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Sample records for chlorites

  1. Diagenetic Chlorite

    DEFF Research Database (Denmark)

    Kazerouni, Afsoon Moatari; Friis, Henrik; Hansen, Jens Peter Vind

    different diffraction pattern. It fills the porosity and reduced permeability in the upper marginal part of the reservoir which had preserved porosity and permeability due to microquartz cementation. The pore-filling chlorite acts as an impermeable seal to hydrocarbon migration and prevents the topmost part...... and relates its possible formation to high-porosity/high-permeability zones of the reservoir. The study suggests that the formation of an intra-sandstone seal of diagenetic chlorite relates to the distribution of early diagenetic microquartz (which preserve porosity and permeability), and early......-coating berthierine. It also preserves porosity and permeability in marginal and isolated parts of the sandstone.In other parts of the sandstone grain coating berthierine precipitated. It was transformed to chlorite with increased depth. A second phase chlorite is distinguished by its morphology and slightly...

  2. Experimental determination of chlorite dissolution rates

    International Nuclear Information System (INIS)

    Current concepts of the geological disposal of low- and intermediate-level radioactive wastes in the UK envisage the construction of a mined facility (incorporating cementitious engineered barriers) in chlorite-bearing rocks. To model accurately the fluid-rock reactions within the disturbed zone surrounding a repository requires functions that describe mineral dissolution kinetics under pH conditions that vary from near neutral to highly alkaline. Therefore, an experimental study to determine the dissolution rates of Fe-rich chlorite has been undertaken as part of the Nirex Safety Assessment Research Program. Four experiments have been carried out at 25 C and four at 70 C, both sets using a range of NaCl/NaOH solutions of differing pH (of nominal pH 9.0, 10.3, 11.6 and 13.0 [at 25 C]). Dissolution rates have been calculated and were found to increase with increasing pH and temperature. However, increased pH resulted in non-stoichiometric dissolution possibly due to preferential dissolution of part of the chlorite structure relative to another, or reprecipitation of some elements as thin hydroxide or oxyhydroxide surface coatings on the chlorite. These results also show that chlorite dissolution is appreciably slower than that of albite and quartz at both 25 and 70 C, but slightly faster than that of muscovite at 70 C

  3. Moessbauer study of some Argentinian chlorites

    International Nuclear Information System (INIS)

    Three chlorite samples obtained from mining areas in Mendoza, Argentina, have been studied by wet chemical analysis, X-ray diffraction and 57Fe Moessbauer spectroscopy. The total Fe contents and the Fe2+/Fe3+ atomic ratio are used to characterize the samples and are discussed in connection to the likely genesis of the minerals. (orig.)

  4. Moessbauer study of some Argentinian chlorites

    Energy Technology Data Exchange (ETDEWEB)

    Gregori, D.A. (Dept. de Geologia, Univ. Nacional del Sur, Bahia Blanca (Argentina)); Mercader, R.C. (Dept. de Fisica, Univ. Nacional de La Plata, La Plata (Argentina))

    1994-02-01

    Three chlorite samples obtained from mining areas in Mendoza, Argentina, have been studied by wet chemical analysis, X-ray diffraction and [sup 57]Fe Moessbauer spectroscopy. The total Fe contents and the Fe[sup 2+]/Fe[sup 3+] atomic ratio are used to characterize the samples and are discussed in connection to the likely genesis of the minerals. (orig.)

  5. Mechanism of reaction of chlorite with mammalian heme peroxidases

    OpenAIRE

    Jakopitsch, Christa; Pirker, Katharina F.; Flemmig, Jörg; Hofbauer, Stefan; Schlorke, Denise; Furtmüller, Paul G.; Arnhold, Jürgen; Obinger, Christian

    2014-01-01

    This study demonstrates that heme peroxidases from different superfamilies react differently with chlorite. In contrast to plant peroxidases, like horseradish peroxidase (HRP), the mammalian counterparts myeloperoxidase (MPO) and lactoperoxidase (LPO) are rapidly and irreversibly inactivated by chlorite in the micromolar concentration range. Chlorite acts as efficient one-electron donor for Compound I and Compound II of MPO and LPO and reacts with the corresponding ferric resting states in a ...

  6. Methane oxidation linked to chlorite dismutation.

    Directory of Open Access Journals (Sweden)

    Laurence G. Miller

    2014-06-01

    Full Text Available We examined the potential for CH4 oxidation to be coupled with oxygen derived from the dissimilatory reduction of perchlorate, chlorate or via chlorite (ClO2- dismutation. Although dissimilatory reduction of ClO4- and ClO3- could be inferred from the accumulation of chloride ions either in spent media or in soil slurries prepared from exposed freshwater lake sediment, neither of these oxyanions evoked methane oxidation when added to either anaerobic mixed cultures or soil enriched in methanotrophs. In contrast, ClO2- amendment elicited such activity. Methane (0.2 kPa was completely removed within several days from the headspace of cell suspensions of Dechloromonas agitata CKB incubated with either Methylococcus capsulatus Bath or Methylomicrobium album BG8 in the presence of 5 mM ClO2-. We also observed complete removal of 0.2 kPa CH4 in bottles containing soil enriched in methanotrophs when co-incubated with D. agitata CKB and 10 mM ClO2-. However, to be effective these experiments required physical separation of soil from D. agitata CKB to allow for the partitioning of O2 liberated from chlorite dismutation into the shared headspace. Although a link between ClO2- and CH4 consumption was established in soils and cultures, no upstream connection with either ClO4- or ClO3- was discerned. This result suggests that the release of O2 during enzymatic perchlorate reduction was negligible, and that the oxygen produced was unavailable to the aerobic methanotrophs.

  7. Sorption of selenite onto chlorite considering mineral dissolution

    International Nuclear Information System (INIS)

    In this study we investigated the sorption of selenite (SeO32-) onto chlorite as a function of Se(IV) concentration, pH, and ionic strength. The sorption isotherm of Se(IV) onto chlorite was successfully presented by both the Langmuir isotherm and Tempkin equation although the Langmuir isotherm is somewhat better than the Tempkin equation. The sorption of Se(IV) onto chlorite was maintained to be constant at an acidic pH region, while the sorption decreased with an increasing pH at neutral and alkaline pH regions. However, the Se(IV) sorption onto chlorite was independent of the ionic strength of NaClO4 solution. The amount of Se(IV) sorbed onto chlorite was significantly low compared to those of iron oxides such as apatite, goethite, hematite, and magnetite because of the lower content of Fe. We also investigated the effect of Fe(II) ions dissolved from chlorite on the Se(IV) sorption as a function of contact time. The chemical oxidation states of selenium sorbed onto chlorite surface were identified using X-ray absorption near edge structure (XANES) at the Pohang synchrotron light source. The amount of Fe(II) dissolved was increased by the contact time of 28 days but decreased after 28-56 days although the amount of dissolved Fe(II) ions was significantly small. This decrease of the dissolved Fe(II) may be due to the formation of Fe-oxