Ma and finally over the last 3 million years a rapid change from neritic to pelagic burial is seen. The lack of continues increase of pelagic CaCO3 burial rates suggests that silicate weathering rates have not increased monotonically over the past 35 Ma implying strong feedbacks operating in the climate system - lower atmospheric pCO2 and cooling trends (which control chemical weathering as seen from carbonate deposition in the ocean) countered the effects of uplift (which controls physical weathering) - modulating weathering rates and preventing a runaway ice-house. In addition the data suggests considerable fluctuations in seawater Sr concentrations over time. These data demonstrate how using multiple isotope proxies can help constrain interpretations of the geological record.

  11. 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)

    Barros, Frieda S.; Schelin, Hugo R.; Tilly Junior, Joao G.; Costa, Paulo R.; Nersissian, Denise Y.; Pereira, Marco A.G.

    2001-01-01

    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 6cm 3 , 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)

  12. Strategic planning and performance measurement using balanced scorecard: A case study of Iran Kaolin and Barite company

    Directory of Open Access Journals (Sweden)

    A. Danaei

    2013-06-01

    Full Text Available This paper presents an empirical investigation to measure the performance of a mining firm in province of Semnan, Iran based on balanced scorecard (BSC. The proposed study investigates the present status of the case study in terms of four BSC perspectives including internal process, learning and growth, customer and financial figures. The firm uses BSC for one year and after that, we compared the performance of the firm prior and after BSC implementation. The preliminary results indicate that the firm was able to make a 30% improvement on its performance after one-year implementation of BSC. In other words, the firm was able to make 59% improvement on learning and growth, 33% growth on internal process, 32% growth on customer and 21% improvement on financial figures.

  13. Thermodynamics of the solid solution - Aqueous solution system (Ba,Sr,Ra)SO$_{4}$ + H$_{2}$O: I. The effect of strontium content on radium uptake by barite

    OpenAIRE

    Vinograd, Victor; Kulik, D. A.; Brandt, F.; Klinkenberg, M.; Weber, J.; Winkler, B.; Bosbach, D.

    2017-01-01

    Thermodynamic properties of mixing in the ternary (Ba,Sr,Ra)SO4 solid solution are determined using first principles based total energy calculations and Monte Carlo simulations. Two levels of theory, which correspond to the regular mixing and the generalized Ising model, are considered. The results show that the regular mixing parameters increase along the row of Ba-Ra, Ba-Sr and Sr-Ra binary systems proportionally to the squared difference of molar volumes of the end-members. The magnitudes ...

  14. 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.

    on existing spheres. So it can be hypothesized that the growth of new spheres was likely started through partial melting of parent spheres wall in contact with hot volatile rich fluid inside. Thus fluid-flow channels connect the microspheres into chains....D. and Shevchenko, V.P., 1997. Hydrological and geochemical anomalies associated with hydrothermal activity in SW Pacific marginal and back-arc basins. Marine Geology 142, 7-45. Martinez, F., Taylor, B., Goodliffe, A., 1999. Contrusting styles of seafloor...

  15. Regional tectonic effects on the composition and mode of ...

    African Journals Online (AJOL)

    Reconnaissance geologic mapping for barite mineralization within Akpet Central and environs had been successfully done. The results of the study show that the mineralization of barite is largely structurally controlled although minor sedimentary processes have also contributed. Barite mineralization in the area therefore ...

  16. 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)

  17. 76 FR 4284 - Foreign-Trade Zone 124-Gramercy, LA; Application for Subzone; Halliburton Energy Services, Inc...

    Science.gov (United States)

    2011-01-25

    ... used in export production. The company anticipates that less than one percent of the plant's shipments... Energy Services, Inc. (Barite Milling); Larose, LA An application has been submitted to the Foreign-Trade... subzone status for the barite manufacturing facility of Halliburton Energy Services, Inc. (Halliburton...

  18. Experimental determination of ideal concrete density used for applications in bunkers

    International Nuclear Information System (INIS)

    Bitelli, T.; Coelho, G.M.

    1988-01-01

    Comparisons between barite concrete of different densities and exactly equal measures, subjected to gamma irradiation of 192 Ir source, with changeless measure of geometry are presented. The experimental results and the applied statistics with 95% of trust, confirm that the barite added supplies a significant increase of irradiation attenuation. (C.M.) [pt

  19. An investigation of X-ray and radio isotope energy absorption of ...

    Indian Academy of Sciences (India)

    Abstract. 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, ...

  20. An investigation of X-ray and radio isotope energy absorption of ...

    Indian Academy of Sciences (India)

    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, ...

  1. Determination of attenuation properties of massive ceramic bricks cladded with mortars containing barite used as protective barrier for radiodiagnostic rooms; Determinacao das propriedades de atenuacao de tijolos ceramicos macicos revestidos com argamassa baritada em sua utilizacao como barreira de protecao em salas de radiodiagnostico

    Energy Technology Data Exchange (ETDEWEB)

    Barros, Frieda S.; Schelin, Hugo R.; Tilly Junior, Joao G. [Centro Federal de Educacao Tecnologica do Parana (CEFET-PR), Curitiba, PR (Brazil); Costa, Paulo R.; Nersissian, Denise Y.; Pereira, Marco A.G. [Sao Paulo Univ., SP (Brazil). Inst. de Eletrotecnica e Energia

    2001-07-01

    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 6cm{sup 3}, 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)

  2. Regional sulfate-hematite-sulfide zoning in the auriferous Mariana anticline, Quadrilátero Ferrífero of Minas Gerais, Brazil

    Science.gov (United States)

    Cabral, Alexandre Raphael; Koglin, Nikola; Strauss, Harald; Brätz, Helene; Kwitko-Ribeiro, Rogerio

    2013-10-01

    The distribution of mineral deposits, characterised as barite deposits, hematite-rich auriferous deposits and auriferous tourmaline-sulfide deposits, displays a regional sulfate-hematite-sulfide zoning along the thrust-delineated limbs of the Mariana anticline, in the south-eastern part of the Quadrilátero Ferrífero of Minas Gerais, Brazil. Cross-cut relationships of barite veins and sulfide lodes indicate that sulfidation occurred in a late-tectonic context, which is here attributed to the collapse of the ˜0.6-Ga Brasiliano thrust front. Reconnaissance S-isotopic data from barite and pyrite (Antônio Pereira barite deposit and its adjacent gold deposit, respectively), and arsenopyrite (Passagem de Mariana gold deposit), suggest a new interpretation for the hydrothermal fluid overprint in the Mariana anticline. The Antônio Pereira barite has Δ33S values that are near zero, constraining the sulfate source to rocks younger than 2.45 Ga. The barite-δ34S values are between +19.6 and +20.8 ‰. The Passagem arsenopyrite and tourmaline have Co/Ni ratios that define a positive linear trend with the Antônio Pereira pyrite. The latter has homogenous δ34S values, between +8.8 and +8.9 ‰, which are compatible with thermochemical reduction of aqueous sulfate with the S-isotopic composition of the Antônio Pereira barite.

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

    Energy Technology Data Exchange (ETDEWEB)

    Almeida Junior, Airton T., E-mail: airton.almeida@fundacentro.gov.br [Fundacao Jorge Duprat Figueiredo de Seguranca e Medicina do Trabalho (FUNDACENTRO), Belo Horizonte, MG (Brazil); Araujo, F.G.S. [Universidade Federal de Ouro Preto (UFOP/REDEMAT), MG (Brazil); Nogueira, M.S. [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Santos, M.A.P. [Centro Regional de Ciencias Nucleares (CRCN-NE/CNEN-PE), Recife, PE (Brazil)

    2013-07-01

    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 {sup 60}Co. 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 {sup 60}Co. 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)

  4. Las mineralizaciones de barita de Cerro del Hierro (Sevilla. Características mineralógicas y geoquímica

    Directory of Open Access Journals (Sweden)

    Galán Huertos, E.

    1992-08-01

    Full Text Available Different barite deposits (stratabound, vein and karstic types are occurring in the Lower Cambrian carbonatic materials of the Cerro del Hierro, Sevilla (Ossa-Morena Zone. Calcite, hematite, goethite and minor chalcopyrite are common associated minerals, with limonite and malachite as alterations. The content of barite can be as high as 98 %. There is a close relationship between barite type and Sr content (vein 34S ranges between 32,7 ‰ (stratiform barites and 20,7 ‰ (epigenetic barites. The 87Sr/86Sr ratio for the epigenetic barites oscillates between 0.70873 and 0.71112 which could be the result of the infiuence of different mineralization solutions. A primary origin for the stratabound barites is proposed, in relation with the diagenesis of the limestones occurred during the Lower Cambrian. Epigenetic barites were formed after the Hercynian Orogenesis by remobilization of the stratiform ores, with Ba and Sr supplied from the lixiviation of the host rocks. The last process could be much more important for the karstic barite formation.En los materiales carbonatados del Cámbrico inferior del Cerro del Hierro (Zona de Ossa-Morena existen diversos tipos de mineralizaciones de barita (estratoligadas, filonianas y kársticas. La barita está acompañada de calcita, hematites, goethita, y calcopirita accesoria, y limonitas y malaquita como fases tardías de alteración, y presenta una gran pureza química [ > 98% SO4(Ba,Sr]. Existe una relación entre la tipología de la barita y el contenido en Sr, en el sentido de filonianas 34S en las baritas oscila entre 32,7 ‰ para las estratoligadas y 20,7 ‰ para las epigenéticas. Las razones 87Sr/86Sr determinadas sobre baritas epigenéticas varían entre 0.70873 y 0.71112, lo que puede interpretarse como consecuencia de la participación de diversos tipos de soluciones mineralizantes. Se propone un origen primario de las baritas estratoligadas, en relación con la diagénesis de los

  5. 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.

  6. Study of local Agregate for Gamma radiation concrete shield

    International Nuclear Information System (INIS)

    Tochrul-Binowo; Endro-Kismolo; Darsono

    1996-01-01

    Investigation on the composition of gamma radiation concrete shield made of local barite, manganese fine and coarse aggregates from Kulon Progo, Yogyakarta has been done. The purpose of the research was to find out the quality of these local material for an aggregate of gamma radiation concrete shield. The research was done where each mineral was used as coarse aggregate and the fine aggregate from Kulon Progo was used as fine basic aggregate. Firstly a normal concrete was made by mixing cement, fine aggregate, coarse aggregate and water at a weight ratio of cement: fine aggregate: coarse: water 1: 2.304: 3.456: 0.58. The gamma radiation absorption capacity of the concrete tested by using Cs-137 as source standard. The same method was done on barite concrete at the weight ratio of cement: fine aggregate: barite aggregate: water 1: 2.303: 3.456: 0.58 and manganese concrete at the weight ratio of cement: fine aggregate: manganese aggregate: and water 1: 1.896: 2.844: 0.58. The result of the study showed that the gamma radiation absorption capacity of barite aggregate was greater than that of normal concrete and manganese concrete. The coefficient linear attenuation (for 6.0 cm thickness) of each concrete were μ barite concrete = 0.23071 cm -1 , μ manganese concrete = 0.08401 cm -1 and μ normal concrete = 0.1669 cm -1

  7. Special concrete shield selection using the analytic hierarchy process

    International Nuclear Information System (INIS)

    Abulfaraj, W.H.

    1994-01-01

    Special types of concrete radiation shields that depend on locally available materials and have improved properties for both neutron and gamma-ray attenuation were developed by using plastic materials and heavy ores. The analytic hierarchy process (AHP) is implemented to evaluate these types for selecting the best biological radiation shield for nuclear reactors. Factors affecting the selection decision are degree of protection against neutrons, degree of protection against gamma rays, suitability of the concrete as building material, and economic considerations. The seven concrete alternatives are barite-polyethylene concrete, barite-polyvinyl chloride (PVC) concrete, barite-portland cement concrete, pyrite-polyethylene concrete, pyrite-PVC concrete, pyrite-portland cement concrete, and ordinary concrete. The AHP analysis shows the superiority of pyrite-polyethylene concrete over the others

  8. Absorção de bário por plantas de arroz (Oryza sativa L. e mobilidade em solo tratado com baritina sob diferentes condições de potencial redox

    Directory of Open Access Journals (Sweden)

    Erica Souto Abreu Lima

    2012-01-01

    Full Text Available Two parallel tests were carried out to evaluate barium solubility in soils treated with barite under reducing conditions: one in leaching columns and another with potted plants cultivated with rice. Soils were treated with three doses of barite and kept at two humidity levels. The reduction (-200 mV condition promoted an increase in barium in the geochemical fraction of higher liability, higher concentrations of barium in the leached extracts, and higher absorption by rice plants. As a result of increased uptake and accumulation of barium, the plants showed stunted growth

  9. SANDIA MOUNTAIN WILDERNESS, NEW MEXICO.

    Science.gov (United States)

    Hedlund, D.C.; Kness, R.F.

    1984-01-01

    Geologic and mineral-resource investigations in the Sandia Mountains in New Mexico indicate that a small part of the area has a probable mineral-resource potential. Most of the mineral occurrences are small barite-fluorite veins that occur along faults on the eastern slope of the range. The barite veins in the Landsend area and in the Tunnel Spring area are classed as having a probable mineral-resource potential. Fluorite veins which occur at the La Luz mine contain silver-bearing galeana and the area near this mine is regarded as having a probable resource potential for silver. No energy resources were identified in this study.

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

    International Nuclear Information System (INIS)

    Scaglia, S.; Muzio, R.; Masquelin, H.

    2010-01-01

    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

  11. Author Details

    African Journals Online (AJOL)

    Ogubunka, R O. Vol 6, No 1 (2013) - Articles Fourier-transform Infrared Characterization of Kaolin, Granite, Bentonite and Barite Abstract PDF. ISSN: 1596-6035. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

  12. Multi-elemental analysis of some Nigerian mineral rocks for a ...

    African Journals Online (AJOL)

    The physical densities of Serpentinite rock from Katsina/ Zamfara state, Hematite rock from Kogi state and Barite from Benue states of Nigeria were measured, and their moisture content analyzed with the Am-Be neutron source irradiation facility at Centre for Energy Research and Training (CERT) A.B.U. in Nigeria ...

  13. Determination of carbon in uranium and its compounds

    International Nuclear Information System (INIS)

    Perez-Garcia, M. M.

    1972-01-01

    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 2 is collected in barite solution. Where it is backtitrated with potassium biphthalate. (Author)

  14. Fulltext PDF

    Indian Academy of Sciences (India)

    Administrator

    Both barium sulfate (barite) and strontium sulfate (ce- lestite) are important inorganic chemical products, and have been widely used as significant industrial raw materials in ceramics, pigments, cosmetics, papermaking, electron- ics and high temperature solid lubricants and so on. Ba- rite and celestite as well as the family ...

  15. Fourier-transform Infrared Characterization of Kaolin, Granite ...

    African Journals Online (AJOL)

    Fourier-transform Infrared Characterization of Kaolin, Granite, Bentonite and Barite. ... Diazonium salts at the peak region frequency of 3200-3100cm-1, organic substance at peak region of 2900-2700cm-1, by comparing the spectra obtained with those ... Keywords: characterization; clays; infrared; minerals; spectroscopy ...

  16. Development of high-performance heavy density concrete using different aggregates for gamma-ray shielding

    Directory of Open Access Journals (Sweden)

    Ahmed S. Ouda

    2015-12-01

    Full Text Available The performance requirements of the concrete of containment structures are mainly radiological protection, structural integrity, durability, etc. For this purpose, high-performance heavy density concrete can be used. After extensive trials and errors, 15 concrete mixes were prepared by using coarse aggregates of barite, magnetite, goethite and serpentine with an addition of 10% silica fume (SF, 20% fly ash (FA and 30% ground granulated blast furnace slag (GGBFS to the total content of OPC. The compressive strength of hardened concrete was determined after 7, 28 and 90 days. In some concrete mixes, compressive strength was also tested up to 90 days upon replacing sand with the fine portions of magnetite, barite and goethite. The results revealed that, the concrete mixes containing magnetite coarse aggregate with 10% SF reaches the highest compressive strength values exceeding over the M60 requirement by 14% after 28 days. Whereas, the compressive strength of concrete containing barite aggregate was very close to M60 concrete and exceeds for 90 days. The results also indicated that, the compressive strength of the high-performance concrete incorporating magnetite as fine aggregate was significantly higher than that containing sand by 23%. Also, concrete made with magnetite fine aggregate has higher physico-mechanical properties than those containing barite and goethite. High-performance concrete incorporating magnetite as fine aggregate enhances the shielding efficiency against γ-rays.

  17. Geologic, geochemical, and geographic controls on NORM in produced water from Texas oil, gas, and geothermal reservoirs. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, R.

    1995-08-01

    Water from Texas oil, gas, and geothermal wells contains natural radioactivity that ranges from several hundred to several thousand Picocuries per liter (pCi/L). This natural radioactivity in produced fluids and the scale that forms in producing and processing equipment can lead to increased concerns for worker safety and additional costs for handling and disposing of water and scale. Naturally occurring radioactive materials (NORM) in oil and gas operations are mainly caused by concentrations of radium-226 ({sup 226}Ra) and radium-228 ({sup 228}Ra), daughter products of uranium-238 ({sup 238}U) and thorium-232 ({sup 232}Th), respectively, in barite scale. We examined (1) the geographic distribution of high NORM levels in oil-producing and gas-processing equipment, (2) geologic controls on uranium (U), thorium (Th), and radium (Ra) in sedimentary basins and reservoirs, (3) mineralogy of NORM scale, (4) chemical variability and potential to form barite scale in Texas formation waters, (5) Ra activity in Texas formation waters, and (6) geochemical controls on Ra isotopes in formation water and barite scale to explore natural controls on radioactivity. Our approach combined extensive compilations of published data, collection and analyses of new water samples and scale material, and geochemical modeling of scale Precipitation and Ra incorporation in barite.

  18. Author Details

    African Journals Online (AJOL)

    Aroke, U O. Vol 6, No 1 (2013) - Articles Fourier-transform Infrared Characterization of Kaolin, Granite, Bentonite and Barite Abstract PDF. ISSN: 1596-6035. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions ...

  19. 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)

  20. Radiobarites from the Cenozoic volcanic region of the Bohemian Massif: radiochemical study, history, and lead isotopic composition

    Czech Academy of Sciences Publication Activity Database

    Řanda, Zdeněk; Ulrych, Jaromír; Turek, Karel; Mihaljevič, M.; Adamovič, Jiří; Mizera, Jiří

    2010-01-01

    Roč. 283, č. 1 (2010), s. 89-94 ISSN 0236-5731 R&D Projects: GA ČR GA205/07/0522 Institutional research plan: CEZ:AV0Z10480505; CEZ:AV0Z30130516 Keywords : Barite * Radiometry * Lead isotopes Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 0.777, year: 2010

  1. Textural, compositional, and sulfur isotope variations of sulfide minerals in the Red Dog Zn-Pb-Ag deposits, Brooks Range, Alaska: Implications for Ore Formation

    Science.gov (United States)

    Kelley, K.D.; Leach, D.L.; Johnson, C.A.; Clark, J.L.; Fayek, M.; Slack, J.F.; Anderson, V.M.; Ayuso, R.A.; Ridley, W.I.

    2004-01-01

    The Red Dog Zn-Pb deposits are hosted in organic-rich mudstone and shale of the Mississippian Kuna Formation. A complex mineralization history is defined by four sphalerite types or stages: (1) early brown sphalerite, (2) yellow-brown sphalerite, (3) red-brown sphalerite, and (4) late tan sphalerite. Stages 2 and 3 constitute the main ore-forming event and are volumetrically the most important. Sulfides in stages 1 and 2 were deposited with barite, whereas stage 3 largely replaces barite. Distinct chemical differences exist among the different stages of sphalerite. From early brown sphalerite to later yellow-brown sphalerite and red-brown sphalerite, Fe and Co content generally increase and Mn and Tl content generally decrease. Early brown sphalerite contains no more than 1.9 wt percent Fe and 63 ppm Co, with high Mn (up to 37 ppm) and Tl (126 ppm), whereas yellow-brown sphalerite and red-brown sphalerite contain high Fe (up to 7.3 wt %) and Co (up to 382 ppm), and low Mn (ion microprobe sulfur isotope analyses show a progression from extremely low ??34S values for stage 1 (as low as -37.20???) to much higher values for yellow-brown sphalerite (mean of 3.3???; n = 30) and red-brown sphalerite (mean of 3.4; n = 20). Late tan sphalerite is isotopically light (-16.4 to -27.2???). The textural, chem ical, and isotopic data indicate the following paragenesis: (1) deposition of early brown sphalerite with abundant barite, minor pyrite, and trace galena immediately beneath the sea floor in unconsolidated mud; (2) deposition of yellow-brown sphalerite during subsea-floor hydrothermal recrystallization and coarsening of preexisting barite; (3) open-space deposition of barite, red-brown sphalerite and other sulfides in veins and coeval replacement of barite; and (4) postore sulfide deposition, including the formation of late tan sphalerite breccias. Stage 1 mineralization took place in a low-temperature environment where fluids rich in Ba mixed with pore water or water

  2. Attenuation of Chemical Reactivity of Shale Matrixes following Scale Precipitation

    Science.gov (United States)

    Li, Q.; Jew, A. D.; Kohli, A. H.; Alalli, G.; Kiss, A. M.; Kovscek, A. R.; Zoback, M. D.; Brown, G. E.; Maher, K.; Bargar, J.

    2017-12-01

    Introduction of fracture fluids into shales initiates a myriad of fluid-rock reactions that can strongly influence migration of fluid and hydrocarbon through shale/fracture interfaces. Due to the extremely low permeability of shale matrixes, studies on chemical reactivity of shales have mostly focused on shale surfaces. Shale-fluid interactions inside within shale matrixes have not been examined, yet the matrix is the primary conduit through which hydrocarbons and potential contaminants are transmitted. To characterize changes in matrix mineralogy, porosity, diffusivity, and permeability during hydraulic stimulation, we reacted Marcellus (high clay and low carbonate) and Eagle Ford (low clay and high carbonate) shale cores with fracture fluids for 3 weeks at elevated pressure and temperature (80 oC, and 77 bars). In the carbonate-poor Marcellus system, fluid pH increased from 2 to 4, and secondary Fe(OH)3 precipitates were observed in the fluid. Sulfur X-ray fluorescence maps show that fluids had saturated and reacted with the entire 1-cm-diameter core. In the carbonate-rich Eagle Ford system, pH increased from 2 to 6 due to calcite dissolution. When additional Ba2+ and SO42- were present (log10(Q/K)=1.3), extensive barite precipitation was observed in the matrix of the Eagle Ford core (and on the surface). Barite precipitation was also observed on the surface of the Marcellus core, although to a lesser extent. In the Marcellus system, the presence of barite scale attenuated diffusivity in the matrix, as demonstrated by sharply reduced Fe leaching and much less sulfide oxidation. Systematic studies in homogeneous solution show that barite scale precipitation rates are highly sensitive to pH, salinity, and the presence of organic compounds. These findings imply that chemical reactions are not confined to shale/fluid interfaces but can penetrate into shale matrices, and that barite scale formation can clog diffusion pathways for both fluid and hydrocarbon.

  3. Using coral Ba/Ca records to investigate seasonal to decadal scale biogeochemical cycling in the surface and intermediate ocean.

    Science.gov (United States)

    LaVigne, M.; Cobb, K. M.; DeLong, K. L.; Freiberger, M. M.; Grottoli, A. G.; Hill, T. M.; Miller, H. R.; Nurhati, I. S.; Richey, J. N.; Serrato Marks, G.; Sherrell, R. M.

    2016-12-01

    Dissolved barium (BaSW), a bio-intermediate element, is linked to several biogeochemical processes such as the cycling and export of nutrients, organic carbon (Corg), and barite in surface and intermediate oceans. Dynamic BaSW cycling has been demonstrated in the water column on short timescales (days-weeks) while sedimentary records have documented geologic-scale changes in barite preservation driven by export production. Our understanding of how seasonal-decadal scale climate variability impacts these biogeochemical processes currently lacks robust records. Ba/Ca calibrations in surface and deep sea corals suggest barium is incorporated via cationic substitution in both aragonite and calcite. Here we demonstrate the utility of Ba/Ca for reconstructing biogeochemical variability using examples of surface and deep sea coral records. Century-long deep sea coral records from the California Current System (bamboo corals: 900-1500m) record interannual variations in Ba/Ca, likely reflecting changes in barite formation via bacterial Corg respiration or barite saturation state. A surface Porites coral Ba/Ca record from Christmas Island (central equatorial Pacific: 1978-1995) shows maxima during low productivity El Niño warm periods, suggesting that variations in BaSW are driven by biological removal via direct cellular uptake or indirectly via barite precipitation with the decomposition of large phytoplankton blooms at this location. Similarly, a sixteen-year long Siderastera siderea surface coral record from Dry Tortugas, FL (Gulf of Mexico: 1991-2007) shows seasonal Ba/Ca cycles that align with annual chlorophyll and δ13C. Taken together, these records demonstrate the linkages among Corg, nutrient cycling and BaSW in the surface and intermediate ocean on seasonal to decadal timescales. Multi-proxy paleoceanographic reconstructions including Ba/Ca have the potential to elucidate the mechanisms linking past climate, productivity, nutrients, and BaSW cycling in the past.

  4. TEM analysis of the initial stages of BaSO4 crystallization

    Science.gov (United States)

    Ruiz Agudo, Cristina; Putnis, Christine V.; Ruiz Agudo, Encarnación; Putnis, Andrew

    2014-05-01

    Barite scales in oilfields are formed by mixing of seawater with high SO42- content and formation water (high Ba2+ content) in the reservoir. Although barite precipitation has been widely studied, a lack of a complete understanding of the mechanisms of barite nucleation and growth at the early stages poses a problem in the development of preventive methods designed to reduce the damaging consequences associated with scale formation. A general strategy to reduce scale formation is the use of additives that act as inhibitors of barite precipitation. These scale inhibitors act by hampering and delaying nucleation and growth of barite and in most cases they modify the habit of the crystal. The performance of these inhibitors depends on numerous parameters, such as pH, temperature and concentration, and they can affect different stages of the precipitation process (e.g. blocking active growth sites at the surface, sequestering the scale-forming metal ion, influencing the type of amorphous phase or crystalline polymorph formed, as well as promoting solid-cluster formation (Gebauer et al., 2009)). In recent studies, the precipitation of several minerals, e.g. calcite (Gebauer et al., 2008), gypsum (Van Driessche et al., 2012), magnetite (Baumgartner et al., 2013) and iron oxyhydroxide (Li et. al 2012) has been shown to follow a non-classical crystallization process. Primary crystalline nanoparticles that coalesce after previous co-alignment, and amorphous and crystalline precursor phases have been observed in the crystallization processes of these minerals. The purpose of the present work was to gain a better understanding of the early stages of barium sulfate precipitation with the objective of obtaining fundamental knowledge that allows us to select the appropriate inhibitors for barite scale formation. With this aim, barite was precipitated by mixing BaCl2 and Na2SO4 solutions. The process was quenched with ethanol at different times and the particles obtained were

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. Gel Evolution in Oil Based Drilling Fluids

    OpenAIRE

    Sandvold, Ida

    2012-01-01

    Drilling fluids make up an essential part of the drilling operation. Successful drilling operations rely on adequate drilling fluid quality. With the development of new drilling techniques such as long deviated sections and drilling in ultra-deep waters, the standard of required performance of the drilling fluids continue to increase. Narrow pressure margins and low tolerance for barite sag requires accurate prediction of the gel evolution in drilling fluids. Increased knowledge of how dri...

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

    OpenAIRE

    Randive Kirtikumar; Hurai Vratislav

    2015-01-01

    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 xen...

  11. Marine Export Production and Remineralization During Early Eocene Hyperthermal Events at ODP Site 1263, Walvis Ridge, ODP Site 1209, Shatsky Rise and ODP Site 1215, Equatorial Pacific Ocean

    Science.gov (United States)

    Lewis, A.; Griffith, E. M.; Thomas, E.; Winguth, A. M. E.

    2017-12-01

    Understanding the impacts of global hyperthermal events on marine productivity and remineralization is important for understanding the reaction of the ocean to major climate change. Marine export production and remineralization was reconstructed using marine (pelagic) barite accumulation rates (BAR) coupled with records of benthic foraminiferal assemblages across the Paleocene - Eocene Thermal Maximum (PETM) at 55.3 Ma, Eocene Thermal Maximum 2 (ETM2) 2 Ma later, and ETM3 3.1 Ma after the PETM. Marine barite accumulates in deep sea sediment precipitating in the overlying water column during degradation of organic matter exported from the photic zone. Foraminiferal data indicate the amount of organic matter reaching the seafloor. We use the difference between these records to infer changes in rates of remineralization. We present data from ODP Site on Walvis Ridge, Southeastern Atlantic; ODP Site 1209 on Shatsky Rise, North Pacific; and ODP Site 1215, equatorial Pacific. Sites 1263 and 1215 had maximum BAR roughly centered over the maximum negative PETM CIE, whereas at Site 1209 the maximum was before the PETM. The maximum BAR across ETM2 and ETM3 (0.5 and 0.25 of that at the PETM, respectively) was centered over the maximum negative CIE at Site 1263. At Site 1209, the BAR (0.5 the maximum value before the PETM) peaked before ETM2. Barite concentration at Site 1215 was low across at the smaller hyperthermals, but the onset of ETM2 had a maximum value food arrival at the seafloor during elevated BAR, thus indicating enhanced remineralization. During the PETM, at all 3 sites, increases in barite coincided with reduced BFAR. Similar trends were observed during ETM2 at Sites 1263 and 1215, suggesting dramatic changes in remineralization over all hyperthermal events at these sites. Increased remineralization rates could partly account for differences in planktonic and benthic extinction, as observed during the PETM.

  12. An investigation of X-ray and radio isotope energy absorption of ...

    Indian Academy of Sciences (India)

    ing body organs from damage, a concrete with a unit weight of >3·2 ... In unit weight experi- ments performed on aggregates, a unit of barite aggregate was measured as 4·0 g/cm3 and the unit weight of the normal aggregate was measured as 2·60 g/cm3. ... Energy Authority, Çekmece Nuclear Research and Training.

  13. Development of high-performance heavy density concrete using different aggregates for gamma-ray shielding

    OpenAIRE

    Ouda, Ahmed S.

    2015-01-01

    The performance requirements of the concrete of containment structures are mainly radiological protection, structural integrity, durability, etc. For this purpose, high-performance heavy density concrete can be used. After extensive trials and errors, 15 concrete mixes were prepared by using coarse aggregates of barite, magnetite, goethite and serpentine with an addition of 10% silica fume (SF), 20% fly ash (FA) and 30% ground granulated blast furnace slag (GGBFS) to the total content of OPC....

  14. Failed State 2030: Nigeria - A Case Study

    Science.gov (United States)

    2011-02-01

    Nigeria’s oil, gas, and mining revenues.12 President Yar’Adua pledges to uphold this transparency and serves as minister of en- ergy to oversee this...kaolin. Further, Nigeria possesses large natural resources of developable coal, gold, diamonds, bauxite , gypsum, barite, zinc, aluminum, copper, and... mining conglomerates. Investors in Nigeria’s strategic mineral mines will likely pave and widen existing roads to facilitate the transport of

  15. Multiple sources of metals of mineralization in Lower Cambrian black shales of South China: Evidence from geochemical and petrographic study

    Czech Academy of Sciences Publication Activity Database

    Pašava, J.; Kříbek, B.; Vymazalová, A.; Sýkorová, Ivana; Žák, Karel; Orberger, B.

    2008-01-01

    Roč. 58, č. 1 (2008), s. 25-42 ISSN 1344-1698 R&D Projects: GA AV ČR IAA300460510 Institutional research plan: CEZ:AV0Z30460519; CEZ:AV0Z30130516 Keywords : multiple source * Cambrian Ni-Mo-polymetalic black shale * SEDEX barite deposit Subject RIV: DD - Geochemistry Impact factor: 0.377, year: 2008

  16. MODELING THE RADIATION SHIELDING OF BORON NEUTRON CAPTURE THERAPY BASED ON 2.4 MEV D-D NEUTRON GENERATOR FACILITY

    Directory of Open Access Journals (Sweden)

    Muhammad Mu’Alim

    2018-01-01

    PEMODELAN PERISAI RADIASI PADA FASILITAS BORON NEUTRON CAPTURE THERAPY BERBASIS GENERATOR NEUTRON D-D 2,4 MeV. Telah dimodelkan perisai radiasi pada fasilitas Boron Neutron Capture Therapy (BNCT berbasis reaksi D-D pada Neutron Generator 2,4 MeV dengan Beam Shaping Assembly (BSA yang telah didesain sebelumnya. Pemodelan ini dilakukan untuk memperoleh suatu desain perisai radiasi untuk fasilitas BNCT berbasis generator neutron 2,4 MeV. Pemodelan dilakukan dengan cara memvariasikan bahan dan ketebalan perisasi radiasi. Bahan yang dipilih adalah beton barit, parafin, polietilen terborasi dan timbal. Perhitungan dilakukan menggunakan program MCNPX dengan tally F4 untuk menentukan laju dosis yang keluar dari perisai radiasi. Desain periasi radiasi dinyatakan optimal jika radiasi yang dihasilkan diluar perisai radiasi tidak melebihi Nilai Batas Dosis (NBD yang telah ditentukan oleh BAPETEN. Hasilnya, diperoleh suatu desain perisai radiasi menggunakan lapisan utama beton barit setebal 100 cm yang mengelilingi ruangan 100 cm x 100 cm x 166,4 cm dan polietilen terborasi 40 cm yang mengelilingi bahan beton barit. Kemudian ditambahkan beton barit 10 cm dan polietilen terborasi 10 cm untuk mengurangi radiasi primer yang lurus dari BSA setelah keluar dari lapisan utama. Laju dosis terbesar adalah 4,58 μSv·jam-1 pada sel 227 dan laju dosis rata-rata yang dihasilkan adalah sebesar 0,65 µSv·jam-1. Nilai laju dosis tersebut masih dibawah ambang batas NBD yang diperbolehkan oleh BAPETEN untuk pekerja radiasi. Kata kunci: Perisai radiasi, tally, laju dosis radiasi, BSA, BNCT

  17. Cenozoic "radiobarite" occurrences in the Ohře (Eger) Rift, Bohemian Massif: Mineralogical and geochemical revision

    Czech Academy of Sciences Publication Activity Database

    Ulrych, Jaromír; Adamovič, Jiří; Žák, Karel; Frána, Jaroslav; Řanda, Zdeněk; Langrová, Anna; Skála, Roman; Chvátal, M.

    2007-01-01

    Roč. 67, č. 4 (2007), s. 301-312 ISSN 0009-2819 R&D Projects: GA AV ČR IAA3013302 Institutional research plan: CEZ:AV0Z30130516; CEZ:AV0Z10480505 Keywords : barite * radioactivity * geochemistry * sulphur and oxygen isotopes * Ohře/Eger Rift, Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.179, year: 2007

  18. Mineral Resource Team 2010 Activities Summary

    Science.gov (United States)

    2011-01-29

    brecciated and copper carbonate-stained phyllite at the “Shaida Deposit”. Gossans such as this form when valuable metals, dissolved in oxidizing surface ...the assays indicate that surface samples in the Balkhab prospect consist mostly of oxide ore that is easily mined and converted to copper metal with...market. Many carbonatites also host significant ores of phosphorus, titanium, iron, manganese, apatite, barite, fluorite , vermiculite, and nepheline, all

  19. Syngenetic Au on the Carlin trend: Implications for Carlin-type deposits

    Science.gov (United States)

    Emsbo, P.; Hutchinson, R.W.; Hofstra, A.H.; Volk, J.A.; Bettles, K.H.; Baschuk, G.J.; Johnson, C.A.

    1999-01-01

    A new type of gold occurrence recently discovered in the Carlin trend, north-central Nevada, is clearly distinct from classic Carlin-type gold ore. These occurrences are interpreted to be of sedimentary exhalative (sedex) origin because they are stratiform and predate compaction and lithification of their unaltered Devonian host rocks. They contain barite that exhibits ??34S and ??18O values identical to sulfate in Late Devonian seawater and sedex-type barite deposits. Abrupt facies changes in the host rocks strongly suggest synsedimentary faulting and foundering of the carbonate shelf during mineralization, as is characteristic of sedex deposits. Gold occurs both as native inclusions in synsedimentary base-metal sulfides and barite, and as chemical enrichments in sulfide minerals. The absence of alteration and lack of ??13C and ??18O isotopic shift of primary carbonates in these rocks is strong evidence that this gold was not introduced with classic Carlin-type mineralization. Collectively, these features show that the Devonian strata were significantly enriched in gold some 300 m.y. prior to generation of the mid-Tertiary Carlin-type deposits. These strata may have been an important, perhaps even vital, source of gold for the latter. Although gold is typically low in most Zn-Pb-rich sedex deposits, our evidence suggests that transport of gold in basinal fluids, and its subsequent deposition in the sedex environment, can be significant.

  20. 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

  1. 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.

  2. Polarization effects in the ionization cross section of Ar, Kr, and Xe by laser-excited Ne sup ** ((2 p ) sup 5 (3 p ); J =3, M ) atoms

    Energy Technology Data Exchange (ETDEWEB)

    Driessen, J.P.J.; van de Weijer, F.J.M.; Zonneveld, M.J.; Somers, L.M.T.; Janssens, M.F.M.; Beijerinck, H.C.W.; Verhaar, B.J. (Physics Department, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (The Netherlands))

    1990-10-01

    In a crossed-beam experiment the total ionization cross section for the title systems has been investigated in the range 0.1{le}{ital E} (eV) {lt}=4 of collision energies. The population of the short-lived Ne{sup **}((3{ital p});{ital J}=3) state is produced by saturated optical pumping of the Ne{sup *}((3{ital s});{ital J}=2){leftrightarrow}Ne{sup **}((3{ital p});{ital J}=3) two-level system with a polarized laser beam, resulting in a well-determined distribution of the magnetic substates {vert bar}{ital J},{ital M}{r angle} with respect to the relative velocity {bold g}. By measuring the ion yield in the scattering center at five different orientations of the laser polarization (linear and circular) with respect to {bold g}, the data can be analyzed in terms of pure-state total ionization cross sections {sup 3}{ital Q{vert bar}{ital M}{vert bar}} corresponding to a single asymptotic state {vert bar}{ital J},{ital M}{r angle}.

  3. 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

  4. Mineral saturation states in natural waters and their sensitivity to thermodynamic and analytical errors

    Science.gov (United States)

    Nordstrom, D. Kirk; Ball, James W.

    1989-01-01

    Saturation indices computed with WATEQ4F chemical analyses from a groundwater in crystalline bedrock and a surface water receiving acid mine drainage are frequently at or above saturation with respect to calcite, fluorite, barite, gibbsite and ferrihydrite. Deep granitic groundwaters from Stripa, Sweden, are supersaturated with respect to calcite and fluorite. Acid mine waters from the Leviathan Mine drainage basin in California are supersaturated with respect to barite by about a factor of three. These mine waters also are 10 times supersaturated with respect to the most soluble form of ferric hydroxide but are near saturation with respect to microcrystalline gibbsite. A sensitivity analysis has been performed by varying the analytic and thermodynamic parameters for which the saturation indices are most sensitive. For calcite, fluorite and barite, the supersaturation effect appears to be real because it is only slightly decreased by sources of uncertainty. Apparent supersaturation for gibbsite is most likely caused by the degree of crystallinity on solubility behavior. Apparent supersaturation for ferric hydroxide is likely caused by small colloidal particles (< 0.1 µm) in the water sample that cannot be removed by standard field filtration, although several other possible explanations cannot be easily excluded.

  5. Seismic valve as the main mechanism for sedimentary fluid entrapment within extensional basin: example of the Lodève Permian Basin (Hérault, South of France).

    Science.gov (United States)

    Laurent, D.; Lopez, M.; Chauvet, A.; Imbert, P.; Sauvage, A. C.; Martine, B.; Thomas, M.

    2014-12-01

    During syn-sedimentary burial in basin, interstitial fluids initially trapped within the sedimentary pile are easily moving under overpressure gradient. Indeed, they have a significant role on deformation during basin evolution, particularly on fault reactivation. The Lodève Permian Basin (Hérault, France) is an exhumed half graben with exceptional outcrop conditions providing access to barite-sulfides mineralized systems and hydrocarbon trapped into rollover faults of the basin. Architectural studies shows a cyclic infilling of fault zone and associated S0-parallel veins according to three main fluid events during dextral/normal faulting. Contrasting fluid entrapment conditions are deduced from textural analysis, fluid inclusion microthermometry and sulfide isotope geothermometer: (i) the first stage is characterized by an implosion breccia cemented by silicifications and barite during abrupt pressure drop within fault zone; (ii) the second stage consists in succession of barite ribbons precipitated under overpressure fluctuations, derived from fault-valve action, with reactivation planes formed by sulphide-rich micro-shearing structures showing normal movement; and (iii) the third stage is associated to the formation of dextral strike-slip pull-apart infilling by large barite crystals and contemporary hydrocarbons under suprahydrostatic pressure values. Microthermometry, sulfide and strontium isotopic compositions of the barite-sulfides veins indicate that all stages were formed by mixing between deep basinal fluids at 230°C, derived from cinerite dewatering, and formation water from overlying sedimentary cover channelized trough fault planes. We conclude to a polyphase history of fluid trapping during Permian synrift formation of the basin: (i) a first event, associated with the dextral strike-slip motion on faults, leads to a first sealing of the fault zone; (ii) periodic reactivations of fault planes and bedding-controlled shearing form the main mineralized

  6. Fluid inclusions and preliminary studies of hydrothermal alteration in core hole PLTG-1, Platanares geothermal area, Honduras

    Science.gov (United States)

    Bargar, K.E.

    1991-01-01

    The Platanares geothermal area in western Honduras consists of more than 100 hot springs that issue from numerous hot-spring groups along the banks or within the streambed of the Quebrada de Agua Caliente (brook of hot water). Evaluation of this geothermal area included drilling a 650-m deep PLTG-1 drill hole which penetrated a surface mantling of stream terrace deposits, about 550 m of Tertiary andesitic lava flows, and Cretaceous to lower Tertiary sedimentary rocks in the lower 90 m of the drill core. Fractures and cavities in the drill core are partly to completely filled by hydrothermal minerals that include quartz, kaolinite, mixed-layer illite-smectite, barite, fluorite, chlorite, calcite, laumontite, biotite, hematite, marcasite, pyrite, arsenopyrite, stibnite, and sphalerite; the most common open-space fillings are calcite and quartz. Biotite from 138.9-m depth, dated at 37.41 Ma by replicate 40Ar/39 Ar analyses using a continuous laser system, is the earliest hydrothermal mineral deposited in the PLTG-1 drill core. This mid-Tertiary age indicates that at least some of the hydrothermal alteration encountered in the PLTG-1 drill core occured in the distant past and is unrelated to the present geothermal system. Furthermore, homogenization temperatures (Th) and melting-point temperatures (Tm) for fluid inclusions in two of the later-formed hydrothermal minerals, calcite and barite, suggest that the temperatures and concentration of dissolved solids of the fluids present at the time these fluid inclusions formed were very different from the present temperatures and fluid chemistry measured in the drill hole. Liquid-rich secondary fluid inclusions in barite and caicite from drill hole PLTG-1 have Th values that range from about 20??C less than the present measured temperature curve at 590.1-m depth to as much as 90??C higher than the temperature curve at 46.75-m depth. Many of the barite Th measurements (ranging between 114?? and 265??C) plot above the

  7. Phanerozoic Rifting Phases And Mineral Deposits

    Science.gov (United States)

    Hassaan, Mahmoud

    2016-04-01

    In North Africa occur Mediterranean and Red Sea metallogenic provinces. In each province distribute 47 iron- manganese- barite and lead-zinc deposits with tectonic-structural control. The author presents in this paper aspects of position of these deposits in the two provinces with Phanerozoic rifting . The Mediterranean Province belongs to two epochs, Hercynian and Alpine. The Hercynian Epoch manganese deposits in only Moroccoa- Algeria belong to Paleozoic tectonic zones and Proterozoic volcanics. The Alpine Epoch iron-manganese deposits are of post-orogenic exhalative-sedimentary origin. Manganese deposits in southern Morocco occur in Kabil-Rief quartz-chalcedony veins controlled by faults in andesitic sheets and in bedded pelitic tuffs, strata-form lenses and ore veins, in Precambrian schist and in Triassic and Cretaceous dolomites. Disseminated manganese with quartz and barite and effusive hydrothermal veins are hosted in Paleocene volcanics. Manganese deposits in Algeria are limited and unrecorded in Tunisia. Strata-form iron deposits in Atlas Heights are widespread in sub-rift zone among Jurassic sediments inter-bedding volcanic rocks. In Algeria, Group Beni-Saf iron deposits are localized along the Mediterranean coast in terrigenous and carbonate rocks of Jurassic, Cretaceous and Eocene age within faults and bedding planes. In Morocco strata-form hydrothermal lead-zinc deposits occur in contact zone of Tertiary andesite inter-bedding Cambrian shale, Lias dolomites and Eocene andesite. In both Algeria and Tunisia metasomatic Pb-Zn veins occur in Campanian - Maastrichtian carbonates, Triassic breccia, Jurassic limestone, Paleocene sandstones and limestone and Neogene conglomerates and sandstones. The Red Sea metallogenic province belongs to the Late Tertiary-Miocene times. In Wadi Araba hydrothermal iron-manganese deposits occur in Cretaceous sediments within 320°and 310 NW faults related to Tertiary basalt. Um-Bogma iron-manganese deposits are closely

  8. Barium and calcium analyses in sediment cores using µ-XRF core scanners

    Science.gov (United States)

    Acar, Dursun; Çaǧatay, Namık; Genç, S. Can; Eriş, K. Kadir; Sarı, Erol; Uçarkus, Gülsen

    2017-04-01

    Barium and Ca are used as proxies for organic productivity in paleooceanographic studies. With its heavy atomic weight (137.33 u), barium is easily detectable in small concentrations (several ppm levels) in marine sediments using XRF methods, including the analysis by µ-XRF core scanners. Calcium has an intermediate atomic weight (40.078 u) but is a major element in the earth's crust and in sediments and sedimentary rocks, and hence it is easily detectable by µ-XRF techniques. Normally, µ-XRF elemental analysis of cores are carried out using split half cores or 1-2 cm thich u-channels with an original moisture. Sediment cores show variation in different water content (and porosity) along their length. This in turn results in variation in the XRF counts of the elements and causes error in the elemental concentrations. We tried µ-XRF elemental analysis of split half cores, subsampled as 1 cm thick u-channels with original moisture and 0.3 mm-thin film slices of the core with original wet sample and after air drying with humidity protector mylar film. We found considerable increase in counts of most elements, and in particular for Ba and Ca, when we used 0.3 mm thin film, dried slice. In the case of Ba, the counts increased about three times that of the analysis made with wet and 1 cm thick u-channels. The higher Ba and Ca counts are mainly due to the possible precipitation of Ba as barite and Ca as gypsum from oxidation of Fe-sulphides and the evaporation of pore waters. The secondary barite and gypsum precipitation would be especially serious in unoxic sediment units, such as sapropels, with considerable Fe-sulphides and bio-barite.It is therefore suggested that reseachers should be cautious of such secondary precipitation on core surfaces when analyzing cores that have long been exposed to the atmospheric conditions.

  9. Radionuclides, trace elements, and radium residence in phosphogypsum of Jordan.

    Science.gov (United States)

    Zielinski, Robert A; Al-Hwaiti, Mohammad S; Budahn, James R; Ranville, James F

    2011-04-01

    Voluminous stockpiles of phosphogypsum (PG) generated during the wet process production of phosphoric acid are stored at many sites around the world and pose problems for their safe storage, disposal, or utilization. A major concern is the elevated concentration of long-lived (226)Ra (half-life = 1,600 years) inherited from the processed phosphate rock. Knowledge of the abundance and mode-of-occurrence of radium (Ra) in PG is critical for accurate prediction of Ra leachability and radon (Rn) emanation, and for prediction of radiation-exposure pathways to workers and to the public. The mean (±SD) of (226)Ra concentrations in ten samples of Jordan PG is 601 ± 98 Bq/kg, which falls near the midrange of values reported for PG samples collected worldwide. Jordan PG generally shows no analytically significant enrichment (Phosphogypsum samples collected from two industrial sites with different sources of phosphate rock feedstock show consistent differences in concentration of (226)Ra and rare earth elements, and also consistent trends of enrichment in these elements with increasing age of PG. Water-insoluble residues from Jordan PG constitute <10% of PG mass but contain 30-65% of the (226)Ra. (226)Ra correlates closely with Ba in the water-insoluble residues. Uniformly tiny (<10 μm) grains of barite (barium sulfate) observed with scanning electron microscopy have crystal morphologies that indicate their formation during the wet process. Barite is a well-documented and efficient scavenger of Ra from solution and is also very insoluble in water and mineral acids. Radium-bearing barite in PG influences the environmental mobility of radium and the radiation-exposure pathways near PG stockpiles.

  10. Triple oxygen isotope evidence for elevated CO2 levels after a Neoproterozoic glaciation.

    Science.gov (United States)

    Bao, Huiming; Lyons, J R; Zhou, Chuanming

    2008-05-22

    Understanding the composition of the atmosphere over geological time is critical to understanding the history of the Earth system, as the atmosphere is closely linked to the lithosphere, hydrosphere and biosphere. Although much of the history of the lithosphere and hydrosphere is contained in rock and mineral records, corresponding information about the atmosphere is scarce and elusive owing to the lack of direct records. Geologists have used sedimentary minerals, fossils and geochemical models to place constraints on the concentrations of carbon dioxide, oxygen or methane in the past. Here we show that the triple oxygen isotope composition of sulphate from ancient evaporites and barites shows variable negative oxygen-17 isotope anomalies over the past 750 million years. We propose that these anomalies track those of atmospheric oxygen and in turn reflect the partial pressure of carbon dioxide (P(CO2)) in the past through a photochemical reaction network linking stratospheric ozone to carbon dioxide and to oxygen. Our results suggest that P(CO2) was much higher in the early Cambrian than in younger eras, agreeing with previous modelling results. We also find that the (17)O isotope anomalies of barites from Marinoan (approximately 635 million years ago) cap carbonates display a distinct negative spike (around -0.70 per thousand), suggesting that by the time barite was precipitating in the immediate aftermath of a Neoproterozoic global glaciation, the P(CO2) was at its highest level in the past 750 million years. Our finding is consistent with the 'snowball Earth' hypothesis and/or a massive methane release after the Marinoan glaciation.

  11. 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)

    Abdelouas, A.

    1996-06-01

    Alteration experiments with the R7T7 glass in three salt brines, saturated respectively in MgCl 2 , MgCl 2 -CaCl 2 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 MgCl 2 CaCl 2 -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.) [de

  12. The Influence of Various Vibration Frequency on Barium Sulfate Scale Formation Of Vibrated Piping System In The Presence Citric Acid

    Science.gov (United States)

    Karaman, N.; Mangestiyono, W.; Muryanto, S.; Jamari, J.; Bayuseno, A. P.

    2018-01-01

    In this paper, the influence of vibrated piping system for BaSO4 scale formation was investigated. The vibration frequency and presence of citric acid were independent variables determining the kinetics, mass deposit and polymorph of the crystals. Correspondingly, induction time and mass of scale were obtained during the experiments. The crystalline scale was observed by scanning electron microscopy (SEM) and X-Ray Diffraction (XRD) to investigate the morphology and the phase mineral deposits, respectively. This effect indicated that the increase in vibration frequency promoted the increased deposition rate, while the pure barite with a plate-like morphology was produced in the experiments.

  13. 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.; 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.

  14. 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.

  15. Radioprotection shielding for neutrons induced by the reaction (2H (40 MeV, 12C

    Directory of Open Access Journals (Sweden)

    Fadil M.

    2017-01-01

    Full Text Available In the framework of design studies for SPIRAL2, the simulation of the neutron flux generated by 40 MeV deuterons on a thick 12C target was performed and compared to experimental data. The calculation of the dose rate of these neutrons allowed to compare four materials being considered for radioprotection shielding: barites, gypsum, ordinary concrete and heavy concrete. The simulated map of the neutron dose rate in the production building shows a very high dose rate around the neutron source and in the environment of some of the accelerator equipment.

  16. Assessment of the Radiation Hazard Indices from Terrestrial Radiation in Mining Sites in Benue State, Nigeria

    OpenAIRE

    A. I. Olanrewaju; G. O. Avwiri

    2017-01-01

    The assessment of the radiation hazard indices of solid minerals and sand in mining sites of Benue State, Nigeria was carried out using well calibrated radalert-50 and 100 meters and a Global Positioning System (Garmin 765). The sites investigated are Lessle (Barite), Gboko (Limestone), Owukpa (Coal) and Akuana (Salt) deposits fields. The mean background radiation ionization exposure rate of 0.019±0.004, 0.019±0.004, 0.014±0.002 and 0.023±0.005 mRh-1 were obtained respectively. The mean of ab...

  17. Ore horizons, ore facies, mineralogy and geochemistry of volconogenic massive sulfide (VMS) deposits of the Varandan Ba-Pb-Cu deposit, southwest of Qamsar - Iran

    OpenAIRE

    Fayeq Hashemi; Fardin Mousivand; Mehdi Rezaei-Kahkhaei

    2017-01-01

    Introduction The Varandan Ba-Pb-Cu deposits are located15 km southwest of the town of Qamsar and approximately 7 km south west of the Qazaan village, in the Urumieh- Dokhtar magmatic arc. The Kashan region that is situated in west-central Iran hosts several barite-base metal deposits and occurrences, the biggest ones are the Varandan Ba-Pb-Cu (case considered in this study) and the Tapeh-Sorkh (Khalajmaasomi et al., 2010) and Dorreh Ba (Nazari, 1994) deposits. Previous researchers (Izadi,...

  18. Measurement of gamma-dose caused by built in coal slags with elevated 226Ra concentration, and the modelling of shielding

    International Nuclear Information System (INIS)

    Nemeth, Cs.; Somlai, J.; Nenyei, A.; Skrinyar, M.; Kanyar, B.; Nemeth, P.; Hoffer, K.

    2000-01-01

    Slags, derived from coal mined in the neighbourhood of the town Tatabanya in Hungary, have been used as filling and insulating material for buildings of houses, block of flats, schools and kindergartens. The slag samples come from here have elevated concentrations of 226 Ra (range of 850 - 2400 Bq x kg -1 ). Therefore, the external gamma dose rates at 1 m height were about four times higher than the world average. It has been found, based on the modelling, that the dose rate could be decreased with 70 - 80% using an appropriate thickness of concrete or barite-concrete layers. (author)

  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 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.

  1. 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.

  2. Barium concentration in cast roe deer antlers related to air pollution caused by burning of barium-enriched coals in southern Poland.

    Science.gov (United States)

    Jabłońska, M; Kramarczyk, M; Smieja-Król, B; Janeczek, J

    2016-03-01

    Concentrations of Ba, Zn, Pb, Fe, and Mn were determined by atomic absorption spectroscopy in freshly cast antlers from male roe deer of different ages (2 to 4 years old and older than 4 years) collected in Balin near Chrzanów and in the vicinity of Żywiec, S Poland. Barium content ranged from 124 to 196 ppm (mean 165 ppm) in the Balin 12 samples and from 207 to 351 ppm (mean 287 ppm) in 3 antlers from Żywiec. The concentration of Ba was comparable to that of Zn (134-275 ppm, mean 169 ppm). Elevated concentrations of Ba in antlers most probably originated from direct uptake of airborne barite nanocrystals through the respiratory system and/or by digestion of barite-rich dust particles deposited on plants. Burning of Ba-enriched coals is regarded as the principal source of Ba in the investigated areas inhabited by roe deer. Increased concentrations of Ba in antlers from the Żywiec area compared to Balin reflect particularly high air pollution caused by coal-burning mostly for domestic purposes combined with an unfavorable topography that impedes efficient air circulation.

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

    International Nuclear Information System (INIS)

    Ridwan; Sulungbudi, Grace Tj.; Mujamilah

    2003-01-01

    The magnetic materials of barium hexa ferrites, Ba O.6Fe 2 O 3 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, Fe 2 O 3 . The barium oxide used in this experiments are from BaCO 3 product of Merck, and BaCO 4 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 BaCO 3 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 BaCO 3 or CRM- with barite, the energy product maximum (BH) max are relatively lower than commercial product

  4. Reliability of activation cross sections for estimation of shutdown dose rate in the ITER port cell and port interspace

    Science.gov (United States)

    García, Raquel; García, Mauricio; Ogando, Francisco; Pampin, Raúl; Sanz, Javier

    2017-09-01

    This paper explores the quality of available activation cross section (XS) data for accurate Shutdown Dose Rate (SDDR) prediction in the ITER Port Cell and Port Interspace areas, where different maintenance activities are foreseen. For this purpose the EAF library (2007 and 2010 versions) has been investigated, as it is typically used by the ITER community. Based on both reports/papers on SDDR in ITER and own calculations, major nuclides contributing to the SDDR coming from the activation of i) relevant materials placed in ITER and ii) candidate materials for the bioshield plug as L2N and barite concretes, are identified. Then, relevant production pathways are obtained. EAF XS quality for all pathways is checked following the procedure used for validating and testing the successive EAF versions. Also, possible improvements from using the TENDL-2015 library are assessed by comparing EAF and TENDL XS with available differential experimental data from EXFOR. Results point out that most of the activation XS related to materials currently placed in ITER are reliable, and only a few need improvement. Also, many of the XS related to both L2N and barite concretes need further work for validation.

  5. On the problems of Ba, Pb, Zn Ple{e ore deposit (Slovenia

    Directory of Open Access Journals (Sweden)

    Ivan Mlakar

    2003-12-01

    Full Text Available In this paper we present the years ago collected unpublished data on the Ple{e ore deposit which we completed also with some recent ones. They all speak against the offered interpretation of the geologic structure (Dozet, 1999, and especially against the Skythianage of this Ba, Pb and Zn deposit.We showed that the two large concordant barite bodies of syngenegtic origin are associated with an exactly determined horizon within the Carboniferous beds, that they were formed almost certainly in relation with the Asturian orogenic phase, and that theyoccur by chance in the hanging wall contact with the Skythian dolomite along a thrust plane. During Tertiary the epigenetic remobilization brought the ore substance from Paleozoic rocks into the mentioned dolomite. In one of the carefully investigated geochemictraverses the remobilization distance for Pb and Hg is 70 meters, and for Ba greater than 100 meters.For the existence of the PleŠe barite-bearing formation as conceived by Dozet (1999 there are no infallible proofs.

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

    International Nuclear Information System (INIS)

    Rammah, S.; Al-Hent, R.; Aissa, M.; Yousef, S.

    2003-11-01

    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)

  7. 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).

  8. 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)

  9. Geochemical significance of neoproterozoic rasimalai alkali syenite emplaced along Dharmapuri shear zone in the Northern part of Tamil Nadu

    International Nuclear Information System (INIS)

    Thangavel, S.; Balasubramani, S.; Nagaraju, M.; Bhattacharya, D.; Zakaulla, Syed; Rai, A.K.

    2015-01-01

    The Rasimalai alkali syenite complex is emplaced within Peninsular Gneissic complex and spatially associated with NE-SW trending major Dharmapuri shear zone (DSZ) in the northern part of Tamil Nadu. It is surrounded by epidote hornblend egneiss, which is the fenetised product of Charnockite and occurs about 20 km NE of Alangayam in Vellore district. It is mainly comprised of medium to coarse grained grey syenite (albite and orthoclase) and medium to micro grained pink syenite (orthoclase, microcline and perthite) at places porphyritic in nature with hornblende, riebeckitc, aegirine and acmite as accessory minerals. Grey syenite is non radioactive and uranium mineralisation is associated with pink syenite (syngenetic and disseminated type) and quartz-barite veins (hydrothermal type). Hydrothermal activity is manifested in the form of pyrite, chalcopyrite, galena, barite, calcite and calcian-strontianite which occur in the form of disseminations, stringers, lumps, aggregates, veinlets and veins. Presence of high silica (63.14-75.43%) with high field strength elements (U, Th, Nb and Pb) and large ion lithophile elements (Rb, Sr, K, Ba) possibly indicates that Rasimalai alkali syenite is the product of crustal communication and partial melting of protracted emplacement of parental alkali basaltic magma

  10. Ore horizons, ore facies, mineralogy and geochemistry of volconogenic massive sulfide (VMS deposits of the Varandan Ba-Pb-Cu deposit, southwest of Qamsar - Iran

    Directory of Open Access Journals (Sweden)

    Fayeq Hashemi

    2017-11-01

    Full Text Available Introduction The Varandan Ba-Pb-Cu deposits are located15 km southwest of the town of Qamsar and approximately 7 km south west of the Qazaan village, in the Urumieh- Dokhtar magmatic arc. The Kashan region that is situated in west-central Iran hosts several barite-base metal deposits and occurrences, the biggest ones are the Varandan Ba-Pb-Cu (case considered in this study and the Tapeh-Sorkh (Khalajmaasomi et al., 2010 and Dorreh Ba (Nazari, 1994 deposits. Previous researchers (Izadi, 1996; Farokhpey et al., 2010 have proposed an epithermal model for formation of the Varandan deposit. However, based on some feature of the deposit, it seems that this genetic model may not be correct. Therefore, it is necessary to do more precise research studies on the deposit. The main purpose of this paper is to discuss the genesis of the Varandan deposit based on geological, ore facies, mineralogy, wall rock alterations, and geochemical studies. Materials and methods A field study and sampling was performed during the summer of 2013. To assess the geochemical characteristics of the deposit, about 17 systematic samples from different ore facies of the first, second and third sub-horizon were collected for petrography and mineralogy, and for inductively coupled plasma-atomic emission spectroscopy(ICP-AES, X-ray diffraction (XRD and X-ray fluorescence (XRF geochemical analysis methods. The microscopic studies were done in the optics laboratory of the Shahrood University, and the geochemical analyzes were conducted in laboratories of the Center of Research and Mineral Processing Ore Minerals of Iran, Karaj, Iran. Results The host sequence in the Varandan deposit involves three units, from bottom to top: Unit1: grey, green siliceous tuff, brecciated tuff, crystal tuff and andesite; Unit2: white grey nummulitic limestone, limy tuff and marl: and Unit3: tuff breccia and crystal lithic tuff. Mineralization in the Varandan deposit has occurred as four ore sub

  11. Relations among pH, sulfate, and metals concentrations in anthracite and bituminous coal-mine discharges, Pennsylvania

    Science.gov (United States)

    Cravotta, III, Charles A.

    2006-01-01

    Water-quality data for discharges from 140 abandoned mines in the Bituminous and Anthracite Coalfields of Pennsylvania illustrate relations among pH, sulfate, and dissolved metal concentrations. The pH for the 140 samples ranged from 2.7 to 7.3, with two modes at pH 2.5 to 4 (acidic) and 6 to 7 (near neutral). Generally, flow rates were smaller and solute concentrations were greater for low-pH samples; flow rates increased with pH. Although the pH distribution was similar for the bituminous and anthracite subsets, the bituminous discharges had smaller median flow rates, greater concentrations of sulfate, iron, and aluminum, and smaller concentrations of barium and lead than anthracite discharges with the same pH values. The observed relations between the pH and constituent concentrations can be attributed to (1) dilution of acidic water by alkaline ground water; (2) solubility control of aluminum, iron, manganese, barium, and lead by hydroxide, sulfate, and/or carbonate minerals; and (3) aqueous sulfate-complex formation. The formation of AlSO4+ and AlHSO4+2 complexes adds to the total dissolved aluminum concentration at pH of equilibrium with aluminum hydroxide or hydroxysulfate minerals and can account for 10 to 20 times greater concentrations of dissolved aluminum in bituminous discharges compared to anthracite discharges at similar pH. Sulfate complexation also can account for 10 to 30 times greater concentrations of dissolved ferric iron concentrations at equilibrium with ferrihydrite (Fe(OH)3) and/or schwertmannite (Fe8O8(OH)4.5(SO4)1.75) at pH of 3 to 5. In contrast, lower barium and lead concentrations in bituminous than anthracite discharges indicates elevated sulfate concentration could decrease mobility of these metals by the formation of insoluble minerals such as barite (BaSO4) or anglesite (PbSO4). Most samples were saturated with barite, but none were saturated with anglesite. Hence, lead concentrations could be controlled by coprecipitation with

  12. Late-stage anhydrite-gypsum-siderite-dolomite-calcite assemblages record the transition from a deep to a shallow hydrothermal system in the Schwarzwald mining district, SW Germany

    Science.gov (United States)

    Burisch, Mathias; Walter, Benjamin F.; Gerdes, Axel; Lanz, Maximilian; Markl, Gregor

    2018-02-01

    The majority of hydrothermal vein systems of economic interest occur at relatively shallow crustal levels, although many of them formed at significantly greater depths. Their present position is a consequence of uplift and erosion. Although, many aspects of their formation are well constrained, the temporal chemical evolution of such systems during uplift and erosion is still poorly understood. These vein minerals comprise calcite, dolomite-ankerite, siderite-magnesite, anhydrite and gypsum forming the last gangue assemblages in Jurassic and Tertiary sulphide-fluorite-quartz-barite veins of the Schwarzwald mining district, SW Germany. Mineral textures of samples from nine localities reveal that in these sequences, mineral precipitation follows a recurring pattern: early calcite is followed by anhydrite or gypsum, siderite and/or dolomite. This succession may repeat up to three times. In-situ (LA-ICP-MS) U-Pb age dating of 15 carbonates from three subsequent generations of the late-stage vein assemblage yield robust ages between 20 and 0.6 Ma. Each mineral sequence forms in a distinctive period of about 2-5 Ma. These ages clearly relate these late-stage mineral phases to the youngest geological episode of the Schwarzwald, which is associated with the Cenozoic Rhine Graben rifting and basement uplift. Based on thermodynamic modelling, the formation of the observed mineral assemblages required an deeply sourced Mg-, Fe- and SO4-rich fluid (b), which was episodically mixed with a shallow crustal HCO3-rich fluid (a). As a consequence of fluid mixing, concentrations of Mg, Fe and SO4 temporarily increased and initiated the formation of the observed sulphate-carbonate mineral sequences. This discontinuous large-scale vertical fluid mixing was presumably directly related to episodes of active tectonics associated with the Cenozoic strike-slip regime of the Upper Rhine Graben. Analogously, episodic fluid mixing is a major key in the formation of older (Jurassic to early

  13. Multidisciplinary work on barium contamination of the karstic upper Kupa River drainage basin (Croatia and Slovenia); calling for watershed management.

    Science.gov (United States)

    Francisković-Bilinski, S; Bilinski, H; Grbac, R; Zunić, J; Necemer, M; Hanzel, D

    2007-02-01

    The present work was designed as an extension of a previous study of a barium anomaly observed in stream sediments of the Kupa River. In its upper part the Kupa River drains a region underlain by a trans-boundary aquifer. The river is a significant water resource in a region of tourism, sport, and fishing in both Croatia and Slovenia. The contamination source is situated in Homer (Lokve), Croatia, where barite was mined until 10 years ago. The barium processing waste material (waste and stream sediments were analyzed using comparative techniques: X-ray diffraction (XRD), X-ray fluorescence (XRF), Mössbauer spectroscopy, and grain size analysis. XRD of the waste material identified the major minerals quartz, barite, and dolomite and the Fe-containing minor minerals muscovite and goethite. Barite was identified as a minor or trace mineral in the Kupica River sediments. XRF analysis of the waste material has shown Ba and Fe to be the predominant elements, Ca and K to be minor elements, and Mn, Zn, Sr, Pb, Co, Cu, As, Zr, Rb, Y, and Mo to be trace elements. Mössbauer spectroscopy performed at room temperature (RT) was used to study iron minerals, particularly to obtain information on the valence status of Fe ions. Grain size analysis of the waste material (waste disposal on human health in Lokve. At this stage of the work, concentrations of Ba and other toxic elements in the water compartment of the Kupica River (a source of drinking water) have not been monitored by Croatian Waters (name of the Croatian water authorities). The necessity of such measurements in future studies has been highlighted. A preliminary study of diseases diagnosed in Lokve shows that about 18% of the total inhabitants have serious medical problems. Diseases of the circulatory system, endocrine, nutritional, and metabolic diseases, neoplasms, and respiratory diseases predominate. This paper calls for further multidisciplinary research on the health effects of barium and trace elements, as well

  14. Mineralisation of amethyst-bearing geodes in Ametista do Sul (Brazil) from low-temperature sedimentary brines: evidence from monophase liquid inclusions and stable isotopes

    Science.gov (United States)

    Gilg, H. Albert; Krüger, Yves; Taubald, Heinrich; van den Kerkhof, Alfons M.; Frenz, Martin; Morteani, Giulio

    2014-10-01

    Fluid inclusion studies in combination with hydrogen, oxygen and sulphur isotope data provide novel insights into the genesis of giant amethyst-bearing geodes in Early Cretaceous Paraná continental flood basalts at Amestita do Sul, Brazil. Monophase liquid inclusions in colourless quartz, amethyst, calcite, barite and gypsum were analysed by microthermometry after stimulating bubble nucleation using single femtosecond laser pulses. The salinity of the fluid inclusions was determined from ice-melting temperatures and a combination of prograde and retrograde homogenisation temperatures via the density maximum of the aqueous solutions. Four mineralisation stages are distinguished. In stage I, celadonite, chalcedony and pyrite formed under reducing conditions in a thermally stable environment. Low δ34SV-CDT values of pyrite (-25 to -32 ‰) suggest biogenic sulphate reduction by organotrophic bacteria. During the subsequent stages II (amethyst, goethite and anhydrite), III (early subhedral calcite) and IV (barite, late subhedral calcite and gypsum), the oxidation state of the fluid changed towards more oxidising conditions and microbial sulphate reduction ceased. Three distinct modes of fluid salinities around 5.3, 3.4 and 0.3 wt% NaCl-equivalent characterise the mineralisation stages II, III and IV, respectively. The salinity of the stage I fluid is unknown due to lack of fluid inclusions. Variation in homogenisation temperatures and in δ18O values of amethyst show evidence of repeated pulses of ascending hydrothermal fluids of up to 80-90 °C infiltrating a basaltic host rock of less than 45 °C. Colourless quartz and amethyst formed at temperatures between 40 and 80 °C, while the different calcite generations and late gypsum precipitated at temperatures below 45 °C. Calculated oxygen isotope composition of the amethyst-precipitating fluid in combination with δD values of amethyst-hosted fluid inclusions (-59 to -51 ‰) show a significant 18O-shift from the

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

    International Nuclear Information System (INIS)

    Hogarth, D.D.

    1996-01-01

    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

  16. Non-destructive identification of micrometer-scale minerals and their position within a bulk sample

    DEFF Research Database (Denmark)

    Sørensen, Henning O.; Hakim, Sepide S.; Pedersen, Stefan

    2012-01-01

    . Crushing or disintegrating a sample annihilates any possibility for gathering information from the texture of the porous media or the mineral assemblage close to the grains in question. A new method using three-dimensional X-ray diffraction (3DXRD) microscopy can be successfully applied to natural...... materials. We combined X-ray microtomography (XMT) and 3DXRD to investigate a sample of very fine-grained chalk containing fracture minerals. The XMT technique provides three-dimensional images of the particles and pore structure at very high resolution (350 nm voxel dimension) on samples less than 500 μm...... on this pattern, Bragg diffraction peaks from the other crystalline phases were observed. Individual crystals of barite and pyrite only a few micrometers in diameter are present in the fractures. Magnetite, celestine and siderite, other minerals that might have been expected based on the XMT absorption contrast...

  17. 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.

  18. An instrument for measuring thermal inertia in the field

    Science.gov (United States)

    Marsh, S. E.; Schieldge, J. P.; Kahle, A. B.

    1982-01-01

    Features and test results of a thermal inertial meter (TIM) for cataloging the thermal inertial of surface material in situ as a basis for satellite remote sensing of geologic materials are described. The instrument is employed to determine the temperature rise of the materials in the field, with the assumptions that the sample and a standard are homogeneous in composition, the heat flux density is constant at the surface of each material, and the specimens are thick enough to be treated as semi-infinite bodies. A formula for calculating thermal inertia is presented, and the components of the TIM are detailed. A box with three compartments, two holding standards, is placed on the sample surface with the third compartment open to the specimen. Dolomite and quartz are used as references when all samples are measured after heating. Tests with rocks and sand in Nevada and California revealed that chert has a higher thermal inertia than barite.

  19. Fluid mixing and ore deposition during the geodynamic evolution of the Sierra Almagrera (Betics, Spain)

    Science.gov (United States)

    Dyja, Vanessa; Tarantola, Alexandre; Hibsch, Christian; Boiron, Marie-Christine; Cathelineau, Michel

    2013-04-01

    Marine and continental intramountaineous basins developed during the Neogene orographic evolution of the Betico-rifan orogenic wedge, as well as the related uplifted ranges within the Sierra Almagrera Metamorphic Core Complexes (MCC). The NNE-SSW striking trans-Alboran transcurrent fault system crosscuts the MCC post-dating the extensional exhumation stages recorded in the metamorphic fabric. Iron ores (± Pb, Cu, Zn) are encountered either as stratabound ore deposits in the Neogene basins or as vein networks crosscutting the metamorphic fabric of graphitic phyllites from the Sierra Almagrera. These Late Miocene ore deposits are related to the activity of the N-S striking Palomares fault segment of the Trans-Alboran fault system. Three sets of quartz veins (Vα, Vαβ and Vβ) and one set of mineralized vein (Vγ, siderite, barite) are distinguished. The Vα and Vαβ respectively are totally or partially transposed into the foliation. The Vβ and Vγ veins are discordant to the foliation. The problem addressed in this study concerns the nature of the fluids involved in the metal deposits and their relationships with the main reservoir fluids, e.g. the deep metamorphic fluids, the basinal fluids, and eventually the recharge meteoric fluids. This study focuses thus on the evolution of the fluids at different stages of ductile-brittle exhumation of the metamorphic ranges (Sierras) and their role during the exhumation and later on in relation with the hydrothermalism and metal deposition at a regional scale. Paleofluids were studied as inclusions in quartz, siderite and barite from veins by microthermometry and Raman spectroscopy, and a stable isotope study is in progress. Earliest fluids recorded in (Vαβ) quartz veins are H2O- NaCl + CaCl2 (17 wt. %) - (traces of CO2, CH4, N2) metamorphic brines trapped at the ductile brittle transition at a minimum trapping temperatures (Th) of 340 °C. Older metamorphic fluids in (Vα) veins were lost during the complete

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

    DEFF Research Database (Denmark)

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

    2010-01-01

    The Coniacian Arnager Limestone Formation is exposed on the Danish island of Bornholm in the Baltic Sea. It is composed of mound-bedded siliceous chalk, and X-ray diffraction and scanning electron microscopy indicate a content of 30-70% insoluble minerals, including authigenic opal-CT, quartz...... 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...... 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...

  1. Determination of average conversion coefficients between kerma in air and H⁎(10) using primary and secondary X-ray beams and transmitted in the diagnostic radiology energy range; Determinacao dos coeficientes de conversao medios entre kerma no ar e H*(10) usando feixes de raios-X primarios, secundarios e transmitidos na faixa de energia da radiologia diagnostica

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Josilene C.; Gonzalez, Alejandro H.L.; Costa, Paulo R. [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto de Fisica

    2016-07-01

    Brazilian regulation establishes 1.14 Sv/Gy as unique conversion coefficient to convert air-kerma into the operational quantity ambient dose equivalent H⁎(10) disregarding its beam quality dependence. The present study computed mean conversion coefficients from primary, secondary and transmitted X-ray beams through barite mortar plates used in shielding of dedicated chest radiographic facilities in order to improve the current assessment of H⁎(10). To compute the mean conversion coefficients, the weighting of conversion coefficients corresponding to monoenergetic beams with the spectrum energy distribution in terms of air-kerma was considered. The maximum difference between the obtained conversion coefficients and the constant value recommended in national regulation is 53.4%. The conclusion based on these results is that a constant coefficient is not adequate for deriving the H⁎(10) from air-kerma measurements. (author)

  2. Depletion of barium and radium-226 in Black Sea surface waters over the past thirty years

    International Nuclear Information System (INIS)

    Kenison Falkner, K.K.; Edmond, J.M.; O'Neill, D.J.; Todd, J.F.; Moore, W.S.

    1991-01-01

    The nearly landlocked waters of the Black Sea support a valuable fishery, but are also particularly vulnerable to anthropogenic disturbance. Here we use dissolved barium and radium-226 as tracers, to investigate the biogeochemical health of the sea. Both elements are brought to surface waters by vertical mixing of deeper, enriched waters, and by rivers; these inputs should ordinarily be balanced by outflow of surface waters at the Bosphorus, and by biologically mediated removal of 226 Ra-bearing barite. We show, however, that surface-water inventories have been substantially depleted over the past few decades: recent (1988-89) barium concentrations were 1.6 times lower than in 1958 and 1967. These observations suggest that steady-state cycling of these elements has been perturbed by increased primary productivity, presumably fuelled by nutrients from industry and agricultural runoff, and to a lesser extent by decreased fluvial sediment loads owing to extensive impoundment of rivers in the region. (author)

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

    International Nuclear Information System (INIS)

    Rhein, M.

    1986-01-01

    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 SiO 2 . 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/m 2 s. (DG) [de

  4. 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)

    Benitez, A.F.; Fuente, A.; Maloberti, A.; Landi, V.A.; Bianchi, R.E.; Marveggio de Bianchi, N.; Gayone, M.R.

    1993-01-01

    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)

  5. Mineralogy of Non-Silicified Fossil Wood

    Directory of Open Access Journals (Sweden)

    George E. Mustoe

    2018-03-01

    Full Text Available The best-known and most-studied petrified wood specimens are those that are mineralized with polymorphs of silica: opal-A, opal-C, chalcedony, and quartz. Less familiar are fossil woods preserved with non-silica minerals. This report reviews discoveries of woods mineralized with calcium carbonate, calcium phosphate, various iron and copper minerals, manganese oxide, fluorite, barite, natrolite, and smectite clay. Regardless of composition, the processes of mineralization involve the same factors: availability of dissolved elements, pH, Eh, and burial temperature. Permeability of the wood and anatomical features also plays important roles in determining mineralization. When precipitation occurs in several episodes, fossil wood may have complex mineralogy.

  6. 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.

  7. Speciation of radium in uranium mill tailings from Ecarpiere (Vendee, France)

    International Nuclear Information System (INIS)

    Somot, S.; Pagel, M.

    1997-01-01

    The uranium ores of Vendee (France) have been treated with sulfuric acid and mill tailings disposed of in an impoundment at Ecarpiere. Sequential and selective extractions have been performed to determine the amount of 226 RA, and also metals and uranium, bound to different mineralogical phases. The 226 Ra fraction bound to gypsum is only 10-20% of the 226 Ra concentration in the tailings, the 226 Ra fraction bound to Fe and Mn minerals and barite (5-10 weight % of the tailings) ranges from 75 to 85% and the residual silicates and accessory minerals (60 to 72 weight % of the tailings) contain only 3 to 7% of the 226 Ra concentration. (author)

  8. The application of SEM in analyzing the damage to the petroleum reservoirs caused by drilling fluids

    International Nuclear Information System (INIS)

    Abdul Razak Ismail

    1996-01-01

    An experimental study has been conducted to analyze the damage to the potential oil and gas reservoirs due to the invasion of drilling fluid during drilling operation. Two types of rock samples representing low and high permeability were used to stimulate the petroleum reservoirs. Sea water based drilling fluids were used in this study. Detail observations to the rock samples were analyzed using scanning electron microscope (SEM). The results of both permeability restoration and SEM observation showed that severe permeability impairments were obtained for high permeability rock. These results indicate that the relative size of the barite particles and the pore size distribution and characteristics of the formation play an important role in determining the damage caused by the drilling fluids

  9. Accurate rates of the complex mechanisms for growth and dissolution of minerals using a combination of rare event theories

    International Nuclear Information System (INIS)

    Stack, Andrew G.; Raiten, Paolo; Gale, Julian D.

    2012-01-01

    Mineral growth and dissolution are often treated as occurring via a single, reversible process that governs the rate of reaction. We show that multiple, distinct intermediate states can occur during both growth and dissolution. Specifically, we have used metadynamics, a method to efficiently explore the free energy landscape of a system, coupled to umbrella sampling and reactive flux calculations, to examine the mechanism and rates of attachment and detachment of a barium ion onto a stepped, barite (BaSO4) surface. The activation energies calculated for the rate limiting reactions, which are different for attachment and detachment, precisely match those measured experimentally during both growth and dissolution. These results can potentially explain anomalous, non-steady state mineral reaction rates observed experimentally, and will enable the design of more efficient growth inhibitors and facilitate an understanding of the effect of impurities.

  10. 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

  11. [Results of monitoring of pollution by metallic impurities of environment of districts of anthropogenic impact in Georgia and methods to reduce their technogenic load].

    Science.gov (United States)

    Svanidze, Z S; Guniya, G S; Tsertsvadze, T T

    2014-01-01

    There was performed a comprehensive study of consistent pattern of the accumulation of toxic heavy metals in the natural environments of mentioned areas and there were developed methods and recommendations for improvement of their ecological status. The aim of the study--a performance of the study of pollution of natural environments by major mining regions of Georgia: Madneuli copper pyrite and barite-polymetallic deposit, Chiatura manganese deposit, Lukhumi arsenic deposits. In the process of the work, the special attention was paid to the consistent patterns of accumulation of heavy toxic contaminants in natural waters and soils, as well as to the development of methods and recommendations for their purification from impurities. At the same time there were used: field geochemical, and hydrogeochemical pedological methods, modern ultrasensitive analytical equipment, laboratory experiments for the identification of tools of water and soil purification from heavy metals etc.

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

    International Nuclear Information System (INIS)

    Fernandes, S.M.; Leonardos, O.H.

    1984-01-01

    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) [pt

  13. Case history: high density weighted polymer drilling fluid used in the deepest horizontal well Dan no. 21 in Sichuan basin of China

    Energy Technology Data Exchange (ETDEWEB)

    Li, J.; Zhang, J.; Luo, P.; Xiao, Y.; He, L. [East China Petroleum Inst., Dongying, SD (China)

    1996-12-31

    Hole cleaning, borehole stability, gas formation protection, and torque and drag program developed with high density weighted polymer drilling fluid for the horizontal well Dan no. 21 (China) was described. By using amphoteric polymer, improved rheology and inhibition performance were observed in weighted drilling fluid. The special rheological properties at low shear rate and initial structure yield stress were shown to prevent cutting bed form and barite sag. Wellbore stability had been achieved by use of amphoteric polymer in combination with soft particles to seal minifractures. The drilling fluid demonstrated a lower coefficient of friction and performed more effectively at lower torque and drag. This system proved to protect the formation from damage by limiting fluid loss, fine particles migration and solids invasion. 10 refs., 7 tabs., 5 figs.

  14. 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.

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

    International Nuclear Information System (INIS)

    Murao, S.; Sie, S.H.; Suter, G.F.

    1996-01-01

    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

  16. Effect of non-homogeneity on orthotropic creep stresses in a pressurized circular cylinder

    Science.gov (United States)

    Sharma, Sanjeev; Panchal, Rekha

    2017-10-01

    The effect of anisotropy on the creep stresses of a functionally graded infinite hollow cylinder with inhomogeneity in terms of compressibility varying according to power law is investigated. Transition theory given by Seth for finite deformation is used for analysis of creep stresses which overcome the use of creep strain laws and jump conditions. Analytical solution for orthotropic and isotropic cylinder subjected to internal and external pressure is derived. The results indicate that the effect of inhomogeneity is very pronounced. Highly non-homogeneous isotropic material Steel with non-linear measure is safer for the design as compared to orthotropic material Barite and Uranium (alpha) as hoop stress generated are less. Circumferential creep stresses generated for the cylinder are less for highly functionally graded cylinder as compared to less functionally graded cylinder. Also, the cylinder with isotropic properties is on the safer side of design.

  17. Investigation and assessment of lead slag concrete as nuclear shields

    International Nuclear Information System (INIS)

    Zaghloul, Y.R.

    2009-01-01

    The present work is concerned with the efficiency of heavy weight concrete as a shielding material in constructing nuclear installations as well as for radioactive wastes disposal facilities.In this context, lead slag was used as a replacement for fine aggregates in heavy concrete shields that include local heavy weight aggregates (namely; barite and ilmenite) as well as normal concrete includes dolomite and sand as coarse and fine aggregates, as a reference. The effect of different percentages of lead slag was investigated to assess the produced lead slag concrete as a nuclear shielding material. The different properties (physical, mechanical and nuclear) of the produced lead slag concrete were investigated. The results obtained showed that increasing the lead slag percentage improving the investigated properties of the different concrete mixes. In addition, ilmenite concrete with 20% lead slag showed the best results for all the investigated properties.

  18. Determination of average conversion coefficients between kerma in air and H⁎(10) using primary and secondary X-ray beams and transmitted in the diagnostic radiology energy range

    International Nuclear Information System (INIS)

    Santos, Josilene C.; Gonzalez, Alejandro H.L.; Costa, Paulo R.

    2016-01-01

    Brazilian regulation establishes 1.14 Sv/Gy as unique conversion coefficient to convert air-kerma into the operational quantity ambient dose equivalent H⁎(10) disregarding its beam quality dependence. The present study computed mean conversion coefficients from primary, secondary and transmitted X-ray beams through barite mortar plates used in shielding of dedicated chest radiographic facilities in order to improve the current assessment of H⁎(10). To compute the mean conversion coefficients, the weighting of conversion coefficients corresponding to monoenergetic beams with the spectrum energy distribution in terms of air-kerma was considered. The maximum difference between the obtained conversion coefficients and the constant value recommended in national regulation is 53.4%. The conclusion based on these results is that a constant coefficient is not adequate for deriving the H⁎(10) from air-kerma measurements. (author)

  19. 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.

  20. Release measurements, release from regulatory control and inactive removal of the heavy concrete from the biological shield of the Seibersdorf research reactor; Freimessen, Freigabe und Entsorgung des Barytbetons vom biologischen Schild des Forschungsreaktors Seibersdorf

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, F.; Steger, F.; Djuricic, M.; Metzker, E.; Lechner, C. [Nuclear Engineering Seibersdorf GmbH (NES), Seibersdorf (Austria); Feichtinger, J. [Oesterreichisches Forschungszentrum Seibersdorf GmbH, Vienna (Austria)

    2009-07-01

    The ASTRA reactor in the Research Centre Seibersdorf was switched off finally on 31 July 1999 after 38 years successful operation and thus the decommissioning and dismantling of the reactor was decided. Apart from other system parts the biological shield, made of barite concrete was dismantled. As a dismantling and/or deconstruct method 'a block-by-block' removal was selected and used. Because on the upper parts of the biological shield no activation could be expected, these parts were free-measured only gammaspectrometrically using ISOCS (in-Situ Object Counting system) and disposed. Afterwards the lower, neutronactivated part was removed with the same cut technology as the upper part, mechanically reduced and the reinforcing irons removed. The broken heavy concrete was filled into Standard-200-Liter-barrels, was free-measured by the measuring system RADOS and disposed. Not released parts were taken to the interim storage facility of NES. (orig.)

  1. Penentuan Mineral dan Logam sebagai Material Dasar dalam Pengembangan Potensi Kalimantan Selatan sebagai Daerah Penghasil Nanomaterial

    Directory of Open Access Journals (Sweden)

    Totok Wianto

    2017-03-01

    Full Text Available Telah dilakukan penelitian penentuan mineral dan logam sebagai material dasar dalam pengembangan potensi Kalimantan Selatan sebagai daerah penghasil Nanomaterial. Hasil dari pengamatan tersebut didapatkan berbagai macam mineral yang potensial dikembangkan sebagai material nano. Material tersebut adalah zirkonium, emas, kaolin, nikel, barit, asbes (Mg yang besar, talk, chrom, pasir besi, bentonit, fireclay, magnesit, kuarsa/silika, mangan, perak dan zeolit. Dari hasil pengukuran didapatkan mineral/logam yang potensial dikembangkan sebagai material nano adalah pasir besi, kuarsa/silika, kaolin yang mengandung clay dan zirkonium. Kandungan material tersebut adalah zirkonium (puya sebagai hasil tambahan dari tambang intan dengan cadangan ± 21.350 ton, kaolin degan kadar kaolinit yang besar, chrom (sedang dalam eksplorasi, pasir besi dengan potensi ± 300 juta ton dengan kadar Fe sampai dengan 62,57%, kuarsa/silika dengan kadar SiO2 antara 94,4 % - 99%.

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

    International Nuclear Information System (INIS)

    Manso, M.; Valadas, S.; Pessanha, S.; Guilherme, A.; Queralt, I.; Candeias, A.E.; Carvalho, M.L.

    2010-01-01

    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.

  3. 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.

  4. Gamma ray shielding and structural properties of Bi{sub 2}O{sub 3}−PbO−B{sub 2}O{sub 3}−V{sub 2}O{sub 5} glass system

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Kulwinder, E-mail: kanwarjitsingh@yahoo.com; Singh, K. J., E-mail: kanwarjitsingh@yahoo.com; Anand, Vikas, E-mail: kanwarjitsingh@yahoo.com [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India)

    2014-04-24

    The present work has been undertaken to evaluate the applicability of Bi{sub 2}O{sub 3}−PbO−B{sub 2}O{sub 3}−V{sub 2}O{sub 5} 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.

  5. 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

  6. Sr isotope geochemistry of East Alpine mineral deposits and mass spectrometric analyses of fluid inclusions

    International Nuclear Information System (INIS)

    Grum, W.

    1995-05-01

    Strontium isotope geochemistry and deformational history of selected carbonate-hosted deposits from different tectonic positions in the Eastern Alps were studied. In this context an equipment has been constructed to analyze the composition of volatile components of fluid inclusions (FI). Based on the results of Sr-isotopic investigations two groups of deposits are discriminated: Deposits formed by formation waters and/or metamorphogenic fluids: Tux (magnesite, scheelite), Otterzug (barite), Lassing (magnesite), Rabenwald (talc), Laussa and Mooseck (fluorite). The mineralizing fluids are derived from different sedimentary rock series and therefore 87 Sr/ 86 Sr-ratios vary between 0.707 and 0.719. Deposits situated along fault zones: Lassing (talc), Gasteiner Tal (Silberpfennig area; gold), Schlaining (stibnite) and Waldenstein (specularite). Sr isotope ratios of the mineralizing fluids from Lassing, Waldenstein and Schlaining ranges from 0.7112 to 0.7127 and are therefore thought to have scavenged the East Alpine crystalline. The mineralizing solutions of the Gasteiner Tal deposit may either have equilibrated with low radiogenic sedimentary or with (ultra-)basic rocks. A cracking chamber has been constructed in order to open FI by cracking for mass spectrometric analysis of volatile components. Gases are analysed using a quadrupole mass spectrometer. The desorption of gas from metal and sample surfaces during cracking can be neglected. The amount of gas released from the mineral lattices was studied. With that fast method ore bearing from barren host rocks have been distinguished by different composition of the FI at the Brixlegg barite mineralization (Eastern Alps). Within the Galway fluorite deposit (Ireland) different fluids were involved and mass spectrometric analysis were carried out to characterize these different fluids and to identify their origin. (author)

  7. Effects of oil and gas well-drilling fluids on the biomass and community structure of microbiota that colonize sands in running seawater.

    Science.gov (United States)

    Smith, G A; Nickels, J S; Bobbie, R J; Richards, N L; White, D C

    1982-01-01

    Well-drilling fluid and a number of the known components (barite, clay, Aldacide, Surflo, and Dowicide, were tested for effects on the biomass and community structure of the microbiota that colonize marine sands exposed for eight weeks to running ambient seawater. Shading the microbiota from light depressed the microflora without a significant effect on the biomass, while well-drilling fluids layered on the surface or mixed with the sand significantly increased a component of the bacteria and the microfauna as reflected in changes in the fatty acid composition. There were some shading effects from the surface layering of well-drilling fluids as reflected in the fatty acids from the microflora when compared to the sands mixed with well-drilling fluids. Barite had essentially no effect on the biomass or community structure while clays increased nearly all of the biomass indicators for the bacteria as well as the microfauna; the clay overlay mirrors the effect of the drilling fluids. Aldacide shifted the bacterial composition, depressing the proportions of microbes containing the cyclopropane fatty acids and the anaerobic pathways of desaturation. Concentrations of 1 and 15 microgram/L increased the bacterial biomass as reflected in the total lipid (16:0) and extractable lipid phosphate coupled with a decrease in the total microeukaryotes. Surflo increased the biomass and shifted the bacterial community structure at concentrations between 4 and 800 microgram/L. The lowest level also stimulated the microfauna. Dowicide at 100 microgram/L increased the bacteria forming cis-vaccenic acid and the microfauna similar to low concentrations of Surflo.

  8. Phosphorite-hosted zinc and lead mineralization in the Sekarna deposit (Central Tunisia)

    Science.gov (United States)

    Garnit, Hechmi; Bouhel, Salah; Barca, Donatella; Johnson, Craig A.; Chtara, Chaker

    2012-01-01

    The Sekarna Zn–Pb deposit is located in Central Tunisia at the northeastern edge of the Cenozoic Rohia graben. Mineralization comprises two major ore types: (1) disseminated Zn–Pb sulfides that occur as lenses in sedimentary phosphorite layers and (2) cavity-filling zinc oxides (calamine-type ores) that crosscut Late Cretaceous and Early Eocene limestone. We studied Zn sulfide mineralization in the Saint Pierre ore body, which is hosted in a 5-m-thick sedimentary phosphorite unit of Early Eocene age. The sulfide mineralization occurs as replacements of carbonate cement in phosphorite. The ores comprise stratiform lenses rich in sphalerite with minor galena, Fe sulfides, and earlier diagenetic barite. Laser ablation–inductively coupled plasma mass spectrometry analyses of sphalerite and galena show a wide range of minor element contents with significant enrichment of cadmium in both sphalerite (6,000–20,000 ppm) and galena (12–189 ppm). The minor element enrichments likely reflect the influence of the immediate organic-rich host rocks. Fluid inclusions in sphalerite give homogenization temperatures of 80–130°C. The final ice melting temperatures range from −22°C to −11°C, which correspond to salinities of 15–24 wt.% NaCl eq. and suggest a basinal brine origin for the fluids. Sulfur isotope analyses show uniformly negative values for sphalerite (−11.2‰ to −9.3‰) and galena (−16‰ to −12.3‰). The δ34S of barite, which averages 25.1‰, is 4‰ higher than the value for Eocene seawater sulfate. The sulfur isotopic compositions are inferred to reflect sulfur derivation through bacterial reduction of contemporaneous seawater sulfate, possibly in restricted basins where organic matter was abundant. The Pb isotopes suggest an upper crustal lead source.

  9. Oceanic circulation changes during early Pliocene marine ice-sheet instability in Wilkes Land, East Antarctica

    Science.gov (United States)

    Hansen, Melissa A.; Passchier, Sandra

    2017-06-01

    In the Southern Ocean, unconstrained Westerlies allow for intense mixing between deep waters and the atmosphere. How this system interacts with Antarctic ice sheets and the global ocean circulation is poorly understood due to a paucity of data. The poor abundance and preservation of foraminiferal carbonate in ice-proximal sediments is a major challenge in high-latitude paleoceanography. A new approach is to examine a sediment geochemical record of changing paleoproductivity and sediment redox environment that can be tied to changes in water mass properties. This study focuses on the paleoceanography of the George V Land margin between 4.7 and 4.3 Ma. This interval at the onset of the early Pliocene Climatic Optimum was characterized by the highest global sea surface temperatures and the lowest sea ice concentrations in East Antarctica in the past 5 million years. At IODP Site U1359, an abrupt increase in Mn/Al ratios 4.6 Ma indicates an episode of oxic bottom conditions resulting from enhanced wind-driven downwelling of Antarctic surface water. Above, extremely high concentrations of sedimentary barite (Ba excess >40,000 ppm) point to biogenic barite deposition, preservation, and concentration through enhanced upwelling of nutrient-rich Circumpolar Deep Water (CDW). Incursion of CDW onto the continental shelf affected ice discharge and resulted in a stable but reduced ice-sheet configuration over several glacial cycles. The geochemical results along with previous work on Site U1359 for the first time link paleoceanography and cryospheric change based on data from the same high-latitude site.

  10. Oceanic minerals: their origin, nature of their environment, and significance.

    Science.gov (United States)

    Kastner, M

    1999-03-30

    The chemical and isotopic compositions of oceanic biogenic and authigenic minerals contain invaluable information on the evolution of seawater, hence on the history of interaction between tectonics, climate, ocean circulation, and the evolution of life. Important advances and greater understanding of (a) key minor and trace element cycles with various residence times, (b) isotopic sources and sinks and fractionation behaviors, and (c) potential diagenetic problems, as well as developments in high-precision instrumentation, recently have been achieved. These advances provided new compelling evidence that neither gradualism nor uniformitarianism can explain many of the new important discoveries obtained from the chemistry and isotopic compositions of oceanic minerals. Presently, the best-developed geochemical proxies in biogenic carbonates are 18O/16O and Sr/Ca ratios (possibly Mg/Ca) for temperature; 87Sr/86Sr for input sources, Cd/Ca and Ba/Ca ratios for phosphate and alkalinity concentrations, respectively, thus also for ocean circulation; 13C/12C for ocean productivity; B isotopes for seawater pH;, U, Th isotopes, and 14C for dating; and Sr and Mn concentrations for diagenesis. The oceanic authigenic minerals most widely used for chemical paleoceanography are barite, evaporite sulfates, and hydrogenous ferromanganese nodules. Marine barite is an effective alternative monitor of seawater 87Sr/86Sr, especially where carbonates are diagenetically altered or absent. It also provides a high-resolution record of seawater sulfate S isotopes, (evaporite sulfates only carry an episodic record), with new insights on factors affecting the S and C cycles and atmospheric oxygen. High-resolution studies of Sr, Nd, and Pb isotopes of well-dated ferromanganese nodules contain invaluable records on climate driven changes in oceanic circulation.

  11. 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.

  12. 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

  13. Benthic foraminiferal responses to operational drill cutting discharge in the SW Barents Sea - a case study.

    Science.gov (United States)

    Aagaard-Sørensen, Steffen; Junttila, Juho; Dijkstra, Noortje

    2016-04-01

    Petroleum related exploration activities started in the Barents Sea 1980, reaching 97 exploration wells drilled per January 2013. The biggest operational discharge from drilling operations in the Barents Sea is the release of drill cuttings (crushed seabed and/or bedrock) and water based drilling muds including the commonly used weighing material barite (BaSO4). Barium (Ba), a constituent of barite, does not degrade and can be used to evaluate dispersion and accumulation of drill waste. The environmental impact associated with exploration drilling within the Goliat Field, SW Barents Sea in 2006 was evaluated via a multiproxy investigation of local sediments. The sediments were retrieved in November 2014 at ~350 meters water depth and coring sites were selected at distances of 5, 30, 60, 125 and 250 meters from the drill hole in the eastward downstream direction. The dispersion pattern of drill waste was estimated via measurements of sediment parameters including grain size distribution and water content in addition to heavy metal and total organic carbon contents. The environmental impact was evaluated via micro faunal analysis based on benthic foraminiferal (marine shell bearing protists) fauna composition and concentration changes. Observing the sediment parameters, most notably Ba levels, reveals that dispersion of drill waste was limited to <125 meters from the drill site with drill waste thicknesses decreasing downstream. The abruptness and quantity of drill waste sedimentation initially smothered the foraminiferal fauna at ≤ 30 meters from the drill site, while at a distance of 60 meters, the fauna seemingly survived and bioturbation persisted. Analysis of the live (Nov 2014) foraminiferal fauna reveals a natural species composition at all distances from the drill site within the top sediments (0-5 cm core depth). Furthermore, the fossil foraminiferal fauna composition found within post-impacted top sediment sections, particularly in the cores situated at

  14. Mineralogy and geological significance of hydrothermal deposits from the Okinawa Trough

    Science.gov (United States)

    Zhang, Xia; Zhai, Shikui; Yu, Zenghui; Wang, Shujie; Cai, Zongwei

    2018-04-01

    The study of hydrothermal deposits in the Okinawa Trough can help us to uncover the hydrothermal mineralization characteristics in the back-arc basin during the early expanding stage. Mineralogy and geological significance of hydrothermal deposits from both the middle and southern trough are studied in this paper. First of all, using optical microscope to confirm the mineral compositions, characteristics of crystal shape, paragenetic relationship and minerals crystallization order. Then the minerals chemical composition were analyzed in virtue of electron microprobe. On these basis, the paragenetic sequence and the mineralization characteristics of the hydrothermal deposits were discussed. The results show that the hydrothermal deposit from the mid-Okinawa Trough belongs to Zn-Cu-rich type, consisting dominantly of sulfide minerals such as sphalerite, chalcopyrite, pyrite, etc. The minerals crystallization order is first generation pyrite(PyI)-sphalerite-chalcopyrite-galena-second generation pyrite(PyII)-amorphous silica. While the deposit from the southern Okinawa Trough is Ba-Zn-Pb-rich type mainly composing of barite, sphalerite, galena, etc. The minerals crystallization order is barite-pyrite-sphalerite-tetrahedrite-galena-chalcopyrite-amorphous silica. Hydrothermal fluid temperature in the mid-Okinawa Trough undergoes a process from high to low, which is high up to 350 °C in the early stage, but decreasing gradually with the evolution of hydrothermal fluid. On the contrary, the hydrothermal activity in the southern Okinawa Trough is low temperature dominated, but the mineralization environment is unstable and the fluid temperature changes drastically during the period of hydrothermal activity.

  15. Effects of ocean acidification on the marine calcium isotope record at the Paleocene-Eocene Thermal Maximum

    Science.gov (United States)

    Griffith, Elizabeth M.; Fantle, Matthew S.; Eisenhauer, Anton; Paytan, Adina; Bullen, Thomas D.

    2015-06-01

    Carbonates are used extensively to reconstruct paleoclimate and paleoceanographic conditions over geologic time scales. However, these archives are susceptible to diagenetic alteration via dissolution, recrystallization and secondary precipitation, particularly during ocean acidification events when intense dissolution can occur. Despite the possible effects of diagenesis on proxy fidelity, the impacts of diagenesis on the calcium isotopic composition (δ44Ca) of carbonates are unclear. To shed light on this issue, bulk carbonate δ44Ca was measured at high resolution in two Pacific deep sea sediment cores (ODP Sites 1212 and 1221) with considerably different dissolution histories over the Paleocene-Eocene Thermal Maximum (PETM, ∼ 55 Ma). The δ44Ca of marine barite was also measured at the deeper Site 1221, which experienced severe carbonate dissolution during the PETM. Large variations (∼ 0.8 ‰) in bulk carbonate δ44Ca occur in the deeper of the two sites at depths corresponding to the peak carbon isotope excursion, which correlate with a large drop in carbonate weight percent. Such an effect is not observed in either the 1221 barite record or the bulk carbonate record at the shallower Site 1212, which is also less affected by dissolution. We contend that ocean chemical changes associated with abrupt and massive carbon release into the ocean-atmosphere system and subsequent ocean acidification at the PETM affected the bulk carbonate δ44Ca record via diagenesis in the sedimentary column. Such effects are considerable, and need to be taken into account when interpreting Ca isotope data and, potentially, other geochemical proxies over extreme climatic events that drive sediment dissolution.

  16. Mineralogical and Geochemical Compositions of the Lopingian Coals in the Zhongliangshan Coalfield, Southwestern China

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    Jianhua Zou

    2018-03-01

    Full Text Available The mineralogical and geochemical compositions of the Lopingian coals from an exploratory drill core (ZK4-1 in the Zhongliangshan Coalfield, southwestern China are reported in this paper. The Zhongliangshan coals are medium volatile bituminous in rank (random vitrinite reflectance, average 1.38%, characterized by a medium-ash yield (26.84% and high sulfur content (3.38%. Minerals in the Zhongliangshan coals are mainly composed of clay assemblages (kaolinite, the illite/smectite mixed layer (I/S and chamosite, pyrite, quartz, carbonate minerals (calcite, marcasite, ankerite, and dolomite, and anatase, followed by rutile, jarosite, natrojarosite, bassanite, gypsum and K-feldspar, with traces of apatite, rhabdophane and barite. Compared with the average concentrations of the world hard coals, some trace elements including Li, V, Co, Cu, Se, Y, Zr, Nb, rare earth elements (REE, Cd, Ta, Hf and Hg, are enriched in the Zhongliangshan coals. The modes of occurrence of chamosite, barite, rhabdophane, quartz and calcite in the Zhongliangshan coals indicate that the coals have probably been affected by the injection of low-temperature hydrothermal fluids. Based on the concentrations of Sc, V, Cr, Co, Ni, Cu and Zn, the ratios of Al2O3/TiO2 and the upper continental crust-normalized rare earth element and yttrium (REY distribution patterns of the Zhongliangshan coals, the dominant sediment source regions are the Leshan–Longnvsi Uplift, Hannan Upland, and Dabashan Uplift, with a small proportion of terrigenous materials from the Kangdian Upland. The K7 and the upper portion of K1 coals have the potential as raw materials for the recovery of REY.

  17. 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

  18. LASER step-heating 40Ar /39Ar age spectra from early Archean (~3.5 Ga) Barberton greenstone belt sediments: A technique for detecting cryptic tectono-thermal events

    Science.gov (United States)

    De Ronde, C. E. J.; Hall, C. M.; York, D.; Spooner, E. T. C.

    1991-07-01

    Samples from sediments of the Fig Tree Group located in the central part of the circa 3.2 to 3.5 Ga Barberton greenstone belt (BGB) have been analyzed by the 40Ar /39Ar laser step-heating technique. This technique has enabled previously cryptic thermal overprints to be detected in various sedimentary units which include: reworked chemical sediments (barite), clastic sediments (sandstone/shale), and one stromatolite. In most cases the apparent age plateaux can be identified by corresponding Ca/K and Cl/K ratio plots as belonging to separate mineral phases. Most of the samples exhibit simple Ar diffusion loss during the low temperature part of the experiments while occasionally showing excess Ar, or possible 39Ar recoil, effects. The various sediments analyzed show evidence for distinct overprinting between 2025 and 2090 Ma. One barite sample gave T0 (original blocking age) = 2673 ± 3 Ma (1σ) which is close to a calculated model Ar diffusion-loss age for the same sample of 2688 ± 3 Ma (1σ). This age is interpreted as representing final granitoid activity adjacent to the BGB, and/or craton-scale tectonism associated with the Limpopo Orogeny. Two samples gave T0 ages of ˜2350-2400 Ma which may reflect increased thermal gradients associated with the formation of the thick Transvaal sedimentary basin that may once have covered the BGB. The dominant apparent age plateaux together with modelled diffusive Ar loss ages of 2025-2090 Ma, are thought to represent regional thermal anomalies related to large-scale tectono-thermal activity in the Kaapvaal craton, of which the Bushveld Complex (which covers a surface area of ~ 60,000 km 2) and formation of the Vredefort Structure are obvious manifestations. The strong thermal overprinting recorded by the sediments has effectively removed any ancient atmosphere (i.e., 40Ar /36Ar ratios < 295.5) signatures.

  19. Geochemical modelling of water-rock interactions at the Osamu Utsumi mine and Morro do Ferro analogue study sites, Pocos de Caldas, Brazil

    International Nuclear Information System (INIS)

    Nordstrom, D.K.; Puigdomenech, I.; McNutt, R.H.

    1990-01-01

    Geochemical processes involving water-rock interactions have been modelled using groundwater composition, mineralogical data, ion plots and computations of speciation, non-thermodynamic mass balance and thermodynamic mass transfer for two natural analogue sites near Pocos de Caldas, Brazil: the Osamu Utsumi mine and Morro do Ferro. The main rock type is an alkaline igneous complex composed of volcanic and sub-volcanic phonolites that have been hydrothermally altered and highly weathered. This altered rock mass grades from a laterite at the surface to a saprolite and finally to unweathered, hydrothermally altered bedrock at depth. The mine site contains high concentrations of uranium and Morro do Ferro contains high concentrations of thorium and rare-earths. The reaction models can reproduce the water chemistry and mineral occurences and they were validated by predicting the masses of minerals precipitated and the pH of the final water. The model computations can also reproduce the pH and iron concentrations of the water samples during CO 2 degassing and iron(II) oxidation from exposure to air. The results from the geochemical reaction models reveal that the dominant processes are production of CO 2 in the soil zone through aerobic decay of organic matter, dissolution of fluorite, calcite, K-feldspar, albite and manganese oxides, oxidation of pyrite and sphalerite and precipitation of ferric oxides, silica and kaolinite. Recharge waters are undersaturated with respect to barite and discharging waters and deeper groundwaters are saturated to supersaturated with respect to barite, demonstrating a strong equilibrium solubility control. Strontium isotope data demonstrate that sources other than calcium-bearing minerals are required to account for the dissolved strontium in the ground. These may include K-feldspar, smectite-chlorite mixed-layer clays and goyazite. (author) 24 figs., 4 tabs., 18 refs

  20. Co-treatment of abandoned mine drainage and Marcellus Shale flowback water for use in hydraulic fracturing.

    Science.gov (United States)

    He, Can; Zhang, Tieyuan; Vidic, Radisav D

    2016-11-01

    Flowback water generated during shale gas extraction in Pennsylvania is mostly reused for hydraulic fracturing operation. Abandoned mine drainage (AMD), one of the most widespread threats to water quality in Pennsylvania, can potentially serve as a make-up water source to enable flowback water reuse. This study demonstrated co-treatment of flowback water and AMD produced in northeastern Pennsylvania in a pilot-scale system consisting of rapid mix reactor, flocculation tank and sedimentation tank. Sulfate concentration in the finished water can be controlled at a desired level (i.e., below 100 mg/L) by adjusting the ratio of flowback water and AMD in the influent. Fe 3+ contained in the AMD can serve as a coagulant to enhance the removal of suspended solids, during which Fe 2+ is co-precipitated and the total iron is reduced to a desirable level. Solid waste generated in this process (i.e., barite) will incorporate over 99% of radium present in the flowback water, which offers the possibility to control the fate of naturally occurring radioactive materials (NORM) brought to the surface by unconventional gas extraction. Sludge recirculation in the treatment process can be used to increase the size of barite particles formed by mixing flowback water and AMD to meet specifications for use as a weighting agent in drilling fluid. This alternative management approach for NORM can be used to offset the treatment cost and promote flowback water reuse, reduce environmental impacts of AMD and reduce pressure on fresh water sources. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Mineral and energy resources of the Roswell Resource Area, East-Central New Mexico

    Science.gov (United States)

    Bartsch-Winkler, Susan B.; Donatich, Alessandro J.

    1995-01-01

    The sedimentary formations of the Roswell Resource Area have significant mineral and energy resources. Some of the pre-Pennsylvanian sequences in the Northwestern Shelf of the Permian Basin are oil and gas reservoirs, and Pennsylvanian rocks in Tucumcari Basin are reservoirs of oil and gas as well as source rocks for oil and gas in Triassic rocks. Pre-Permian rocks also contain minor deposits of uranium and vanadium, limestone, and gases. Hydrocarbon reservoirs in Permian rocks include associated gases such as carbon dioxide, helium, and nitrogen. Permian rocks are mineralized adjacent to the Lincoln County porphyry belt, and include deposits of copper, uranium, manganese, iron, polymetallic veins, and Mississippi-Valley-type lead-zinc. Industrial minerals in Permian rocks include fluorite, barite, potash, halite, polyhalite, gypsum, anhydrite, sulfur, limestone, dolomite, brine deposits (iodine and bromine), aggregate (sand), and dimension stone. Doubly terminated quartz crystals, called 'Pecos diamonds' and collected as mineral specimens, occur in Permian rocks along the Pecos River. Mesozoic sedimentary rocks are hosts for copper, uranium, and small quantities of gold-silver-tellurium veins, as well as significant deposits of oil and gas, carbon dioxide, asphalt, coal, and dimension stone. Mesozoic rocks contain limited amounts of limestone, gypsum, petrified wood, and clay. Tertiary rocks host ore deposits commonly associated with intrusive rocks, including platinum-group elements, iron skarns, manganese, uranium and vanadium, molybdenum, polymetallic vein deposits, gold-silver-tellurium veins, and thorium-rare-earth veins. Museum-quality quartz crystals are associated with Tertiary intrusive rocks. Industrial minerals in Tertiary rocks include fluorite, vein- and bedded-barite, caliche, limestone, and aggregate. Tertiary and Quaternary sediments host important placer deposits of gold and titanium, and occurrences of silver and uranium. Important industrial

  2. Mineral and energy resources of the BLM Roswell Resource Area, east-central New Mexico

    Science.gov (United States)

    Bartsch-Winkler, Susan B.

    1992-01-01

    The sedimentary formations of the Roswell Resource Area have significant mineral and energy resources. Some of the pre-Pennsylvanian sequences in the Northwestern Shelf of the Permian Basin are oil and gas reservoirs, and Pennsylvanian rocks in Tucumcari basin are reservoirs of oil and gas as well as source rocks for oil and gas in Triassic rocks. Pre-Permian rocks also contain minor deposits of uranium and vanadium, limestone, and associated gases. Hydrocarbon reservoirs in Permian rocks include associated gases such as carbon dioxide, helium, and nitrogen. Permian rocks are mineralized adjacent to the Lincoln County porphyry belt, and include deposits of copper, uranium, manganese, iron, polymetallic veins, and Mississippi-valley-type (MVT) lead-zinc. Industrial minerals in Permian rocks include fluorite, barite, potash, halite, polyhalite, gypsum, anhydrite, sulfur, limestone, dolomite, brine deposits (iodine and bromine), aggregate (sand), and dimension stone. Doubly terminated quartz crystals, called "Pecos diamonds" and collected as mineral specimens, occur in Permian rocks along the Pecos River. Mesozoic sedimentary rocks are hosts for copper, uranium, and small quantities of gold-silver-tellurium veins, as well as significant deposits of oil and gas, COa, asphalt, coal, and dimension stone. Mesozoic rocks contain limited amounts of limestone, gypsum, petrified wood, dinosaur remains, and clays. Tertiary rocks host ore deposits commonly associated with intrusive rocks, including platinum group elements, iron skarns, manganese, uranium and vanadium, molybdenum, polymetallic vein deposits, gold-silver- tellurium veins, and thorium-rare earth veins. Museum-quality quartz crystals in Lincoln County were formed in association with intrusive rocks in the Lincoln County porphyry belt. Industrial minerals in Tertiary rocks include fluorite, vein- and bedded-barite, caliche, limestone, and aggregate. Tertiary and Quaternary sediments host important placer deposits of

  3. Diagenetic and post-diagenetic fabrics in the Kamarposht fluorite mine (east of Mazandaran province: Explainaton and genetic interpretation

    Directory of Open Access Journals (Sweden)

    Faezeh Nabiloo

    2017-11-01

    Full Text Available Introduction Upper part of Elika Formation (middle Triassic in the central Alborz as one of the most important fluorite districts in Iran is the host of some carbonate rock-hosted fluorite deposits such as Kamarposht, Pachi-Miana, Shashroodbar, Era (Alirezaee, 1989; Gorjizad, 1996; Rastad and Shariatmadar, 2001; Rajabi et al., 2013; Vahabzadeh et al., 2013; Zabihitabar and Shafiei, 2015. One of the main active fluorite mines in the central Alborz is Kamarposht which is located at the southeast of DoAb in the Mazandaran province. The Kamarposht mine has 75000 tons of ores and mining there has begun in 2005. The effects and evidences of underground mining in the northern and southern parts of this mine indicate high-grade and coarse-grained ore zones which have fluorite, galena and barite. Until now, basic economic geology studies in the Kamarposht mine including mineralogy, fabric and texture of mineralization for introducing a new fluorite mine in Iran have not been carried out. The present study is based on field observations and macroscopic as well as microscopic studies aimed at identification of morphology and mode of occurrence of the ore body, mineralogy and fabric of mineralization and discussion of as well as presentation of a new genetic model for the Kamarposht mine. Materials and methods For the present research study, field geology and sampling were carried out to collect 100 samples from various fluorite ore-types and carbonate host rocks. The samples prepared for thin section (n=55 and polished-thin sections (n=22. Results Field observations indicate that economic mineable ore zones of the Kamarposht mine are mainly hosted by dolomitic limestone and silicified carbonate horizons of the Elika Formation. The ore zones have fluorite, barite and galena which are mainly located in fractured and faulted zones as well as karstic cavities in the host horizons. Coarse grain and euhedral fluorites with various colors, significant presence of

  4. Palaeoredox indicators from the organic-rich Messinian early post-evaporitic deposits of the Apennines (Central Italy)

    Science.gov (United States)

    Sampalmieri, G.; Iadanza, A.; Cipollari, P.; Cosentino, D.; Lo Mastro, S.

    2009-04-01

    Bottom redox conditions in marine and lacustrine ancient basins are often inferred by the occurrence of peculiar sedimentological structures and microfaunal assemblages. The co-occurrence, in such environments, of authigenic uranium, framboidal pyrite, barite and Fe-Mn nodules and encrustations, provides a good constraint for palaeo reconstructions. Authigenic uranium is a common constituent of hydrocarbon source rocks: it forms at the sediment-water interface under oxygen-deficient conditions and accumulates together with organic matter (OM). Its precipitation is triggered by the reduction of the soluble U6+ion in seawater to insoluble U4+. With respect to black shales, uranium content has even been used to estimate the TOC. Also authigenic pyrite forms under anoxic conditions and replaces organic matter: 1) the increase in pyrite content and in organic matter are directly correlated; 2) the size distribution of framboidal pyrite (consistent with sulphate-reducing bacterial activity) is considered a measure of redox conditions within the sediment. Barite is an authigenic mineral related to Corg content, since its organic precipitation is triggered by sulphate-reduction processes occurring in decaying OM-bearing microenvironments. Finally, also Fe-Mn oxyhydroxide are typical indicators of redox conditions. About 6 My ago the Mediterranean Sea underwent a giant event of concentration referred to as Messinian Salinity Crisis, which can be roughly subdivided into an evaporitic and a post evaporitic phase. The post evaporitic phase (p-ev; 5.61-5.33 Ma) developed in a context of humid conditions and can be further distinguished into two steps: p-ev1 (early post evaporitic phase) and p-ev2 (late post evaporitic phase). Previous works focused on pev2, which is interpreted to represent the establishment of brackish water conditions (Lago-Mare biofacies). In other respects, the palaeoenvironment of p-ev1 deposits, mostly represented by resedimented evaporitic deposits or

  5. 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

  6. Origin of secondary sulfate minerals on active andesitic stratovolcanoes

    Science.gov (United States)

    Zimbelman, D.R.; Rye, R.O.; Breit, G.N.

    2005-01-01

    Sulfate minerals in altered rocks on the upper flanks and summits of active andesitic stratovolcanoes result from multiple processes. The origin of these sulfates at five active volcanoes, Citlalte??petl (Mexico), and Mount Adams, Hood, Rainier, and Shasta (Cascade Range, USA), was investigated using field observations, petrography, mineralogy, chemical modeling, and stable-isotope data. The four general groups of sulfate minerals identified are: (1) alunite group, (2) jarosite group, (3) readily soluble Fe- and Al-hydroxysulfates, and (4) simple alkaline-earth sulfates such as anhydrite, gypsum, and barite. Generalized assemblages of spatially associated secondary minerals were recognized: (1) alunite+silica??pyrite??kaolinite?? gypsum??sulfur, (2) jarosite+alunite+silica; (3) jarosite+smectite+silica??pyrite, (4) Fe- and Al-hydroxysulfates+silica, and (5) simple sulfates+silica??Al-hydroxysulfates??alunite. Isotopic data verify that all sulfate and sulfide minerals and their associated alteration assemblages result largely from the introduction of sulfur-bearing magmatic gases into meteoric water in the upper levels of the volcanoes. The sulfur and oxygen isotopic data for all minerals indicate the general mixing of aqueous sulfate derived from deep (largely disproportionation of SO2 in magmatic vapor) and shallow (oxidation of pyrite or H2S) sources. The hydrogen and oxygen isotopic data of alunite indicate the mixing of magmatic and meteoric fluids. Some alunite-group minerals, along with kaolinite, formed from sulfuric acid created by the disproportionation of SO2 in a condensing magmatic vapor. Such alunite, observed only in those volcanoes whose interiors are exposed by erosion or edifice collapse, may have ??34S values that reflect equilibrium (350??50 ??C) between aqueous sulfate and H2S. Alunite with ??34S values indicating disequilibrium between parent aqueous sulfate and H2S may form from aqueous sulfate created in higher level low

  7. Uranium in Surface Waters and Sediments Affected by Historical Mining in the Denver West 1:100,000 Quadrangle, Colorado

    Science.gov (United States)

    Zielinski, Robert A.; Otton, James K.; Schumann, R. Randall; Wirt, Laurie

    2008-01-01

    .05), and this distinctive isotopic composition may be preserved in iron-oxyhydroxide precipitates of acid drainage origin. The study area includes a particularly large vein-type uranium deposit (Schwartzwalder mine) with past uranium production. Stream water and sediment collected downstream from the mine's surface operations have locally anomalous concentrations of uranium. Fine-grained sediments downstream from the mine contain rare minute particles (10-20 micrometers) of uraninite, which is unstable in a stream environment and thus probably of recent origin related to mining. Additional rare particles of very fine grained (less than 5 micrometer) barite likely entered the stream as discharge from settling ponds in which barite precipitation was formerly used to scavenge dissolved radium from mine effluent.

  8. Study of rhyolitic glasses alteration in contact with natural brines (Bolivia). Application to the study of the long-term behaviour of the R7T7 nuclear glass

    International Nuclear Information System (INIS)

    Abdelouas, A.

    1996-01-01

    The purpose of this work is to complement an experimental program on the R7T7 nuclear waste glass alteration in brines at 190 deg C in Germany by the analysis of the structure and the chemical composition of the alteration layers, and to study the alteration of rhyolitic glasses in natural brines from Bolivia as analogue for nuclear waste glasses disposed in salt formations. Alteration experiments with the R7T7 and basaltic glasses and obsidian in MgCl 2 -CaCl 2 -saturated brine at 190 deg. C were also conducted in order to study the influence of the glass composition on the nature of the secondary phases. The experiments with the R7T7 glass in three salt brines, saturated respectively in MgCl 2 , MgCl 2 -CaCl 2 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. These phases are stable for more than one year. There is a good similarity between the secondary phases formed experimentally on volcanic glasses and the R7T7 glass altered in MgCl 2 -CaCl 2 -saturated brine. The abundance of Mg in solution permits the formation of similar magnesian clays on the glass samples independently of the nature of the initial glasses. These results support the use of volcanic glasses alteration patterns in Mg-rich solutions 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 deg. C is 12 to 30 time lower than those of rhyolitic glasses altered in high dilute conditions. 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

  9. 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.

  10. 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

  11. 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

  12. Experimental insights into geochemical changes in hydraulically fractured Marcellus Shale

    International Nuclear Information System (INIS)

    Marcon, Virginia; Joseph, Craig; Carter, Kimberly E.; Hedges, Sheila W.; Lopano, Christina L.; Guthrie, George D.; Hakala, J. Alexandra

    2017-01-01

    Hydraulic fracturing applied to organic-rich shales has significantly increased the recoverable volume of methane available for U.S. energy consumption. Fluid-shale reactions in the reservoir may affect long-term reservoir productivity and waste management needs through changes to fracture mineral composition and produced fluid chemical composition. We performed laboratory experiments with Marcellus Shale and lab-generated hydraulic fracturing fluid at elevated pressures and temperatures to evaluate mineral reactions and the release of trace elements into solution. Results from the experiment containing fracturing chemicals show evidence for clay and carbonate dissolution, secondary clay and anhydrite precipitation, and early-stage (24–48 h) fluid enrichment of certain elements followed by depletion in later stages (i.e. Al, Cd, Co, Cr, Cu, Ni, Sc, Zn). Other elements such as As, Fe, Mn, Sr, and Y increased in concentration and remained elevated throughout the duration of the experiment with fracturing fluid. Geochemical modeling of experimental fluid data indicates primary clay dissolution, and secondary formation of smectites and barite, after reaction with fracturing fluid. Changes in aqueous organic composition were observed, indicating organic additives may be chemically transformed or sequestered by the formation after hydraulic fracturing. The NaCl concentrations in our fluids are similar to measured concentrations in Marcellus Shale produced waters, showing that these experiments are representative of reservoir fluid chemistries and can provide insight on geochemical reactions that occur in the field. These results can be applied towards evaluating the evolution of hydraulically-fractured reservoirs, and towards understanding geochemical processes that control the composition of produced water from unconventional shales. - Highlights: • Metal concentrations could be at their peak in produced waters recovered 24–48 after fracturing. • Carbonate

  13. 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

  14. Mineralogy and geochemical environment of formation of the Perama Hill high-sulfidation epithermal Au-Ag-Te-Se deposit, Petrota Graben, NE Greece

    Science.gov (United States)

    Voudouris, Panagiotis Christos; Melfos, Vasilios; Spry, Paul G.; Moritz, Robert; Papavassiliou, Constantinos; Falalakis, George

    2011-11-01

    The Perama Hill deposit is a high-sulfidation Au-Ag-Te-Se epithermal system hosted in silicic- and argillic altered andesitic rocks and overlying sandstones, which were emplaced on the eastern margin of the Petrota graben, northeastern Greece. The deposit evolved from an early stage silica-pyrite rock and argillic alteration followed by the deposition of sulfide-, sulfosalt- and telluride-bearing quartz-barite veins and stockworks. Early ore formation is characterized by a high-sulfidation-type enargite-galena-bearing ore assemblage (consisting of enargite, watanabeite, Fe-free sphalerite, covellite, kesterite, bismuthinite, selenian bismuthinite, lillianite homologues, kawazulite-tetradymite, goldfieldite, and native gold), followed by the formation of an intermediate-sulfidation-type tennantite-bearing assemblage characterized by ferrian/zincian tennantite, tellurobismuthite, tetradymite, melonite, native tellurium, Au-Ag-tellurides (calaverite, krennerite, sylvanite, hessite, petzite, stützite), altaite and electrum. Quartz, barite, kaolinite, sericite and minor aluminum-phosphate-sulfate minerals are gangue minerals. Fluid inclusion data demonstrate that the ore system evolved from an initial high temperature (up to 330°C) and low salinity (up to 4.9 wt.% NaCl equiv.) fluid towards a cooler (200°C) and very low salinity (0.7 wt.% NaCl equiv.) hydrothermal fluid suggesting progressive cooling and dilution of the ore fluid. The ore minerals at Perama Hill reflect variable fS2 and fTe2 conditions during base and precious metal deposition. Early ore deposition took place at ~300°C, at log fS2 values between ≈-8.2 and -5.5, and log fTe2 from -11.8 and -7.8. Late ore deposition occurred at log fS2 = -11.8 to -9.8 and log fTe2 of ≈-9.2 and -7.8. These data and paragenetic studies indicate a shift towards higher log fTe2 and lower log fS2 and log fSe2 values for the mineralizing fluids with time. The kawazulite/tetradymitess-gold association at Perama Hill

  15. Reactive Transport of Marcellus Shale Waters in Natural Aquifers: the Role of Mineralogical Compositions and Spatial Distribution Patterns

    Science.gov (United States)

    Cai, Z.; Wen, H.; Li, L.

    2017-12-01

    Accidental release of Marcellus Shale waters (MSW) can release high concentrations of chemicals that can deteriorate groundwater quality. It is important to understand the reactive transport and fate of chemicals from MSW. Natural aquifers typically have complex mineralogical compositions and are heterogeneous with large spatial variation in terms of physical and geochemical properties. To investigate the effects of mineralogical compositions, flow-through experiments and reactive transport modeling were carried out using 3 large columns (5 cm×50 cm, Quartz, Calcite, and Vermiculite). Results indicate calcite immobilizes heavy metals by precipitation and solid solution partitioning (coprecipitation). Vermiculite retards heavy metals through ion exchange. The sorbed chemicals however slowly release back to the groundwater. Na and Ca transport similarly to Br in Qtz and Cal columns however become sorbed in Vrm column during release through ion exchange by 27.8% and 46.5%, respectively and later slowly release back to aqueous phase. To understand the role of mineral spatial patterns, three 2D flow-cell (40 cm×12 cm×1 cm) experiments were carried out. All flow cells have the same clay mass within quartz matrix but different spatial patterns characterized by the relative length of the clay zone ( 0, ¼, ½) of the domain length (L). Results show that in the uniform column, ion exchange dominates and most Ba sorbs to the solid phase, to an extent Ba cannot precipitate out with SO4 as barite. In 1/2-Zone, however, most Ba precipitates as barite. In 1/4-Zone, both ion exchange and mineral precipitation occur. In general, the 1/2-Zone has the smallest ion exchange capacity for other species including Na, Ca, Mg, K and heavy metals (Mn, Cu, Zn, Cd and Pb) as well. Our flow cell experiment emphasizes the importance of mineral spatial patterns in regulating not only reaction rates but also the type of reactions in controlling the reactive transport of MSW chemicals. The

  16. Long-term observation of particulate barium fluxes in the subtropical Northeast Atlantic (33 N, 22 W)

    Science.gov (United States)

    Stern, Judith; Dellwig, Olaf; Waniek, Joanna J.

    2017-04-01

    Particle flux material was collected with a sediment trap in 2000 m depth of the deep-sea mooring Kiel 276. The mooring is located in the oligotrophic subtropical NE Atlantic (33˚ N, 22˚ W), which is influenced by the Azores Current and its associated front and lithogenic particle inputs via atmospheric transport pathways. Total barium fluxes and biogenic barium (Babio) fluxes between 2002 and 2008, calculated on the basis of Ba amounts measured with ICP-OES (inductively coupled plasma optical emission spectrometry), are demonstrated in this study. The behavior of (biogenic) barium in the deep-sea is of great interest because it is used as a proxy for surface ocean productivity. Nevertheless, formation and transport mechanisms of particulate Ba, especially barite, in the oceans are still under debate. Especially, long-term Ba flux studies demonstrating inter and intra annual variability are missing. To fill this gap we used time-series measurements of Ba fluxes observed at Kiel 276 to demonstrate the variability of particulate Ba formation and transport. Total Ba fluxes and Babio fluxes at the mooring are characterized by flux pattern attributed to the behavior of the total particle flux. The particle flux is highly variable with peak fluxes up to 365 mg m-2 d-1 during winter and early spring just after highest primary production (winter bloom of coccolithophores) and maximum dust concentration in the atmosphere occurred. The Babioflux (up to 97 % of the total Ba flux) is influenced by productivity but also by the position of the Azores Front leading to a clear reduced Babio flux from 2005 onwards related to changes in shape and size of the catchment area of the sediment trap and reduced productivity due to lower nutrient availability. We observed a close connection of Babio flux and Ca flux results from incorporation of Ba in biogenic CaCO3 and from the formation of aggregates including Ba-bearing particles like barite and biogenic CaCO3. The transport of

  17. 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

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

    International Nuclear Information System (INIS)

    Gazineu, Maria Helena Paranhos

    2005-06-01

    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 226 Ra and 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 ( 226 Ra, 228 Ra, 228 Th and 210 Pb) in sludge and scales were very high when compared with the literature, particularly much higher than the values for 226 Ra and 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 226 Ra, 228 Ra, 228 Th and 210 Pb (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, 226 Ra and

  19. Significance of detrital zircons in upper Devonian ocean-basin strata of the Sonora allochthon and Lower Permian synorogenic strata of the Mina Mexico foredeep, central Sonora, Mexico

    Science.gov (United States)

    Poole, F.G.; Gehrels, G.E.; Stewart, John H.

    2008-01-01

    U-Pb isotopic dating of detrital zircons from a conglomeratic barite sandstone in the Sonora allochthon and a calciclastic sandstone in the Mina Mexico foredeep of the Minas de Barita area reveals two main age groups in the Upper Devonian part of the Los Pozos Formation, 1.73-1.65 Ga and 1.44-1.42 Ga; and three main age groups in the Lower Permian part of the Mina Mexico Formation, 1.93-1.91 Ga, 1.45-1.42 Ga, and 1.1-1.0 Ga. Small numbers of zircons with ages of 2.72-2.65 Ga, 1.30-1.24 Ga, ca. 2.46 Ga, ca. 1.83 Ga, and ca. 0.53 Ga are also present in the Los Pozos sandstone. Detrital zircons ranging in age from 1.73 to 1.65 Ga are considered to have been derived from the Yavapai, Mojave, and Mazatzal Provinces and their transition zones of the southwestern United States and northwestern Mexico. The 1.45-1.30 Ga detrital zircons were probably derived from scattered granite bodies within the Mojave and Mazatzal basement rocks in the southwestern United States and northwestern Mexico, and possibly from the Southern and Eastern Granite-Rhyolite Provinces of the southern United States. The 1.24-1.0 Ga detrital zircons are believed to have been derived from the Grenville (Llano) Province to the east and northeast or from Grenvilleage intrusions or anatectites to the north. Several detrital zircon ages ranging from 2.72 to 1.91 Ga were probably derived originally from the Archean Wyoming Province and Early Paleoproterozoic rocks of the Lake Superior region. These older detrital zircons most likely have been recycled one or more times into the Paleozoic sandstones of central Sonora. The 0.53 Ga zircon is believed to have been derived from a Lower Cambrian granitoid or meta-morphic rock northeast of central Sonora, possibly in New Mexico and Colorado, or Oklahoma. Detrital zircon geochronology suggests that most of the detritus in both samples was derived from Laurentia to the north, whereas some detritus in the Permian synorogenic foredeep sequence was derived from the

  20. 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

  1. The fate of minor alkali elements in the chemical evolution of salt lakes

    Science.gov (United States)

    2011-01-01

    Alkaline earth elements and alkali metals (Mg, Ca, Na and K) play an important role in the geochemical evolution of saline lakes as the final brine type is defined by the abundance of these elements. The role of major ions in brine evolution has been studied in great detail, but little has been done to investigate the behaviour of minor alkali elements in these systems despite their similar chemical affinities to the major cations. We have examined three major anionic brine types, chloride, sulphate, and bicarbonate-carbonate, in fifteen lakes in North America and Antarctica to determine the geochemical behaviour of lithium, rubidium, strontium, and barium. Lithium and rubidium are largely conservative in all water types, and their concentrations are the result of long-term solute input and concentration through evaporation and/or sublimation. Strontium and barium behaviours vary with anionic brine type. Strontium can be removed in sulphate and carbonate-rich lakes by the precipitation of carbonate minerals. Barium may be removed in chloride and sulphate brines by either the precipitation of barite and perhaps biological uptake. PMID:21992434

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

    International Nuclear Information System (INIS)

    Matoso, Erika; Cadore, Solange

    2015-01-01

    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)

  3. Well logging with natural gamma radiation

    International Nuclear Information System (INIS)

    Ellis, D.V.

    1983-01-01

    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.)

  4. High-pressure high-temperature rheological studies of colloidal suspensions with carbon nanotube

    Science.gov (United States)

    Baby, Anoop; Sadr, Reza; Yarc, Rommel; Amani, Mahmood

    2017-11-01

    Selection of the drilling fluid, drilling mud, is vital in minimizing the cost and time required for the drilling in oil fields. Drilling mud aids in cooling, lubricating drilling bit, removing the debries from the drill bore and maintaining the wellbore stability. Owing to the enhanced thermo-physical properties and stable nature, suspensions of nanoparticles have been suggested for drilling fluids. High-pressure and high-temperature rheology of a nanomud suspension (nano particles suspended in a mud solution) is studied here. The nanomud is prepared by dispersing a water-based drilling mud suspension (water with 1% Bentonite and 7% Barite particles) with multi-walled carbon nanotubes, MWCNT. The effect of pressure, temperature, and shear rate are independently studied for the various particle loading of the nanoparticles. Viscosity values are measured at a maximum pressure of 170MPa with temperatures ranging from ambient to 180oC. The effect of MWCNT concentration and variation in shear rate are also investigated A shear thinning non-Newtonian behavior is observed for the basemud and the nanomud samples for all cases. The basemud showed an increase in viscosity with an increase in pressure. However, with MWCNT particle addition, this trend is observed to have reversed.

  5. Diagenetic history of Early Cambrian sandstones, at Gazouieyeh outcrop, Central Iran

    Directory of Open Access Journals (Sweden)

    Mohammadreza Ghotbi

    2015-01-01

    Full Text Available The siliciclastic Dahu Strata (Early Cambrian, in the Central Iran, 280 metres thick, in the Gazouieyeh area, rests with an erosional surface on Protrozoic-Early Cambrian sedimentary rocks (Dezu Series. This strata disconformably overlain by Middle Cambrian-Late Cambrian marine carbonate rockse (Kouh-Banan Formation. Based on field and Laboratory studies, 3 association facies, shale-sandstone and conglomerate have been identified. Mainly, sandstones are rich in quartz, feldspars, and rarely contain rock fragments (metamorphic and sedimentary. The sandstones have a wide compositional range from quartzarenite to arkose, feldspathic litharenite and rarely litharenite (chertarenite. According to plots of feldspar garins, total quartzose grains, and total unstable lithic fragments, they were derived from craton interior, transitional continental, and recycled orogen sources. The Dahu sandstones experienced diagenetic events that included compaction and pressure solution, cementation (mostly by silica, carbonate, Fe-oxide, clay and rarely by barite, grain fracturing, alteration of unstable grains, dissolution and replacement. Based on petrological and geochemical studies, we interpreted the diagenetic history for the Dahu sandstones, which consists of early, deep burial and late stages. The above results are based on surface studies, but it might be changed during increasing the depth.

  6. The Morro do Resende orthogneiss: mineralogy, petrography, geochemistry and geochronology; Ortognaisse Morro do Resende: mineralogia, petrografia, geoquimica e geocronologia

    Energy Technology Data Exchange (ETDEWEB)

    Vasconcelos, Fabiana Franco de; Avila, Ciro Alexandre; Bongiolo, Everton Marques; Camara, Beatriz de Oliveira; Menezes, Victor Hugo Riboura; Cunha, Fernanda Caetano de Mattos, E-mail: fma3003@globo.com, E-mail: avila@mn.ufrj.br, E-mail: ebongiolo@geologia.ufrj.br, E-mail: camara_b@hotmail.com, E-mail: vmenezes92@gmail.com, E-mail: fefemattos@gmail.com [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil); Neumann, Reiner, E-mail: reiner.neumann@gmail.com [Centro de Tecnologia Mineral (CETEM), Rio de Janeiro, RJ (Brazil); Teixeira, Wilson; Barbosa, Natali, E-mail: wteixeir@usp.br, E-mail: natali@usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto de Geociencias

    2017-01-15

    The Morro do Resende orthogneiss is a hololeucocratic to leucocratic, fine-grained body with monzogranitic to granodioritic composition, cropping out near the Volta Grande mine in Nazareno County, State of Minas Gerais, Brazil. It bears xenoliths of metamafic rocks of the Rio das Mortes metavolcano-sedimentary sequence and yields a U-Pb SHRIMP crystallization age of 2174 ± 4 Ma, relating it to one of the magmatic pulses of the Mineiro Belt. The primary mineralogy includes quartz, albite, microcline, biotite, allanite, zircon, magnetite, titanite and apatite, while sericite, epidote, zoisite, clinozoisite, carbonate and chlorite are metamorphic minerals. Maghemite, barite, fluorite, monazite, xenotime, garnet and REE fluorides (possibly gagarinite) are hydrothermal, as they fill the fractures, intergrow or replace the primary and metamorphic minerals. Fluid interaction was not homogeneous throughout the body. Metamorphic paragenesis points to greenschist facies conditions, which could be related to the Paleoproterozoic II event of the Mineiro Belt, which lasted from 2131 to 2101 Ma. The Morro do Resende orthogneiss is distinguished by significant REE enrichment, as well as a negative Eu anomaly linked to the magmatic crystallization and a negative Ce anomaly related to oxidizing hydrothermal fluids circulation. (author)

  7. Impact of porosity variation on diffusive transport: experimentation vs simulation

    International Nuclear Information System (INIS)

    Fatnassi, Ikram

    2015-01-01

    Reactions induced by the diffusion of reactants from different sources may alter rock confinement properties, and are therefore critical processes to assess short-term and long-term behaviour of rocks displaying a low permeability, such as argillites which are used as barriers in underground storage installation. In order to test transport-chemistry codes based on a continuous approach, the author of this research thesis reports the development and performance of simplest as possible experiments of sealing/dissolution diffusion, by using porous media of increasing complexity: compact sand, sintered glass, stoneware, chalk, until a material close to that envisaged within the frame of a storage like a Tournemire argillite. The principle of these experiments relies on the characterisation of the diffusive behaviour of an inert tracer within a porous medium submitted to dissolution reactions (attack of a carbonate matrix by an acid solution) and/or precipitation of mineral compounds (calcium oxalate, gypsum or barite) which results in an evolution of porosity and a modification of the diffusive transport of the studied tracer. At the end of the experiment, porous media and precipitates are characterised by SEM-EDS [fr

  8. Ore petrology and geochemistry of Tertiary gold telluride deposits of the Colorado mineral belt

    Energy Technology Data Exchange (ETDEWEB)

    Saunders, J.A.; Romberger, S.B.

    1985-01-01

    Epithermal gold telluride deposits from the Colorado mineral belt share a number of similarities: relationship to alkalic stocks; high fluorine and CO/sub 2/ content; and similar paragenesis. Petrography of deposits in the Jamestown, Cripple Creek, and La Plata districts has resulted in a composite paragenesis: early Fe-Cu-Pb-Zn sulfides + hematite; tetrahedrite; high Te tellurides; low Te tellurides; late native gold. Fluid inclusion studies suggest telluride deposition occurred below 200/sup 0/C from low salinity. Gangue and alteration mineralogy indicates the ore fluids were near neutral pH during telluride deposition. The presence of hematite and locally barite suggest relatively oxidizing conditions. Evaluation of thermodynamic stabilities of tellurides and aqueous tellurium species indicates that progressive oxidation is consistent with the observed ore mineral paragenesis. Available data on gold bisulfide and chloride complexes suggest neither were important in the transport of gold in these systems. Thermodynamic data suggest the ditelluride ion (Te/sub 2//sup 2 -/) predominates in the range of inferred physiochemical conditions for the transport and deposition of gold in these systems. Inferred complexes such as AuTe/sub 2//sup -/ could account for the gold transport, and oxidation would be the most effective mechanism of precipitation of gold telluride or native gold. Published data suggest the associated alkalic stocks may be the ultimate source of the metals, since they are enriched in Au, Ag, Te, As, and Bi.

  9. Optimization of Tribological Properties of Nonasbestos Brake Pad Material by Using Steel Wool

    Directory of Open Access Journals (Sweden)

    R. Vijay

    2013-01-01

    Full Text Available The gradual phasing out of typical brake pad material led to the spark of extensive research in development of alternatives. Henceforth we have performed a tribological study to improve the performance characteristics of the friction product (brake pad by using steel wool, a metallic material which has an excellent structural reinforcement property and high thermal stability which are indeed required to improve the performance of the brake pad. Under the study, five frictional composites were developed and optimized using the same ingredients in an appropriate proportion except steel wool (0%, 4%, 8%, 12%, and 16% which is compensated by synthetic barite, and the synthesized compositions are designated as Na01 to Na05. The developed pads are tested for tribological behaviour under conventional environment in a standard pin on disc tribometer. It is observed that increase in steel wool concentration resulted in high coefficient of friction and low wear rate of pad as resulted in Na05 composition. SEM analysis of the wear surface has proved to be useful in understanding the wear behaviour of the composites.

  10. MMH fluids reduce formation damage in horizontal wells

    Energy Technology Data Exchange (ETDEWEB)

    Fraser, L. (Dowell Fluids Services, Houston, TX (United States)); Williamson, D. (Dowell Fluids Services, Aberdeen (United Kingdom)); Haydel, S. (Ambar Inc., LaFayette, LA (United States))

    1994-02-01

    It has been more than 3 years since a mixed metal hydroxide fluid was used by Texaco to drill the Gulf of Mexico's first horizontal hole. Since, the fluid has been used to drill dozens of horizontal sections worldwide, including Australia, Indonesia, CIS, UAE, UK, and in North an South America. Due to Texaco's drilling success on the first Gulf of Mexico horizontal well in 1990, several horizontal wells were drilled in the Gulf's shallow gas sands. Fluids were weighted exclusively with ground marble. The marble, with measured grind size distributions similar to commercial barite, is used as a combination weighting and bridging material and is about 99% acid soluble. Completions were carried out by running a slotted liner, displacing the mixed metal hydroxide (MMH) fluid with calcium chloride brine, and running prepacked screens. Clean-up times where short and production rates equaled or exceeded expectations. Since the technique was relatively new, no comparisons could be made. One operator, however, achieved success during 18 months of production. During this period, the fluid was also used to drill a horizontal section through the Cardium Sandstone at Lodgepole in Alberta, Canada. The fluid out-performed other in return permeability tests on cores from the reservoir. Its performance was enhanced by addition of propylene glycol. High field production rates supported laboratory findings.

  11. Effects of Mixing the Steel and Carbon Fibers on the Friction and Wear Properties of a PMC Friction Material

    Science.gov (United States)

    Bagheri Kazem Abadi, Sedigheh; Khavandi, Alireza; Kharazi, Yosouf

    2010-04-01

    Friction, fade and wear characteristics of a PMC friction material containing phenolic resin, short carbon fiber, graphite, quartz, barite and steel fiber were investigated through using a small-scale friction testing machine. Four different friction materials with different relative amounts of the carbon fiber and steel fiber were manufactured and tested. Comparing with our previous work which contained only steel fiber as reinforcement, friction characteristics such as fade and recovery and wear resistance were improved significantly by adding a small amount of carbon fiber. For the mixing of carbon and steel fiber, the best frictional and wear behavior was observed with sample containing 4 weight percentage carbon fiber. Worn surface of this specimen was observed by optical microscopy. Results showed that carbon fibers played a significant role in the formation of friction film, which was closely related to the friction performance. The brake pad with Steel fibers in our previous work, showed low friction coefficient and high wear rate. In addition, a friction film was formed on the surface with a relatively poor quality. In contrast, the samples with mixing the steel and carbon fiber generated a stable friction film on the pad surface, which provided excellent friction stability with less wear.

  12. The shielding performance of multilayer composite shielding structures to 14.8 MeV fast neutrons

    International Nuclear Information System (INIS)

    Shen Zhiqiang; Kang Qing; Xu Jun; Wang Zhenggang; Lu Nan

    2014-01-01

    Cement-based round thin-layer samples mixed with 30% quality content of barite, and 20% quality content of carbide boron has Prepared, the same-diameter sliced samples of pure graphite and pure polyethylene has cut, then, samples combination and cross stack order has designed, formed four species Multilayer Composite shield structure, at last, neutron attenuation measurements has been done by experimental system of using 14.8 MeV neutrons from the 5SDH-2 accelerator and long counter composition, penetrating rate of samples and the shield structure to 14.8 MeV fast neutron has tested, and attenuation section has calculated. Results show that 14.8 MeV fast neutrons to higher penetration rates of thin layer samples, attenuation cross section of samples distinguish small between each other, must be increasing the thickness of the samples to reduce the experimental uncertainty; through composed of attenuation cross section and thickness parameters of composite structure, can more accurately predict the shielding ability of composite structures, error between calculation results and experimental results in 4%. (authors)

  13. Determination of radionuclides contaminated in chemical reagents

    International Nuclear Information System (INIS)

    Inoue, M.; Komura, K.

    2006-01-01

    In order to examine reagent blanks of radionuclides ( 7 Be, 60 Co, 134 Cs, 137 Cs, 210 Pb, 226 Ra, 228 Ra and 234 Th), we applied extremely low-background gamma-spectrometry to Ba, Pb and other reagents used for coprecipitation methods. While blank levels of 226 Ra and 228 Ra in Ba reagents and 210 Pb in Pb reagents were high and varied widely (e.g., 226 Ra, 6-90 mBq/g-Ba), regardless of their chemical purity, they were notably lower in barite mineral (BaSO 4 ) (0.7-1.5 mBq/g-Ba for 226 Ra) and old Pb (from the Kanazawa Castle, the Edo period). In addition, the negligible 134 Cs and 137 Cs were detected in CsCl reagents. By using least contaminated carrier reagents together, the coprecipitation method has enabled simultaneous measurement of low-level activities of these nuclides in sea/environmental water samples. (author)

  14. Very heavy iron-punching concretes

    International Nuclear Information System (INIS)

    Dubois, F.

    1966-01-01

    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) [fr

  15. 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

  16. 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.

  17. Obtaining Highly Crystalline Barium Sulphate Nanoparticles via Chemical Precipitation and Quenching in Absence of Polymer Stabilizers

    Directory of Open Access Journals (Sweden)

    Ángela B. Sifontes

    2015-01-01

    Full Text Available Here we report the synthesis of barium sulphate (BaSO4 nanoparticles from Ba(OH2/BaCl2 solutions by a combined method of precipitation and quenching in absence of polymer stabilizers. Transmission electron microscopy (HRTEM, Fourier transforms infrared spectroscopy (FTIR, and X-ray diffraction (XRD were employed to characterize the particles. The Scherrer formula was applied to estimate the particle size using the width of the diffraction peaks. The obtained results indicate that the synthesized material is mainly composed of nanocrystalline barite, with nearly spherical morphology, and diameters ranging from 4 to 92 nm. The lattice images of nanoparticles were clearly observed by HRTEM, indicating a high degree of crystallinity and phase purity. In addition, agglomerates with diameters between 20 and 300 nm were observed in both lattice images and dynamic light scattering measurements. The latter allowed obtaining the particle size distribution, the evolution of the aggregate size in time of BaSO4 in aqueous solutions, and the sedimentation rate of these solutions from turbidimetry measurements. A short discussion on the possible medical applications is presented.

  18. Sulfate reduction and methane oxidation activity below the sulfate-methane transition zone in Alaskan Beaufort Sea continental margin sediments: Implications for deep sulfur cycling

    Science.gov (United States)

    Treude, Tina; Krause, Stefan; Maltby, Johanna; Dale, Andrew W.; Coffin, Richard; Hamdan, Leila J.

    2014-11-01

    Two ∼6 m long sediment cores were collected along the ∼300 m isobath on the Alaskan Beaufort Sea continental margin. Both cores showed distinct sulfate-methane transition zones (SMTZ) at 105 and 120 cm below seafloor (cmbsf). Sulfate was not completely depleted below the SMTZ but remained between 30 and 500 μM. Sulfate reduction and anaerobic oxidation of methane (AOM) determined by radiotracer incubations were active throughout the methanogenic zone. Although a mass balance could not explain the source of sulfate below the SMTZ, geochemical profiles and correlation network analyses of biotic and abiotic data suggest a cryptic sulfur cycle involving iron, manganese and barite. Inhibition experiments with molybdate and 2-bromoethanesulfonate (BES) indicated decoupling of sulfate reduction and AOM and competition between sulfate reducers and methanogens for substrates. While correlation network analyses predicted coupling of AOM to iron reduction, the addition of manganese or iron did not stimulate AOM. Since none of the classical archaeal anaerobic methanotrophs (ANME) were abundant, the involvement of unknown or unconventional phylotypes in AOM is conceivable. The resistance of AOM activity to inhibitors implies deviation from conventional enzymatic pathways. This work suggests that the classical redox cascade of electron acceptor utilization based on Gibbs energy yields does not always hold in diffusion-dominated systems, and instead biotic processes may be more strongly coupled to mineralogy.

  19. The Morro do Resende orthogneiss: mineralogy, petrography, geochemistry and geochronology

    International Nuclear Information System (INIS)

    Vasconcelos, Fabiana Franco de; Avila, Ciro Alexandre; Bongiolo, Everton Marques; Camara, Beatriz de Oliveira; Menezes, Victor Hugo Riboura; Cunha, Fernanda Caetano de Mattos; Neumann, Reiner; Teixeira, Wilson; Barbosa, Natali

    2017-01-01

    The Morro do Resende orthogneiss is a hololeucocratic to leucocratic, fine-grained body with monzogranitic to granodioritic composition, cropping out near the Volta Grande mine in Nazareno County, State of Minas Gerais, Brazil. It bears xenoliths of metamafic rocks of the Rio das Mortes metavolcano-sedimentary sequence and yields a U-Pb SHRIMP crystallization age of 2174 ± 4 Ma, relating it to one of the magmatic pulses of the Mineiro Belt. The primary mineralogy includes quartz, albite, microcline, biotite, allanite, zircon, magnetite, titanite and apatite, while sericite, epidote, zoisite, clinozoisite, carbonate and chlorite are metamorphic minerals. Maghemite, barite, fluorite, monazite, xenotime, garnet and REE fluorides (possibly gagarinite) are hydrothermal, as they fill the fractures, intergrow or replace the primary and metamorphic minerals. Fluid interaction was not homogeneous throughout the body. Metamorphic paragenesis points to greenschist facies conditions, which could be related to the Paleoproterozoic II event of the Mineiro Belt, which lasted from 2131 to 2101 Ma. The Morro do Resende orthogneiss is distinguished by significant REE enrichment, as well as a negative Eu anomaly linked to the magmatic crystallization and a negative Ce anomaly related to oxidizing hydrothermal fluids circulation. (author)

  20. Low enthalpy Na-chloride waters from the Lunigiana and Garfagnana grabens, Northern Apennines, Italy: Tracing fluid connections and basement interactions via chemical and isotopic compositions

    Science.gov (United States)

    Boschetti, Tiziano; Toscani, Lorenzo; Barbieri, Maurizio; Mucchino, Claudio; Marino, Tiziana

    2017-12-01

    The Na-Cl waters from NW Tuscany (central Italy) record similar water isotopic and major chemical compositions, which demonstrate their meteoric origin and interactions with Upper Triassic evaporites and the metamorphic units of the Paleozoic basement. Slight differences are found in the deep temperature-pressure conditions of the Lunigiana graben (39-42 °C/143-145 bar) and the Garfagnana graben (73-78 °C/250-256 bar). In particular, the thermal fluids outpouring from Garfagnana are probably related to a common deep reservoir or interconnected fluids. Their differences are mainly evidenced by strontium isotopic ratio data (87Sr/86Sr), which combined with previously published sulfur isotope ratios (34S/32S) demonstrate the involvement of vein barites in water-rock interactions. Most likely, these minerals formed during Upper Oligocene-Miocene tectogenesis due to the mixing of fluids from the Verrucano Group and Upper Triassic units. The results of this hydrogeochemical study of the deep Na-Cl fluids could better clarify the distribution of the Verrucano Group within this area and the related discrepancies in the stratigraphic interpretations of the Palaeozoic-Mesozoic transition. Furthermore, the possible presence of an interconnected reservoir could be used to help interpret data produced by the local geochemical monitoring of seismic activity.

  1. Evaluation of transmitted spectra of megavoltage X rays through concrete using Monte Carlo simulation

    International Nuclear Information System (INIS)

    Cordeiro, Thaiana de Paula Vieira; Silva, Ademir Xavier da

    2010-01-01

    With the improvement of technology in radiotherapic centers, medical linear accelerators are largely replacing Cobalt-60 teletherapy units. In most of the cases, the same room that, before, was used to place a 60 Co teletherapy unit is reused to install, in replacement, a linear accelerator. When the room physical space can not be changed, high - density concrete is employed to provide shielding against the primary, scatter and leakage radiation. This work presents a study based on Monte Carlo simulations of transmission of some clinical photon spectra (of 10, 15 and 25 MV accelerators) through concrete of two different densities. Concrete walls of thickness 1.0, 1.5 and 2.0 m were irradiated with 30 cm x 30 cm primary beam spectra. The results show that the thickness of the barrier decreases up to approximately 35%, when barite (high - density concrete) is used instead of ordinary concrete. The average energies of primary and transmitted beam spectra were also calculated. (author)

  2. 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.

  3. High concentrations of lead and barium in hair of the rural population caused by water pollution in the Thar Jath oilfields in South Sudan.

    Science.gov (United States)

    Pragst, Fritz; Stieglitz, Klaus; Runge, Hella; Runow, Klaus-Dietrich; Quig, David; Osborne, Robert; Runge, Christian; Ariki, John

    2017-05-01

    In the oil fields of Thar Jath, South Sudan, increasing salinity of drinking water was observed together with human incompatibilities and rise in livestock mortalities. Hair analysis was used to characterize the toxic exposure of the population. Hair samples of volunteers from four communities with different distance from the center of the oil field (Koch 23km, n=24; Leer 50km, n=26; Nyal 110km, n=21; and Rumbek 220km, n=25) were analyzed for altogether 39 elements by inductively coupled plasma-mass spectrometry. Very high concentrations and a toxic health endangerment were assessed for lead and barium. The concentration of lead increased steadily with decreasing distance from the oil field from Rumbek (mean 2.8μg/g) to Koch (mean 18.7μg/g) and was there in the same range as in highly contaminated mining regions in Kosovo, China or Bolivia. The weighting materials in drilling muds barite (BaSO 4 ) and galena (PbS) were considered to be the sources of drinking water pollution and high hair values. The high concentrations of lead and barium in hair demonstrate clearly the health risk caused by harmful deposition of toxic industrial waste but cannot be used for diagnosis of a chronic intoxication of the individuals. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  4. Seawater calcium isotope ratios across the Eocene-Oligocene transition

    Science.gov (United States)

    Griffith, E.M.; Paytan, A.; Eisenhauer, A.; Bullen, T.D.; Thomas, E.

    2011-01-01

    During the Eocene-Oligocene transition (EOT, ca. 34 Ma), Earth's climate cooled significantly from a greenhouse to an icehouse climate, while the calcite (CaCO3) compensation depth (CCD) in the Pacific Ocean increased rapidly. Fluctuations in the CCD could result from various processes that create an imbalance between calcium (Ca) sources to, and sinks from, the ocean (e.g., weathering and CaCO3 deposition), with different effects on the isotopic composition of dissolved Ca in the oceans due to differences in the Ca isotopic composition of various inputs and outputs. We used Ca isotope ratios (??44/40Ca) of coeval pelagic marine barite and bulk carbonate to evaluate changes in the marine Ca cycle across the EOT. We show that the permanent deepening of the CCD was not accompanied by a pronounced change in seawater ??44/40Ca, whereas time intervals in the Neogene with smaller carbonate depositional changes are characterized by seawater ??44/40Ca shifts. This suggests that the response of seawater ??44/40Ca to changes in weathering fluxes and to imbalances in the oceanic alkalinity budget depends on the chemical composition of seawater. A minor and transient fluctuation in the Ca isotope ratio of bulk carbonate may reflect a change in isotopic fractionation associated with CaCO3 precipitation from seawater due to a combination of factors, including changes in temperature and/or in the assemblages of calcifying organisms. ?? 2011 Geological Society of America.

  5. Measurements and FLUKA simulations of bismuth and aluminium activation at the CERN Shielding Benchmark Facility (CSBF)

    Science.gov (United States)

    Iliopoulou, E.; Bamidis, P.; Brugger, M.; Froeschl, R.; Infantino, A.; Kajimoto, T.; Nakao, N.; Roesler, S.; Sanami, T.; Siountas, A.

    2018-03-01

    The CERN High Energy AcceleRator Mixed field facility (CHARM) is located in the CERN Proton Synchrotron (PS) East Experimental Area. The facility receives a pulsed proton beam from the CERN PS with a beam momentum of 24 GeV/c with 5 ṡ1011 protons per pulse with a pulse length of 350 ms and with a maximum average beam intensity of 6.7 ṡ1010 p/s that then impacts on the CHARM target. The shielding of the CHARM facility also includes the CERN Shielding Benchmark Facility (CSBF) situated laterally above the target. This facility consists of 80 cm of cast iron and 360 cm of concrete with barite concrete in some places. Activation samples of bismuth and aluminium were placed in the CSBF and in the CHARM access corridor in July 2015. Monte Carlo simulations with the FLUKA code have been performed to estimate the specific production yields for these samples. The results estimated by FLUKA Monte Carlo simulations are compared to activation measurements of these samples. The comparison between FLUKA simulations and the measured values from γ-spectrometry gives an agreement better than a factor of 2.

  6. Explanation for many of the unusual features of the massive sulfide deposits of the Iberian pyrite belt

    Science.gov (United States)

    Solomon, M.; Tornos, F.; Gaspar, O. C.

    2002-01-01

    Newly published fluid-inclusion data from quartz in stockwork veins beneath seven massive sulfide lenses in the Iberian pyrite belt suggest that the lenses were formed from fluids that on reaching the sea reversed buoyancy and ponded in basins. Sulfides quenched in the resulting brine pool would have settled to form a sulfide mud. This process provides a relatively efficient trapping mechanism for metal in the fluids and effectively excludes ambient seawater, accounting for the deposits tending to have the characteristics of large size, sheet-like form, absence of relict chimney structures, and a mineral content characterized by pyrite-arsenopyrite, and absence or scarcity of barite, marcasite, and Fe oxides. If total S was less than total metals in the stockwork fluids, some or all of the more soluble Zn and Pb could have been swept from the basin at the overflow, accounting for the variable but generally low Zn and Pb contents of the ores. The lack of sedimentary source for the high salinities implicates magmatic intrusions, possibly similar to those related to Sn-W mineralization.

  7. Au-bearing magnetite mineralizaion in Kashmar (alteration, mineralization, geochemistry, geochemistry and fluid inclusions;

    Directory of Open Access Journals (Sweden)

    Alireza Almasi

    2017-02-01

    Full Text Available Introduction The study area is located in the central part of the Khaf- Kashmar- Bardaskan volcano-plotunic belt (briefly KKBB. Several IOCG deposits such as Tanourjeh Au-bearing magnetite deposit and Kuh-e-Zar Specularite-rich Au deposit have been explored in KKBB. Geology, alteration, mineralization, geochemistry and fluid inclusion results in Kashmar suggest the IOCG type Au-bearing magnetite mineralization. These IOCG deposits at KKBB form at an active continental arc related to SSZ-type Sabzevar oceanic subduction. Materials and methods Use of Landsat 7+, IRS and Aster satellites. Petrography and alteration Studies in 150 thin sections of volcanic and intrusive rocks. Sampling of ore-bearing quartz vein and mineralography. Preparation of 28 geochemistry samples by the chip composite method of ore-bearing quartz vein and analyzing them in the ACME laboratory by Aqua Regia 1DX1. Fluid inclusions studies of 14 samples of quartz and barite related to the ore minerals of ore-bearing quartz vein by THM600 stage of Linkam company. Results Magmatic events in Kashmar occur at Paleocene-Eocene and include: (1 old mafic - intermediate volcano-plutonic series; (2 felsic volcanic and granitoids; and (3 parallel swarm dykes which are youngest (Almasi et al., 2016. Geochemically, Kashmar rocks are metaluminous to highly peraluminous and Tholeitic to calc-alkaline and shoshonitic in composition (Almasi et al., 2016. The field characteristics, together with isotope and geochemical analyses show that all rock types are essentially co-magmatic and post-collisional I-type (Almasi et al., 2016. Alteration of Kashmar is described in two ways: (1 intense ellipsoidal-linear Argillic-Sillicification and low sericitic with Silica caps and with medium widespread and propylitic alterations in triple regions, next to Dorouneh fault; and (2 Medium Hematite-Carbonate-Chlorite-Silicification alterations in Kamarmard heights. In parts of near the Doruneh fault, sometimes

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

    International Nuclear Information System (INIS)

    Castor, S.B.; Lock, D.E.

    1996-01-01

    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 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

  9. Pb-free Radiation Shielding Glass Using Coal Fly Ash

    Directory of Open Access Journals (Sweden)

    Watcharin Rachniyom

    2015-12-01

    Full Text Available In this work, Pb-free shielding glass samples were prepared by the melt quenching technique using subbituminous fly ash (SFA composed of xBi2O3 : (60-xB2O3 : 10Na2O : 30SFA (where x = 10, 15, 20, 25, 30 and 35 by wt%. The samples were investigated for their physical and radiation shielding properties. The density and hardness were measured. The results showed that the density increased with the increase of Bi2O3 content. The highest value of hardness was observed for glass sample with 30 wt% of Bi2O3 concentration. The samples were investigated under 662 keV gamma ray and the results were compared with theoretical calculations. The values of the mass attenuation coefficient (μm, the atomic cross section (σe and the effective atomic number (Zeff were found to increase with an increase of the Bi2O3 concentration and were in good agreement with the theoretical calculations. The best results for the half-value layer (HVL were observed in the sample with 35 wt% of Bi2O3 concentration, better than the values of barite concrete. These results demonstrate the viability of using coal fly ash waste for radiation shielding glass without PbO in the glass matrices.

  10. Mechanical and radiation shielding properties of mortars with additive fine aggregate mine waste

    International Nuclear Information System (INIS)

    Gallala, Wissem; Hayouni, Yousra; Gaied, Mohamed Essghaier; Fusco, Michael; Alsaied, Jasmin; Bailey, Kathryn; Bourham, Mohamed

    2017-01-01

    Highlights: • Effectiveness of mine waste as additive fine aggregate has been investigated. • Experimental results are verified by computationally from composition of synthesized samples. • Work focuses on shielding materials for nuclear systems including spent fuel storage and drycasks. - Abstract: Incorporation of barite-fluorspar mine waste (BFMW) as a fine aggregate additive has been investigated for its effect on the mechanical and shielding properties of cement mortar. Several mortar mixtures were prepared with different proportions of BFMW ranging from 0% to 30% as fine aggregate replacement. Cement mortar mixtures were evaluated for density, compressive and tensile strengths, and gamma ray radiation shielding. The results revealed that the mortar mixes containing 25% BFMW reaches the highest compressive strength values, which exceeded 50 MPa. Evaluation of gamma-ray attenuation was both measured by experimental tests and computationally calculated using MicroShield software package, and results have shown that using BFMW aggregates increases attenuation coefficient by about 20%. These findings have demonstrated that the mine waste can be suitably used as partial replacement aggregate to improve radiation shielding as well as to reduce the mortar and concrete costs.

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

    International Nuclear Information System (INIS)

    Miranda, Marcia Valeria de Fatima da Encarnacao Sa

    2009-01-01

    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 (BaSO 4 ), that easily incorporates 226 Ra and 228 Ra 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 222 Rn 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 222 Rn was proportional to the number of these tracks the methodology permitted the comparison of contamination levels of the analyzed samples. (author)

  12. Calculation of conversion coefficients for air kerma to ambient dose equivalent using transmitted spectra of megavoltage X-rays through concrete.

    Science.gov (United States)

    Cordeiro, T P V; Silva, A X

    2012-12-01

    With the fast advancement of technology, (60)Co teletherapy units are largely being replaced with medical linear accelerators. In most cases, the linear accelerator tends to be installed in the same room in which the (60)Co teletherapy unit was previously placed. If in-depth structural remodelling is out of the question, high-density concrete is usually used to improve shielding against primary, scatter and leakage radiation originating in the new equipment. This work presents a study based on Monte Carlo simulations of the transmission of some clinical photon spectra (from 6, 10, 15, 18 and 25 MV accelerators) through concrete, considering two different densities. Concrete walls with thickness ranging from 0.70 to 2.0 m were irradiated with 30 cm×30 cm primary beam spectra. The results show that the thickness of the barrier decreases up to ∼65 % when barite (high-density concrete) is used instead of ordinary concrete. The average energies of primary and transmitted beam spectra were also calculated. In addition, conversion coefficients from air kerma to ambient dose equivalent, H*(d)/K(air), and air kerma to effective dose, E/K(air), for photon spectra from the transmitted spectra were calculated and compared. The results suggest that the 10-mm depth is not the best choice to represent the effective dose.

  13. Neutron and photon scattering properties of high density concretes used in radiation therapy facilities: A Monte Carlo study

    Science.gov (United States)

    Mesbahi, Asghar; Khaldari, Rezvan

    2017-09-01

    In the current study the neutron and photon scattering properties of some newly developed high density concretes (HDCs) were calculated by using MCNPX Monte Carlo code. Five high-density concretes including Steel-Magnetite, Barite, Datolite-Galena, Ilmenite-ilmenite, Magnetite-Lead with the densities ranging from 5.11 g/cm3 and ordinary concrete with density of 2.3 g/cm3 were studied in our simulations. The photon beam spectra of 4 and 18 MV from Varian linac and neutron spectra of clinical 18 MeV photon beam was used for calculations. The fluence of scattered photon and neutron from all studied concretes was calculated in different angles. Overall, the ordinary concrete showed higher scattered photons and Datolite-Galena concrete (4.42 g/cm3) had the lowest scattered photons among all studied concretes. For neutron scattering, fluence at the angle of 180 was higher relative to other angles while for photons scattering fluence was maximum at 90 degree. The scattering fluence for photons and neutrons was dependent on the angle and composition of concrete. The results showed that the fluence of scattered photons and neutrons changes with the composition of high density concrete. Also, for high density concretes, the variation of scattered fluence with angle was very pronounced for neutrons but it changed slightly for photons. The results can be used for design of radiation therapy bunkers.

  14. Microbial isotopic signatures in calcareous tufa from Punta Mita coastal vents, Mexico

    Science.gov (United States)

    Canet, C.; Prol-Ledesma, R. M.; Melgarejo, J. C.; Reyes, A.

    2002-12-01

    Numerous small calcareous mounds accompanied by Ba, Hg and Tl mineralization occur in shallow submarine hydrothermal manifestations on the sea bottom, at 10 m depth, in Punta Mita (Western coast of Mexico). The formation of calcite mounds in these coastal vents provides an uncommon example of calcareous tufa deposits in a submarine hydrothermal environment. The hydrothermal activity consists in water and gas (essentially nitrogen and methane) venting at 85°C, through a 100 m fissure hosted in basaltic rocks and partially covered by unconsolidated sediments. The mounds consist of travertine-like metre-sized calcite aggregates that develop around the main submarine hot springs. Barite, sulphides (mostly pyrite and cinnabar) and phosphates (carbonate-hydroxylapatite) are also present in these mounds. Two main calcite types are texturally distinguished: firstly an earlier radial-fibrous generation, and a later fine-grained calcite generation that cements the detrital grains and fills the pore spaces. Stable isotope analyses were performed in calcite from these mounds. The δ13C measured values show a strong depletion in 13C, with values as low as -39.2 per mil (PDB). These values agree with a microbially mediated calcite mineralization process, by means of bacterial oxidation of vent derived methane. In contrast to most known cases of microbial methane oxidation, in Punta Mita this process took place under hydrothermal conditions.

  15. Bulk additive system reduces mud costs and waste

    International Nuclear Information System (INIS)

    Wisnie, A.P.

    1994-01-01

    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

  16. Characteristics and origin of agates from Płóczki Górne (Lower Silesia, Poland): A combined microscopic, micro-Raman, and cathodoluminescence study

    Science.gov (United States)

    Dumańska-Słowik, Magdalena; Powolny, Tomasz; Sikorska-Jaworowska, Magdalena; Gaweł, Adam; Kogut, Lucyna; Poloński, Krzysztof

    2018-03-01

    Agates from Płóczki Górne hosted by Permian basaltic rocks are predominantly made of length-fast chalcedony, and subordinately megaquartz and quartzine. Moganite occurs in traces mainly in transparent, outer, darker regions of white-grey coloured agates. Silica matrix of agates comprises a wide variety of solid inclusions represented by celadonite, plagioclases, hematite, goethite, barite, calcite, heulandite-clinoptyloite, nontronite-saponite, and Mn-dioxides (ramsdellite). Mineral phases are locally accompanied by black aggregations of carbonaceous matter, which gives a Raman signature of disordered carbon. These organic components were probably deposited from a hydrothermal fluids at low-temperature conditions and originated from sedimentary rocks found in the surrounding area of Płóczki Górne. The abundance of various SiO2 phases, mineral inclusions as well as various micro-textures (colloform, comb, feathery, and jigsaw-puzzle) in agates resulted from physicochemical fluctuations of SiO2-bearing mineralizing solutions at various stages of these gems formation. Agates from Płóczki Górne formed during post-magmatic stage of basaltic host rocks evolution. Not only were the hydrothermal fluids enriched in silica, but also they contained other elements such as Na, Ca, Al, Mg, Mn, Fe, Ba, SO4, and CO2, which were mobilized from host rocks or surrounding area.

  17. 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.

  18. Visualising the Micro World of Chemical/Geochemical Interactions Using Atomic Force Microscopy (AFM)

    Energy Technology Data Exchange (ETDEWEB)

    Graham, G.M.; Sorbie, K.S.

    1996-12-31

    Scanning force microscopy, in particular AFM (Atomic Force Microscopy), provides a particular useful and interesting tool for the examination of surface structure at the near-atomic level. AFM is particularly well suited to the study of interactions at the surface in aqueous solutions using real time in-situ measurements. In this paper there is presented AFM images showing in situ crystal growth from supersaturated BaSO{sub 4} solutions onto the surface of barite. Growth structures in the form of spiral crystal growth features, presumably originating from screw dislocations, are illustrated. AFM images of novel scale crystal growth inhibition experiments are presented. Examination of the manner in which generically different species adsorb onto growth structures may help to explain mechanistic differences in the way which different inhibitor species perform against barium sulphate scale formation. Adsorption of polyacrylamide species onto mica surfaces have been viewed. The general utility of AFM to a number of other common surface interactions in oil field chemistry will be discussed. 17 refs., 3 figs.

  19. Composition of Ruapehu Crater Lake, New Zealand. ; Evolution of a vent hosted hydrothermal system

    Energy Technology Data Exchange (ETDEWEB)

    Christenson, B. (DSIR Cheistry, Geothermal Research Centre, Taupo (New Zealand)); Wood, C. (DSIR Geology and Geophysics, Rotorua (New Zealand))

    1992-08-31

    Variations in the Ruapehu Crater Lake composition have been investigated from the viewpoint of evolution of a vent hosted hydrothermal system. Based on the observations of volcanic activity which were obtained previously, a hydrothermal model was made. In this model, a heat pipe is portrayed operating between the upper region of degassing magma and a zone of recirculating lake water in the upper portion of the vent. Condensate forming in the lower part of the two-phase envelope returns under gravity to the heat source whereas that forming higher in the system mixes with recirculating lake water and is convectively swept upward into the crater lake. It was suggested that such processes have obvious implications for the formation of high sulfidation ore deposits. It was illustrated that condensate formation is accompanied by the precipitation of elemental sulfur, and dissolution of the enclosing andesite ensues, resulting in the sequential precipitation of cristobalite, pyrite, anhydrite, alunite, covellite, pyrophyllite, barite and fluorapatite, and the dissolution of the earlier formed sulfur. 3 refs., 2 figs.

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

    International Nuclear Information System (INIS)

    Nulk, H.; Ipbuker, C.; Gulik, V.; Tkaczyk, A.; Biland, A.

    2015-01-01

    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 N e (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

  1. Phosphate and sulfate-phosphate mineralization in sillimanite-bearing rocks at the Kyakhta deposit, western Transbaikal region

    Science.gov (United States)

    Izbrodin, I. A.; Ripp, G. S.; Karmanov, N. S.

    2009-12-01

    The phosphate and sulfate-phosphate minerals in the sillimanite-bearing rocks of the Kyakhta deposit are considered. The mineral assemblages of the high-Al rocks were formed during prograde and retrograde stages of metamorphism. The first stage is characterized by the formation of sillimanite, corundum, muscovite, quartz, rutile, titanohematite, magnetite, feldspar, biotite, lazulite, and wagnerite. The muscovite composition showed that sillimanite paragenesis was formed at temperatures above 510-600°C. According to oxygen isotope thermometry, the minimum metamorphic temperature for quartz and titanohematite is 690°C. Andalusite, diaspore, quartz, pyrophyllite, muscovite, and a wide range of phosphates and sulfate-phosphates crystallized during the retrograde stage. The decrease in temperature and increase in the water content led to the following sequence of mineral formation: Mg-Fe-Al-Ca-REE-rich phosphates (lazulite, scorzalite, augelite, apatite, and monazite) → Ca-Sr sulfate-phosphates (woodhouseite and svanbergite) → sulfate (barite) → Sr-Ca-Ba aluminophosphates (goyazite, crandallite, and gorceixite). The chemical compositions of phosphates and sulfate-phosphates minerals and their formation conditions are discussed.

  2. On strontium and barium anomalies in the sediments of Charkadio Cave (Tilos Island, Dodekanese, Greece)

    International Nuclear Information System (INIS)

    Steinhauser, G.; Sterba, J.H.; Bichler, M.; Hujer, W.; Seemann, R.; Symeonidis, N.

    2008-01-01

    The sediments of Charkadio Cave (Island of Tilos) have been object of chemical and mineralogical investigation. Sampling the speleothems of Charkadio Cave, it is possible to look back into the island's younger geological history. Tilos is of non-volcanic origin but neighbored to several volcanoes of the Aegean (Kos, Nisyros, and Giali). We observed a certain coincidence of increased Ba and Sr values in such samples and volcanic activity. Some of the layers of these fine-grained sediments contain volcanic particles (ash grains and lapilli). Interestingly, these strata have the highest content of Ba and Sr, as determined by neutron activation analysis. Additionally to this discovery, Sr-rich barite crystals were found in some of these layers. Thus, Ba and Sr must either exist on the surface of tephra particles in volatile and water-soluble compounds and/or were released by weathering from Ba and Sr containing feldspars (originating from pumice) in the cave sediment environment. Since other cave sediments from Tilos, which were not exposed to volcanic products, contain very much lesser quantities of Ba and Sr, we conclude that mobile Ba and Sr compounds are contributed to the sediment by volcanic fallout. (author)

  3. Microbial Life and Death in a Foxing Stain: a Suggested Mechanism of Photographic Prints Defacement.

    Science.gov (United States)

    Sclocchi, Maria Carla; Kraková, Lucia; Pinzari, Flavia; Colaizzi, Piero; Bicchieri, Marina; Šaková, Nikoleta; Pangallo, Domenico

    2017-05-01

    The gelatin-silver halide black and white prints represent an enormous photography heritage with a great value. Unaesthetic phenomena, the foxing stains that are caused by microbial growth on surface, have been described in stamps, drawings, books, and tissues but, until now, scarcely for photographic materials. In this study, a combination of various techniques, including culture-dependent and culture-independent approaches (RNA and DNA analysis), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and μ-Raman spectroscopy supported by X-ray fluorescence analysis (XRF), permitted to describe the microbial contamination dynamics of foxing stains present on the surface of two gelatin-silver halide photographs. The investigation provided also information on the effects of microbial activity on the materials' chemistry of the two prints. The action of microbial community resulted locally in either (a) formation of mixed aluminum-iron-potassium phosphate compounds that could be attributed to the hydrolytic activity of bacteria, (b) leaching of barite, (c) precipitation of a mixture of oxides, and (d) a change in the barium sulfate chemical structures.

  4. Violent volcanism, stagnant oceans and some inferences regarding petroleum, strata-bound ores and mass extinctions

    Science.gov (United States)

    Keith, M. L.

    1982-12-01

    Past changes from a well-mixed aerated ocean to a stratified stagnant ocean are indicated by decreasing δ13C of limestone (opposite to prior conclusions) as well as by increasing δ34S of marine sulfates. The proposed stagnant ocean model includes a warm CO 2-enriched atmosphere and a bathyal to abyssal marine system dominated by bacterial components in the food web and by consequent 'light' carbon in organic material and biogenic carbonates. Culminations of prolonged stagnant episodes correspond with marine faunal extinctions of Late Permian and Late Cretaceous time, and the protracted changes and correlations provide evidence against any hypothesis of mass extinction by sudden worldwide catastrophe, including the asteroid impact hypothesis. The Cretaceous stagnant ocean, taken as the prime example, is attributed to climatic warming triggered by volcanic CO 2 (greenhouse effect) and several feedbacks, including decreased Earth albedo and increased sinking of warm evaporite brines instead of aerated polar waters. Marine extinctions are attributed to upward expansion of the oxygen minimum zone and to catastrophic mixing of surface waters with poisonous sulfidic waters of the deeps. The stagnant ocean provided a counterbalance between deep reduction and shallow oxidation, conditions that favored maximal formation of black sulfidic shales, protopetroleum and sedimentary sulfide ores and shallow to mid-depth barite, phosphorite, iron ore, cherty iron formation, and sulfate-bearing red-beds. Trace elements concentrated in stagnant ocean sediments include chalcophile and Pt-group metals, negating claims that Ir provides a unique 'fingerprint' of meteorite impact and cosmic accretion.

  5. Effect of oxidation on base liquids of oil and synthetic-based drilling fluids at high pressure and high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Shahbazi, K.; Mehta, S.A.; Moore, R.G.; Ursenbach, M.G. [Calgary Univ., AB (Canada)

    2005-07-01

    Diesels and distillates are used as a base liquid for most oil-based drilling fluids in conventional drilling and as the liquid phase in gasified liquids in some underbalanced drilling operations. They are also used as friction reducing agents to free stuck pipes. It is important to understand the true downhole rheological properties because they affect equivalent circulating density, hole cleaning, barite sag, surge/swab pressures during tripping, pump pressure and bit hydraulics. Also, gelation and high viscosity are major concerns, particularly at high temperatures. An experimental study was conducted to evaluate the effect of oxidation on some base liquids for oil-based and synthetic-based drilling fluids at high pressures and high temperatures. Gas and liquid phases were characterized and the solid phase was measured along with viscosity measurements at temperatures and pressures ranging from 20 to 152 degrees C at atmospheric pressures to 103.4 MPa. The viscosity of the liquid samples after aging was compared with that of corresponding fresh samples. The results indicate that the degree of oxidation plays an important role in increasing the sample viscosity. The increase in viscosity depends on temperature, and is more significant at low temperatures. Agitation of samples during aging with air resulted in increased amounts of solid precipitation while lowering the viscosity of the liquid phase. This study demonstrated that oxidation has an important influence on rheological properties of the oil, because it affects the mobility of the oil and therefore the recovery factor. 11 refs., 7 tabs., 22 figs.

  6. Study of concrete activation with IFMIF-like neutron irradiation: Status of EAF and TENDL neutron activation cross-sections

    Science.gov (United States)

    García, Mauricio; Sauvan, Patrick; García, Raquel; Ogando, Francisco; Sanz, Javier

    2017-09-01

    The aim of this paper is to check the performance of last versions of EAF and TENDL libraries (EAF2007, EAF2010, and TENDL2014) in the prediction of concrete activation under the neutron irradiation environment expected in IFMIF, an accelerator-based neutron source conceived for fusion materials testing. For this purpose Activity and dose rate responses of three types of concrete (ITER-Bioshield kind, barite and magnetite concretes) have been studied. For these quantities, dominant nuclides and production pathways have been determined and, then, a qualitative analysis of the relevant activation cross-sections involved has been performed by comparing data from mentioned libraries with experimental data from EXFOR database. Concrete activation studies have been carried out with IFMIF-like neutron irradiation conditions using the ACAB code and EAF and TENDL libraries. The cooling times assessed are related to safety and maintenance operations, specifically 1 hour, 1 day and 12 days. Final conclusions are focused on the recommendations for the activation library to be used among those analyzed and cross-section data to be improved.

  7. Panorama of mining activities in France during 1993-1994

    International Nuclear Information System (INIS)

    Michel, J.C.; Bornuat, M.; Heinry, C.; Le Berre, P.

    1995-01-01

    Demand, and thus prices and activities, in the French mining sector continued to suffer from the effects of the 1993 recession. The moderate economic recovery seen in 1994 has not had an immediate impact on the mining industry partly because of previously built up stocks, but some encouraging signs have appeared: a clear resumption of oil exploration, the anti-dumping measures of the European Union, and a new Chinese pricing policy particularly concerning tungsten, antimony and fluorite. In general, French mining continued its decline as illustrated by the closures of further iron, uranium and zinc mines and the loss of all tungsten, bauxite, lead, zinc and germanium mines. The very marked decrease in zinc, silver, uranium, iron and coal production reflects the programmed closure of certain mines. In detail, the balance is more varied and the situation and outlook are not as bleak for all mineral substances: decline is moderate for potassium, barite and fluorite; oil and gas in France and nickel in new Caledonia are stable; sulphur, talc, salt, kaolin, feldspar and silica production have recorded a slight growth while gold is in clear progression. However, these positive aspects cannot counter-balance the lack of significant new resources (hydrocarbons, potassium) and of sufficient exploration effort relative to the stakes (metal ore mines). The end of the National Mineral Inventory in 1993 and the very long procedures for mining permits obtention do not favor national or international private investment. (J.S.). 14 figs., 11 tabs

  8. Fungal Ferromanganese Mineralisation in Cretaceous Dinosaur Bones from the Gobi Desert, Mongolia.

    Science.gov (United States)

    Owocki, Krzysztof; Kremer, Barbara; Wrzosek, Beata; Królikowska, Agata; Kaźmierczak, Józef

    2016-01-01

    Well-preserved mycelia of fungal- or saprolegnia-like biota mineralised by ferromanganese oxides were found for the first time in long bones of Late Cretaceous dinosaurs from the Gobi Desert (Nemegt Valley, Mongolia). The mycelia formed a biofilm on the wall of the bone marrow cavity and penetrated the osteon channels of the nearby bone tissue. Optical microscopy, Raman, SEM/EDS, SEM/BSE, electron microprobe and cathodoluminescence analyses revealed that the mineralisation of the mycelia proceeded in two stages. The first stage was early post-mortem mineralisation of the hyphae by Fe/Mn-oxide coatings and microconcretions. Probably this proceeded in a mildly acidic to circumneutral environment, predominantly due to heterotrophic bacteria degrading the mycelial necromass and liberating Fe and Mn sorbed by the mycelia during its lifetime. The second stage of mineralisation, which proceeded much later following the final burial of the bones in an alkaline environment, resulted from the massive precipitation of calcite and occasionally barite on the iron/manganese-oxide-coated mycelia. The mineral phases produced by fungal biofilms colonising the interiors of decaying dinosaur bones not only enhance the preservation (fossilisation) of fungal remains but can also be used as indicators of the geochemistry of the dinosaur burial sites.

  9. Fungal Ferromanganese Mineralisation in Cretaceous Dinosaur Bones from the Gobi Desert, Mongolia.

    Directory of Open Access Journals (Sweden)

    Krzysztof Owocki

    Full Text Available Well-preserved mycelia of fungal- or saprolegnia-like biota mineralised by ferromanganese oxides were found for the first time in long bones of Late Cretaceous dinosaurs from the Gobi Desert (Nemegt Valley, Mongolia. The mycelia formed a biofilm on the wall of the bone marrow cavity and penetrated the osteon channels of the nearby bone tissue. Optical microscopy, Raman, SEM/EDS, SEM/BSE, electron microprobe and cathodoluminescence analyses revealed that the mineralisation of the mycelia proceeded in two stages. The first stage was early post-mortem mineralisation of the hyphae by Fe/Mn-oxide coatings and microconcretions. Probably this proceeded in a mildly acidic to circumneutral environment, predominantly due to heterotrophic bacteria degrading the mycelial necromass and liberating Fe and Mn sorbed by the mycelia during its lifetime. The second stage of mineralisation, which proceeded much later following the final burial of the bones in an alkaline environment, resulted from the massive precipitation of calcite and occasionally barite on the iron/manganese-oxide-coated mycelia. The mineral phases produced by fungal biofilms colonising the interiors of decaying dinosaur bones not only enhance the preservation (fossilisation of fungal remains but can also be used as indicators of the geochemistry of the dinosaur burial sites.

  10. Synchrotron powder diffraction on Aztec blue pigments

    International Nuclear Information System (INIS)

    Sanchez del Rio, M.; Gutierrez-Leon, A.; Castro, G.R.; Rubio-Zuazo, J.; Solis, C.; Sanchez-Hernandez, R.; Robles-Camacho, J.; Rojas-Gaytan, J.

    2008-01-01

    Some samples of raw blue pigments coming from an archaeological rescue mission in downtown Mexico City have been characterized using different techniques. The samples, some recovered as a part of a ritual offering, could be assigned to the late Aztec period (XVth century). The striking characteristic of these samples is that they seem to be raw pigments prior to any use in artworks, and it was possible to collect a few μg of pigment after manual grain selection under a microscopy monitoring. All pigments are made of indigo, an organic colorant locally known as anil or xiuhquilitl. The colorant is always found in combination with an inorganic matrix, studied by powder diffraction. In one case the mineral base is palygorskite, a rare clay mineral featuring micro-channels in its structure, well known as the main ingredient of the Maya blue pigment. However, other samples present the minerals sepiolite (a clay mineral of the palygorskite family) and calcite. Another sample contains barite, a mineral never reported in prehispanic paints. We present the results of characterization using high resolution powder diffraction recorded at the European Synchrotron Radiation Facility (BM25A, SpLine beamline) complemented with other techniques. All of them gave consistent results on the composition. A chemical test on resistance to acids was done, showing a high resistance for the palygorskite and eventually sepiolite compounds, in good agreement with the excellent resistance of the Maya blue. (orig.)

  11. 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)

  12. Preliminary Assessment of Non-Fuel Mineral Resources of Afghanistan, 2007

    Science.gov (United States)

    ,

    2007-01-01

    Introduction Afghanistan has abundant mineral resources, including known deposits of copper, iron, barite, sulfur, talc, chromium, magnesium, salt, mica, marble, rubies, emeralds, lapis lazuli, asbestos, nickel, mercury, gold and silver, lead, zinc, fluorspar, bauxite, beryllium, and lithium (fig. 1). Between 2005 and 2007, the U.S. Agency for International Development (USAID) funded a cooperative study by the U.S. Geological Survey (USGS) and the Afghanistan Geological Survey (AGS) to assess the non-fuel mineral resources of Afghanistan as part of the effort to aid in the reconstruction of that country. An assessment is an estimation or evaluation, in this instance of undiscovered non-fuel mineral resources. Mineral resources are materials that are in such form that economic extraction of a commodity is currently or potentially feasible. In this assessment, teams of scientists from the USGS and the AGS compiled information about known mineral deposits and then evaluated the possible occurrence of undiscovered deposits of all types. Quantitative probabilistic estimates were made for undiscovered deposits of copper, mercury, rare-earth elements, sulfur, chromite, asbestos, potash, graphite, and sand and gravel. These estimates were made for undiscovered deposits at depths less than a kilometer. Other deposit types were considered and discussed in the assessment, but quantitative estimates of numbers of undiscovered deposits were not made. In addition, the assessment resulted in the delineation of 20 mineralized areas for further study, of which several may contain resources amenable to rapid development.

  13. Paragenesis of ``box-work geodes'', Tampa Bay, Florida

    Science.gov (United States)

    Strom, Richard N.; Upchurch, Sam B.; Rosenzweig, Abraham

    1981-12-01

    An unusual suite of silicified rocks was excavated during a recent harbour-deepening project in Tampa Bay, Florida. These rocks, which we have termed "box-work geodes", are composed of convoluted, intersecting silica walls enclosing cavities which are either voids or filled with relatively pure monoclinic palygorskite. The "box-work geodes" are interpreted as having formed in shallow lagoonal environments, similar to the Coorong Lagoon of South Australia. Synaeresis of syngenetic palygorskite was followed by opal deposition and case hardening of the material. Subsequent chemical deposition of chalcedony, megacrystalline quartz, barite, and calcite on the void facing walls indicates an open chemical system. The existence of opal saturated lagoons, as inferred from the "box-work geodes", suggests that much of the replacement chert, porcelanite, and silicified fossils in the Tertiary deposits of peninsular Florida formed in the shallow subsurface. Subsequent weathering of carbonates and clays not encapsulated in the box works has resulted in formation of a green montmorillonite residual clay bed.

  14. 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.

  15. Green Synthesis of Barium Sulfate Particles Using Plant Extracts

    Directory of Open Access Journals (Sweden)

    Chen Long

    2016-01-01

    Full Text Available The biological molecules in the extracts of four fruits or vegetables: kiwifruit, oranges, tomato and carrot, were used as templates to synthesize barium sulfate (BaSO4 particles. The products were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray power diffractometry. The results showed that, leaf-shaped barite BaSO4 crystals with toothed edge were obtained with kiwifruit extracts; thorn spherical barium sulfate crystals with diameter of 2-4 micrometers were produced with tomato extracts; rod-like or quasi-spherical BaSO4 crystals with size of several hundred nanometers to several micrometers were gained with orange extracts; while quasi-spherical BaSO4 nano-crystals were obtained with carrot extracts. The formation mechanism of BaSO4 is also discussed, showing that the proteins, carbohydrates, vitamins and organic acids in above four kinds of fruits or vegetables may provide nucleation sites, controlling the growth of BaSO4 crystals with different morphologies.

  16. Are modern geothermal waters in northwest Nevada forming epithermal gold deposits?

    Science.gov (United States)

    Breit, George N.; Hunt, Andrew G.; Wolf, Ruth E.; Koenig, Alan E.; Fifarek, Richard; Coolbaugh, Mark F.

    2010-01-01

    Hydrothermal systems currently are active near some gold deposits in northwestern Nevada. Possible links of these modern systems to gold mineralization were evaluated by chemically and isotopically analyzing water samples from the Brady, Dixie Valley, Humboldt House, San Emidio-Empire, Soda Lake, and Wabuska geothermal areas. In addition, quartz veins from Humboldt House and the adjacent Florida Canyon Mine were analyzed to compare ore and gangue phases with those predicted to form from proximal hydrothermal fluids.Nearly all water samples are alkali-chloride-type. Total dissolved solids range from 800 to 3900 mg/L, and pH varies from 5.6 to 7.8. Geochemical modeling with SOLVEQ, WATCH, and CHILLER predict the precipitation of silica in all systems during cooling. Anhydrite, calcite, barite, pyrite, base-metal sulfides, and alumino-silicates are variably saturated at calculated reservoir temperatures and also precipitate during boiling/cooling of some fluids. Measured dissolved gold concentrations are low (<0.2μg/L), but are generally consistent with contents predicted by equilibrium of sampled solutions with elemental gold at reservoir temperatures.  Although the modern geothermal waters can precipitate ore minerals, the low gold and other ore metal concentrations require very large fluid volumes to form a deposit of economic interest.

  17. Draft critical mineral list—Summary of methodology and background information—U.S. Geological Survey technical input document in response to Secretarial Order No. 3359

    Science.gov (United States)

    Fortier, Steven M.; Nassar, Nedal T.; Lederer, Graham W.; Brainard, Jamie; Gambogi, Joseph; McCullough, Erin A.

    2018-02-16

    Pursuant to the Presidential Executive Order (EO) No. 13817, “A Federal Strategy to Ensure Secure and Reliable Supplies of Critical Minerals,” the Secretary of the Interior, in coordination with the Secretary of Defense, and in consultation with the heads of other relevant executive departments and agencies, was tasked with developing and submitting a draft list of minerals defined as “critical minerals” to the Federal Register within 60 days of the issue of the EO (December 20, 2017).Based on an analysis by the U.S. Geological Survey and other U.S. Government agencies, using multiple criteria, 35 minerals or mineral material groups have been identified that are currently (February 2018) considered critical. These include the following: aluminum (bauxite), antimony, arsenic, barite, beryllium, bismuth, cesium, chromium, cobalt, fluorspar, gallium, germanium, graphite (natural), hafnium, helium, indium, lithium, magnesium, manganese, niobium, platinum group metals, potash, rare earth elements group, rhenium, rubidium, scandium, strontium, tantalum, tellurium, tin, titanium, tungsten, uranium, vanadium, and zirconium. The categorization of minerals as critical may change during the course of the review process and is thus provisional.

  18. Egyptian diatomite as high fluid loss squeeze slurry in sealing fractures and

    Directory of Open Access Journals (Sweden)

    A.M. Al-Sabagh

    2016-09-01

    Full Text Available Lost circulation is the most costly mud related drilling problem, and induced fracture. Water slurry of diatomite is used as the high fluid loss squeeze slurry in the treatment of lost circulation and in decreasing fluid loss. Egypt has diatomite deposits, especially in El-Fayuom Depression. Fourteen samples were collected from Qasr El-Sagha at the northern shore of Birket Qarun. Samples were examined to identify the diatom species then subjected to X-ray fluorescence, XRD and grain size distribution tests. A total of 38 species related to 13 diatom genera were identified. Cocconeis, Epithemia and Rhopalodia were the predominant genera. The diatomaceous earth which acts as a filter aid material was tested with different additives; bentonite, lime, finely divided paper, polymer, barite and different concentrations with different types of lost circulation materials (LCM to form a high fluid loss squeeze slurry. As a result the required time for collecting the filtrate was decreased to be in the range of 50 s to 1 min and 49 s comparing with the international standard which recommended the filtrate should be collected maximum within 2–3 min.

  19. 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.

  20. 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)

    Tassinari, C.C.G.; Barbour, A.P.; Sato, K.; Daitx, E.C.

    1990-01-01

    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)

  1. Geology, geochemistry, and genesis of the Greens Creek massive sulfide deposit, Admiralty Island, southeastern Alaska

    Science.gov (United States)

    Taylor, Cliff D.; Johnson, Craig A.

    2010-01-01

    precious-metal-rich silica-barite-carbonate white ores began at low temperature in a shallow, subaqueous setting, probably a thin carbonate shelf on the flanks of the Alexander landmass. Epigenetic carbonate replacement textures in the footwall dolostones are overlain by stratiform silica-carbonate-barite-rich ores and indicate that early mineralization formed at and just beneath the paleo sea floor by mixing of a reduced, precious-metal-rich, base-metal-poor hydrothermal fluid with oxygenated seawater. As rifting intensified, the shelf was downfaulted and isolated as a graben. Isolation of the basin and onset of starved-basin shale sedimentation was concurrent with emplacement of mafic-ultramafic intrusives at shallow levels in the rift, resulting in an increasingly higher temperature and progressively more anoxic ore-forming environment. The formation of the main stage of massive sulfide ores began as the supply of bacterially reduced sulfur increased in the accumulating shales. As the main-stage mineralization intensified, shale sedimentation inundated the hydrothermal system, eventually forming a cap. Biogenic sulfate reduction supplied reduced sulfur to the base of the shales where mixing occurred with hot, base-metal-rich hydrothermal fluids. Ore deposition continued by destruction and epigenetic replacement of the early white ores in proximal areas and by inflation and diagenetic replacement of unlithified shale at the interface between the white ores and the base of the shale cap. Ore deposition waned as the shales became lithified and as the supply of bacterially reduced sulfur to the site of ore deposition ceased. The final stages of rifting resulted in the emplacement of mafic-ultramafic intrusive rocks into the Greens Creek system and extrusion of voluminous basaltic flows at the top of the Triassic section. Greenschist facies metamorphism during the Jurassic-Cretaceous accretion of the Alexander terrane to the continental margin resulted in recrystalli

  2. Fluid paleocirculations at the cover/granite interface in the Rhine graben

    Science.gov (United States)

    Lerouge, Catherine; Dezayes, Chrystel; Bailly, Laurent; Flehoc, Christine; Guerrot, Catherine; Wille, Guillaume

    2017-04-01

    dolomite was identified in fractures crosscutting Hercynian granite and in Permian and Triassic sandstones of the Rhine Graben (EPS1 borehole) but also on the flank of the Rhine Graben in Hercynian granite of Waldhambach, Heidelberg and Windstein quarries, and in Permian rhyolite at Waldhambach. This dolomite is Fe and Mn poor, formed at 120-130°C, and has a 87Sr/86Sr of 0.708-0.709. Barite is the major sulphate observed in fracture filling, already formed later than dolomite. Rare microthermometric data combined with strontium isotopes provide evidence of several generations of barite with one generation formed at 130°C. Preliminary data on dolomite provide evidence of large fluid circulations at the cover/granite interface. This dolomite is observed at least at depth down to 1650 m of the granite in the EPS1 borehole, i.e. with a minimum penetration of 200 m into the granite. Alternating deposition of ankerite and dolomite in fracture corridors strongly suggest pulses of fluids. Such fracture fillings at 1641 meters depth were attributed to present-day fluid circulations. However similar generation of dolomite also observed in fracture corridor crosscutting the Hercynian granite and Permian rhyolite at Waldhambach on the flank of the Rhine graben demonstrate that the fluid circulations associated to these fillings were already active at the cover/granite interface before the formation of the Rhine graben.

  3. 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

  4. Influences of the Tonga Subduction Zone on seafloor massive sulfide deposits along the Eastern Lau Spreading Center and Valu Fa Ridge

    Science.gov (United States)

    Evans, Guy N.; Tivey, Margaret K.; Seewald, Jeffrey S.; Wheat, C. Geoff

    2017-10-01

    This study investigates the morphology, mineralogy, and geochemistry of seafloor massive sulfide (SMS) deposits from six back-arc hydrothermal vent fields along the Eastern Lau Spreading Center (ELSC) and Valu Fa Ridge (VFR) in the context of endmember vent fluid chemistry and proximity to the Tonga Subduction Zone. To complement deposit geochemistry, vent fluid analyses of Cu, Zn, Ba, Pb and H2,(aq) were completed to supplement existing data and enable thermodynamic calculations of mineral saturation states at in situ conditions. Results document southward increases in the abundance of mantle-incompatible elements in hydrothermal fluids (Ba and Pb) and SMS deposits (Ba, Pb, As, and Sb), which is also expressed in the abundance of barite (BaSO4) and galena (PbS) in SMS deposits. These increases correspond to a decrease in distance between the ELSC/VFR and the Tonga Subduction Zone that correlates with a change in crustal lithology from back-arc basin basalt in the north to mixed andesite, rhyolite, and dacite in the south. Barite influences deposit morphology, contributing to the formation of horizontal flanges and squat terraces. Results are also consistent with a regional-scale lowering of hydrothermal reaction zone temperatures from north to south (except at the southernmost Mariner vent field) that leads to lower-temperature, higher-pH vent fluids relative to mid-ocean ridges of similar spreading rates (Mottl et al., 2011). These fluids are Cu- and Zn-poor and the deposits formed from these fluids are Cu-poor but Zn-rich. In contrast, at the Mariner vent field, higher-temperature and lower pH vent fluids are hypothesized to result from higher reaction zone temperatures and the localized addition of acidic magmatic volatiles (Mottl et al., 2011). The Mariner fluids are Cu- and Zn-rich and vent from SMS deposits that are rich in Cu but poor in Zn with moderate amounts of Pb. Thermodynamic calculations indicate that the contrasting metal contents of vent fluids

  5. Descriptions of mineral occurrences and interpretation of mineralized rock geochemical data in the Stikine geophysical survey area, Southeastern Alaska

    Science.gov (United States)

    Taylor, Cliff D.

    2003-01-01

    Detailed descriptions of some of the more significant mineral occurrences in the Stikine Airborne Geophysical Survey Project Area are presented based upon site-specific examinations by the U.S. Geological Survey in May of 1998. Reconnaissance geochemical data on unmineralized igneous and sedimentary host rocks, and mineralized rocks are also presented and are accompanied by a brief analysis of geochemical signatures typical of each occurrence. Consistent with the stated goal of the geophysical survey; to stimulate exploration for polymetallic massive sulfides similar to the Greens Creek deposit, the majority of the described occurrences are possible members of a belt of Late Triassic mineral deposits that are distributed along the eastern edge of the Alexander terrane in southeastern Alaska. Many of the described occurrences in the Duncan Canal-Zarembo Island area share similarities to the Greens Creek deposit. When considered as a whole, the geology, mineralogy, and geochemistry of these occurrences help to define a transitional portion of the Late Triassic mineral belt where changes in shallow to deeper water stratigraphy and arc-like to rift-related igneous rocks are accompanied by concomitant changes in the size, morphology, and metal endowments of the mineral occurrences. As a result, Late Triassic mineral occurrences in the area appear as: 1) small, discontinuous, structurally controlled stockwork veins in mafic volcanic rocks, 2) small, irregular replacements and stratabound horizons of diagenetic semi-massive sulfides in dolostones and calcareous shales, and as 3) larger, recognizably stratiform accumulations of baritic, semi-massive to massive sulfides at and near the contact between mafic volcanic rocks and overlying sedimentary rocks. Empirical exploration guidelines for Greens Creek-like polymetallic massive sulfide deposits in southeastern Alaska include: 1) a Late Triassic volcano-sedimentary host sequence exhibiting evidence of succession from

  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. Archean cherts: field, petrographic and geochemical criteria to determine their origin

    Science.gov (United States)

    Ledevin, Morgane; Arndt, Nicholas T.; Simionovici, Alexandre

    2013-04-01

    Archean cherts provide valuable information about conditions on the sea floor during the early history of Earth. We conducted field, petrological and geochemical studies on examples from different environments in the Barberton Greenstone Belt (3.2-3.5 Ga), South Africa, with the aim of improving our understanding of these enigmatic rocks. We distinguish three different origins for cherts: direct precipitation from seawater (C-cherts); precipitation in fractures from silica-rich fluids (F-cherts); and replacement of preexisting rocks (silicification) either at or near the surface (S-cherts). The three types were distinguished using a combination of sedimentary and deformation structures, petrological observations (RAMAN, electron microprobe, X-Ray microfluorescence, cathodoluminescence) and geochemical data. C-cherts best record the composition and physical conditions in primitive oceans and the depositional environment because they precipitated from seawater. Based on sedimentary structures, we show that the silica was deposited as a siliceous ooze or amorphous gel on the seafloor, with variable precipitation rates that depend on the amount and nature of co-precipitated phases (called here the "contaminant"), such as detrital grains, carbonates, carbonaceous matter and oxides. We observe a complex rheology of C-cherts, which show both ductile to brittle deformation structures, sometimes in the same layer. We infer that the cherts underwent extremely rapid diagenetic induration at or near the surface, a process that proceeded faster when contaminants are lacking. Geochemical data (ICP-MS/ICP-AES) indicate that whole rock chemistries are dominated by the contaminant phases. Detrital grains with continental signatures dominate the compositions of cherts in the turbidite sequence of the Komati River whereas carbonates preserving modern, seawater-like compositions control the compositions of cherts of Fig Tree Fm in the Barite Valley. The silica minerals do not

  8. 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.

  9. Groundwater-Lake Interaction in the Dead Sea Area

    Science.gov (United States)

    Kiro, Y.; Weinstein, Y.; Starinsky, A.; Yechieli, Y.

    2011-12-01

    The Dead Sea hypersaline water system is unique in terms of its unusual geochemical composition, rapid lake level changes and water composition of the brines discharging along its shoreline. The Dead Sea can be used as a natural lab for studying groundwater-seawater interaction and saline water hydrological circulation along the aquifer-sea boundary. It provides an opportunity to follow the geochemical processes along a flow path from the lake into the aquifer and back into the lake. The lake level has been dropping since the 1960's due to human interference in its water budget, reaching a rate of 1 m/yr in recent years. Saline water circulation in coastal aquifers may be a major process that governs trace element mass balances in coastal areas. This study uses radium isotopes in order to quantify the lake water circulation in the Dead Sea aquifer. There are four naturally-occurring radium isotopes, with half-lives ranging from 3.7 days to 1600 years which are chain products of uranium and thorium isotopes. Radium isotopes are usually enriched in saline groundwater and therefore are good candidates for estimating seawater or hypersaline lake water circulation in the aquifer. Compared to most natural water bodies, the Dead Sea is extremely enriched in radium and barium, where both 226Ra and 228Ra activities and Ba concentration (145, 1-2 dpm/L and 5 mg/L, respectively) are 2-3 orders of magnitude higher than in ocean water, whereas the salinity of the Dead Sea is only 10 times higher. Circulated Dead Sea water in the aquifer contains decreased concentrations of 226Ra (60 dpm/L), Ba (1.5 mg/L), Sr (300 relative to 340 mg/L in the Dead Sea) and Sulfate (250 relative to 392 mg/L). We suggest that the low 226Ra and Ba concentrations are due to precipitation of barite and celestine from the supersaturated Dead Sea water on entering the aquifer. 228Ra and the shorter-lived 224Ra and 223Ra, which have much lower activities in the Dead Sea (up to 1.8, 3 and 0.8 dpm

  10. Lithologic controls on mineralization at the Lagunas Norte high-sulfidation epithermal gold deposit, northern Peru

    Science.gov (United States)

    Cerpa, Luis M.; Bissig, Thomas; Kyser, Kurt; McEwan, Craig; Macassi, Arturo; Rios, Hugo W.

    2013-06-01

    , auriferous pyrite, and enargite. Alteration and mineralization in the breccias were controlled by permeability, which depends on the type and composition of the matrix, cement, and clast abundance. Coarse alunite from the main mineralization stage in textural equilibrium with pyrite and enargite has δ34S values of 24.8-29.4 ‰ and {δ^{18 }}{{O}_{{S{{O}_4}}}} values of 6.8-13.9 ‰, consistent with H2S as the dominant sulfur species in the mostly magmatic fluid and constraining the fluid composition to low pH (0-2) and log fO2 of -28 to -30. Alunite-pyrite sulfur isotope thermometry records temperatures of 190-260 °C; the highest temperatures corresponding to samples from near the diatremes. Alunite of the third hydrothermal stage has been dated by 40Ar/39Ar at 17.0 ± 0.22 Ma. The fourth hydrothermal stage introduced only modest amounts of gold and is characterized by the presence of massive alunite-pyrite in fractures, whereas barite, drusy quartz, and native sulfur were deposited in the volcanic rocks. The {δ^{18 }}{{O}_{{S{{O}_4}}}} values of stage IV alunite vary between 11.5 and 11.7 ‰ and indicate that the fluid was magmatic, an interpretation also supported by the isotopic composition of barite (δ34S = 27.1 to 33.8 ‰ and {δ^{18 }}{{O}_{{S{{O}_4}}}} = 8.1 to 12.7 ‰). The Δ34Spy-alu isotope thermometry records temperatures of 210 to 280 °C with the highest values concentrated around the Josefa diatreme. The Lagunas Norte deposit was oxidized to a depth of about 80 m below the current surface making exploitation by heap leach methods viable.

  11. Rapid and accurate determination of barium by instrumental neutron activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Armelin, Maria Jose A.; Maihara, Vera A.; Saiki, Mitiko, E-mail: marmelin@ipen.br, E-mail: vmaihara@ipen.br, E-mail: mitiko@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Trevizam, Anderson R., E-mail: aanrt@hotmail.com [Universidade Estadual do Centro Oeste (UNICENTRO), Guarapuava, PR (Brazil)

    2013-07-01

    Barium is an alkaline earth metal naturally present in soils. When available at a high level in the soil it can cause toxicity to plants and animals. Not all the barium is readily available to living organisms. Inorganic and organic barium compounds can be presented as soluble or insoluble forms in the soil. The soluble form of BaS is extremely toxic to humans, animals and plants. Researchers have noted a decrease of K absorption in the plant when Ba concentrations are increased and a change in overall plant growth. In case of animals, Ba tends to be concentrated in the bones which may compete with calcium, although only about 2% barium ingested in dietary is absorbed by the body. Another effect is that the Ba can interfere with the availability of sulfur in the soil due to the sulphate formation of low solubility. Barium and some other elements are considered palioclimatic proxies. For some researchers, barite is perhaps the most appropriate indicator of paleoproductivity because of a high resistance to dissolution. As explained about the barium effects in various situations, it was considered important to study the more appropriated experimental conditions for determination of this element by INAA. Conditions established for this analysis were: a) Irradiation time, 15 and 40 seconds, under thermal flux neutron about 4 x 10{sup 12} n cm{sup -2} s{sup -1}, for determining barium in geological and biological matrices, respectively; b) Decay time, approximately of 4 minutes; c) Counting time of 30 minutes; d) Radionuclide measured {sup 139}Ba. The quality of Ba results was evaluated from the analysis of certified reference materials. The performance of the method was satisfactory, according to the criterion of E.ζ score. Results obtained in this study indicate INAA is a good alternative for Ba determination in geological and biological samples. (author)

  12. Rapid and accurate determination of barium by instrumental neutron activation analysis

    International Nuclear Information System (INIS)

    Armelin, Maria Jose A.; Maihara, Vera A.; Saiki, Mitiko; Trevizam, Anderson R.

    2013-01-01

    Barium is an alkaline earth metal naturally present in soils. When available at a high level in the soil it can cause toxicity to plants and animals. Not all the barium is readily available to living organisms. Inorganic and organic barium compounds can be presented as soluble or insoluble forms in the soil. The soluble form of BaS is extremely toxic to humans, animals and plants. Researchers have noted a decrease of K absorption in the plant when Ba concentrations are increased and a change in overall plant growth. In case of animals, Ba tends to be concentrated in the bones which may compete with calcium, although only about 2% barium ingested in dietary is absorbed by the body. Another effect is that the Ba can interfere with the availability of sulfur in the soil due to the sulphate formation of low solubility. Barium and some other elements are considered palioclimatic proxies. For some researchers, barite is perhaps the most appropriate indicator of paleoproductivity because of a high resistance to dissolution. As explained about the barium effects in various situations, it was considered important to study the more appropriated experimental conditions for determination of this element by INAA. Conditions established for this analysis were: a) Irradiation time, 15 and 40 seconds, under thermal flux neutron about 4 x 10 12 n cm -2 s -1 , for determining barium in geological and biological matrices, respectively; b) Decay time, approximately of 4 minutes; c) Counting time of 30 minutes; d) Radionuclide measured 139 Ba. The quality of Ba results was evaluated from the analysis of certified reference materials. The performance of the method was satisfactory, according to the criterion of E.ζ score. Results obtained in this study indicate INAA is a good alternative for Ba determination in geological and biological samples. (author)

  13. 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. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Non-invasive techniques for revealing the palette of the Romantic painter Francesco Hayez

    Science.gov (United States)

    Rampazzi, Laura; Brunello, Valentina; Corti, Cristina; Lissoni, Elena

    2017-04-01

    This paper describes the first systematic analysis of the palette of Francesco Hayez, one of the most outstanding artists of European Romanticism, whose painting technique has never been extensively investigated despite the plethora of artistic studies. He lived in a particular moment in the history of painting, as in the first half of the 19th century many synthetic pigments were available, also in tin tubes, but traditional materials were still used. Sixteen paintings on canvas and on panels, created between 1823 and 1868, were analyzed in situ through non-invasive techniques (infrared reflectography and infrared reflection spectroscopy). Imaging investigation provided clues on painting technique, revealing some cases of pentimenti and underdrawings. A preliminary survey was carried out on a hundred pure pigments used up to the 19th century and on new synthetic colours, in order to attain reference spectra for the interpretation of painting spectra. The portable infrared instrument provided insight into Hayez's painting materials, identifying barite, ivory black, lead-tin yellow, Naples yellow, ochres, Prussian blue, and white lead. The pigments were often blended, to obtain a unique fabric appearance or to attain cold shades. The results pointed to a siccative oil as a binder, mixed with white lead so that it could act as a catalyzer in polymerization reactions, and in some cases with a proteinaceous binder and resins. The preparation was made with gypsum and white lead mixed with a siccative oil. The results showed that the artist used a typical traditional palette, throughout his career, in order to lead to brilliant colours and with long-term stability. Anyway, the possible presence of cobalt blue in a few paintings suggests that Hayez had probably started testing the new colours, since the second decade of 19th century.

  15. 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. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

  16. Synchrotron Micro-XRF Mapping of Ag Storage in a Coastal Marine Diatom: Implications for Ag as a Novel Paleoproductivity Proxy

    Science.gov (United States)

    King, M. W.; Hendy, I. L.; Lai, B.

    2012-12-01

    Silver (Ag) has potential for use as a paleoproductivity proxy in environments where a high flux of organic matter creates reducing conditions in sediments. Its proposed sequestration under reducing conditions as the species Ag2S confers an advantage over the more conventional productivity proxy barite, which becomes unreliable when sulfate reduction occurs in sediments. Other conventional productivity proxies (organic carbon and biogenic silica) are subject to rapid remineralization during early diagenesis, whereas Ag is likely to be preserved. Prior studies have hinted that Ag may be delivered to sediments via diatom debris. However, whether Ag is primarily associated with the frustule silica matrix or with diatom organic matter has not been established, and hence the mechanism of Ag delivery to sediments remains ambiguous. In this study we investigated the location of Ag storage in diatoms using synchrotron micro-XRF to map Ag, along with Ca, P, S, Si, and Fe, in single cells of the coastal marine diatom Thalassiosira pseudonana. Diatoms were cultured in the laboratory with Ag added to the growth medium at 50 and 100 ppb. Samples were analyzed at the sub-micron scale at the Advanced Photon Source, Argonne National Laboratory. Detectable Ag concentrations appear to be localized to intracellular "hotspots" that are not associated with frustule Si, either as part of the matrix or surface-adsorbed. Silver "hotspots" are co-localized with Fe, suggesting that Ag is stored within vacuoles, as recently shown for Fe in centric diatoms. Overall, our results support the hypothesis that Ag is delivered to sediments with diatom organic matter and suggest a common strategy by centric diatoms for intracellular sequestration of micronutrient (Fe) and nonessential (Ag) trace metals.

  17. Methodological aspects and development of techniques for neutron activation analysis of microcomponents in materials of geologic origin

    International Nuclear Information System (INIS)

    Cohen, I.M.

    1982-01-01

    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.) [es

  18. Chemical and mineralogical analysis of devonian black-shale samples from Martin County, Kentucky; Carroll and Washington counties, Ohio; Wise County, Virginia; and Overton County, Tennessee, U.S.A.

    Science.gov (United States)

    Leventhal, J.S.; Hosterman, J.W.

    1982-01-01

    Core samples of Devonian shales from five localities in the Appalachian basin have been analyzed chemically and mineralogically. The amounts of major elements are similar; however, the minor constituents, organic C, S, phosphate and carbonate show ten-fold variations in amounts. Trace elements Mo, Ni, Cu, V, Co, U, Zn, Hg, As and Mn show variations in amounts that can be related to the minor constituents. All samples contain major amounts of quartz, illite, two types of mixed-layer clays, and chlorite in differing quantities. Pyrite, calcite, feldspar and kaolinite are also present in many samples in minor amounts. Dolomite, apatite, gypsum, barite, biotite and marcasite are present in a few samples in trace amounts. Trace elements listed above are strongly controlled by organic C with the exception of Mn which is associated with carbonate minerals. Amounts of organic C generally range from 3 to 6%, and S is in the range of 2-5%. Amounts of trace elements show the following general ranges in ppm (parts per million): Co, 20-40; Cu, 40-70; U, 10-40; As, 20-40; V, 150-300; Ni, 80-150; high values are as much as twice these values. The organic C was probably the concentrating agent, and the organic C and sulfide S together created an environment that immobilized and preserved these trace elements. Closely spaced samples showing an abrupt transition in color also show changes in organic C, S and trace-element contents. Several associations exist between mineral and chemical content. Pyrite and marcasite are the only minerals found to contain sulfide-S. In general, the illite-chlorite mixed-layer clay mineral shows covariation with organic C if calcite is not present. The enriched trace elements are not related to the clay types, although the clay and organic matter are intimately associated as the bulk fabric of the rock. ?? 1982.

  19. Advanced Characterization of Rare Earth Elements in Coal Utilization Byproducts

    Science.gov (United States)

    Verba, C.; Scott, M.; Dieterich, M.; Poston, J.; Collins, K.

    2016-12-01

    Rare earth elements (REE) in various forms (e.g., crystalline mineral phases; adsorbed/absorbed state on and into organic macerals, neoformed glass from flyash or bottom ash) from domestic feedstocks such as coal deposits to coal utilization byproducts (CUB) have the potential to reduce foreign REE dependence and increase domestic resource security. Characterization is critical for understanding environmental risks related to their fate and transport as well as determining the most practical and economical techniques for concentrating the REE and converting them into chemical stocks for manufacturing. Several complementary electron microscopy (SEM-EDS, EPMA-WDS, FIB-SEM, cathodoluminescence, and XRD) and post image processing techniques were used to understand REE transition from coal to CUB. Sites of interest were identified and imaged and respective elemental x-ray maps acquired and montaged. Pixel classification of SEM imagers was completed using image analysis techniques to quantify the distribution of REE associated features. Quantitative elemental analysis of phases were completed using EMPA-WDS followed by FIB-SEM. The FIB-SEM results were reconstructed into 3D volumes and features of interest (e.g. monazite) were analyzed to determine the structure and volumetric estimation of REEs and thus predict detrital REE phases to ICP-MS results. Trace minerals were identified as pyrite, zircon, REE-phosphates' (monazite, xenotime), and barite within the coal tailings. In CUB, amorphous aluminosilicates, iron oxide cenospheres, and calcium oxides were present; monazite appear to be unaltered and unaffected by the combustion process in these samples. Thermal decomposition may have occurred due to presence of detrital zircon and xenotime and subsequent thin Ca-oxide coating enriched in trace REEs.

  20. Geology mineralogy, structure and texture of Agh-Otagh base- precious metal mineralization (North Takab

    Directory of Open Access Journals (Sweden)

    Nahid Rahmati

    2017-07-01

    Full Text Available The Agh-Otagh mineralization area in the north of Takab, was formed within the andesistic tuffaceous rocks of the Oligo- Miocene age. Mineralization include polymetallic (Cu-Pb-Zn-Au-Ag quartz veins and silicified zones, which occurred as breccia and vein- veinlets with comb, cockade and disseminated textures. Chalcopyrite, pyrite, galena and sphalerite are common ore minerals. Alteration zones consist of silicification, sericitization, argillitic, propelitic and carbonatization. Cu-Au mineralization is associated with silicification and sericitization. Analytical results of the samples from the ore- bearing quartz veins and the silicified zones indicate that the highest grade for Au is 664 ppb (ave.181 ppb. The highest and the average grades for Ag, Cu, Pb, and Zn are 120 ppm (300 ppm, 1.3 % (0.38 %, 5.5 % (0.06 % and 4.5 % (0.28 %, respectively. The investigations indicate that the Agh-Otagh mineralization was formed in four stages. In the first stage or the pre-mineralization stage, the host rock, as a result of hydrothermal process, underwent brecciation and some quartz veins and siliceous cap were formed. In the second stage or the mineralization stage the sulfide minerals formed within the quartz veins and silicification zones developed at the third stage, some unmineralized quartz, barite and carbonate vein- veinlets crosscut the previous stages. The last stage of mineralization related to supergene processes. Based on geological, mineralogical, alteration, structural and textural evidences, the Agh-Otagh base- precious metal mineralization is similar to the medium sulfidation epithermal deposits.

  1. Origin of carbonatites of the Matcha alkaline pluton from Turkestan-Alai ridge, Kyrgyz Southern Tien Shan

    Science.gov (United States)

    Vrublevskii, V. V.

    2017-12-01

    Postorogenic alkaline intrusions in the Turkestan-Alai segment of the Southern Tien Shan coexist with dikes and veins of carbonatites dated at ˜220 Ma. They are primarily composed of calcite and dolomite (60-85 %), as well as sodic amphibole, phlogopite, clinopyroxene, microcline, albite, apatite, and magnetite, with accessory niobate, ilmenite, Nb-rutile, titanite, zircon, baddeleyite, monazite-(Ce), barite, and sulfides. The rocks share mineralogical and geochemical similarity with carbonatites that originated by liquid immiscibility at high temperatures above 500°C. Silicate and salt-carbonate melts are derived from sources with mainly negative bulk ɛND(t) ˜ from -11 to 0 and high initial 87Sr/86Sr ratios (˜ 0.7061-0.7095) which may be due to mixing of PREMA and EM-type mantle material. Pb isotopic ratios in accessory pyrrhotite (206Pb/204Pb = 18.38; 207Pb/204Pb = 15.64; 208Pb/204Pb = 38.41) exhibit an EM 2 trend. The intrusions bear signatures of significant crustal contamination as a result of magma genesis by syntexis and hybridism. Concordant isotope composition changes of δ 13C (-6.5 to -1.9 ‰), δ 18O (9.2-23 %„), δD (-58 to -41 %„), and δ 34S (12.6-12.8 ‰) in minerals and rocks indicate inputs of crustal material at the stage of melting and effect of hot fluids released during dehydration of metamorphosed oceanic basalts or sediments. The observed HFSE patterns of the oldest alkaline gabbro may be due to interaction of the primary mafic magma with IAB-type material. The isotope similarity of alkaline rocks with spatially proximal basalts of the Tarim large igneous province does not contradict the evolution of the Turkestan-Alai Triassic magmatism as the «last echo» of the Tarim mantle plume.

  2. Geology, fluid inclusion and sulphur isotope characteristics of the El Cobre VHMS deposit, Southern Cuba

    Science.gov (United States)

    Cazañas, Xiomara; Alfonso, Pura; Melgarejo, Joan Carles; Proenza, Joaquín Antonio; Fallick, Anthony Edward

    2008-09-01

    The El Cobre deposit is located in eastern Cuba within the volcanosedimentary sequence of the Sierra Maestra Paleogene arc. The deposit is hosted by tholeiitic basalts, andesites and tuffs and comprises thick stratiform barite and anhydrite bodies, three stratabound disseminated up to massive sulphide bodies produced by silicification and sulphidation of limestones or sulphates, an anhydrite stockwork and a siliceous stockwork, grading downwards to quartz veins. Sulphides are mainly pyrite, chalcopyrite and sphalerite; gold occurs in the stratabound ores. Fluid inclusions measured in sphalerite, quartz, anhydrite and calcite show salinities between 2.3 and 5.7 wt% NaCl eq. and homogenisation temperatures between 177 and 300°C. Sulphides from the stratabound mineralisation display δ 34S values of 0‰ to +6.0‰, whilst those from the feeder zone lie between -1.4‰ and +7.3‰. Sulphides show an intra-grain sulphur isotope zonation of about 2‰; usually, δ 34S values increase towards the rims. Sulphate sulphur has δ 34S in the range of +17‰ to +21‰, except two samples with values of +5.9‰ and +7.7‰. Sulphur isotope data indicate that the thermochemical reduction of sulphate from a hydrothermal fluid of seawater origin was the main source of sulphide sulphur and that most of the sulphates precipitated by heating of seawater. The structure of the deposit, mineralogy, fluid inclusion and isotope data suggest that the deposit formed from seawater-derived fluids with probably minor supply of magmatic fluids.

  3. 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)

  4. Design and optimization of HPLWR high pressure Turbine gamma ray shield

    Energy Technology Data Exchange (ETDEWEB)

    Kebwaro, Jeremiah Monari; Zhao, Yaolin, E-mail: zhaoyaolin@mail.xjtu.edu.cn; He, Chaohui

    2015-04-01

    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

  5. Mineralogical Characterization of The Alteration Facies at Gabal El-Missikat Area, Central Eastern Desert, Egypt

    International Nuclear Information System (INIS)

    El-Sherif, A.M.

    2013-01-01

    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

  6. A guide for effective anatomical vascularization studies: useful ex vivo methods for both CT and MRI imaging before dissection.

    Science.gov (United States)

    Renard, Yohann; Hossu, Gabriela; Chen, Bailiang; Krebs, Marine; Labrousse, Marc; Perez, Manuela

    2018-01-01

    The objective of this study was to develop a simple and useful injection protocol for imaging cadaveric vascularization and dissection. Mixtures of contrast agent and cast product should provide adequate contrast for two types of ex vivo imaging (MRI and CT) and should harden to allow gross dissection of the injected structures. We tested the most popular contrast agents and cast products, and selected the optimal mixture composition based on their availability and ease of use. All mixtures were first tested in vitro to adjust dilution parameters of each contrast agent and to fine-tune MR imaging acquisition sequences. Mixtures were then injected in 24 pig livers and one human pancreas for MR and computed tomography (CT) imaging before anatomical dissection. Colorized latex, gadobutrol and barite mixture met the above objective. Mixtures composed of copper sulfate (CuSO 4 ) gadoxetic acid (for MRI) and iodine (for CT) gave an inhomogeneous signal or extravasation of the contrast agent. Agar did not harden sufficiently for gross dissection but appears useful for CT and magnetic resonance imaging (MRI) studies without dissection. Silicone was very hard to inject but achieved the goals of the study. Resin is particularly difficult to use but could replace latex as an alternative for corrosion instead of dissection. This injection protocol allows CT and MRI images to be obtained of cadaveric vascularization and anatomical casts in the same anatomic specimen. Post-imaging processing software allow easy 3D reconstruction of complex anatomical structures using this technique. Applications are numerous, e.g. surgical training, teaching methods, postmortem anatomic studies, pathologic studies, and forensic diagnoses. © 2017 Anatomical Society.

  7. 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.

  8. Geochemical Characterization of Trace MVT Mineralization in Paleozoic Sedimentary Rocks of Northeastern Wisconsin, USA

    Directory of Open Access Journals (Sweden)

    John A. Luczaj

    2016-06-01

    Full Text Available Disseminated Mississippi Valley-type (MVT mineralization occurs throughout northeastern Wisconsin, USA, and is recognized as the source of regionally extensive natural groundwater contamination in the form of dissolved arsenic, nickel, and other related metals. Although considerable attention has been given to arsenic contamination of groundwater in the region, limited attention has been focused on characterizing the bedrock sources of these and other metals. A better understanding of the potential sources of groundwater contamination is needed, especially in areas where groundwater is the dominant source of drinking water. This article describes the regional, stratigraphic, and petrographic distribution of MVT mineralization in Paleozoic rocks of northeastern Wisconsin, with a focus on sulfide minerals. Whole-rock geochemical analysis performed on 310 samples of dolomite, sandstone, and shale show detectable levels of arsenic, nickel, cobalt, copper, lead, zinc, and other metals related to various sulfide mineral phases identified using scanning electron microscopy. MVT minerals include pyrite, marcasite, sphalerite, galena, chalcopyrite, fluorite, celestine, barite, and others. We describe the first nickel- and cobalt-bearing sulfide mineral phases known from Paleozoic strata in the region. Arsenic, nickel, and cobalt are sometimes present as isomorphous substitutions in pyrite and marcasite, but discrete mineral phases containing nickel and cobalt elements are also observed, including bravoite and vaesite. Locally abundant stratigraphic zones of sulfide minerals occur across the region, especially in the highly enriched Sulfide Cement Horizon at the top of the Ordovician St. Peter Sandstone. Abundant quantities of sulfides also appear near the contact between the Silurian Mayville Formation and the underlying Maquoketa and Neda formations in certain areas along and east of the Niagara escarpment. This article illustrates how a detailed

  9. Hydrothermal processes in the Edmond deposits, slow- to intermediate-spreading Central Indian Ridge

    Science.gov (United States)

    Cao, Hong; Sun, Zhilei; Zhai, Shikui; Cao, Zhimin; Jiang, Xuejun; Huang, Wei; Wang, Libo; Zhang, Xilin; He, Yongjun

    2018-04-01

    The Edmond hydrothermal field, located on the Central Indian Ridge (CIR), has a distinct mineralization history owing to its unique magmatic, tectonic, and alteration processes. Here, we report the detailed mineralogical and geochemical characteristics of hydrothermal metal sulfides recovered from this area. Based on the mineralogical investigations, the Edmond hydrothermal deposits comprise of high-temperature Fe-rich massive sulfides, medium-temperature Zn-rich sulfide chimney and low-temperature Ca-rich sulfate mineral assemblages. According to these compositions, three distinctive mineralization stages have been identified: (1) low-temperature consisting largely of anhydrite and pyrite/marcasite; (2) medium-high temperature distinguished by the mineral assemblage of pyrite, sphalerite and chalcopyrite; and (3) low-temperature stage characterized by the mineral assemblage of colloidal pyrite/marcasite, barite, quartz, anglesite. Several lines of evidence suggest that the sulfides were influenced by pervasive low-temperature diffuse flows in this area. The hydrothermal deposits are relatively enriched in Fe (5.99-18.93 wt%), Zn (2.10-10.00 wt%) and Ca (0.02-19.15 wt%), but display low Cu (0.28-0.81 wt%). The mineralogical varieties and low metal content of sulfides in the Edmond hydrothermal field both indicate that extensive water circulation is prevalent below the Edmond hydrothermal field. With regard to trace elements, the contents of Pb, Ba, Sr, As, Au, Ag, and Cd are significantly higher than those in other sediment-starved mid-ocean ridges, which is indicative of contribution from felsic rock sources. Furthermore, the multiphase hydrothermal activity and the pervasive water circulation underneath are speculated to play important roles in element remobilization and enrichment. Our findings deepen our understanding about the complex mineralization process in slow- to intermediate-spreading ridges globally.

  10. Selectivity in biomineralization of barium and strontium.

    Science.gov (United States)

    Krejci, Minna R; Wasserman, Brian; Finney, Lydia; McNulty, Ian; Legnini, Daniel; Vogt, Stefan; Joester, Derk

    2011-11-01

    The desmid green alga Closterium moniliferum belongs to a small number of organisms that form barite (BaSO(4)) or celestite (SrSO(4)) biominerals. The ability to sequester Sr in the presence of an excess of Ca is of considerable interest for the remediation of (90)Sr from the environment and nuclear waste. While most cells dynamically regulate the concentration of the second messenger Ca(2+) in the cytosol and various organelles, transport proteins rarely discriminate strongly between Ca, Sr, and Ba. Herein, we investigate how these ions are trafficked in C. moniliferum and how precipitation of (Ba,Sr)SO(4) crystals occurs in the terminal vacuoles. Towards this goal, we simultaneously visualize intracellular dynamics of multiple elements using X-ray fluorescence microscopy (XFM) of cryo-fixed/freeze-dried samples. We correlate the resulting elemental maps with ultrastructural information gleaned from freeze-fracture cryo-SEM of frozen-hydrated cells and use micro X-ray absorption near edge structure (micro-XANES) to determine sulfur speciation. We find that the kinetics of Sr uptake and efflux depend on external Ca concentrations, and Sr, Ba, and Ca show similar intracellular localization. A highly ion-selective cross-membrane transport step is not evident. Based on elevated levels of sulfate detected in the terminal vacuoles, we propose a "sulfate trap" model, where the presence of dissolved barium leads to preferential precipitation of (Ba,Sr)SO(4) due to its low solubility relative to SrSO(4) and CaSO(4). Engineering the sulfate concentration in the vacuole may thus be the most direct way to increase the Sr sequestered per cell, an important consideration in using desmids for phytoremediation of (90)Sr. Copyright © 2011 Elsevier Inc. All rights reserved.

  11. Socio-Economic and Environmental Challenges of Mining Industry in the Komi Republic

    Directory of Open Access Journals (Sweden)

    Irina Grigor’evna Burtseva

    2015-07-01

    Full Text Available Mineral resources of the Komi Republic and the trends and dynamics of their development determine to a great degree the level of the regions’ economic development. The Republic has significant reserves of oil, gas, coal, aluminum, chromium, manganese, titanium, rare metals, gold, barite, fluorite, and quartz raw materials. However, the region’s mining industry is still in the process of formation, this fact makes it possible to foresee and handle major social and environmental issues that accompany mining activities. The analysis of global trends in the implementation of mining projects substantiates the necessity to build a positive reputation of mining companies for ensuring stable production and for solving social and economic problems of territories. The paper also determines staffing requirements of prospective mining enterprises and possible social risks. The authors substantiate the necessity to redistribute taxes and payments in favor of the areas where mining companies operate, and they propose ways of attracting investment in mining projects on the stage of exploration with the help of a flexible fiscal policy. The main environmental problems of perspective objects of mining complex development can include the concentration of hazardous emissions, discharges and waste and the aggravation of environmental impact. The transformation of living organisms is moving toward the reduction of species diversity, simplification and changing community structure due to the disappearance of sensitive and rare species. The assessment of environmental impact intensity, based on the point estimation of the correlation between existing anthropogenic load and environmental resistance, has shown that the levels are medium and high. Taking into consideration the increased anthropogenic load, it is necessary to determine restrictions of nature management during pre-investment stage, to set out in the license the overall admissible amount of land

  12. 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

  13. Microbial colonization of basaltic glasses in hydrothermal organic-rich sediments at Guaymas Basin

    Science.gov (United States)

    Callac, Nolwenn; Rommevaux-Jestin, Céline; Rouxel, Olivier; Lesongeur, Françoise; Liorzou, Céline; Bollinger, Claire; Ferrant, Antony; Godfroy, Anne

    2013-01-01

    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 was primarily linked to the deployment duration, as well as the depth for the short deployment time module. Some 16s rRNA sequences formed 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. PMID:23986754

  14. Chemical considerations for an updated National assessment of brackish groundwater resources

    Science.gov (United States)

    McMahon, Peter B.; Böhlke, John Karl; Dahm, Katharine; Parkhurst, David L.; Anning, David W.; Stanton, Jennifer S.

    2016-01-01

    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.

  15. 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)

    Fu, Yunjiao; Berk, Wolfgang van; Schulz, Hans-Martin

    2012-01-01

    A hydrogeochemical model is presented and applied to quantitatively elucidate interdependent reactions among minerals and formation water–seawater mixtures at elevated levels of CO 2 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, CaSO 4 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 CaSO 4 phases and dolomite are triggered by intense seawater admixture

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

    International Nuclear Information System (INIS)

    Berezkin, V.V.; Mamikonyan, S.V.; Shchekin, K.I.

    1979-01-01

    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 [ru

  17. 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)

  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. Decoupling of Mg-C and Sr-Nd-O isotopes traces the role of recycled carbon in magnesiocarbonatites from the Tarim Large Igneous Province

    Science.gov (United States)

    Cheng, Zhiguo; Zhang, Zhaochong; Hou, Tong; Santosh, M.; Chen, Lili; Ke, Shan; Xu, Lijuan

    2017-04-01

    The Tarim Large Igneous Province in NW China hosts numerous magmatic carbonatite dikes along its northern margin. The carbonatites are composed mainly of dolomite (90 vol.%) and minor calcite (5 vol.%), with apatite, barite, celestine, aegirine, monazite and bastnaesite as accessory minerals. The rocks correspond to magnesiocarbonatites with a compositional range of 13.73-19.59 wt.% MgO, and 20.03-30.11 wt.% CaO, along with 1.65-3.31 wt.% total Fe2O3, 0.02-2.39 wt.% SiO2 and other minor elements, such as P2O5, Na2O and K2O. These magnesiocarbonatites are characterized by extreme enrichment in incompatible elements with high total rare earth element (REE) contents of 372-36965 ppm. The strontium [(87Sr/86Sr)i = 0.70378-0.70386], neodymium [εNd(t) = +2.51 - +3.59] and oxygen (δ18OV-SMOW = 5.9‰-8.0‰) isotope values of these rocks are consistent with a mantle origin, whereas the magnesium (δ26Mg = -1.09‰ to -0.85‰) and carbon (δ13CV-PDB = -4.1‰ to -5.9‰) isotopes are decoupled from mantle values and reflect signature of recycled sedimentary carbonates. Global plate tectonic models predict that sedimentary carbonates in convergent margins are subducted to deep domains in the mantle, with phase transitions from calcite/dolomite to magnesite, and eventually to periclase/perovskite. The involvement of a mantle plume enhances the normal mantle geotherms and promotes decomposition reactions of magnesite. The decoupling of Mg-C and Sr-Nd-O isotopes in the mangesiocarbonatites provides insights on the origin of carbonatites, and also illustrates a case of interaction between mantle plume and subduction-related components.

  20. Geochemical Characterization Of Cherts From The 3.46Ga Apex Basalt To Assess The Origins Of Possible Biosignatures

    Science.gov (United States)

    Bower, D. M.; Steele, A.; Ackerson, M. R.; Bullock, E. S.; Green, O. R.; Fries, M.; Conrad, P. G.

    2017-12-01

    Many terrestrial cherts contain compelling microtextures and mineral phases that are indicative of ancient life in hydrothermal systems on early Earth. In volcanically-derived hydrothermal deposits, cherts have undergone multiple alteration events often resulting in separate generations of quartz veins that are much younger than the host rocks. In some cases, multiple episodes of hydrothermal alteration obscure otherwise syngenetic biosignatures and likewise create false signatures in the form of secondary carbon emplacement or diagenetic phase changes. To better identify possible biosignatures in hydrothermal deposits and understand their origins, we used confocal micro Raman spectroscopy, electron probe microanalysis, and cathodoluminescence (CL) imaging to characterize the quartz fabrics, mineral phases, trace elements, and macromolecular carbon (MMC) in quartz veins from the 3.46 Ga Apex Basalt chert samples. MMC, anatase (TiO2), pyrite (Fe2S), jarosite-alunite (KFe3(SO4)2(OH)6 - Kal3(SO4)2(OH)6), chamosite-phyllosilicates, and Fe-oxides all occur in close association in multiple generations of quartz veins throughout the sample suite. Mineral phases xenotime (YPO4), scorodite (FeAsO4 . H2O), apatite (CaPO4), pentlandite ((Fe,Ni)9S8), barite (BaSO4), sphalerite ((Zn,Fe)S), dolomite ((CaMg(CO3)2) and halides occur in specific generations of quartz. Trace elements (Cr, Mn, Mo, Cu, Sc, Va, Sb, and Co) are heterogeneously distributed within individual samples and likely occur due to fluid scavenging of the host basalts. CL imaging of quartz demonstrates that the majority of silicate material in the Apex cherts underwent recrystallization. This could result in the alteration of MMC and associated mineral assemblages. The biogencity and true origins of morphological features and chemical signatures in the Apex cherts are hotly debated, yet discovering the causes and nature of these puzzling attributes will be key for determining the usefulness of interrogating

  1. The Carbon and Sulfur Cycles through the Cenozoic: Insight from Oxygen Isotopes in Marine Sulfate

    Science.gov (United States)

    Turchyn, A. V.; Schrag, D. P.

    2004-12-01

    Marine sulfate plays an important role in the cycling of biochemicals in organic rich sediments, serving as the terminal electron acceptor in the remineralization of organic matter and responsible for nearly all anaerobic methane oxidation. Because sulfur isotopes are largely conserved during sulfur cycling in organic rich sediments, they reflect mostly changes in net sulfur burial, and have been used to study fluctuations in sulfur mineral burial over Earth history. Recently, we have shown that temporal variability in oxygen isotopes measured in marine sulfate (d18O-SO4) highlight changes the pathways of sulfur cycling on continental margins because the d18O-SO4 is reset during sulfate reduction and sulfide reoxidation. The fluxes associated with sulfur cycling, predominantly in shallow sediments, are nearly three times larger than riverine input. We present a continuous record of d18O-SO4 in marine barite over the Cenozoic. There is considerable variability in the d18OSO4, with major peaks 55, 15, and 3 million years ago. There is little correlation between sulfur isotopes in marine sulfate and d18O-SO4, illustrating the fact that different processes control the sulfur and oxygen isotopic composition of sulfate. The peaks in the d18O-SO4 at 55 and 15 Ma coincide with peaks in the d13C of benthic foraminifera, highlighting the connection between the carbon and sulfur cycles in organic rich sediments. In addition, the increase in the d18O of the ocean (measured in benthic foraminifera) between 34 and 28 Ma coincides with a slight increase in the d18O-SO4. We have modeled the sulfur cycle for both sulfur and oxygen isotopes and will show model results and interpretation over several key intervals over the Cenozoic, including the Mid-Miocene Climate Optimum, the Eocene-Oligocene boundary, and the Paleocene productivity high.

  2. Significance of tourmaline-rich rocks in the north range group of the cuyuna iron range, East-Central Minnesota

    Science.gov (United States)

    Cleland, J.M.; Morey, G.B.; McSwiggen, P.L.

    1996-01-01

    Concentrations of tourmaline in Early Proterozoic metasedirnentary rocks of the Cuyuna iron range, east-central Minnesota, provide a basis for redefinition of the evolutionary history of the area. Manganiferous iron ore forms beds within the Early Proterozoic Trommald Formation, between thick-bedded granular iron-formation having shallow-water depositional attributes and thin-bedded, nongranular iron-formation having deeper water attributes. These manganese-rich units were previously assumed to be sedimentary in origin. However, a revaluation of drill core and mine samples from the Cuyuna North range has identified strata-bound tourmaline and tourmalinite, which has led to a rethinking of genetic models for the geology of the North range. We interpret the tourmaline-rich rocks of the area to be a product of submarine-hydrothermal solutions flowing along and beneath the sedirnent-seawater interface. This model for the depositional environment of the tourmaline is supported by previously reported mineral assemblages within the Trommald Formation that comprise aegirine; barium feldspar; manganese silicates, carbonates, and oxides; and Sr-rich barite veins. In many places, tourmaline-rich metasedimentary rocks and tourmalinites are associated locally with strata-bound sulfide deposits. At those localities, the tourmaline-rich strata are thought to be lateral equivalents of exhalative sulfide zones or genetically related subsea-floor replacements. On the basis of the occurrence of the tourmaline-rich rocks and tourmalinites, and on the associated minerals, we suggest that there is a previously unrecognized potential for sediment-hosted sulfide deposits in the Cuyuna North range.

  3. Biodegradation of BTEX and Other Petroleum Hydrocarbons by Enhanced and Controlled Sulfate Reduction

    Energy Technology Data Exchange (ETDEWEB)

    Song Jin

    2007-07-01

    High concentrations of sulfide in the groundwater at a field site near South Lovedale, OK, were inhibiting sulfate reducing bacteria (SRB) that are known to degrade contaminants including benzene, toluene, ethylbenzene, and m+p-xylenes (BTEX). Microcosms were established in the laboratory using groundwater and sediment collected from the field site and amended with various nutrient, substrate, and inhibitor treatments. All microcosms were initially amended with FeCl{sub 2} to induce FeS precipitation and, thereby, reduce sulfide concentrations. Complete removal of BTEX was observed within 39 days in treatments with various combinations of nutrient and substrate amendments. Results indicate that elevated concentration of sulfide is a limiting factor to BTEX biodegradation at this site, and that treating the groundwater with FeCl{sub 2} is an effective remedy to facilitate and enhance BTEX degradation by the indigenous SRB population. On another site in Moore, OK, studies were conducted to investigate barium in the groundwater. BTEX biodegradation by SRB is suspected to mobilize barium from its precipitants in groundwater. Data from microcosms demonstrated instantaneous precipitation of barium when sulfate was added; however, barium was detected redissolving for a short period and precipitating eventually, when active sulfate reduction was occurring and BTEX was degraded through the process. SEM elemental spectra of the evolved show that sulfur was not present, which may exclude BaSO{sub 4} and BaS as a possible precipitates. The XRD analysis suggests that barium probably ended in BaS complexing with other amorphous species. Results from this study suggest that SRB may be able to use the sulfate from barite (BaSO{sub 4}) as an electron acceptor, resulting in the release of free barium ions (Ba{sup 2+}), and re-precipitate it in BaS, which exposes more toxicity to human and ecological health.

  4. Aeromagnetic expression of rare earth element (REE) deposits in New Mexico, USA

    Science.gov (United States)

    Li, M.

    2016-12-01

    With the development of high-tech devices and the expanding demands in industrial production, rare earth elements(REE) has been playing an increasingly important role in the global economy in the past several decades. Different types of REE serve irreplaceable functions in high-tech industry, as well as for developing sustainable energy and catalysis of manufacturing. Given that the global supply of REE has become strained since 2009 and no known substitutes for REE have been found, exploration for new REE deposits is imperative for economic sustainability. Ten main regions have REE deposits in New Mexico, some of which have not been exploited, while some sites such as Gallinas mountains vein deposits are in early exploration stage. Exploration for the reserves and quantization of mineral compositions of New Mexico's REE depositional districts can have economic benefits in general. In this study, high-resolution airborne magnetic and gravity data were used for studying the Gallinas mountains REE deposit. The purposes of this study are to: (1) characterize specific aeromagnetic anomaly and gravity features from the REE deposits, and (2) apply the characterized features to suggest other areas among the ten REE depositional regions for further exploration. All REE deposits in the study area are found associated with alkaline to alkali-calcic volcanic rocks. A quantitative modeling based on aeromagnetic and gravity anomaly mapping was constructed with an assumption of three units: carbonatites, alkaline volcanic intrusions and REE-concentrated minerals (barite, bastnaesite, etc.). The results of this study show that alkaline deposit is characterized by negative magnetic anomalies and carbonatite is associated with gravity anomaly and vertical gravity gradient high. The area with significantly high aeromagnetic anomaly area and also gravity anomaly high supposed to reflect REE-concentrated minerals such as bastnaesite. For further research, hyperspectral information and

  5. 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.

  6. The Use of Univariate and Multivariate Analyses in the Geochemical Exploration, Ravanj Lead Mine, Delijan, Iran

    Directory of Open Access Journals (Sweden)

    Mostafa Nejadhadad

    2017-11-01

    Full Text Available A geochemical exploration program was applied to recognize the anomalous geochemical haloes at the Ravanj lead mine, Delijan, Iran. Sampling of unweathered rocks were undertaken across rock exposures on a 10 × 10 meter grid (n = 302 as well as the accessible parts of underground mine A (n = 42. First, the threshold values of all elements were determined using the cut-off values used in the exploratory data analysis (EDA method. Then, for further studies, elements with lognormal distributions (Pb, Zn, Ag, As, Cd, Co, Cu, Sb, S, Sr, Th, Ba, Bi, Fe, Ni and Mn were selected. Robustness against outliers is achieved by application of central log ratio transformation to address the closure problems with compositional data prior to principle components analysis (PCA. Results of these analyses show that, in the Ravanj deposit, Pb mineralization is characterized by a Pb-Ba-Ag-Sb ± Zn ± Cd association. The supra-mineralization haloes are characterized by barite and tetrahedrite in a Ba- Th- Ag- Cu- Sb- As- Sr association and sub-mineralization haloes are comprised of pyrite and tetrahedrite, probably reflecting a Fe-Cu-As-Bi-Ni-Co-Mo-Mn association. Using univariate and multivariate geostatistical analyses (e.g., EDA and robust PCA, four anomalies were detected and mapped in Block A of the Ravanj deposit. Anomalies 1 and 2 are around the ancient orebodies. Anomaly 3 is located in a thin bedded limestone-shale intercalation unit that does not show significant mineralization. Drilling of the fourth anomaly suggested a low grade, non-economic Pb mineralization.

  7. Pigment analyses of a portrait and paint box of Turkish artist Feyhaman Duran (1886-1970): The EDXRF, FT-IR and micro Raman spectroscopic studies

    Science.gov (United States)

    Akyuz, Sevim; Akyuz, Tanil; Emre, Gulder; Gulec, Ahmet; Basaran, Sait

    2012-04-01

    The samples obtained from nine different places of Ataturk portrait (oil on canvas, 86 cm × 136 cm) by Feyhaman Duran (1886-1970), one of the famous Turkish painters of the 20th century, together with five pigment samples (two different white, two different yellow and blue), obtained as powders from artist's paint box, were analysed by EDXRF, FT-IR and micro-Raman spectroscopic methods, in order to characterise the pigments used by the artist. Informative Raman signals were not obtained from most of the samples of the portrait, due to huge fluorescence caused by the presence of impurities and organic materials in the samples, however the Raman spectrum of the sample from skin coloured part of the portrait and the pigment samples obtained from the paint box of the artist were found to be very informative to shed light on the determination of the pigments used. Analysis revealed the presences of chrome yellow (PbCrO4), strontium yellow (SrCrO4) and Cadmium yellow (CdS) as yellow, chromium oxides (Cr2O3 and Cr2O3·2H2O) as green, natural red ochre as red, brown ochre as brown and ivory black or bone black (C + Ca3(PO4)2) and manganese oxides (Mn2O3 and MnO2) as black pigments, in the composition of the Ataturk portrait. Lead white (2PbCO3·Pb(OH)2), calcite (CaCO3), barite (BaSO4), zinc white (ZnO) and titanium white (TiO2) were used as extenders to lighten the colours and/or as for ground level painting. Powder pigment samples, obtained from the paint box of artist, were found to be mixed pigments rather than pure ones.

  8. Manganese Ores from South Sulawesi: Their Potential Uses as Raw Materials for Metallurgical Industry

    Directory of Open Access Journals (Sweden)

    Sufriadin Sufriadin

    2017-03-01

    Full Text Available Characterization of manganese ores from Barru and Bone regencies of South Sulawesi has been conducted with the aim at clarification of their mineralogical and chemical composition for their potential uses as the raw materials for metallurgical industry. Mineralogical properties of the ores analyzed by means of optical microscopy and X-ray diffractometry (XRD show that samples from Barru consist mainly of rhodochrosite (MnCO3 with less cryptomelane, groutite, bixbyite, and todorokite. Goethite, calcite and small amount of quartz present as impurities. Manganese ore samples from Bone are predominantly composed of pyrolusite (MnO2 with subordinate ramsdellite and hollandite. Barite, quartz, hematite and clay are present as gangue minerals. Chemical compositions determined by using XRF method revealed that Barru samples contain higher in MnO (average is 40.07 wt% than the Bone samples (average is 34.36 wt%. Similarly, Fe2O3 and CaO are also higher in Barru than those of the Bone samples. In contrast, concentrations of SiO2 and total alkali (K2O + Na2O are lower in the Barru samples. The average P2O5 content of samples in both areas is low (<0.2 wt%. Relatively higher grade of Fe2O3 in the Barru ore implies that it has potential application for ferromanganese production; whereas the elevated SiO2 content of the Bone ore is a good indication for silicomanganese manufacture. However, both ores may not favorable to be directly used as raw materials in metallurgical uses. Prior to be used, the ores should be treated by applying physical beneficiation in order to reduce deleterious elements.

  9. Optimization of radiation protection in gamma radiography facilities

    International Nuclear Information System (INIS)

    Antonio Filho, Joao

    1999-01-01

    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 ( 192 Ir and 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)

  10. Origins of and countermeasures for the abnormal pressures in well production of the Ojarly gas field in the Right Bank of the Amu-Darya River, Turkmenistan

    Directory of Open Access Journals (Sweden)

    Peijun Zhang

    2017-01-01

    Full Text Available The Ojarly gas field, the major supplier of the Project Phase Ⅱ of the Right Bank of the Amu Darya River, is just small but valuable like a golden bean, although it has good reservoir properties and a high gas production capacity, the occurrence of continuous sharp decline of pressure in the well production shows a great difference from the previous well test program. In view of this, an integrated analysis method was established for the whole gas well production process to discover the three main reasons causing the abnormal well pressure. First, the formation energy and pressure dropped so fast that the wellhead pressure also fell over the period. Second, there was abnormal fluids pressure drop in the wellbore tube and throttling effect might occur in the production tube, so the pressure drop became abnormally increased. Third, due to the abnormally-increasing gas-yield pressure drop and unusually-decreasing gas productivity, the wellhead oil pressure dropped significantly. Also, through dynamic monitoring and in-depth analysis, it is also considered that due to the high density of drilling fluids and well-developed pores and caverns in the reservoirs, more and more barites separated from the fluids would be settled down covering the pay zones, so both the gas-generating capacity and production pressure significantly decreased. On this basis, some technical countermeasures were taken such as re-stimulation of reservoirs, removal of gas-producing channels, increase of seepage capacity, etc. In addition, by use of sand-flushing and acidizing, both the comprehensive skin factor and the production pressure drop were reduced to improve the well gas production capacity and maintain high productivity effectively. This study provides a technical support for long-term sustainable development and production of this gas field.

  11. The Elk Creek Carbonatite, Southeast Nebraska-An Overview

    International Nuclear Information System (INIS)

    Carlson, M. P.; Treves, S. B.

    2005-01-01

    A framework geophysical program in southeastern Nebraska during 1970 identified a near-circular feature having gravity relief of about 8 mgal and a magnetic anomaly of about 800 gammas. Analysis of the geophysical data provided a model of a cylindrical mass of indefinite length with a radius of 5500 ft (1676 m) and beveled at the basement surface at about 600 ft (183 m). At the approximate depth at which Precambrian rocks were expected, the initial test hole (2-B-71) encountered an iron-rich weathered zone overlying carbonate-rich rock. The carbonate rocks consist essentially of dolomite, calcite, and ankerite and lesser amounts of hematite, chlorite, phlogopite, barite, serpentine, pyrochlore, and quartz and contain barium, strontium, and rare earths. Total REE, P2O5, and 87Sr/86Sr ratios confirm the carbonatite identification. Texturally, the rocks range from fragmental to contorted to massive. Associated with the carbonatite are lesser amounts of basalt, lamprophyre, and syenite. Additional exploratory drilling has provided about 80,000 ft (24,384 m) of rock record and has penetrated about 3400 ft (1038 m) of carbonatite. The carbonatite is overlain by marine sediments of Pennsylvanian (Missourian) age. The surrounding Precambrian basement rocks are low-to medium-grade metamorphic gneiss and schist of island arc origin and granitic plutons. The Elk Creek carbonatite is located near the boundary between the Penokean orogen created at about 1.84 Ga (billion years) and the Dawes terrane (1.78 Ga) of the Central Plains orogen. This boundary strongly influenced the geometry of both the Midcontinent Rift System (1.1 Ga) and the Nemaha uplift (0.3 Ga). It is assumed that the emplacement of the Elk Creek carbonatite (0.5 Ga) was influenced similarly by the pre-existing tectonic sutures

  12. Characterisation of heavy metal-bearing phases in stream sediments of the Meza River Valley, Slovenia, by means of SEM/EDS analysis

    International Nuclear Information System (INIS)

    Miler, M; Gosar, M

    2010-01-01

    Stream sediment reflects the rock structure of the catchment area, its geochemical characteristics and possible recent contamination upstream of the sampling point and thus, it is most frequently used in geochemical researches of heavy metal pollution. Stream sediment samples were collected along the Mez'a River and its tributaries and the Drava River, located in the NNE part of Slovenia. Previous geochemical studies have shown that these sediments are heavily polluted with heavy metals as a consequence of past mining of Pb-Zn ore and steelworks activities. Conventional geochemical analyses (ICP-MS, AAS, etc.) provided limited information on mineralogy, morphology and sources of heavy metal-bearing phases therefore SEM/EDS was utilized. Several problems were confronted with during EDS analysis, which are related to identification and quantification of light elements, identification of elements due to peak overlaps and quantification of spectra from unpolished samples. These problems were successfully dealt with. SEM/EDS enabled successful identification of heavy metal-bearing phases in stream sediments. Ore mineral phases, such as cerussite, sphalerite, smithsonite and galena, different heavy metal-bearing Fe-alloys, Fe-oxides and spherical particles and common rock-forming and accessory mineral phases, such as barite, rutile, ilmenite, zircon and monazite, were identified using solely SEM/EDS. These results were used for subsequent geochemical interpretation and source apportionment of heavy metals, according to associations of different heavy metal-bearing phases. Heavy metal-bearing phases were arranged by their source and genesis into three groups, denoted as geogenic/technogenic, technogenic and geogenic.

  13. Summary of the mineral- and energy-resource endowment, BLM roswell resource area, east-central New Mexico

    Science.gov (United States)

    Bartsch-Winkler, S.; Sutphin, D.M.; Ball, M.M.; Korzeb, S.L.; Kness, R.F.; Dutchover, J.T.

    1993-01-01

    In this summary of two comprehensive resource reports produced by the U.S. Bureau of Mines and the U.S. Geological Survey for the U.S. Bureau of Land Management, we discuss the mineral- and energyresource endowment of the 14-millon-acre Roswell Resource Area, New Mexico, managed by the Bureau of Land Management. The Bureau and Survey reports result from separate studies that are compilations of published and unpublished data and integrate new findings on the geology, geochemistry, geophysics, mineral, industrial, and energy commodities, and resources for the seven-county area. The reports have been used by the Bureau of Land Management in preparation of the Roswell Resource Area Resource Management Plan, and will have future use in nationwide mineral- and energy-resource inventories and assessments, as reference and training documents, and as public-information tools. In the Roswell Resource Area, many metals, industrial mineral commodities, and energy resources are being, or have been, produced or prospected. These include metals and high-technology materials, such as copper, gold, silver, thorium, uranium and/or vanadium, rare-earth element minerals, iron, manganese, tungsten, lead, zinc, and molybdenum; industrial mineral resources, including barite, limestone/dolomite, caliche, clay, fluorspar, gypsum, scoria, aggregate, and sand and gravel; and fuels and associated resources, such as oil, gas, tar sand and heavy oil, coal, and gases associated with hydrocarbons. Other commodities that have yet to be identified in economic concentrations include potash, halite, polyhalite, anhydrite, sulfur, feldspar, building stone and decorative rock, brines, various gases associated with oil and gas exploration, and carbon dioxide. ?? 1993 Oxford University Press.

  14. Evidence for an Early Cretaceous mineralizing event above the basement/sediment unconformity in the intracratonic Paris Basin: paragenetic sequence and Sm-Nd dating of the world-class Pierre-Perthuis stratabound fluorite deposit

    Science.gov (United States)

    Gigoux, Morgane; Delpech, Guillaume; Guerrot, Catherine; Pagel, Maurice; Augé, Thierry; Négrel, Philippe; Brigaud, Benjamin

    2015-04-01

    World-class stratabound fluorite deposits are spatially associated with the basement/sediment unconformity of the intracratonic Paris Basin and the Morvan Massif in Burgundy (France). The reserves are estimated to be about 5.5 Mt of fluorite within six fluorite deposits. In this study, we aim to determine the age of the major fluorite mineralization event of the Pierre-Perthuis deposit (1.4 Mt fluorite) by a combined study of the paragenetic mineral sequence and Sm-Nd dating on fluorite crystals. Fluorite occurs as isolated cubes or filling geodes in a Triassic, silicified, dolomitic formation. Three fluorite stages associated with sphalerite, pyrite, galena, barite, and quartz have been distinguished using optical, cathodoluminescence, and scanning electron microscopes. Seven crystals of the geodic fluorite stage were analyzed for their rare earth element (REE) contents and their 147Sm/144Nd and 143Nd/144Nd isotopic compositions. The normalized REE distribution displays homogeneous bell-shaped patterns for all the geodic fluorite samples with a Mid-REE enrichment over the Light-REE and Heavy-REE. The 147Sm/144Nd varies from 0.3108 to 0.5504 and the 143Nd/144Nd from 0.512313 to 0.512518. A six-point Sm-Nd isochron defines an age of 130 ± 15 Ma (initial 143Nd/144Nd = 0.512054, MSWD = 0.21). This Sm-Nd isochron provides the first age for the stratabound fluorite sediment-hosted deposit, related to an unconformity in the Paris Basin, and highlights a major Early Cretaceous fluid circulation event mainly above the basement/sediment unconformity during a flexural deformation of the Paris Basin, which relates to the rifting of the Bay of Biscay and the formation of the Ligurian Sea in the Western Europe domain.

  15. The Malines Cambrian carbonate-shale-hosted Pb-Zn deposit, France: Thermometric and isotopic (H, O) evidence for pulsating hydrothermal mineralization

    Science.gov (United States)

    Charef, A.; Sheppard, S. M. F.

    1988-04-01

    Microthermometric, stable isotope (D/H, 18O/16O), and Raman spectroscopic data are given for four different mineralization events located beneath a Triassic unconformity. These events include the Pb-Zn-bearing KII mineralization which fills geodes and fractures in the main karstic mineralization KI and the F mineralization which fills fractures in the Cambrian carbonates and shales. Post-KI, pre-KII, and F mineralization fluids were hot (˜150°C), moderately saline (˜10 equiv. wt% NaCl), and precipitated red dolomite. Subsequently, equally hot but more saline (˜20 equiv. wt% NaCl) fluids deposited white dolomite and then sphalerite of the F mineralization; they were followed by another generation of dolomite at about 70°C from fluids with about 15 equiv. wt% NaCl and, even later, barites (˜165°C, 10 equiv. wt% NaCl). Variation in the homogenization temperature with salinity for the different dolomite generations suggests that the hot saline fluids were repeatedly diluted by a cooler, less-saline fluid. The fluids are interpreted to be of formation-water origin having possibly developed in the deep levels of the Rhone basins to the southeast, which was at least 3 km thick at the time of mineralization (post-Hetangian). The inferred metal-bearing hot brines were probably episodically expulsed during the dewatering of the basin, depositing their mineralization in the more permeable fault and karstic zones associated with the uplift of the St. Bresson horst. Cold surface waters probably invaded the mineralized zones between the pulses of hydrothermal solutions. This hydrothermal model with the introduction of sulfides can account for the precipitation and dissolution textures associated with the hydrothermal mineralizations.

  16. The Influence of Used Construction Material and Its Thickness on the Neutron Dose Rate Around the Linear Accelerator - Experimental Results

    International Nuclear Information System (INIS)

    Krpan, I; Miklavcic, I.; Poje, M.; Radolic, V.; Vukovic, B.; Zivkovic, A.; Faj, D.; Ivkovic, A.

    2013-01-01

    Since linear accelerators for medical radiotherapy do not have active radioactive sources it makes them adequate from the radioprotection point of view. However, when operating at the energy higher than 10 MeV, they can become a source of unwanted neutron radiation in the giant dipole resonance reaction between the photon beam and the accelerator head material. Neutrons created in this reaction are almost isotropic in direction with an energy range between 700 keV and 1 MeV. During the accelerator installation and different phases of the construction work around the accelerator, a neutron dose rate at several important locations was investigated. Both passive (solid state nuclear track etched detectors - CR 39 and/or LR-115 with the 10B foil) and active detectors (Thermo Biorem FHT 752) were used. A higher photon dose rate was measured around the accelerator facility. An effective photon dose reduction was achieved using steel plates. However, this was the secondary source of neutrons in the reaction between the photons and steel plates, since higher values were measured. Neutron reduction was done by additional layers of barite concrete. A very conservative assessment of the effective dose was done for the medical personnel inside the control room. At the accelerator extreme operating regime (fixed accelerator direction - gantry angle, highest energy possible used), the neutron dose rate in the control room of 12 μSv/h was measured. Knowing the number of working days and number of patients per technician (per day), an exposure to the neutron dose of 1,1 mSv per year was calculated.(author)

  17. Mineralogical compositions of fault rocks from surface ruptures of Wenchuan earthquake and implication of mineral transformation during the seismic cycle along Yingxiu-Beichuan fault, Sichuan Province, China

    Science.gov (United States)

    Dang, Jiaxiang; Zhou, Yongsheng; He, Changrong; Ma, Shengli

    2017-11-01

    There are two co-seismic bedrock surface ruptures from the Mw 7.9 Wenchuan earthquake in the northern and central parts of the Beichuan-Yingxiu fault, Sichuan Province, southwest China. In this study, we report on the macrostructure of the fault rocks and results from X-ray powder diffraction analysis of minerals from rocks in the fault zone. The most recent fault gouge (the gouge produced by the most recent co-seismic fault movement) in all the studied outcrops is dark or grayish-black, totally unconsolidated and ultrafine-grained. Older fault gouges in the same outcrops are grayish or yellowish and weakly consolidated. X-ray powder diffraction analysis results show that mineral assemblages in both the old fault gouge and the new fault gouge are more complicated than the mineral assemblages in the bedrock as the fault gouge is rich in clay minerals. The fault gouge inherited its major rock-forming minerals from the parent rocks, but the clay minerals in the fault gouge were generated in the fault zone and are therefore authigenic and synkinematic. In profiles across the fault, clay mineral abundances increase as one traverses from the bedrock to the breccia to the old gouge and from the old gouge to the new gouge. Quartz and illite are found in all collected gouge samples. The dominant clay minerals in the new fault gouge are illite and smectite along the northern part of the surface rupture and illite/smectite mixed-layer clay in the middle part of the rupture. Illite/smectite mixed-layer clay found in the middle part of the rupture indicates that fault slip was accompanied by K-rich fluid circulation. The existence of siderite, anhydrite, and barite in the northern part of the rupture suggests that fault slip at this locality was accompanied by acidic fluids containing ions of Fe, Ca, and Ba.

  18. Hydrothermal karst and associated breccias in Neoproterozoic limestone from the Barker-Villa Cacique area (Tandilia belt), Argentina

    Science.gov (United States)

    Dristas, Jorge A.; Martínez, Juan C.; van den Kerkhof, Alfons M.; Massonne, Hans-Joachim; Theye, Thomas; Frisicale, María C.; Gregori, Daniel A.

    2017-07-01

    In the Barker-Villa Cacique area (Tandilia belt), remarkable megabreccias, limestone breccias and phosphate-bearing breccias hosted in black limestone and along the contact with the upper section of the sedimentary succession are exposed. These rocks are the result of extensive hydrothermal alteration of the original micritic limestone and other fine-grained clastic sediments. Typical alteration minerals are sericite, chlorite, interstratified chlorite/K-white mica, kaolinite, dickite, pyrite, chalcopyrite, goethite, quartz, calcite, Fe-calcite, dolomite, ankerite, fluor-apatite, barite and aluminium-phosphate-sulfate (APS) minerals. Quartz and calcite cements from hydraulic breccias in the limestone contain low-salinity aqueous fluid inclusions. Corresponding homogenization temperatures display 200-220 °C and 110-140 °C in hydrothermal quartz, and 130-150 °C in late calcite cement. Carbon and oxygen stable isotope analyses of carbonates from the Loma Negra quarry (LNQ) support the major role of hydrothermal activity. A significant difference was found between δ18Ocar values from unaltered micritic limestone (ca. 23.8‰ SMOW) and secondary calcite (ca. 18.5‰ SMOW). The lower δ18Ocar values are interpreted as a result of calcite precipitation from hot hydrothermal fluids. At a late stage, the hydrothermal fluid containing H2S mixed with descending and oxidizing meteoric waters. Circulation of the ensuing acid fluids resulted in the partly dissolution and collapse brecciation of the Loma Negra Formation. The hydrothermal stage can be tentatively dated ca. 590-620 Ma corresponding to the Brasiliano orogeny.

  19. 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)

    Cruz, Rosana Petinatti da

    2002-01-01

    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)

  20. Procedures for the determination of stable elements in construction materials from the nuclear reactors at Risoe National Laboratory

    International Nuclear Information System (INIS)

    Oestergaard, L.F.

    2006-03-01

    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 Modblock TM digesting unit in a two step procedure involving 40% HF followed by 32% HNO 3 . The heavy barite concrete is first treated as the concrete samples but a large residue of poorly soluble sulphates (mainly BaSO 4 ) is left. The residue is fused with NaOH/Na 2 CO 3 at 575 deg. C and after some work up the product from the fusion is dissolved in dilute HNO 3 . 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

  1. Generic models of deep formation water calculated with PHREEQC using the "gebo"-database

    Science.gov (United States)

    Bozau, E.; van Berk, W.

    2012-04-01

    To identify processes during the use of formation waters for geothermal energy production an extended hydrogeochemical thermodynamic database (named "gebo"-database) for the well known and commonly used software PHREEQC has been developed by collecting and inserting data from literature. The following solution master species: Fe(+2), Fe(+3), S(-2), C(-4), Si, Zn, Pb, and Al are added to the database "pitzer.dat" which is provided with the code PHREEQC. According to the solution master species the necessary solution species and phases (solid phases and gases) are implemented. Furthermore, temperature and pressure adaptations of the mass action law constants, Pitzer parameters for the calculation of activity coefficients in waters of high ionic strength and solubility equilibria among gaseous and aqueous species of CO2, methane, and hydrogen sulphide are implemented into the "gebo"-database. Combined with the "gebo"-database the code PHREEQC can be used to test the behaviour of highly concentrated solutions (e.g. formation waters, brines). Chemical changes caused by temperature and pressure gradients as well as the exposure of the water to the atmosphere and technical equipments can be modelled. To check the plausibility of additional and adapted data/parameters experimental solubility data from literature (e.g. sulfate and carbonate minerals) are compared to modelled mineral solubilities at elevated levels of Total Dissolved Solids (TDS), temperature, and pressure. First results show good matches between modelled and experimental mineral solubility for barite, celestite, anhydrite, and calcite in high TDS waters indicating the plausibility of additional and adapted data and parameters. Furthermore, chemical parameters of geothermal wells in the North German Basin are used to test the "gebo"-database. The analysed water composition (starting with the main cations and anions) is calculated by thermodynamic equilibrium reactions of pure water with the minerals found in

  2. Geochemistry of Monazite within Carbonatite Related REE Deposits

    Directory of Open Access Journals (Sweden)

    Wei Chen

    2017-09-01

    Full Text Available Approximately >50% of global rare earth element (REE resources are hosted by carbonatite related deposits, of which monazite is one of the most important REE minerals. Monazite dominates more than 30 carbonatite-related REE deposits around the world, including currently exploited mineralization at Bayan Obo and Mount Weld. These deposits are widely distributed across all continents, except Antarctica. Though rare, monazite occurs as the primary mineral in carbonatite, and mostly presents as a secondary mineral that has a strong association with apatite. It can partially or completely replace thin or thick overgrowth apatite, depending on the availability of REE. Other mineral phases that usually crystallize together with monazite include barite, fluorite, xenotime, sulfide, and quartz in a carbonate matrix (e.g., dolomite, calcite. This review of monazite geochemistry within carbonatite-related REE deposits aims to provide information regarding the use of monazite as a geochemical indicator to track the formation history of the REE deposits and also supply additional information for the beneficiation of monazite. The chemical compositions of monazite are highly variable, and Ce-monazite is the dominant solid solution in carbonatite related deposits. Most monazite displays steep fractionation from La to Lu, absent of either Eu or Ce anomalies in the chondrite normalized REE plot. The other significant components are huttonite and cheratite. Some rare sulfur-bearing monazite is also identified with an SO3 content up to 4 wt %. A 147Sm/144Nd ratio with an average ~0.071 for monazite within carbonatite-related ores is similar to that of their host rocks (~0.065, and is the lowest among all types of REE deposits. Sm/Nd variation of monazite from a single complex reflects the differentiation stage of magma, which decreases from early to late. Based on the differences of Nd and Sr abundances, Nd isotopic composition for monazite can be used to track

  3. BaSO4:Eu as an energy independent thermoluminescent radiation dosimeter for gamma rays and C6+ ion beam

    Science.gov (United States)

    Sharma, Kanika; Bahl, Shaila; Singh, Birendra; Kumar, Pratik; Lochab, S. P.; Pandey, Anant

    2018-04-01

    BaSO4:Eu nanophosphor is delicately optimized by varying the concentration of the impurity element and compared to the commercially available thermoluminescent dosimeter (TLD) LiF:Mg,Ti (TLD-100) and by extension also to CaSO4:Dy (TLD-900) so as to achieve its maximum thermoluminescence (TL) sensitivity. Further, the energy dependence property of this barite nanophosphor is also explored at length by exposing the phosphor with 1.25 MeV of Co-60, 0.662 MeV of Cs-137, 85 MeV and 65 MeV of Carbon ion beams. Various batches of the phosphor at hand (with impurity concentrations being 0.05, 0.10, 0.20, 0.50 and 1.00 mol%) are prepared by the chemical co-precipitation method out of which BaSO4:Eu with 0.20 mol% Eu exhibits the maximum TL sensitivity. Further, the optimized nanophosphor exhibits a whopping 28.52 times higher TL sensitivity than the commercially available TLD-100 and 1.426 times higher sensitivity than TLD-900, a noteworthy linear response curve for an exceptionally wide range of doses i.e. 10 Gy to 2 kGy and a simple glow curve structure. Furthermore, when the newly optimized nanophosphor is exposed with two different energies of gamma radiations, namely 1.25 MeV of Co-60 (dose range- 10-300 Gy) and 0.662 MeV of Cs-137 (dose range- 1-300 Gy), it is observed that the shape and structure of the glow curves remain remarkably similar for different energies of radiation while the TL response curve shows little to no variation. When exposed to different energies of carbon ion beam BaSO4:Eu displays energy independence at lower doses i.e. from 6.059 to 14.497 kGy. Finally, even though energy independence is lost at higher doses, the material shows high sensitivity to higher energy (85 MeV) of carbon beam compared to the lower energy (65 MeV of C6+) and saturation is apparent only after 121.199 kGy. Therefore the present nanophosphor displays potential as an energy independent TLD.

  4. Co-precipitation of radium with barium and strontium sulfate and its impact on the fate of radium during treatment of produced water from unconventional gas extraction.

    Science.gov (United States)

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

    2014-04-15

    Radium occurs in flowback and produced waters from hydraulic fracturing for unconventional gas extraction along with high concentrations of barium and strontium and elevated salinity. Radium is often removed from this wastewater by co-precipitation with barium or other alkaline earth metals. The distribution equation for Ra in the precipitate is derived from the equilibrium of the lattice replacement reaction (inclusion) between the Ra(2+) ion and the carrier ions (e.g., Ba(2+) and Sr(2+)) in aqueous and solid phases and is often applied to describe the fate of radium in these systems. Although the theoretical distribution coefficient for Ra-SrSO4 (Kd = 237) is much larger than that for Ra-BaSO4 (Kd = 1.54), previous studies have focused on Ra-BaSO4 equilibrium. This study evaluates the equilibria and kinetics of co-precipitation reactions in Ra-Ba-SO4 and Ra-Sr-SO4 binary systems and the Ra-Ba-Sr-SO4 ternary system under varying ionic strength (IS) conditions that are representative of brines generated during unconventional gas extraction. Results show that radium removal generally follows the theoretical distribution law in binary systems and is enhanced in the Ra-Ba-SO4 system and restrained in the Ra-Sr-SO4 system by high IS. However, the experimental distribution coefficient (Kd') varies widely and cannot be accurately described by the distribution equation, which depends on IS, kinetics of carrier precipitation and does not account for radium removal by adsorption. Radium removal in the ternary system is controlled by the co-precipitation of Ra-Ba-SO4, which is attributed to the rapid BaSO4 nucleation rate and closer ionic radii of Ra(2+) with Ba(2+) than with Sr(2+). Carrier (i.e., barite) recycling during water treatment was shown to be effective in enhancing radium removal even after co-precipitation was completed. Calculations based on experimental results show that Ra levels in the precipitate generated in centralized waste treatment facilities far

  5. 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)

    Kalmykov, St.; Khasanova, A.; Kriventsov, V.; Teterin, Y.; Novikov, A.

    2007-01-01

    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 ≅ MnO 2 > 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 MnO 2 while other phases did not sorb actinides. In order to determine actinide speciation bound to HFO colloids XPS and An L 3 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

  6. 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

  7. Solving geological and historical puzzles with advanced gemologic techniques: The Franco Dávila (1772) precious opal case

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Guinea, J.; Gonzalez-Alcalde, J.; Furio, M.; Jorge, A.; Garrido, F.

    2016-07-01

    The large precious opal weighting 33 grams fitted in a silver jewel and exposed to visitors at the Museo Nacional de Ciencias Naturales (MNCN) is well documented in: (i) its own mounting (1772), (ii) at the 775 document of the Archive of the MNCN and (iii) the 395 specimen described in the of Pedro Franco Dávila catalogue. The X-ray diffractogram (XRD) performed onto the opal block is very similar to other opals of volcanic origin containing varied amounts of cristobalite, tridymite and amorphous silica. The Raman spectrum shows a band peaked at 242, 343 and 416 cm−1 associated with O-Si-O stretching groups; other spectral band peaked at 780 and 819 cm−1 corresponding to vibration of symmetrical O-Si-O rings of 3 and 4 link members, plus other minor bands. The Raman spectrum is also very similar to those observed in Mexican opals of volcanic origin containing an spectral band of stretching nodes ν1 (OH) at 3233, 3393, 3511, 3628 cm−1 related to OH groups with hydrogen bonds of isolated silanol groups. The interferometric confocal dual microscope 3D (MCI3D), which is a nondestructive facility of high resolution and LED technology reveals the geometry of graver tools on the silver jewel and the computed tomography X-ray highlights the opal cutting as a squared princess type and silver chloride infillings of a crack probably caused by a shock on a corner. Under the scanning electron microscope we observed barite, sealed veins of silica rich in Mn and opal with high contents of Al and K which, along with the historical data, the piece can be attributed to the historical site of opals hosted in Slovakia andesite rocks, this data explains the optical light behavior in the cabochon. The silver jewel has large amounts of Hg and AgCl indicating amalgam method. In addition the natural AgS2 phases probably come from Nueva España (year 1772) in full production of silver in such time. The association of new analytical non-destructive techniques combines the

  8. 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

  9. Mineralogy and geochemistry of triassic carbonatites in the Matcha alkaline intrusive complex (Turkestan-Alai Ridge, Kyrgyz Southern Tien Shan), SW Central Asian orogenic belt

    Science.gov (United States)

    Vrublevskii, V. V.; Morova, A. A.; Bukharova, O. V.; Konovalenko, S. I.

    2018-03-01

    Postorogenic intrusions of essexites and alkaline and nepheline syenites in the Turkestan-Alai segment of the Kyrgyz Southern Tien Shan coexist with dikes and veins of carbonatites dated at ∼220 Ma by the Ar-Ar and Rb-Sr age methods. They are mainly composed of calcite and dolomite (60-85%), as well as sodic amphibole, phlogopite, clinopyroxene, microcline, albite, apatite, and magnetite, with accessory niobate, ilmenite, Nb-rutile, titanite, zircon, baddeleyite, monazite-(Ce), barite, and sulfides. The rocks share mineralogical and geochemical similarity with carbonatites that originated by liquid immiscibility at high temperatures above 500 °C. Alkaline silicate and salt-carbonate melts are derived from sources with mainly negative bulk εNd(t) ∼ from -11 to 0 and high initial 87Sr/86Sr ratios (∼0.7061-0.7095) which may be due to mixing of PREMA and EM-type mantle material. Pb isotopic ratios in accessory pyrrhotite (206Pb/204Pb = 18.38; 207Pb/204Pb = 15.64; 208Pb/204Pb = 38.41) exhibit an EM2 trend. The intrusions bear signatures of significant crustal contamination as a result of magma genesis by syntexis and hybridism. Concordant isotope composition changes of δ13C (-6.5 to -1.9‰), δ18O (9.2-23‰), δD (-58 to -41‰), and δ34S (12.6-12.8‰) in minerals and rocks indicate inputs of crustal material at the stage of melting and effect of hot fluids released during dehydration of metamorphosed oceanic basalts or sediments. The observed HFSE patterns of the oldest alkaline gabbro may be due to interaction of the primary mafic magma with IAB-type material. The isotope similarity of alkaline rocks with spatially proximal basalts of the Tarim large igneous province does not contradict the evolution of the Turkestan-Alai Triassic magmatism as the "last echo" of the Tarim mantle plume.

  10. Chemical characterization, nano-particle mineralogy and particle size distribution of basalt dust wastes

    Energy Technology Data Exchange (ETDEWEB)

    Dalmora, Adilson C. [Laboratory of Environmental Researches and Nanotechnology Development, Centro Universitário La Salle, Mestrado em Avaliação de Impactos Ambientais em Mineração. Victor Barreto, 2288 Centro 92010-000, Canoas, RS (Brazil); Institute for Environmental Assessment and Water Studies (IDÆA), Spanish National Research Council (CSIC), C/Jordi Girona 18-26, 08034 Barcelona (Spain); Ramos, Claudete G.; Oliveira, Marcos L.S. [Laboratory of Environmental Researches and Nanotechnology Development, Centro Universitário La Salle, Mestrado em Avaliação de Impactos Ambientais em Mineração. Victor Barreto, 2288 Centro 92010-000, Canoas, RS (Brazil); Teixeira, Elba C. [Fundação Estadual de Proteção Ambiental Henrique Luis Roessler, Porto Alegre, RS (Brazil); Kautzmann, Rubens M.; Taffarel, Silvio R. [Laboratory of Environmental Researches and Nanotechnology Development, Centro Universitário La Salle, Mestrado em Avaliação de Impactos Ambientais em Mineração. Victor Barreto, 2288 Centro 92010-000, Canoas, RS (Brazil); Brum, Irineu A.S. de [Universidade Federal do Rio Grande do Sul, Escola de Engenharia, Departamento de Metalurgia, Centro de Tecnologia, Av. Bento Gonçalves, 9500. Bairro Agronomia. CEP: 91501-970 Porto Alegre, RS (Brazil); and others

    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 SiO{sub 2}, Al{sub 2}O{sub 3}, and Fe{sub 2}O{sub 3,} 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

  11. Atmospheric dust deposition on soils around an abandoned fluorite mine (Hammam Zriba, NE Tunisia).

    Science.gov (United States)

    Djebbi, Chaima; Chaabani, Fredj; Font, Oriol; Queralt, Ignasi; Querol, Xavier

    2017-10-01

    The present study focuses on the eolian dispersion and dust deposition, of major and trace elements in soils in a semi-arid climate, around an old fluorite (CaF 2 ) and barite (BaSO 4 ) mine, located in Hammam Zriba in Northern Tunisia. Ore deposits from this site contain a high amount of metal sulphides constituting heavy metal pollution in the surrounding environment. Samples of waste from the surface of mine tailings and agricultural topsoil samples in the vicinity of the mine were collected. The soil samples and a control sample from unpolluted area, were taken in the direction of prevailing northwest and west winds. Chemical analysis of these solids was performed using both X-ray fluorescence and X-ray diffraction. To determine the transfer from mine wastes to the soils, soluble fraction was performed by inductively coupled plasma and ionic chromatography. The fine grained size fraction of the un-restored tailings, still contained significant levels of barium, strontium, sulphur, fluorine, zinc and lead with mean percentages (wt%) of 30 (calculated as BaO), 13 (as SrO), 10 (as SO 3 ), 4 (F), 2 (Zn) and 1.2 (Pb). Also, high concentrations of cadmium (Cd), arsenic (As) and mercury (Hg) were found with an averages of 36, 24 and 1.2mgkg -1 , respectively. As a result of the eolian erosion of the tailings and their subsequent wind transport, the concentrations of Ba, Sr, S, F, Zn and Pb were extremely high in the soils near to the tailings dumps, with 5%, 4%, 7%, 1%, 0.8% and 0.2%, respectively. Concentration of major pollutants decreases with distance, but they were high even in the farthest samples. Same spatial distribution was observed for Cd, As and Hg. While, the other elements follow different spatial patterns. The leaching test revealed that most elements in the mining wastes, except for the anions, had a low solubility despite their high bulk concentrations. According the 2003/33/CE Decision Threshold, some of these tailings samples were considered as

  12. The carbonaceous phyllite rock-hosted Pedra Verde copper mine, Borborema Province, Brazil: Stable isotope constraints, structural controls and metallogenic evolution

    Science.gov (United States)

    da Silva Nogueira de Matos, José Henrique; Saraiva dos Santos, Ticiano José; Virgínia Soares Monteiro, Lena

    2017-12-01

    The Pedra Verde Copper Mine is located in the Viçosa do Ceará municipality, State of Ceará, NE Brazil. The copper mineralization is hosted by the Pedra Verde Phyllite, which is a carbonaceous chlorite-calcite phyllite with subordinate biotite. It belongs to the Neoproterozoic Martinópole Group of the Médio Coreaú Domain, Borborema Province. The Pedra Verde deposit is stratabound and its ore zoning is conspicuous, according to the following sequence, from bottom to top: marcasite/pyrite, native silver, chalcopyrite, bornite, chalcocite, native copper and hematite. Barite and carbonaceous material are reported in ore zones. Zoning reflects the ore formation within a redox boundary developed due to the interaction between oxidized copper- and sulfate-bearing fluids and the reduced phyllite. Structural control on mineralization is evidenced by the association of the ore minerals with veins, hinge folds, shadow pressures, and mylonitic foliation. It was mainly exercised by a dextral transcurrent shear zone developed during the third deformational stage identified in the Médio Coreaú Domain between 590 Ma and 570 Ma. This points to the importance of epigenetic, post-metamorphic deformational events for ore formation. Oxygen isotopic composition (δ18OH2O = 8.94 to 11.28‰, at 250 to 300 °C) estimated for the hydrothermal fluids in equilibrium with calcite indicates metamorphic or evolved meteoric isotopic signatures. The δ13CPDB values (-2.60 to -9.25‰) obtained for hydrothermal calcite indicate mixing of carbon sources derived from marine carbonate rocks and carbonaceous material. The δ34SCDT values (14.88 to 36.91‰) of sulfides suggest evaporites as sulfate sources or a closed system in relation to SO42- availability to form H2S. Carbonaceous matter had a key role in thermochemical sulfate processes and sulfide precipitation. The Pedra Verde Copper Mine is considered the first stratabound meta-sedimentary rock-hosted copper deposit described in Brazil

  13. 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

  14. Critical mineral resources of the United States—An introduction

    Science.gov (United States)

    Schulz, Klaus J.; DeYoung, John H.; Seal, Robert R.; Bradley, Dwight C.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    Many changes have taken place in the mineral resource sector since the publication by the U.S. Geological Survey of Professional Paper 820, “United States Mineral Resources,” which is a review of the long-term United States resource position for 65 mineral commodities or commodity groups. For example, since 1973, the United States has continued to become increasingly dependent on imports to meet its demands for an increasing number of mineral commodities. The global demand for mineral commodities is at an alltime high and is expected to continue to increase, and the development of new technologies and products has led to the use of a greater number of mineral commodities in increasing quantities to the point that, today, essentially all naturally occurring elements have several significant industrial uses. Although most mineral commodities are present in sufficient amounts in the earth to provide adequate supplies for many years to come, their availability can be affected by such factors as social constraints, politics, laws, environmental regulations, land-use restrictions, economics, and infrastructure.This volume presents updated reviews of 23 mineral commodities and commodity groups viewed as critical to a broad range of existing and emerging technologies, renewable energy, and national security. The commodities or commodity groups included are antimony, barite, beryllium, cobalt, fluorine, gallium, germanium, graphite, hafnium, indium, lithium, manganese, niobium, platinum-group elements, rare-earth elements, rhenium, selenium, tantalum, tellurium, tin, titanium, vanadium, and zirconium. All these commodities have been listed as critical and (or) strategic in one or more of the recent studies based on assessed likelihood of supply interruption and the possible cost of such a disruption to the assessor. For some of the minerals, current production is limited to only one or a few countries. For many, the United States currently has no mine production or any

  15. 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

  16. Fault rocks and veins formation in the crystalline Palaeozoic basement of the N margin of the Littoral Chain (Catalan Coastal Ranges, NE Spain)

    Science.gov (United States)

    Alías, Gemma; Belmonte, Alba; Cantarero, Irene; Inglés, Montserrat; Travé, Anna

    2013-04-01

    The Littoral Chain corresponds to a horst of NE-SW direction formed during the Neogene extension which in the studied area (Collserola-Montnegre massif) is mainly composed by Paleozoic materials. At the northern margin the horst limits with the Vallès basin which is infilled by Miocene detrital materials. In the Forques Hill, two km to the est of Martorell, an excellent outcrop of Ordovician phyllites summarise an spread tectonic evolution from Hercynian to Neogene deformation. This work evaluates the behaviour of phyllites during the Hercynian ductile deformation and later during the fragile Mesozoic and Neogene tectonics. The weakness of these rocks together with the situation very close to the Vallès Fault favour that this area concentrates many deformation structures related to extensional tectonics, such as veins, cataclasites and gouges. Phyllites present a pervasive regional hercynian foliation oriented WNW-ESE and dipping moderately to the NNE; a huge amount of quartz veins, up to 20% of the rock volume, were injected during and immediately after the main foliation development. Two groups of fractures cutting the phyllites can be distinguished in the field according to the fault rock products, the vein infilling, the orientation and the geometry. The first one corresponds to Mesozoic fractures that have a NE-SW trend and dip indistinctly to the NW or SE, in a conjugate system. They are characterized by the formation of a broad zone of 0,2 m up to 1,5 m formed either by cataclasites or en echelon veins that indicate a normal movement. The cataclasites are cohesive greenish rocks, with 50% of clasts of wall rock from mm to dm in size. Neoformed minerals in the matrix are chlorite - albite - barite ± titanite and rutile. Veins are white to pinkish in colour and two types of infill have been identified: albite - chlorite - iron oxides± rutile and dolomite - chlorite. The second group belongs to Neogene fractures which although similar orientation than those

  17. Perturbations to the Carbon and Sulfur Cycle During the Permian-Triassic Boundary Event in Southern China

    Science.gov (United States)

    Riccardi, A. L.; Arthur, M. A.; Kump, L. R.; D'Hondt, S.

    2004-12-01

    The Permian-Triassic boundary (251 Ma) is a time of major change in the chemistry of the oceans, as well as the period of the greatest mass extinction of the Phanerozoic. The cause of these changes remains a subject of intense research. Many of the current theories rely on changes to the oceanic sulfur cycle. Carbonate associated sulfate has the potential to provide a high resolution record of variations in the concentration and stable isotopic composition of seawater sulfate. This is of interest because the majority of the current data in this area is from evaporites or pyrites both of which are relatively rare in the stratigraphic record. The isotopic value of seawater sulfate is known to shift from approximately 13‰ in the late Permian to 35‰ during the early Triassic. Our research focuses on CAS found in marine carbonates, and we have obtained samples from two sections that span the Permian-Triassic boundary (PTB) of the Meishan and Changxi sections located in Southern China. The carbonates were powdered and the CAS was extracted as barite. Sulfate content peaks at the event horizon at Meishan, indicating perhaps either substantial changes in local (or global) surface ocean chemistry, pH changes, or changes in rates of mineral precipitation. Isotopic analysis of the CAS provides a detailed record of the isotopic shift is δ 34S across the PTB in two temporally constrained sections, and δ 18O of sulfate also aids in our evaluation of the timing and extent of ocean anoxic events. The δ 13C of kerogen at Meishan reaches a minimum just before the event horizon and the point of lowest δ 13C for carbonate. This differs from many other PTB sections where both sets of carbon isotopes reach a minimum simultaneously. This is not as clear in the Changxi section where the event horizon is not as well resolved. The possibility of primary or secondary diagenetic alteration is also being examined for both sections. The combination of these two data sets provides a

  18. RELAX-1, A Refrigerator Enhanced Laser Analyzer for Xenon

    Science.gov (United States)

    Gilmour, J. D.; Johnston, W. A.; Lyon, I. C.; Turner, G.

    1992-07-01

    A time-of-flight mass spectrometer with a resonance ionization source [1,2] and a cryogenic sample concentrator [3,4] which increases the efficiency of the spectrometer by two orders of magnitude, has been constructed for the isotopic analysis of xenon. In the two-photon excitation, one-photon ionization scheme employed, a wavelength of 249.6 nm excites the 2P(sub)3/26p[1/2](sub)0 level of xenon. A pulsed laser operating at 10 Hz, with a pulse duration of 8 ns and energy of 1.5 mJ is used. The sample concentrator consists of a localised cold spot (5) and a characteristic temperature of 350 K. For sampled atoms of velocity v and characteristic temperature T, the theoretical instrumental discrimination [3] is 3/2m-1.66 x 10^27 v^2/2kT per mil per amu and is confirmed by experiment. Nonresonant ionization of hydrocarbons may occur at the high power densities necessary to saturate the two-photon transition of xenon (about 10^-9 Wcm^-2). Residual hydrocarbon effects in the spectrometer are monitored by detuning the wavelength of the ionizing laser away from resonance and are negligible. One side effect of the sample concentrator is that hydrocarbons tend to condense on parts of the cold spot the heating laser does not reach. Moreover most of the hydrocarbons that are evaporated leave the surface with velocities different from those of xenon and do not see the ionising laser beam. The spectrometer is currently being used to analyse xenon in meteorite residues and cosmogenic xenon in terrestrial barite. References 1. C H Chen, G S Hurst, M G Payne (1980) Chem. Phys. Lett. 75, 473-477. 2. J D Gilmour, S M Hewett, I C Lyon, M Stringer, G Turner (1991) Meas. Sci. Technol. 2, 589-595. 3. J D Gilmour, S M Hewett, I C Lyon, I Perera, G Turner, in prep. 4. G S Hurst, M G Payne, R C Phillips, J W T Dabbs, B E Lehmann (1984) J. Appl. Phys. 55, 1278-1284.

  19. Procedures for the determination of stable elements in construction materials from the nuclear reactors at Risoe National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Oestergaard, L.F.

    2006-03-15

    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 Modblock{sup TM} digesting unit in a two step procedure involving 40% HF followed by 32% HNO{sub 3}. The heavy barite concrete is first treated as the concrete samples but a large residue of poorly soluble sulphates (mainly BaSO{sub 4}) is left. The residue is fused with NaOH/Na{sub 2}CO{sub 3} at 575 deg. C and after some work up the product from the fusion is dissolved in dilute HNO{sub 3}. 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

  20. 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.

    2013-09-01

    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 μg/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. Finally, oxygen in CO2

  1. Critical mineral resources of the United States—Economic and environmental geology and prospects for future supply

    Science.gov (United States)

    Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    SummaryMineral commodities are vital for economic growth, improving the quality of life, providing for national defense, and the overall functioning of modern society. Minerals are being used in larger quantities than ever before and in an increasingly diverse range of applications. With the increasing demand for a considerably more diverse suite of mineral commodities has come renewed recognition that competition and conflict over mineral resources can pose significant risks to the manufacturing industries that depend on them. In addition, production of many mineral commodities has become concentrated in relatively few countries (for example, tungsten, rare-earth elements, and antimony in China; niobium in Brazil; and platinum-group elements in South Africa and Russia), thus increasing the risk for supply disruption owing to political, social, or other factors. At the same time, an increasing awareness of and sensitivity to potential environmental and health issues caused by the mining and processing of many mineral commodities may place additional restrictions on mineral supplies. These factors have led a number of Governments, including the Government of the United States, to attempt to identify those mineral commodities that are viewed as most “critical” to the national economy and (or) security if supplies should be curtailed.This book presents resource and geologic information on the following 23 mineral commodities currently among those viewed as important to the national economy and national security of the United States: antimony (Sb), barite (barium, Ba), beryllium (Be), cobalt (Co), fluorite or fluorspar (fluorine, F), gallium (Ga), germanium (Ge), graphite (carbon, C), hafnium (Hf), indium (In), lithium (Li), manganese (Mn), niobium (Nb), platinum-group elements (PGE), rare-earth elements (REE), rhenium (Re), selenium (Se), tantalum (Ta), tellurium (Te), tin (Sn), titanium (Ti), vanadium (V), and zirconium (Zr). For a number of these commodities

  2. 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.

  3. 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

    Directory of Open Access Journals (Sweden)

    I. Ssemmanda

    2012-11-01

    evaporation of the lake water. 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.

  4. The review of recent carbonate minerals processing technology

    Science.gov (United States)

    Solihin

    2018-02-01

    Carbonate is one of the groups of minerals that can be found in relatively large amount in the earth crust. The common carbonate minerals are calcium carbonate (calcite, aragonite, depending on its crystal structure), magnesium carbonate (magnesite), calcium-magnesium carbonate (dolomite), and barium carbonate (barite). A large amount of calcite can be found in many places in Indonesia such as Padalarang, Sukabumi, and Tasikmalaya (West Java Provence). Dolomite can be found in a large amount in Gresik, Lamongan, and Tuban (East Java Provence). Magnesite is quite rare in Indonesia, and up to the recent years it can only be found in Padamarang Island (South East Sulawesi Provence). The carbonate has been being exploited through open pit mining activity. Traditionally, calcite can be ground to produce material for brick production, be carved to produce craft product, or be roasted to produce lime for many applications such as raw materials for cement, flux for metal smelting, etc. Meanwhile, dolomite has traditionally been used as a raw material to make brick for local buildings and to make fertilizer for coconut oil plant. Carbonate minerals actually consist of important elements needed by modern application. Calcium is one of the elements needed in artificial bone formation, slow release fertilizer synthesis, dielectric material production, etc. Magnesium is an important material in automotive industry to produce the alloy for vehicle main parts. It is also used as alloying element in the production of special steel for special purpose. Magnesium oxide can be used to produce slow release fertilizer, catalyst and any other modern applications. The aim of this review article is to present in brief the recent technology in processing carbonate minerals. This review covers both the technology that has been industrially proven and the technology that is still in research and development stage. One of the industrially proven technologies to process carbonate mineral is

  5. Minerals and clay minerals assemblages in organic-rich facies: the case study of the Sinemurian-Pliensbachian carbonate deposits of the western Lusitanian Basin (Portugal)

    Science.gov (United States)

    Caniço, Ana; Duarte, Luís V.; Silva, Ricardo L.; Rocha, Fernando; Graciano Mendonça Filho, João

    2015-04-01

    The uppermost Sinemurian-Pliensbachian series of the western part of the Lusitanian Basin is composed by hemipelagic carbonates particularly enriched in organic matter. Great part of this succession, considered to be one of the most important potential source rock intervals of Portugal, crops out in the S. Pedro de Moel and Peniche sectors, belonging to the Água de Madeiros and Vale das Fontes formations. In this study, supported by a detailed and integrated stratigraphic framework, we analyzed 98 marly samples (whole-rock mineralogy and clay minerals assemblages) from the aforementioned formations in the S. Pedro de Moel and Peniche sectors. X-ray Diffraction analysis followed the standard procedures and the semi-quantification of the different mineral phases was calculated using MacDiff 4.2.6. The goals of this work are to demonstrate the vertical variability of the mineral composition of these two units and investigate the relationship between the clay minerals assemblages and the content in organic matter (Total organic carbon: TOC). Besides the abundance of calcite and phyllosilicates, whole-rock mineralogy revealed the presence of quartz, potassium feldspar, dolomite, and pyrite (trace amounts). Other minerals like anhydrite, barite and gypsum occur sporadically. The clay minerals assemblages are dominated by illite+illite/smectite mixed-layers (minimum of 59%), always associated with kaolinite (maximum of 37%) and chlorite (maximum of 25%); sporadically smectite occurs in trace amounts. Generally, high TOC levels (i.e., black shale facies with TOC reaching up to 22 wt.% in both units, see Duarte et al., 2010), show a major increase in chlorite and kaolinite (lower values of illite+illite/smectite mixed layers). A kaolinite enrichment is also observed just above the Sinemurian-Pliensbachian boundary (base of Praia da Pedra Lisa Member of Água de Madeiros Formation; values varying between 30 and 37%). This event is associated with a second-order regressive

  6. Time-Series Radiocarbon Measurements Indicate Carbon Turnover Across Soil Fractions is Correlated With Productivity in a Long-Term Agricultural Experiment

    Science.gov (United States)

    Sanderman, J.; Baisden, W. T.; Creamer, C.; Farrell, M.; Fallon, S.

    2016-12-01

    Carbonatites and alkaline intrusions are important sources of REEs. Environmental risks related to these deposit types have been assessed through literature review and evaluation of the geochemical properties of representative samples of mill tailings and their leachates. The main ore mineral in carbonatite deposits is bastnasite [(Ce,La)(CO3)F], which is found with dolomite and calcite ( 65 %), barite (20 - 25 %), plus a number of minor accessory minerals including sulfides such as galena and pyrite. Generally, alkaline intrusion-related REE deposits either occur in layered complexes or with dikes and veins cutting alkaline intrusions. Such intrusions have a more diverse group of REE ore minerals that include fluorcarbonates, oxides, silicates, and phosphates. Ore also can include minor calcite and iron (Fe), lead (Pb), and zinc (Zn) sulfides. The acid-generating potential of both deposit types is low because of a predominance of carbonate minerals in the carbonatite deposits, the presence of feldspars and minor calcite in alkaline intrusion-related deposits, and to only minor to trace occurrence of potentially acid-generating sulfide minerals. Both deposit types, however, are produced by igneous and hydrothermal processes that enrich high-field strength, incompatible elements, which typically are excluded from common rock-forming minerals. Elements such as yttrium (Y), niobium Nb), zirconium (Zr), hafnium (Hf), tungsten (W), titanium (Ti), tantalum (Ta), scandium (Sc), thorium (Th), and uranium (U) can be characteristic of these deposits and may be of environmental concern. Most of these elements, including the REEs, but with the exception of U, have low solubilities in water at the near-neutral pH values expected around these deposits. Mill tailings from carbonatite deposits can exceed residential soil and sediment criteria for Pb, and leachates from mill tailings can exceed drinking water guidelines for Pb. The greatest environmental challenges, however, are

  7. The spontaneous combustion of coal and its by-products in the Witbank and Sasolburg coalfields of South Africa

    Energy Technology Data Exchange (ETDEWEB)

    Pone, J. Denis N. [Energy and Geo-Environmental Engineering, The Pennsylvania State University, 228 Housler Building, University Park, PA 16802 (United States); Hein, Kim A.A. [School of Geosciences, University of the Witwatersrand Johannesburg, P/Bag 3, 2050, WITS (South Africa); Stracher, Glenn B. [Division of Science and Mathematics, East Georgia College, Swainsboro, Georgia 30401 (United States); Annegarn, Harold J. [Department of Geography and Environmental Management, University of Johannesburg, P.O. Box 524, Auckland Park, 2006 (South Africa); Finkleman, Robert B. [University of Texas at Dallas, Department of Geosciences, Richardson, TX 75083-0688 (United States); Blake, Donald R. [Department of Chemistry, 570 Rowland Hall, University of California, Irvine, CA 92697-2025 (United States); McCormack, John K. [Electron Microbeam Facility, Department of Geological Sciences, MS 172, Mackay School of Mines, University of Nevada, Reno, Navada 8955-0047 (United States); Schroeder, Paul [Department of Geology, University of Georgia, 210 Field Street, Athens, GA 30602-2501 (United States)

    2007-10-01

    Spontaneous combustion of coal seams in the Witbank and Sasolburg coalfields, South Africa, was studied in order to determine if toxic chemical elements and compounds are being mobilised into the environment. Samples of the minerals forming on the surface of coal seams, and gases escaping from vents, were analysed to verify the presence of these elements and compounds. Gas temperature measurements at coal-fire vents range from 34 C to 630 C. The coal-fire gas minerals (CFGM) identified included sulphur compounds and salammoniac. X-ray diffraction (XRD) studies of CFGM by-products confirmed the presence of mascagnite ((NH{sub 4}){sub 2}SO{sub 4}), illite ((Al,Si){sub 4}O{sub 10}[(OH){sub 2},H{sub 2}O]) letovicite ((NH{sub 4}){sub 3}H(SO{sub 4}){sub 2}), phlogopite (KMg{sub 3}(AlSi{sub 3})O{sub 10}(F,OH){sub 2}), titanium dioxide (TiO{sub 2}), barite (BaSO{sub 4}), iron sulphate (FeSO{sub 4}), gypsum (CaSO{sub 4}.2H{sub 2}O) and silicate. An unknown and unclassified sulphur-nitrogen-chlorine CFGM was also identified. The minerals are interpreted to have formed by condensation or sublimation; several may be alteration products. Other heavy elements found in the CFGM's are mercury, arsenic, lead, zinc, and copper. Arsenic and mercury were the major elements of potential environmental significance found accumulating around coal-fire vents. Relatively high concentrations of toluene, benzene and xylene were found in the gas collected at both Witbank and Sasolburg coalfields. Benzene, toluene and xylenes are known to possess carcinogenic proprieties. Thirty-two aliphatic compounds were detected, as well as halogenated compounds including bromomethane, iodomethane and trichloromethane in low concentrations, and dichloromethane and chloromethane in high concentrations. The highest concentrations of halogenated compounds were measured for gas samples from the Witbank coalfield. High concentrations of carbon monoxide, carbon dioxide, and methane were also detected. The

  8. Evidence of trace element emission during the combustion of sulfide-bearing metallurgical slags

    International Nuclear Information System (INIS)

    Bortnikova, Svetlana Borisovna; Olenchenko, Vladimir Vladimirovich; Gaskova, Olga Lukinichna; Chernii, Konstantin Ivanovich; Devyatova, Anna Yurevna; Kucher, Dmitrii Olegovich

    2017-01-01

    The present study shows the results of field and laboratory studies of trace element transfer from waste heaps of metallurgical slags (Kemerovo region, town of Belovo). Temperature anomalies were observed, with high temperatures up to 81.2 °C on the top of the heap. A visual geophysical model of the inner parts of the heap with contrasting resistivity zones was obtained using the electrical resistivity tomography (ERT) method, and quantitative characteristics were derived. Dry and frozen slag zones were characterized by resistivity of 50–500 Ohm·m. The resistivity of wet slag varied from 5 to 10 Ohm·m for slag with low humidity of 1–2 Ohm·m for slag saturated with highly mineralized solutions. The local anomaly of extremely low resistivity (0.3–0.5 Ohm·m) might be associated with a combustion centre or high pore solutions TDS. Basic major elements (Ca, Mg, K, Na, Si, and Al), metals (Cu, Zn, Pb, and Cd) and anionic elements (As, Sb, and V) were determined in gas condensates in situ. The most volatile elements were basic elements: Ca > Cu > Mg > Na > Mn > Fe, Zn. Lower concentration in the condensates was determined for Si > K > As > Sr > Al > V and Pb, Ba, La were also found. The observed mineral paragenetic sequences were primary minerals of barite-polymetallic ores and sphalerite concentrate, high-temperature minerals formed during pyrometallurgical processing and/or permanent combustion of the heap surface, efflorescence minerals formed by atmospheric oxidation accelerated by acid steam condensation. An experimental investigations using stepwise and 500 °C heating of the same samples were performed to compare the elements that were released into the gas phase in situ and off-site. - Highlights: • Sulfide tailings temperature anomalies up to 81.2 °C. • A visual geophysical model of the bowels of the heap with contrasting resistivity zones was obtained. • Base rock-forming elements, metals and anionogenic elements were

  9. Mineralogy of Gas Hydrate Bearing Sediment in Green Canyon Block 955 Northern Gulf of Mexico

    Science.gov (United States)

    Heber, R.; Kinash, N.; Cook, A.; Sawyer, D.; Sheets, J.; Johnson, J. E.

    2017-12-01

    Natural gas hydrates are of interest as a future hydrocarbon source, however, the formation and physical properties of such systems are not fully understood. In May 2017, the University of Texas drilled two holes in Green Canyon Block 955, northern Gulf of Mexico to collect pressurized core from a thick, 100 m accumulation of gas hydrate in a silt dominated submarine canyon levee system. The expedition, known as UT-GOM2-01, collected 21, 10-m pressure cores from Holes H002 and H005. Approximately half of the cores successfully pressurized and were fully recovered. Unsuccessful cores that did not pressurize generally had low core recovery. By analyzing the sediment composition in known gas hydrate reservoirs, we can construct a more detailed picture of how and why gas hydrates accumulate, as mineralogy can affect physical properties such as porosity and permeability as well as geophysical measurements such as resistivity. Using X-ray diffraction (XRD) on bulk sediment powders, we determined the bulk mineralogy of the samples. Moreover, we investigated drilling mud contamination using XRD and light optical analysis. In some cores, contamination was easily recognized visually as dense sludge between the core barrel and the recovered sediment core, however drilling mud is best observed both along the liner and interbedded within the sediment on X-ray computed tomography scans. To fully identify the presence and influence of drilling mud, we use XRD to analyze samples on cores collected both while drilling mud was used in hole and when only seawater was used in hole and consider the density anomalies observed on the XCT scans. The preliminary XRD light optical microscopy results show that the silt-dominated reservoir is primarily composed of quartz, with minor alkali feldspar, amphibole, muscovite, dolomite, and calcite. Samples from intervals with suspected drilling mud contamination show a similar composition, but with the addition of barite, a common component in

  10. Development of a ceramic material to cover walls to be applied in diagnostic radiological protection

    International Nuclear Information System (INIS)

    Frimaio, Audrew

    2006-01-01

    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 2 , Fe 2 O 3 , Al 2 O 3 , CaO and Ti 2 O 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 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 radiation attenuation were evaluated for

  11. High-pressure crystal chemistry of zircon, monazite, scheelite and related minerals

    International Nuclear Information System (INIS)

    Errandonea, D.

    2010-01-01

    Full text: Many crystal structures of ABO 4 compounds consists AO 8 bisdisphenoids and BO 4 tetrahedra. They include important mineral structures, e.g. zircon (ZrSiO 4 ), anhydrite (CaSO 4 ), silver perchlorate (AgClO 4 ), and scheelite (CaWO 4 ). 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 ABO 4 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

  12. New data towards the development of a comprehensive taphonomic framework for the Late Jurassic Cleveland-Lloyd Dinosaur Quarry, Central Utah

    Directory of Open Access Journals (Sweden)

    Joseph E. Peterson

    2017-06-01

    Full Text Available The Cleveland-Lloyd Dinosaur Quarry (CLDQ is the densest deposit of Jurassic theropod dinosaurs discovered to date. Unlike typical Jurassic bone deposits, it is dominated by the presence of Allosaurus fragilis. Since excavation began in the 1920s, numerous hypotheses have been put forward to explain the taphonomy of CLDQ, including a predator trap, a drought assemblage, and a poison spring. In an effort to reconcile the various interpretations of the quarry and reach a consensus on the depositional history of CLDQ, new data is required to develop a robust taphonomic framework congruent with all available data. Here we present two new data sets that aid in the development of such a robust taphonomic framework for CLDQ. First, x-ray fluorescence of CLDQ sediments indicate elevated barite and sulfide minerals relative to other sediments from the Morrison Formation in the region, suggesting an ephemeral environment dominated by periods of hypereutrophic conditions during bone accumulation. Second, the degree of abrasion and hydraulic equivalency of small bone fragments dispersed throughout the matrix were analyzed from CLDQ. Results of these analyses suggest that bone fragments are autochthonous or parautochthonous and are derived from bones deposited in the assemblage rather than transported. The variability in abrasion exhibited by the fragments is most parsimoniously explained by local periodic re-working and re-deposition during seasonal fluctuations throughout the duration of the quarry assemblage. Collectively, these data support previous interpretations that the CLDQ represents an attritional assemblage in a poorly-drained overbank deposit where vertebrate remains were introduced post-mortem to an ephemeral pond during flood conditions. Furthermore, while the elevated heavy metals detected at the Cleveland-Lloyd Dinosaur Quarry are not likely the primary driver for the accumulation of carcasses, they are likely the result of multiple sources

  13. Hydrothermal chimneys and Sulphide mineralised breccias from the Kolbeinsey and the Mohns Ridge

    Science.gov (United States)

    Nygård, T. E.; Bjerkgård, T.; Kelly, D.; Thorseth, I.; Pedersen, R. B.

    2003-04-01

    An inactive hydrothermal ventsite was discovered at the Kolbeinsey Ridge, (68^o56'N,17^o12'W) during the SUBMAR-99 cruise. The field is located in the neovolcanic sone at the flat top of a circular volcano at 900 m water depth. Two major fields contain about 30 chimneys. The top of one chimney was collected for further research. The mineralogy of the chimney is dominated by sphalerite, silica and barite, with minor amounts of galena and pyrrhotite, an assemblage which suggest a formation temperature white smokers [1]. The outer part of the chimney is enriched in LREE and shows a large positive Eu-anomaly compared to the inner parts of the chimney. Variation in Ce-anomaly reflects varying degrees of seawater infiltration during mineral precipitation. The first formed minerals in the lower part, and the outer part of the chimney appears to contain the most seawater-affected minerals. The Ag content of sphalerite may be as high as 1 wt%, but is restricted to small domains especially around fluid channels. A zonation in the Fe/Zn ratio of sphalerite is observed across fluid channels, suggesting variations in the fluid composition with time. The Pb-content of the chimney is extremely high, with up to 10 wt% in some sphalerite grains, and the bulk values are as high as 10 000 ppm. These high values suggest that sediments may have been present in the reaction zone of this hydrothermal system. Sulphide mineralised breccias were recovered by dredging the northern fault wall of the Mohns Ridge at 72^o39,33'N, 02^o40,87'E, during the SUBMAR-2000 cruise. The breccias exhibit several progressive stages of hydrothermal alteration: 1) the least altered parts are composed of partly altered basalt clasts and some chlorite, 2) more strongly altered samples mainly consist of quarts in a chlorite matrix, 3) and the most heavily mineralised parts contain secondary quarts and chalcopyrite. The final hydrothermal stage recorded by the breccias involved oxidation of chalcopyrite and

  14. 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

  15. New data towards the development of a comprehensive taphonomic framework for the Late Jurassic Cleveland-Lloyd Dinosaur Quarry, Central Utah

    Science.gov (United States)

    Warnock, Jonathan P.; Eberhart, Shawn L.; Clawson, Steven R.; Noto, Christopher R.

    2017-01-01

    The Cleveland-Lloyd Dinosaur Quarry (CLDQ) is the densest deposit of Jurassic theropod dinosaurs discovered to date. Unlike typical Jurassic bone deposits, it is dominated by the presence of Allosaurus fragilis. Since excavation began in the 1920s, numerous hypotheses have been put forward to explain the taphonomy of CLDQ, including a predator trap, a drought assemblage, and a poison spring. In an effort to reconcile the various interpretations of the quarry and reach a consensus on the depositional history of CLDQ, new data is required to develop a robust taphonomic framework congruent with all available data. Here we present two new data sets that aid in the development of such a robust taphonomic framework for CLDQ. First, x-ray fluorescence of CLDQ sediments indicate elevated barite and sulfide minerals relative to other sediments from the Morrison Formation in the region, suggesting an ephemeral environment dominated by periods of hypereutrophic conditions during bone accumulation. Second, the degree of abrasion and hydraulic equivalency of small bone fragments dispersed throughout the matrix were analyzed from CLDQ. Results of these analyses suggest that bone fragments are autochthonous or parautochthonous and are derived from bones deposited in the assemblage rather than transported. The variability in abrasion exhibited by the fragments is most parsimoniously explained by local periodic re-working and re-deposition during seasonal fluctuations throughout the duration of the quarry assemblage. Collectively, these data support previous interpretations that the CLDQ represents an attritional assemblage in a poorly-drained overbank deposit where vertebrate remains were introduced post-mortem to an ephemeral pond during flood conditions. Furthermore, while the elevated heavy metals detected at the Cleveland-Lloyd Dinosaur Quarry are not likely the primary driver for the accumulation of carcasses, they are likely the result of multiple sources; some metals may be

  16. A simple and reliable anion-exchange resin method for sulfate extraction and purification suitable for multiple O- and S-isotope measurements.

    Science.gov (United States)

    Le Gendre, Erwann; Martin, Erwan; Villemant, Benoit; Cartigny, Pierre; Assayag, Nelly

    2017-01-15

    The O- and S-isotope compositions of sulfates can be used as key tracers of the fate and sink of sulfate in both terrestrial and extra-terrestrial environments. However, their application remains limited in those geological systems where sulfate occurs in low concentrations. Here we present a simple and reliable method to extract, purify and concentrate sulfate from natural samples. The method allows us to take into account the separation of nitrate, which is known to be an issue in O-isotope analysis. The separation and concentration of sulfate from other anions in any aqueous solution are performed within a few hours via anion-exchange resin. The possible O- (δ 18 O and Δ 17 O) and S- (δ 34 S, Δ 33 S and Δ 36 S) isotope exchanges, fractionations and/or contaminations are for the first time monitored during the whole procedure using initial O- and S-mass-dependent and mass-independent sulfate solutions. After elution in HCl, pure sulfate is fully retrieved and precipitated into BaSO 4 , which is suitable for O- and S-isotopic measurements using established techniques. The analysis of retrieved barite presents no variation within 2σ uncertainties: ±0.5‰ and ±0.1‰ in O- (δ 18 O, Δ 17 O) and ±0.2‰, ±0.02‰ and ±0.09‰ in S- (δ 34 S, Δ 33 S and Δ 36 S) isotope ratios, respectively. This study shows that the resin method for sulfate extraction and purification, in addition to being cheap, simple and quick, is applicable for the measurements of all O- and S-isotopic ratios in sulfates (including the Δ 17 O, Δ 33 S and Δ 36 S values). Therefore, this method can be easily used for a high range of natural samples in which sulfate occurs in low concentration including aerosols, ice cores, sediments, volcanic deposits, (paleo)soils and rainwater, and thus it can be a key to our understanding of the sulfur cycle on Earth. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  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. Composition and genesis of ferromanganese deposits from the northern South China Sea

    Science.gov (United States)

    Zhong, Yi; Chen, Zhong; González, Francisco Javier; Hein, James R.; Zheng, Xufeng; Li, Gang; Luo, Yun; Mo, Aibin; Tian, Yuhang; Wang, Shuhong

    2017-05-01

    Marine ferromanganese (Fe-Mn) nodules and crusts are archives of past environmental conditions and potential mineral resources. Over the last 30 years, many have been discovered in the northern South China Sea (SCS). To determine the origin of the Fe-Mn deposits, a comprehensive laboratory analysis of physical properties, mineralogy and geochemistry was conducted on newly collected Fe-Mn nodule/crust samples. The results revealed that there are three types of Fe-Mn deposits: (1) Fe-rich nodules containing essentially goethite occur on the northeastern slope of the SCS, with high Fe, low Mn (Mn/Fe = 0.03) and low trace metals and rare earth elements concentrations; (2) Smooth Fe-Mn nodules and crusts composed of asbolane, todorokite and CFA occur along the northwestern marginal of the SCS that have similar Fe and Mn contents (Mn/Fe = 1.21), moderate trace metal enrichments, and a positive Ce anomaly; (3) Fe-Mn nodules and crusts composed of asbolane, todorokite and birnessite that occur in the central basin of the SCS have higher Mn and lower Fe contents (Mn/Fe = 1.45). This depositional pattern was associated with major changes in oceanographic conditions and tectonic regimes. The northeastern slope deposits occur in a contourite depositional system, are strongly enriched in Fe relative to Mn (average 38.7% and 0.96%, respectively), formed from the combination of hydrogenetic and diagenetic processes. We propose a new genetic model for Fe-Mn nodules, which formed through the oxidation of pyrite and pyrite-barite concretions that formed by rapid early diagenetic growth (average 3320 mm/Myr) on continental margins above the carbonate compensation depth, and dominated by hydrocarbon seep structures and strong erosive action of bottom currents along the northeastern slope. In contrast, the introduction of vigorous deep-water flow from the North Pacific promoted the slow growth (4-7 mm/Myr) of hydrogenetic Fe-Mn nodules and crusts along the northwestern margin. Finally

  19. Metalliferous sediment and a silica-hematite deposit within the Blanco fracture zone, Northeast Pacific

    Science.gov (United States)

    Hein, J.R.; Clague, D.A.; Koski, R.A.; Embley, R.W.; Dunham, R.E.

    2008-01-01

    - and precious-metal-bearing, silica-Fe-oxide-barite deposit. Such deposits are commonly spatially and temporally associated with volcanogenic massive sulfide (VMS) ores. A plot of data for pathfinder elements shows a large hot spot at the northwestern margin of the field, which may mark a region where moderate to high temperature sulfide deposits are forming at depth; further exploration of the hydrothermal field to the northwest is warranted.

  20. 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)

  1. 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

  2. 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

  3. Petrography of sandstones from drill cores BARB4 and BARB5, Paleoarchean Mapepe Formation, Barberton greenstone belt, South Africa: Implications for provenance and tectonic reconstructions.

    Science.gov (United States)

    Drabon, N.; Lowe, D. R.; Heubeck, C. E.

    2014-12-01

    Paleogeographic and tectonic reconstructions in the Barberton greenstone belt (BGB) are challenged by syn- and post-depositional tectonics. The Barberton Drilling Project extracted two drill cores from the sedimentary rocks of the 3.26-3.22 Ga Mapepe Formation of the Fig Tree Group. The cores were taken from the Manzimnyama Syncline (BARB4) and the Barite Valley structural belt (BARB5), which are separated by belts of faulted older Onverwacht and younger Moodies strata. Stratigraphically, there is no clear correlation of Mapape strata in these two belts. Both BARB4 and BARB5 contain 25 to 300 m thick units of lithic sandstone that may represent correlative units. A comparative provenance analysis allows testing a possible correlation and evaluating the nature of tectonic uplifts that sourced the sediments. The sandstones have experienced pervasive metasomatic alteration and most primary silicate minerals except coarse quartz have been transformed into micromosaics of microquartz, phyllosilicates, and trace impurities. The majority of framework grains are chert, impure chert, and lithic grains while monocrystalline quartz and altered feldspar are minor components. The single thick sandstone in BARB4 displays a relatively uniform framework mode with average 38.7 % total quartz, 2.4% feldspars, and 58.9 % lithics and an increasing percentage of mafic to ultramafic grains upsection. In contrast, BARB5 includes three distinct sandstones with varying framework modes. The litharenite at 0 to 95m core depth was mainly sourced from an immediately underlying dacitic tuff. The chertarenite at 320 to 390m core depth is composed of 73% carbonaceous chert grains. All grain types appear to have been derived by erosion of sedimentary and volcanic rocks of the BGB as well as penecontemporaneous volcanism. Erosion did not reach deeper-seated plutonic rocks. The framework mode of the BARB4 sandstones represents a composite of common silicified BGB rocks and resembles those of other

  4. Detrital Zircon Geochronology and Petrology of Sediments from the Barberton greenstone belt: Implications for Provenance and Tectonic Reconstructions

    Science.gov (United States)

    Drabon, N.; Lowe, D. R.; Byerly, G. R.

    2015-12-01

    Paleogeographic and tectonic reconstructions in Paleoarchean rocks are challenged by syn- and post-depositional tectonics. Sediments of the 3.2 Ga Fig Tree Group in the Barberton Greenstone Belt (BGB) represent first significant uplift after almost 300 Ma of tectonic quiescence during the Onverwacht time. The rocks are now exposed in isolated structural belts, which are separated by belts of faulted older Onverwacht and younger Moodies strata. A systematic comparative provenance study of Fig Tree Group utilizing sandstone petrography and detrital zircon geochronology assesses the evolution in the provenance of different isolated structural belts to test a possible correlation and evaluating the nature of tectonic uplifts that sourced the sediments. Samples were obtained from the ICDP drill cores BARB4 and BARB5 of the Mapepe Formation in the Manzimnyama Syncline (MS) and the Barite Valley (BV) structural belts, respectively. The framework mode of the MS and basal BV sandstones represents a composite of common silicified BGB rocks. In contrast, sandstones from the middle and top of the BV are composed of exclusively sedimentary or intermediate volcanic rock fragments. They were derived locally by shallow erosion of immediately underlying sedimentary and volcanic rocks. Detrital zircon spectra show four main age clusters at 3.26-3.24, 3.00, 3.45, and 3.55 Ga. The 3.26-3.24, 3.45, and 3.55 Ga clusters correspond to major magmatic episodes of volcanism of the Fig Tree Group, as well as Hooggenoeg Formation (H6), and the Theespruit Formation, respectively. A cluster of Mendon Formation-age zircons at 3.30 Ga represents a source that has been eroded or is not exposed on the surface. MS sediments and basal BV sandstones were exclusively sourced from H6. Towards the middle of the BV section, sediments erodeds first into Mendon sediments, and then into Fig Tree Formation felsic volcanics. The sandstones in the MS and BV structural belts represent first-cycle sediments

  5. Constraining Δ33S signatures of Archean seawater sulfate with carbonate-associated sulfate

    Science.gov (United States)

    Peng, Y.; Bao, H.; Bekker, A.; Hofmann, A.

    2017-12-01

    Non-mass dependent sulfur isotope deviation of S-bearing phases in Archean sedimentary strata, and expressed as Δ33S, has a consistent pattern, i.e., sulfide (pyrite) predominantly bear positive Δ33S values, while Paleoarchean sulfate (barite) has negative Δ33S values. This pattern was later corroborated by observations of negative Δ33S values in Archean volcanogenic massive sulfide deposits and negative Δ33S values in early diagenetic nodular pyrite with a wide range of δ34S values, which is thought to be due to microbial sulfate reduction. These signatures have provided a set of initial conditions for a mechanistic interpretation at physical chemistry level. Unlike the younger geological times when large bodies of seawater evaporite deposits are common, to expand seawater sulfate records, carbonate-associated sulfate (CAS) was utilized as a proxy for ancient seawater sulfate. CAS extracted from the Archean carbonates carries positive Δ33S values. However, CAS could be derived from pyrite oxidation following exposure to modern oxidizing conditions and/or during laboratory extraction procedures. It is, therefore, important for us understanding context of the overall early earth atmospheric condition to empirically confirm whether Archean seawater sulfate was generally characterized by negative Δ33S signatures. Combined δ18O, Δ17O, δ34S, and Δ33S analyses of sequentially extracted water-leachable sulfate (WLS) and acid-leachable sulfate (ALS = CAS) and δ34S and Δ33S analyses of pyrite can help to identify the source of extracted sulfate. We studied drill-core samples of Archean carbonates from the 2.55 Ga Malmani and Campell Rand supgroups, South Africa. Our preliminary results show that 1) neither WLS nor ALS were extracted from samples with extremely low pyrite contents (less than 0.05 wt.%); 2) extractable WLS and ALS is present in samples with relatively high pyrite contents (more than 1 wt.%), and that δ34S and Δ33S values of WLS, ALS, and

  6. Environmental Characteristics of Carbonatite and Alkaline Intrusion-related Rare Earth Element (REE) Deposits

    Science.gov (United States)

    Seal, R. R., II; Piatak, N. M.

    2017-12-01

    Carbonatites and alkaline intrusions are important sources of REEs. Environmental risks related to these deposit types have been assessed through literature review and evaluation of the geochemical properties of representative samples of mill tailings and their leachates. The main ore mineral in carbonatite deposits is bastnasite [(Ce,La)(CO3)F], which is found with dolomite and calcite ( 65 %), barite (20 - 25 %), plus a number of minor accessory minerals including sulfides such as galena and pyrite. Generally, alkaline intrusion-related REE deposits either occur in layered complexes or with dikes and veins cutting alkaline intrusions. Such intrusions have a more diverse group of REE ore minerals that include fluorcarbonates, oxides, silicates, and phosphates. Ore also can include minor calcite and iron (Fe), lead (Pb), and zinc (Zn) sulfides. The acid-generating potential of both deposit types is low because of a predominance of carbonate minerals in the carbonatite deposits, the presence of feldspars and minor calcite in alkaline intrusion-related deposits, and to only minor to trace occurrence of potentially acid-generating sulfide minerals. Both deposit types, however, are produced by igneous and hydrothermal processes that enrich high-field strength, incompatible elements, which typically are excluded from common rock-forming minerals. Elements such as yttrium (Y), niobium Nb), zirconium (Zr), hafnium (Hf), tungsten (W), titanium (Ti), tantalum (Ta), scandium (Sc), thorium (Th), and uranium (U) can be characteristic of these deposits and may be of environmental concern. Most of these elements, including the REEs, but with the exception of U, have low solubilities in water at the near-neutral pH values expected around these deposits. Mill tailings from carbonatite deposits can exceed residential soil and sediment criteria for Pb, and leachates from mill tailings can exceed drinking water guidelines for Pb. The greatest environmental challenges, however, are

  7. 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

  8. Biogenic Iron-Rich Filaments in the Quartz Veins in the Uppermost Ediacaran Qigebulake Formation, Aksu Area, Northwestern Tarim Basin, China: Implications for Iron Oxidizers in Subseafloor Hydrothermal Systems.

    Science.gov (United States)

    Zhou, Xiqiang; Chen, Daizhao; Tang, Dongjie; Dong, Shaofeng; Guo, Chuan; Guo, Zenghui; Zhang, Yanqiu

    2015-07-01

    Fe-(oxyhydr)oxide-encrusted filamentous microstructures produced by microorganisms have been widely reported in various modern and ancient extreme environments; however, the iron-dependent microorganisms preserved in hydrothermal quartz veins have not been explored in detail because of limited materials available. In this study, abundant well-preserved filamentous microstructures were observed in the hydrothermal quartz veins of the uppermost dolostones of the terminal-Ediacaran Qigebulake Formation in the Aksu area, northwestern Tarim Basin, China. These filamentous microstructures were permineralized by goethite and hematite as revealed by Raman spectroscopy and completely entombed in chalcedony and quartz cements. Microscopically, they are characterized by biogenic filamentous morphologies (commonly 20-200 μm in length and 1-5 μm in diameter) and structures (curved, tubular sheath-like, segmented, and mat-like filaments), similar to the Fe-oxidizing bacteria (FeOB) living in modern and ancient hydrothermal vent fields. A previous study revealed that quartz-barite vein swarms were subseafloor channels of low-temperature, silica-rich, diffusive hydrothermal vents in the earliest Cambrian, which contributed silica to the deposition of the overlying bedded chert of the Yurtus Formation. In this context, this study suggests that the putative filamentous FeOB preserved in the quartz veins might have thrived in the low-temperature, silica- and Fe(II)-rich hydrothermal vent channels in subseafloor mixing zones and were rapidly fossilized by subsequent higher-temperature, silica-rich hydrothermal fluids in response to waning and waxing fluctuations of diffuse hydrothermal venting. In view of the occurrence in a relatively stable passive continental margin shelf environment in Tarim Block, the silica-rich submarine hydrothermal vent system may represent a new and important geological niche favorable for FeOB colonization, which is different from their traditional

  9. 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.

  10. Geometry of the neoproterozoic and paleozoic rift margin of western Laurentia: Implications for mineral deposit settings

    Science.gov (United States)

    Lund, K.

    2008-01-01

    The U.S. and Canadian Cordilleran miogeocline evolved during several phases of Cryogenian-Devonian intracontinental rifting that formed the western mangin of Laurentia. Recent field and dating studies across central Idaho and northern Nevada result in identification of two segments of the rift margin. Resulting interpretations of rift geometry in the northern U.S. Cordillera are compatible with interpretations of northwest- striking asymmetric extensional segments subdivided by northeast-striking transform and transfer segments. The new interpretation permits integration of miogeoclinal segments along the length of the western North American Cordillera. For the U.S. Cordillera, miogeoclinal segments include the St. Mary-Moyie transform, eastern Washington- eastern Idaho upper-plate margin, Snake River transfer, Nevada-Utah lower-plate margin, and Mina transfer. The rift is orthogonal to most older basement domains, but the location of the transform-transfer zones suggests control of them by basement domain boundaries. The zigzag geometry of reentrants and promontories along the rift is paralleled by salients and recesses in younger thrust belts and by segmentation of younger extensional domains. Likewise, transform transfer zones localized subsequent transcurrent structures and igneous activity. Sediment-hosted mineral deposits trace the same zigzag geometry along the margin. Sedimentary exhalative (sedex) Zn-Pb-Ag ??Au and barite mineral deposits formed in continental-slope rocks during the Late Devonian-Mississippian and to a lesser degree, during the Cambrian-Early Ordovician. Such deposits formed during episodes of renewed extension along miogeoclinal segments. Carbonate-hosted Mississippi Valley- type (MVT) Zn-Pb deposits formed in structurally reactivated continental shelf rocks during the Late Devonian-Mississippian and Mesozoic due to reactivation of preexisting structures. The distribution and abundance of sedex and MVT deposits are controlled by the

  11. Texture, mineralogy and geochemistry of the continental slope sediments in front of Los Tuxtlas, Gulf of Mexico, Mexico: implications on weathering, origin and depositional environments

    Science.gov (United States)

    Marca-Castillo, M. E.; Armstrong-Altrin, J.

    2017-12-01

    The textural analysis, mineralogy and geochemistry of two sediment cores recovered from the deep water zone of the southwestern part of the Gulf of Mexico ( 1666 and 1672 m water depth) were studied to infer the provenance and depositional behavior. The textural analysis revealed that both cores are dominated by silt, which occupy more than 50% in both samples and the clay occupy 40%. The petrographic analysis revealed remains of biogenic origin sediments and lithic fragments with an angular shape and low sphericity, indicating a low energy environment and therefore a low level of weathering in the sediment, which suggests that the sediments were not affected by transport and derived from a nearby source rock. In both cores quartz fragments were identified; also volcanic lithic and pyroxenes fragments, which are rocks of intermediate composition and are generally associated with the volcanic activity of the continental margins. SEM-EDS studies showed that the analysed samples have concentrations of minerals such as barite, gibbsite, kaolinite, grossular, magnetite, plagioclase and chlorite, which are probably derived from the mainland to the deep sea zone. In the trace element analysis it was observed a low Sc content, while Co, Ni, V and Cu are slightly enriched with respect to the upper continental crust; this enrichment is related to sediments from intermediate sources. The sediments are classified as shale in the log (SiO2 / Al2O3) - log (Fe2O / K2O) diagram. The fine particles of the shale indicate that a deposit occurred as a result of the gradual sedimentation due to relatively non-turbulent currents, which is consistent with the petrographic analysis. The geochemical features of major and trace elements suggest sediments were derived largely from the natural andesite erosion of coastal regions along the Gulf of Mexico. High values of Fe2O3 and MnO are observed in the upper intervals, reflecting the influence of volcanic sediments. The major element

  12. Chemical characterization, nano-particle mineralogy and particle size distribution of basalt dust wastes

    International Nuclear Information System (INIS)

    Dalmora, Adilson C.; Ramos, Claudete G.; Oliveira, Marcos L.S.; Teixeira, Elba C.; Kautzmann, Rubens M.; Taffarel, Silvio R.; Brum, Irineu A.S. de

    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 SiO 2 , Al 2 O 3 , and Fe 2 O 3, 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

  13. 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

  14. 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

  15. The Role of Anionogenic Elements (As, Sb, Mo, Se, S, P, N, Cl, F, C) In The Formation of Technogenic Geochemical Anomalies

    Science.gov (United States)

    Abrosimova, Natalya; Bortnikova, Svetlana

    2017-12-01

    The study was conducted on the example of sulphide-containing mine tailings with a varying amount of sulphide and arsenide minerals, from three distinct tailings dumps situated in Russia: Karabash Mine Site, South Ural; Komsomolsk tailings impoundment, Kemerovo region; Khovu-Aksy mine site, Tuva Republic. The aim of the study was to compare the mobility of anionogenic elements (As, Sb, Mo, Se, S, P, N, Cl, F, C) and their role in migration, precipitation, and concentration of metals during the water-tailings interaction depending on the physicochemical parameters (pH, Eh) of the medium and the mineral composition of the waste material. Using slightly acidic leaching experiments the quantitative estimation of mobile forms of elements is given. Based on the compositions of the obtained water leaching solutions, aqueous speciation of chemical elements and saturation index of key minerals in the experimental solutions were calculated. The results of calculating forms of chemical elements made it possible to construct series of mobility of metals and metalloids in solutions with different physicochemical parameters. In the alkaline conditions, Sb>As>Cd>Cu>Zn>Fe>Pb, when the medium is acidified, the series changes, As>Cd>Cu>Zn>Pb>Sb>Fe in weakly alkaline conditions, Sb>Mn>As>Zn>Fe however, when the medium is acidified, the series changes to Cd>Mn>Pb>Cu>Zn>Sb>Ni>Fe>As under acidic conditions Cd>Cu>Zn>Pb>Mn>Fe>Se>Mo>Sb>As>Ni. The mineral composition of the tailings was investigated, which will allow to determine the sources of toxic elements and to understand the processes of secondary mineral formation in technogenic objects. Arsenopyrite and pyrite predominate in the heavy fraction of the Komsomolsk tailings impoundment, arsenopyrite grains are often corroded, Sb contained in Sb oxide and Sb sulfide. The pyrite and barite are determined in the solid matter of the Karabash Mine Site and chalcopyrite, sphalerite, tennantite Cu3AsS3, and tetrahedrite (Cu,Fe)12Sb4S13 are

  16. 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

  17. Geology, mineralization, mineral chemistry, and ore-fluid conditions of Irankuh Pb-Zn mining district, south of Isfahan

    Directory of Open Access Journals (Sweden)

    Mohammad Hassan Karimpour

    2017-11-01

    Full Text Available Introduction The Irankuh mining district area located at the southern part of the Malayer-Isfahan metallogenic belt, south of Isfahan, consists of several Zn-Pb deposits and occurrences such as Tappehsorkh, Rowmarmar 5, Kolahdarvazeh, Blind ore, and Gushfil deposits as well as Rowmarmar 1-4 and Gushfil 1 prospects. Based on geology, alteration, form and texture of mineralization, and paragenesis assemblages, Pb-Zn mineralization is Mississippi-type deposit (Rastad, 1981; Ghazban et al., 1994; Ghasemi, 1995; Reichert, 2007; Timoori-Asl (2010; Ayati et al., 2013; Hosseini-Dinani et al., 2015. Geology of the area consists of Jurassic siltstone and shale and different types of Cretaceous dolostone and limestone. The aim of this research is new geological studies such as revision of old geologic map, study of different types of textures and mineral assemblages within carbonate and clastic host rocks, and chemistry of galena, sphalerite, and dolomite. Finally, we combined these results with isotopic and fluid inclusion data and discussed on ore-fluid conditions. Materials and Methods In order to achieve the aims of this work, at first field surveying and sampling were done. Then, 200 thin and 70 polished thin sections were prepared. Some of the samples were selected for microprobe analysis and galena and sphalerite minerals were analyzed by using JEOL- JAX-8230 analyzer at Colorado University, USA. The chemistry of dolomite and fluid inclusion data are used after Boveiri Konari and Rastad (2016 and stable isotope is used after Ghazban et al. (1994. Discussion The Irankuh mineralization is hosted by carbonate rocks (dolostone and limestone and minor clastic rocks as epigenetic. Mineralization has occurred as breccia, veinlet, open space filling, spoted, dessiminated, and replacement (carbonate hosted rock. The mineral assemblages are Fe-rich sphalerite, galena, minor pyrite, Fe- and Mn-rich dolomite, bituminous, ankrite, calcite ± quartz ± barite

  18. 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

  19. 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

  20. 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.; 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

  1. A New Occurrence of Alkaline Magmatism on the Kola Peninsula: An Agpaitic Dyke in the Kandalaksha Region.

    Science.gov (United States)

    Akimenko, Mariya; Kogarko, Lia; Sorokhtina, Natalia; Kononkova, Natalia; Mamontov, Vladimir

    2015-04-01

    A new occurrence of alkaline dyke magmatism was discovered in 2010 during the geological works performed by the Murmansk Geological Prospecting Expedition in the "Mokhnatye Roga" area located 55 km to the southeast of the Kovdor massif (67°15' N, 31°30' E). The "Mokhnatye Roga" area is located in the Ensk segment of the northwestern part of the Belomorian mobile belt. We performed a complete petrological and geochemical description of the sections in Holes 19 and 24, which reveal one of the largest dykes in the area. The dyke, with a length of ≈4 km and a width of ≈160 m, has an eastern orientation with steep dipping (60°-90°) to the north. The thickness of Quaternary deposits ranges from 0.8 to 4.0 m; alkaline rocks occur in the range of 4.0-93.9 m being followed by host amphibole-biotite gneiss with interbeds of plagioamphibolite (AR2 mt) along the section. Among the major minerals of the dyke are the minerals of the lamprophyllite group (20-25 vol %), aegirine-augite (10-15 vol %), enigmatite (10-15 vol %), nepheline (10-15 vol %), orthoclase (15-20 vol %), alkaline amphibole (5-10 vol %), and astrophyllite (up to 5 vol %). The minor minerals are represented by shcherbakovite, sodalite, natrolite, barite, Mn carbonate, ilmenite, rutile, sphalerite, and goethite. The texture of the rock is porphyric: the groundmass is composed of finegranular nepheline and orthoclase, which are observed as individual large euhedral crystals as well. In addition, large phenocrysts are represented by the minerals of the lamprophyllite, enigmatite, pyroxene, and alkaline amphibole groups. Based on the generally accepted classifications [1], the studied agpaitic rock may be related to nepheline syenite; according to the mineral and chemical compositions, it is close to syenite of the Niva massif [2] located 35 km to the northeast from the "Mokhnatye Roga" area. Agpaitic syenite of the "Mokhnatye Roga" area is extremely enriched in dispersed and rare lithophile elements. The

  2. Candoglia Marble and the "Veneranda Fabbrica del Duomo di Milano": a resource for Global Heritage Stone Designation in the Italian Alps

    Science.gov (United States)

    Borghi, Alessandro; Castelli, Daniele; Corbetta, Elio; Antonella Dino, Giovanna

    2015-04-01

    Alpine marbles have been widely used in the past for celebrated, both indoor and outdoor, applications. Among them, the Candoglia Marble, a worldwide known and appreciated georesource, and its "bastard brother" from the nearby Ornavasso area were and are exploited in the Verbano-Cusio-Ossola quarry basin of Northwestern Italian Alps. They crop out as lenses (up to 30 m in thickness) interlayered within high-grade paragneisses of the Ivrea Zone, a section of deep continental crust that experienced amphibolite- to granulite-facies metamorphism of Palaeozoic age. The Candoglia and Ornavasso Marbles are pinkish to greyish, coarse-grained (> 3 mm), calcitic marbles with frequent, cm-thick, dark-greenish silicate layers containing diopside and tremolite; minor minerals include quartz, epidote, sulphides, Ba-feldspar, barite and, occasionally, phlogopite. First record of quarrying activities in the area arises to the Roman age (Ornavasso quarrying area). Both the Ornavasso and Candoglia Marbles were widely employed in local construction (San Nicola Church and Torre della Guardia at Ornavasso, Madonna di Campagna Church at Verbania, San Giovanni in Montorfano Church), but they became famous thanks to their application for the "Duomo di Milano" since the fourteenth century. At the beginning, the building stones employed for the construction of the Gothic style, Duomo di Milano were quarried in the Ornavasso area, but in a short time, the Candoglia quarry (property of the so-called "Veneranda Fabbrica del Duomo" that incessantly takes care of the Cathedral Church from 1387 A.D.) became the main quarry for the construction and maintenance of the Cathedral. The Candoglia quarry developed during the centuries, from open pit small quarries to a unique underground quarry, characterised by a very peculiar quarrying activities (subvertical bench characterized by strong lateral forces, which have to be contrasted and monitored). The Candoglia Marble was preferred to Carrara marbles

  3. 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

  4. Mineral resources of the southern half of Zone III Santander, Norte de Santander and Boyaca, Colombia

    Science.gov (United States)

    Ward, Dwight Edward; Goldsmith, Richard; Cruz, Bruna B.; Restrepo, Jaime; Hernan, A.

    1970-01-01

    The areas covered by this report lies in the eastern Cordillera of the Colombian Andes in the region around Bucaramanga. This part of the eastern Cordillera consists of a structurally complex core of metamorphic and igneous rocks of Precambrian to Mesozoic age, flanked to east and west by faulted and folded sedimentary strata of late Paleozoic to Tertiary age. Infaulted blocks of sedimentary rocks are locally present in the massif. Unconsolidated deposits of Quaternary age, primarily terraced alluvium, are 10cally extensive in valleys on the flanks of the range. The crystalline central core of the range is called the Santander massif. In it are located the principal sold deposits and scattered deposits of copper, lead, zinc, and fluorite. The sedimentary rocks flanking the massif contain significant deposits of phosphate rock and gypsum, as well as other nonmetallic industrial minerals such as limestone, barite, glass sand, and coal. A belt of lead-zinc prospects in carbonate and sandstone beds of Cretaceous age on the east side of the range warrants further investigation. Gold and silver are the only important metallic minerals that have been produced in the Santander massif. Mining dates back to colonial and possibly to pre-colonial times and continues on a small scale at present. The California and Vetas district was the main area of investigation of metallic minerals during the present project. Results of geochemical sampling of stream sediments and assays of vein material indicate that the main potential of the area is in gold with lesser potentials in copper, lead, zinc, and silver. Mineralization of the district is probably younger than Early Cretaceous. Although no copper minerals have been mined elsewhere in the massif, small amounts of copper minerals in various rocks in scattered areas is revealed by green and blue stains of copper carbonates and sulfates. Deposits of greatest areal extent are in arkosic conglomeratic beds of the Giron Formation. These

  5. Rubidium, Strontium, Bromide, and Total Iodine Concentrations Consolidate Evidence for Seawater Dissolution of the Jurassic Louann Salt as the Source of the Orca Basin Brine

    Science.gov (United States)

    Schijf, J.

    2007-05-01

    A profile of filtered seawater and brine samples was collected in the summer of 2003 from a depth of 1500 m down to the bottom of the anoxic, hypersaline Orca Basin (northern Gulf of Mexico). Using ion chromatography and inductively coupled plasma mass spectrometry (ICP-MS), these samples were analyzed for alkali cations (Na+, K+, Rb+), alkaline earth cations (Mg2+, Ca2+, Sr2+, Ba2+), and the major anions chloride (Cl-) and sulfate (SO42-). Major ion concentrations in the brine are consistent with previous studies, confirming that Na plus Cl make up more than 95% of its composition, hence governing its density and hydrodynamic stability. Binary mixing plots across the interface between deep Gulf of Mexico seawater and the anoxic brine are generally linear, but display substantial deviations from conservative behavior at the steepest part of the pycnocline for all analytes except Na, Cl, and Ca. Negative deviations signify localized cation removal by an adsorption or ion-exchange process, probably associated with the dense layers of particles that are trapped there. Especially strong Mg removal may be indicative of dolomitization, whereby the concomitant release of Ca counters its adsorption, resulting in zero net Ca removal. A positive deviation for sulfate is attributed to bacterial sulfide oxidation. Concentrations of Rb, Sr, and Ba in the homogeneous brine, reported here for the first time, are enriched by factors of 1.5, 1.4, and ~9, respectively, with respect to the overlying seawater. Unlike Ca and Sr, Ba concentrations in the brine are clearly controlled by the solubility of its sulfate salt (barite), causing a maximum of 670 nmol/kg at the interface. Several independent lines of evidence, for example downward decreasing salinity gradients in the sediment pore waters, seismic surveys revealing salt exposure on the upper slope, and the discovery of a brine river flowing into the Orca Basin, suggest that the brine is formed outside the basin, most likely by

  6. 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

  7. Processes affecting δ34S and δ18O values of dissolved sulfate in alluvium along the Canadian River, central Oklahoma, USA

    Science.gov (United States)

    Tuttle, Michele L.W.; Breit, George N.; Cozzarelli, Isabelle M.

    2009-01-01

    The δ34S and δ18O values for dissolved sulfate in groundwater are commonly used in aquifer studies to identify sulfate reservoirs and describe biogeochemical processes. The utility of these data, however, often is compromised by mixing of sulfate sources within reservoirs and isotope fractionation during sulfur redox cycling. Our study shows that, after all potential sulfate sources are identified and isotopically characterized, the δ34SSO4 and δ18OSO4 values differentiate processes such as sulfate-source mixing, sulfide oxidation, barite dissolution, and organosulfur decomposition. During bacterial reduction of sulfate, the values reflect kinetic sulfur isotope fractionation and exchange of oxygen isotopes between sulfate and water. Detailed analysis of the chemistry (Cl and SO4 concentrations) and isotopic composition (δ2HH2Oand δ18OH2O) of groundwater in an alluvial aquifer in Central Oklahoma, USA allowed the identification of five distinct end members that supply water to the aquifer (regional groundwater flowing into the study area, river water, leachate from a closed landfill that operated within the site, rain, and surface runoff). The δ34SSO4 and δ18OSO4 values in each end member differentiated three sources of sulfate: sulfate dissolved from Early to Late Permian rocks within the drainage basin (δ34SSO4 = 8–12‰ and δ18OSO4 = 10‰), iron sulfides oxidized by molecular oxygen during low water-table levels (δ34SSO4 = − 16‰ and δ18OSO4 = 10‰), and organosulfur compounds (predominately ester sulfates) from decomposition of vegetation on the surface and from landfill trash buried in the alluvium (δ34SSO4 = 8‰ and δ18OSO4 = 6‰). During bacterial reduction of these sulfate sources, similar isotope fractionation processes are recorded in the parallel trends of increasing δ34SSO4 and δ18OSO4 values. When extensive reduction occurs, the kinetic sulfur isotope fractionation (estimated by εH2S–SO4 = − 23

  8. Roymillerite, Pb24Mg9(Si9AlO28)(SiO4)(BO3)(CO3)10(OH)14O4, a new mineral: mineralogical characterization and crystal chemistry

    Science.gov (United States)

    Chukanov, Nikita V.; Jonsson, Erik; Aksenov, Sergey M.; Britvin, Sergey N.; Rastsvetaeva, Ramiza K.; Belakovskiy, Dmitriy I.; Van, Konstantin V.

    2017-11-01

    The new mineral roymillerite Pb24Mg9(Si9AlO28)(SiO4)(BO3)(CO3)10(OH)14O4, related to britvinite and molybdophyllite, was discovered in a Pb-rich assemblage from the Kombat Mine, Grootfontein district, Otjozondjupa region, Namibia, which includes also jacobsite, cerussite, hausmannite, sahlinite, rhodochrosite, barite, grootfonteinite, Mn-Fe oxides, and melanotekite. Roymillerite forms platy single-crystal grains up to 1.5 mm across and up to 0.3 mm thick. The new mineral is transparent, colorless to light pink, with a strong vitreous lustre. Cleavage is perfect on (001). Density calculated using the empirical formula is equal to 5.973 g/cm3. Roymillerite is optically biaxial, negative, α = 1.86(1), β ≈ γ = 1.94(1), 2 V (meas.) = 5(5)°. The IR spectrum shows the presence of britvinite-type tetrahedral sheets, {CO}3^{2 - }, {BO}3^{3 - }, and OH- groups. The chemical composition is (wt%; electron microprobe, H2O and CO2 determined by gas chromatography, the content of B2O3 derived from structural data): MgO 4.93, MnO 1.24, FeO 0.95, PbO 75.38, B2O3 0.50, Al2O3 0.74, CO2 5.83, SiO2 7.90, H2O 1.8, total 99.27. The empirical formula based on 83 O atoms pfu (i.e. Z = 1) is Pb24.12Mg8.74Mn1.25Fe0.94B1.03Al1.04C9.46Si9.39H14.27O83. The crystal structure was determined using single-crystal X-ray diffraction data. The new mineral is triclinic, space group P \\bar{1}, with a = 9.315(1), b = 9.316(1), c = 26.463(4) Å, α = 83.295(3)°, β = 83.308(3)°, γ = 60.023(2)°, V = 1971.2(6) Å3. The crystal structure of roymillerite is based built by alternating pyrophyllite-type TOT-modules Mg9(OH)8[(Si,Al)10O28] and I-blocks Pb24(OH)6O4(CO3)10(BO3,SiO4). The strongest lines of the powder X-ray diffraction pattern [ d, Å (I, %) ( hkl)] are: 25.9 (100) (001), 13.1 (11) (002), 3.480 (12) (017, 107, -115, 1-15), 3.378 (14) (126, 216), 3.282 (16) (-2-15, -1-25), 3.185 (12) (-116, 1-16), 2.684 (16) (031, 301, 030, 300, 332, -109, 0-19, 1-18), 2.382 (11) (0.0.-11). Roymillerite is

  9. Summary of the mineralogy of the Colorado Plateau uranium ores

    Science.gov (United States)

    Weeks, Alice D.; Coleman, Robert Griffin; Thompson, Mary E.

    1956-01-01

    In the Colorado Plateau uranium has been produced chiefly from very shallow mines in carnotite ores (oxidized vanadiferous uranium ores) until recent deeper mining penetrated black unoxidized ores in water-saturated rocks and extensive exploration has discovered many deposits of low to nonvanadiferous ores. The uranium ores include a wide range from highly vanadiferous and from as much as one percent to a trace of copper, and contain a small amount of iron and traces of lead, zinc, molybdenum, cobalt, nickel, silver, manganese, and other metals. Recent investigation indicates that the carnotite ores have been derived by progressive oxidation of primary (unoxidized) black ores that contain low-valent uranium and vanadium oxides and silicates. The uranium minerals, uraninite and coffinite, are associated with coalified wood or other carbonaceous material. The vanadium minerals, chiefly montroseite, roscoelite, and other vanadium silicates, occur in the interstices of the sandstone and in siltstone and clay pellets as well as associated with fossil wood. Calcite, dolomite, barite and minor amounts of sulfides, arsenides, and selenides occur in the unoxidized ore. Partially oxidized vanadiferous ore is blue black, purplish brown, or greenish black in contrast to the black or dark gray unoxidized ore. Vanadium combines with uranium to form rauvite. The excess vanadium is present in corvusite, fernandinite, melanovanadite and many other quadrivalent and quinquevalent vanadium minerals as well as in vanadium silicates. Pyrite and part or all of the calcite are replaced by iron oxides and gypsum. In oxidized vanadiferous uranium ores the uranium is fixed in the relatively insoluble minerals carnotite and tyuyamunite, and the excess vanadium commonly combines with one or more of the following: calcium, sodium, potassium, magnesium, aluminum, iron, copper, manganese, or barium, or rarely it forms the hydrated pentoxide. The relatively stable vanadium silicates are little

  10. FY12 ARRA-NRAP Report – Studies to Support Risk Assessment of Geologic Carbon Sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Cantrell, Kirk J.; Shao, Hongbo; Thompson, C. J.; Zhong, Lirong; Jung, Hun Bok; Um, Wooyong

    2011-09-27

    This report summarizes results of research conducted during FY2012 to support the assessment of environmental risks associated with geologic carbon dioxide (CO2) sequestration and storage. Several research focus areas are ongoing as part of this project. This includes the quantification of the leachability of metals and organic compounds from representative CO2 storage reservoir and caprock materials, the fate of metals and organic compounds after release, and the development of a method to measure pH in situ under supercritical CO2 (scCO2) conditions. Metal leachability experiments were completed on 6 different rock samples in brine in equilibrium with scCO2 at representative geologic reservoir conditions. In general, the leaching of RCRA metals and other metals of concern was found to be limited and not likely to be a significant issue (at least, for the rocks tested). Metals leaching experiments were also completed on 1 rock sample with scCO2 containing oxygen at concentrations of 0, 1, 5, and 10% to simulate injection of CO2 originating from the oxy-fuel combustion process. Significant differences in the leaching behavior of certain metals were observed when oxygen is present in the CO2. These differences resulted from oxidation of sulfides, release of sulfate, ferric iron and other metals, and subsequent precipitation of iron oxides and some sulfates such as barite. Experiments to evaluate the potential for mobilization of organic compounds from representative reservoir materials and cap rock and their fate in porous media (quartz sand) have been conducted. Results with Fruitland coal and Gothic shale indicate that lighter organic compounds were more susceptible to mobilization by scCO2 compared to heavier compounds. Alkanes demonstrated very low extractability by scCO2. No significant differences were observed between the extractability of organic compounds by dry or water saturated scCO2. Reaction equilibrium appears to have been reached by 96 hours. When

  11. The Lepanto Cu–Au deposit, Philippines: A fossil hyperacidic volcanic lake complex

    Science.gov (United States)

    Berger, Byron R.; Henley, Richard W.; Lowers, Heather; Pribil, Michael

    2014-01-01

    Hyperacidic lakes and associated solfatara in active volcanoes are the expression of magmatic gas expansion from source to surface. Here we show for the first time, that the vein system that comprises the ~ 2 Ma high-sulfidation, Lepanto copper–gold deposit in the Mankayan district (Philippines) was associated with a contemporary hyperacidic volcanic lake complex—possibly the first such lake recognized in the geological record. A 15–20‰ difference in sulfur isotopic composition between barite and sulfides and sulfosalts in the vent fumarole encrustations supports the interpretation that SO2-rich volcanic gas vented into the base of the lake and marginal to it and ties the mineralization directly to magmatic gas expansion, fracture propagation, and mineralization that occurred through a series of decompression steps within the feeder fracture network. These data confirm that crater lake environments such as Kawah Ijen (Java, Indonesia) provide modern day analogs of the Lepanto and other high sulfidation Cu–Au depositing environments.We also provide extensive analysis of sulfosalt–sulfide reactions during vein formation within the hyperacidic lake complex. Pyrite ±  silica deposited first at high temperature followed by enargite that preserves the vapor–solid diffusion of, for example, antimony, tin, and tellurium into the vapor from the crystallizing solid. Subsolidus, intra-crystalline diffusion continued as temperature declined. Pyrite and enargite are replaced by Fe-tennantite in the lodes which initially has low Sb/(Sb + As) atomic ratios around 13.5% close to the ideal tennantite formula, but evolves to higher ratios as crystallization proceeds. Fumarole encrustation clasts and sulfosalts in the lake sediment are more highly evolved with a larger range of trace element substitutions, including antimony. Substitution of especially Zn, Te, Ag, and Sn into tennantite records metal and semi-metal fractionation between the expanding magmatic

  12. Kinematics of low angle normal fault on Mykonos island (Cyclades, Greece)

    Science.gov (United States)

    Lecomte, E.; Jolivet, L.; Lacombe, O.; Denele, Y.; Labrousse, L.; Le Pourhiet, L.

    2009-04-01

    -dipping normal faults soling into gouges. Soft-sediment deformation is observed in the hanging-wall in the vicinity of normal faults. Slumps and fan-shaped deposits related to high-angle normal faults soling into the detachment, testifying for its syn-sedimentary kinematics. The inversion of fault-slip data indicates that the direction of the minimal stress axis is parallel to the stretching lineation and the direction of the maximal stress axis is sub-vertical. This is consistent with late sub-vertical barite dikes cutting all units from the upper part of the granite to the sedimentary unit. Both the attitude of sediments and palaeo-stress results preclude a significant post-slip tilt of the whole structure. The Mykonos detachment shows a continuum from ductile to brittle with a clearly reactivation of the detachment in brittle conditions.

  13. 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)

    Mathieu, Regis

    1999-01-01

    ). The low to moderately saline (3-18 wt% NaCl) fluids with higher temperatures (200-550 deg. C), containing traces of O 2 , CH 4 and CO 2 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 (δ 13 C= 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 87 Sr/ 86 Sr 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 87 Sr/ 86 Sr 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) [fr

  14. Resultados do tratamento cirúrgico da doença do refluxo gastroesofágico em crianças com e sem afecções neurológicas concomitantes Results of surgical treatment of gastroesophageal reflux disease (GERD in children with and without concomitant neurological affections

    Directory of Open Access Journals (Sweden)

    José Lúcio Martins Machado

    2007-03-01

    children; Group II - 60 children with neurological disorders. Barited contrast of aesophagus, stomach and duodenum, high endoscopy with biopsy, 24 hours esophageal pHmetry and cintilography were the tests utilized in the diagnosis and evaluation of the efficacy of the surgery. All operated patients were refractory to clinical treatment prior to surgery. The anti-reflux surgery performed was Lind fundoplication, being associated to gastrostomy in 55% of the Group II patients. RESULTS: In Group II, surgery was indicated earlier than Group I. Among neuropaths, their highly affected neural psyquic motor development and repeated pneumonia were the main causes of surgery indication. Hospitalization time, number of re-operations and the need for post-operation esophageal dilatation were greater in Group II (p<0.01. Three deaths occurred in Group II during late post-operative period (sepsis and severe respiratory infection. CONCLUSION: The procedure performed is satisfactory for surgical reflux treatment. However, further studies of neuropath children population with reflux are imperative as they respond less favorably to surgery with regard to mortality rates, recurrence of respiratory symptoms, re-operation rates and severity of post-operative complications.

  15. Phonolite-hosted zeolite deposits in the Kaiserstuhl Volcanic Complex, Germany

    Science.gov (United States)

    Weisenberger, Tobias; Spürgin, Simon

    2014-05-01

    Several subvolcanic phonolitic intrusions occur within the Miocene Kaiserstuhl Volcanic Complex (KVC) located in the central-southern segment of the Upper Rhine Graben, which is part of the European Cenozoic Rift System. Hydrothermally altered phonolitic rocks are of economic interest, due to the high (>40 wt%) zeolite content, which accounts for the remarkable zeolitic physicochemical properties of the ground rock. These properties have widespread industrial application in water softening, catalysis, remediation of soils and soil quality, wastewater treatment, and as additive in the cement industry. Currently the largest phonolite intrusion Fohberg is active in mining, located in the eastern part of the KVC. The Endhale phonolite, approximately 1.5 km to the north marks a further deposit currently under exploration. Both phonolites are hosted in Tertiary sedimentary units. The aim of this study is to carry out a new mineralogical and geochemical data a) to evaluate the manifestation of hydrothermal alteration of the Fohberg and Endhale phonolitic intrusions, and b) to constrain the physical and chemical properties of the fluids, which promoted hydrothermal replacement of primary igneous minerals. The high degree of alteration is in contrast to the only slightly altered Kirchberg phonolite in the western KVC. The alkaline intrusive bodies are characterized by the primary mineralogy: feldspathoid mineral, K-feldspar, aegirine-augite, wollastonite, and andradite, with additional REE-minerals (e.g. götzenite). Fluid-induced re-equilibration of feldspathoid minerals and wollastonite caused breakdown to a set of secondary phases. Feldspathoid minerals are totally replaced by secondary phases including various zeolite species, calcite, and barite. Wollastonite breakdown results in the formation of various zeolites, calcite, pectolite, sepiolite, and quartz. The large variability of secondary minerals indicates a heterogenic fluid composition throughout the phonolitic

  16. Depositional setting and geochemistry of phosphorites and metalliferous black shales in the Carboniferous-Permian Lisburne Group, Northern Alaska

    Science.gov (United States)

    Dumoulin, Julie A.; Slack, John F.; Whalen, Michael T.; Harris, Anita G.

    2011-01-01

    oxygenation of the atmosphere and oceans during the Carboniferous evolution of large vascular land plants. Black shales within the phosphorite sections have up to 20.2 weight percent Corg and are potential petroleum source rocks. Locally, these strata also are metalliferous, with up to 1,690 ppm Cr, 2,831 ppm V, 551 ppm Ni, 4,670 ppm Zn, 312 ppm Cu, 43.5 ppm Ag, and 12.3 ppm Tl; concentrations of these metals covary broadly with Corg, suggesting coupled redox variations. Calculated marine fractions (MF) of Cr, V, and Mo, used to evaluate the paleoredox state of the bottom waters, show generally high CrMF/MoMF and VMF/MoMF ratios that indicate deposition of the black shales under suboxic denitrifying conditions; Re/Mo ratios also plot mainly within the suboxic field and support this interpretation. Predominantly seawater and biogenic sources are indicated for Cr, V, Mo, Zn, Cd, Ni, and Cu in the black shales, with an additional hydrothermal contribution inferred for Zn, Cd, Ag, and Tl in some samples. Lisburne Group phosphorites formed in the Ikpikpuk Basin and along both sides of the mud- and chert-rich Kuna Basin, which hosts giant massive sulfide and barite deposits of the Red Dog district. Lisburne Group phosphatic strata are coeval with these deposits and formed in response to a nutrient-rich upwelling regime. Phosphate deposition occurred mainly in suboxic bottom waters based on data for paleoredox proxies (Cr, V, Mo, Re) within contemporaneous black shales. Recent global reconstructions are consistent with Carboniferous upwelling in northern Alaska, but differ in the type of upwelling expected (zonal versus meridional). Paleoenvironmental data suggest that meridional upwelling may better explain phosphorite deposition in the Lisburne Group.

  17. Relationship between microbial sulfate reduction rates and sulfur isotopic fractionation

    Science.gov (United States)

    Matsu'Ura, F.

    2009-12-01

    Sulfate reduction is one of the common processes to obtain energy for certain types of microorganisms.They use hydrogen gas or organic substrates as electron donor and sulfates as electron acceptor, and reduce sulfates to sulfides. Sulfate reducing microbes extend across domains Archea and Bacteria, and are believed to be one of the earliest forms of terrestrial life (Shen 2004). The origin of 34S-depleted (light) sulfide sulfur, especially δ34S bacteria (SRB) to explain the 34S-depleted sulfide sulfur. [Experiments] To compare the result with Canfield et al. (2006), I used Desulfovibrio desulfuricans for my laboratory culture experiment. D. desulfuricans was inoculated into glass vials, which contain 40ml of liquid culture media slightly modified from DSMZ #63 medium.Excess amount of Fe (II) is added to the DSMZ#63 medium to precipitate sulfide as iron sulfide. The vials were incubated at 25°C, 30°C, and 37°C, respectively. 21 vials were used for one temperature and sulfide and sulfate was collected from each three glass vials at every 12 hours from 72 hours to 144 hours after start of incubation. The sulfide was precipitated as iron sulfide and the sulfate was precipitated as barite. Sulfur isotope compositions of sulfate and sulfide were measured by standard method using Delta Plus mass-spectrometer. [Results and Discussion] The fractionation between sulfide and sulfate ranged from 2.7 to 11.0. The fractionation values varied among the different incubation temperature and growth phase of D. desulfuricans. The maximum fractionation values of three incubation temperatures were 9.9, 11.0, and 9.7, for 25 °C, 30°C, and 37°C, respectively. These results were different from standard model and Canfield et al. (2006). I could not find the clear correlation between ∂34S values and incubation temperatures in this experiment. The measured fractionation values during the incubation varied with incubation stage. The fractionation values clearly increased with

  18. Coupled Heat and Fluid Flow Modeling of the Earth's Largest Zinc Ore Deposit at Red Dog, Alaska: Implications for Structurally-Focused, Free Convection in Submarine Sedimentary Basins

    Science.gov (United States)

    Garven, G.; Dumoulin, J. A.; Bradley, D. A.; Young, L. E.; Kelley, K. D.; Leach, D. L.

    2002-12-01

    Crustal heat flow can provide a strong mechanism for driving groundwater flow, particularly in submarine basins where other mechanisms for driving pore fluid flow such as topography, compaction and crustal deformation are too weak or too slow to have a significant effect on disturbing conductive heat flow. Fault zones appear to play a crucial role in focusing fluid migration in basins, as inferred in ancient rocks by many examples of hydrothermal deposits of sediment-hosted ores worldwide. Many rift-hosted deposits of lead, zinc, and barite ore appear to have formed at or near the seafloor by focused venting of hot basinal fluids and modified seawater, although the geophysical nature of these systems is not so well known. For example, the upper Kuna Formation, a finely laminated, black, organic-rich siliceous mudstone and shale in the Western Brooks Range of northwest Alaska, is host to the largest resources of zinc yet discovered in the Earth's crust, containing ore reserves in excess of 175 Mt averaging about 16% Zn and 5% Pb. Although situated today in a highly-deformed series of structural allocthonous plates thrusted during the Jurassic to Cretaceous Brookian Orogeny, the stratiform ores are thought to have formed much earlier in the anoxic, mud-rich Carboniferous-age Kuna Basin when adjacent carbonate platforms were drowned by rifting and tectonic subsidence. Fluid inclusion studies of ore-stage sphalerite and gangue minerals indicate sub-seafloor mineralization temperatures less than 200oC and most likely between 120 to 150 oC, during a period of sediment diagenesis and extensional faulting. We have constructed fully-coupled numerical models of heat and fluid flow to test hydrologic theories for free convection, submarine venting and subsequent ore formation, as constrained by paleoheat flow and petrologic observations. A finite element grid was designed and adapted for a cross section of the Kuna Basin, geologically restored to latest Mississippian time

  19. Agarwood Waste as A New Fluid Loss Control Agent in Water-based Drilling Fluid

    Directory of Open Access Journals (Sweden)

    Azlinda Azizi

    2013-10-01

    Full Text Available Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4 Agarwood has been used widely in various ways, including traditional medicine and art. The usage of agarwood has grown broader in modern times include in therapeutic medicines and perfumery. In this paper the agarwood waste has been explored to be used as a fluid loss control agent to control fluid loss without affecting the drilling fluid rheological properties which are density, pH, viscosity, yield point and gel strength. Agarwood waste was used as an additive in the drilling fluid system due to its unique characteristic. Rheological and filtration measurements were performed on the formulated water-based drilling fluid. Formulations of a base solution of fresh water, sodium hydroxide, bentonite, barite, and xanthan gum were presented. The performance of the agarwood waste as the fluid loss control agent was compared with based fluid formulation and water-based drilling fluid with treating with conventional fluid loss control agent (starch. The filtrate volume of drilling fluid with agarwood waste was about 13 ml while for drilling fluid with conventional fluid loss control agent, starch gave 12 ml of filtrate volume after undergoing filtration test by using LPLT filter press. The performance of drilling fluid with agarwood was efficient as drilling fluid with starch. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso

  20. Paleohydrogeological events recorded by stable isotopes, fluid inclusions and trace elements in fracture minerals in crystalline rock, Simpevarp area, SE Sweden

    International Nuclear Information System (INIS)

    Drake, Henrik; Tullborg, Eva-Lena

    2009-01-01

    Fracture minerals calcite, pyrite, gypsum, barite and quartz, formed during several events have been analysed for δ 13 C, δ 18 O, δ 34 S, 87 Sr/ 86 Sr, trace element chemistry and fluid inclusions in order to gain knowledge of the paleohydrogeological evolution of the Simpevarp area, south-eastern Sweden. This area is dominated by Proterozoic crystalline rocks and is currently being investigated by the Swedish Nuclear Fuel and Waste Management Co. (SKB) in order to find a suitable location for a deep-seated repository for spent nuclear fuel. Knowledge of the paleohydrogeological evolution is essential to understand the stability or evolution of the groundwater system over a time scale relevant to the performance assessment for a spent nuclear fuel repository. The ages of the minerals analysed range from the Proterozoic to possibly the Quaternary. The Proterozoic calcite and pyrite show inorganic and hydrothermal-magmatic stable isotope signatures and were probably formed during a long time period as indicated by the large span in temperatures (c. 200-360 deg. C) and salinities (0-24 wt.% eq. CaCl 2 ), obtained from fluid inclusion analyses. The Paleozoic minerals were formed from organically influenced brine-type fluids at temperatures of 80-145 deg. C. The isotopic results indicate that low temperature calcite and pyrite may have formed during different events ranging in time possibly from the end of the Paleozoic until the Quaternary. Formation conditions ranging from fresh to brackish and saline waters have been distinguished based on calcite crystal morphologies. The combination of δ 18 O and crystal morphologies show that the fresh-saline water interface has changed considerably over time, and water similar to the present meteoric water and brackish seawater at the site, have most probably earlier been residing in the bedrock. Organic influence and closed system in situ microbial activity causing disequilibrium are indicated by extremely low δ 13 C (down

  1. Minerals and trace elements in silcretes of the Sado basin (Alentejo, southern Portugal) and implications for silcrete formation

    Science.gov (United States)

    Sauer, Daniela; Kullmann, Sarah; Zarei, Mehdi; Stahr, Karl

    2014-05-01

    sediments; later, on the other hand, the climate became cooler, hence intensity of pedogenesis should have decreased. It is assumed that halloysite was preserved over such long period of time, because it was occluded in the silica mass. The micromorphology of the coatings under the SEM includes laminar coverings, banded and alveolar structures. EDS analysis shows that the coatings consist mainly of silicon; in addition they contain aluminum and some also have minor amounts of iron. Trace element contents of the rock samples and silcretes enabled tracing lateral silica flows from the Alto Alentejo into the Sado basin. Some rock samples and silcretes contained considerable amounts of Barium. Even barite crystals were observed in the silica coatings under the SEM. Acknowledgement The authors thank Beate Podtschaske for her valuable help in the laboratory and the German Research Foundation DFG for financial support (project STA 146/45-3).

  2. Isotopic constraints on the age and early differentiation of the Earth.

    Science.gov (United States)

    McCulloch, M T

    1996-03-01

    The Earth's age and early differentiation history are re-evaluated using updated isotopic constraints. From the most primitive terrestrial Pb isotopic compositions found at Isua Greenland, and the Pilbara of Western Australia, combined with precise geochronology of these localities, an age 4.49 +/- 0.02 Ga is obtained. This is interpreted as the mean age of core formation as U/Pb is fractionated due to sequestering of Pb into the Earth's core. The long-lived Rb-Sr isotopic system provides constraints on the time interval for the accretion of the Earth as Rb underwent significant depletion by volatile loss during accretion of the Earth or its precursor planetesimals. A primitive measured 87Sr/86Sr initial ratio of 0.700502 +/- 10 has been obtained for an early Archean (3.46 Ga) barite from the Pilbara Block of Western Australia. Using conservative models for the evolution of Rb/Sr in the early Archean mantle allows an estimate to be placed on the Earth's initial Sr ratio at approximately 4.50 Ga, of 0.69940 +/- 10. This is significantly higher than that measured for the Moon (0.69900 +/- 2) or in the achondrite, Angra dos Reis (0.69894 +/- 2) and for a Rb/Sr ratio of approximately 1/2 of chondrites corresponds to a mean age for accretion of the Earth of 4.48 + /- 0.04 Ga. The now extinct 146Sm-142Nd (T1/2(146)=103 l0(6)yrs) combined with the long-lived 147Sm-143Nd isotopic systematics can also be used to provide limits on the time of early differentiation of the Earth. High precision analyses of the oldest (3.8-3.9 Ga) Archean gneisses from Greenland (Amitsoq and Akilia gneisses), and Canada (Acasta gneiss) do not show measurable (> +/- l0ppm) variations of 142Nd, in contrast to the 33 ppm 142Nd excess reported for an Archean sample. The general lack of 142Nd variations, combined with the presence of highly positive epsilon 143 values (+4.0) at 3.9 Ga, indicates that the record of large-scale Sm/Nd fractionation events was not preserved in the early-Earth from 4

  3. Radium mobility and the age of groundwater in public-drinking-water supplies from the Cambrian-Ordovician aquifer system, north-central USA

    Science.gov (United States)

    Stackelberg, Paul E.; Szabo, Zoltan; Jurgens, Bryant C.

    2018-01-01

    -precipitation with barite as adsorption capacity and the concentration of Ba decreases. Although 226Ra occurred at concentrations greater than 224Ra or 228Ra, the ingestion exposure risk was greater for 228Ra owing to its greater toxicity. In addition, 224Ra added substantial alpha-particle radioactivity to potable samples from the C-O aquifer system. Thus, monitoring for Ra isotopes and gross-alpha-activity (GAA) is important in upgradient, regionally unconfined areas as downgradient, and GAA measurements made within 72 h of sample collection would best capture alpha-particle radiation from the short-lived 224Ra.

  4. A non-classical view of the modulation of mineral precipitation by organic additives

    Science.gov (United States)

    Ruiz-Agudo, Encarnacion; Ruiz-Agudo, Cristina; Burgos-Cara, Alejandro; Putnis, Christine; Rodriguez-Navarro, Carlos; Putnis, Andrew

    2016-04-01

    inhibit the nucleation of solid phases. These effects are linked to the influence of these molecules on polymorph selection. As well, these additives can affect non-classical growth by oriented assembly of nanoparticles. REFERENCES Rodriguez-Navarro, C., Kudłacz, K., Cizer, Ö., Ruiz-Agudo, E., 2015. Formation of amorphous calcium carbonate and its transformation into mesostructured calcite. CrystEngComm 17 (1), 58-72. Ruiz Agudo, C; Ruiz Agudo, E; Putnis, C.V.; Putnis, A., 2015. Mechanistic principles of barite formation: from nanoparticles to micron-sized crystals. Crystal Growth & Design 15, 3724-3733. Verch, A., Gebauer, D., Antonietti, M., Cölfen, H., 2011. How to control the scaling of CaCO3: a "fingerprinting technique" to classify additives. Physical chemistry chemical physics: PCCP 13 (37), 16811-16820.

  5. Sedimentary carbonate-hosted giant Bayan Obo REE-Fe-Nb ore deposit of Inner Mongolia, China; a cornerstone example for giant polymetallic ore deposits of hydrothermal origin

    Science.gov (United States)

    Chao, E.C.T.; Back, J.M.; Minkin, J.A.; Tatsumoto, M.; Junwen, Wang; Conrad, J.E.; McKee, E.H.; Zonglin, Hou; Qingrun, Meng; Shengguang, Huang

    1997-01-01

    Detailed, integrative field and laboratory studies of the textures, structures, chemical characteristics, and isotopically determined ages and signatures of mineralization of the Bayan Obo deposit provided evidence for the origin and characteristics favorable for its formation and parameters necessary for defining giant polymetallic deposits of hydrothermal origin. Bayan Obo is an epigenetic, metasomatic, hydrothermal rare earth element (REE)-Fe-Nb ore deposit that is hosted in the metasedimentary H8 dolostone marble of the Middle Proterozoic Bayan Obo Group. The metasedimentary sequence was deposited on the northern continental slope of the North China craton. The mine area is about 100 km south of the suture marking Caledonian subduction of the Mongolian oceanic plate from the north beneath the North China craton. The mineralogy of the deposit is very complex, consisting of more than 120 different minerals, some of which are epigenetic minerals introduced by hydrothermal solutions, and some of which are primary and secondary metamorphic minerals. The major REE minerals are monazite and bastnaesite, whereas magnetite and hematite are the dominant Fe-ore minerals, and columbite is the most abundant Nb mineral. Dolomite, alkali amphibole, fluorite, barite, aegirine augite, apatite, phlogopite, albite, and microcline are the most widespread gangue minerals. Three general types of ores occur at Bayan Obo: disseminated, banded, and massive ores. Broad zoning of these ore types occurs in the Main and East Orebodies. Disseminated ores are in the outermost zone, banded ores are in the intermediate zone, and massive ores are in the cores of the orebodies. On the basis of field relations, host rocks, textures, structures, and mineral assemblages, many varieties of these three types of ores have been recognized and mapped. Isotopic dating of monazite, bastnaesite, aeschynite, and metamorphic and metasomatic alkali amphiboles associated with the deposit provides constraints

  6. 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

  7. Geology, mineralization, U-Pb dating and Sr-Nd isotope geochemistry of intrusive bodies in northeast of Kashmar

    Directory of Open Access Journals (Sweden)

    Alireza Almasi

    2015-04-01

    + epidotization+ chloride+ sericite+ barite which are synchronous with IOCG veins (specularite+ chalcopyrite+ pyrite± galena± sphalerite± barite± siderite ± etc.. Primary centralized and sulfide base-metal veins in crosscutting points between Dorouneh fault and minor faults. Bahariyeh, Uchpalang and Sarsefidal areas are located in these crosscutting points. Tourmaline (demorterite ±chloride fill the fractures in the intrusive rocks of southern part of area next to the Dorouneh fault occasionally. Lateral alteration synchronous with IOCG veins occur in Kamarmard area. Geochemical data of all veins show Cu, Pb, Zn anomalies (>1% in two type veins, Au anomalies (to about 15 ppm only in IOCG veins, Mn anomalies in two type veins and Ba anomalies in IOCG veins. Alteration and mineralization in the world-class IOCG deposits identified by sodic-calcic and potassic (hydrothermal actinolite and biotite and magnetite± gold in deep parts (Sillitoe, 2003 and advanced argillic+ pyrite+ sericite+ toulrmaline (demorterite in shallow parts (Ray and Dick, 2002. Generally, alteration in the study area is similar to shallow parts of world-class IOCG deposits. Tanourjeh is a IOCG deposit next to the northwest of the study area. In Tanourjeh, the gold-bearing magnetite is synchronous to potassic alteration (hydrothermal biotite and other alterations are advanced argillic, silicification and sericite. These characteristics are similar to deep parts of world-class IOCG deposits. Bahariyeh, Uchpalang and Sarsefidal have similarities to alterations in Tanourjeh. Considering Tanourjeh lie in the lower level rather to Bahariyeh, Uchpalang and Sarsefidal, we believe they erosion surface in Tanourjeh is lower. Kamarmard lies in the highest erosion surface in the study area. Alterations and Mineralization as similar to Kuh e Zar IOCG deposit (specularite+chalcopyrite+gold which is next to the Kamarmard area in Northeast of study area. In Bahariyeh-Uchpalang areas we can see only one IOCG vein but in

  8. Lithofacies, age, depositional setting, and geochemistry of the Otuk Formation in the Red Dog District, northwestern Alaska

    Science.gov (United States)

    Dumoulin, Julie A.; Burruss, Robert A.; Blome, Charles D.

    2013-01-01

    mudstone immediately above this contains radiolarians, foraminifers, conodonts, and halobiid bivalve fragments. The upper (limestone) member (29 m thick) is lime mudstone with monotid bivalves and late Norian radiolarians, overlain by gray chert that contains Rhaetian (latest Triassic) radiolarians; Rhaetian strata have not previously been documented in the Otuk. Rare gray to black shale interbeds in the upper member have as much as 3.4 weight percent TOC. At least 35 m of black mudstone overlies the limestone member; these strata lack interbeds of oil shale and chert that are characteristic of the Blankenship, and instead they resemble the Kingak Shale. Vitrinite reflectance values (2.45 and 2.47 percent Ro) from two samples of black shale in the chert member indicate that these rocks reached a high level of thermal maturity within the dry gas window. Regional correlations indicate that lithofacies in the Otuk Formation vary with both structural and geographic position. For example, the shale member of the Otuk in the Wolverine Creek plate includes more limy layers and less barite (as blades, nodules, and lenses) than equivalent strata in the structurally higher Red Dog plate of the EMA, but it has fewer limy layers than the shale member in the EMA ~450 kilometers (km) to the east at Tiglukpuk Creek. The limestone member of the Otuk is thicker in the Wolverine Creek plate than in the Red Dog plate and differs from this member in EMA sections to the east in containing an upper cherty interval that lacks monotids; a similar interval is seen at the top of the Otuk Formation ~125 km to the west (Lisburne Peninsula). Our observations are consistent with the interpretations of previous researchers that Otuk facies become more distal in higher structural positions and that within a given structural level more distal facies occur to the west. Recent paleogeographic reconstructions indicate that the Otuk accumulated at a relatively high paleolatitude with a bivalve fauna typical

  9. Existencia de estructuras nodulosas de celestina afectadas por silicificación en el Valle de Losa (N. de Burgos

    Directory of Open Access Journals (Sweden)

    Elorza, J.

    1984-04-01

    Full Text Available The present work describes sorne nodules of celestite, which appear in a marly clay level of the Upper Cretaceous (Santonian in Losa Valley (North of Burgos. A great number of nodules have been in some extent, or totally pseudomorphized by quartzine and lutecite (length-slow chalcedony. These nodules have not been mentioned up to now in the research works carried out in the Basque Cantabric Basin; some nodules present elongated shapes, while some others are subspherical, In the inside, the radial arrangement shows pyramidal shapes with rhombic sections, emerging from a compact nucleus. These nodules are diagenetic structures growing expansively from the nucleus towards the periphery. In this action echinoid spines, pelecypods fragments, bryozoans, etc., are enclosed. Celestite here is highly pure; there is no barite at all. For the celestite ions the following origin in proposed. The sulphate was supplied by fluids which laterally migrate from the Triassic gypsum (Keuper. Sr seems to have been released along the transformation process of aragonite sediments to calcite. Although it can't be forgotten the amount of Sr furnished in the parcial dolomitization process suffered by the sedimentary sequence, In the same level, irregular cherts appear associated to celestite nodules. These cherts have a considerable amount of siliceous sponge spicules (litisteids? replaced by sparry carbonate what doubtless shows the biogenic origin of the silica. The silicification process has allowed the preservation of the nodules, in spite of the strong celestite solution which afterwards originated a great loss celestite.

    En el presente trabajo se describen unos nódulos de celestina que aparecen concentrados en un nivel de margas arcillosas pertenecientes al Cretácico superior (Santoniense del Valle de Losa (N. de Burgos. Gran parte de los nódulos se encuentran parcial o totalmente sustituidos por cuarzo en las formas fibrosas de cuarcina y lutecita

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

    Directory of Open Access Journals (Sweden)

    Durand C.

    2006-11-01

    Full Text Available 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 was vizualized by cryoscanning electron microscopy. Our study establishes the mechanism of filtration reduction properties of drilling filter cakes. Filtration measurements and cryomicroscopy show that a well dispersed suspension forms a well connected, homogeneous network that prevents fluid loss. Addition of salts to the drilling fluid promotes the aggregation of the clay particles and introduces heterogeneities so that the fluid loss is increased. Addition of anionic polymers causes a better dispersion of the clay particles in the suspension which lowers the filtration rate. In the presence of both salts and polymers, there is a competition effect between the salt-induced aggregation of the clay particles and the dispersion due to polymers, largely governed by the concentration and valence of the electrolytes and the flexibility of the polymers. During the filtration process more filtration reduction properties are obtained by non adsorbed polymers which clog the pores of the cake network and further reduce the filtration rate. The different behavior of the flexible (Drispac and the rigid polymer (xanthan, can be used to optimize their applications in drilling fluids depending on field conditions (temperature, salt conditions. Afin d'éviter l'endommagement des puits par une perte de fluides, il est nécessaire de former, au cours du forage, un cakeaussi imperméable que possible sur la paroi des puits. L'objectif de l'étude est d'établir des relations

  11. Remote Sensing Analysis of Mineralized Alteration in the Ramand Area (Qazvin Province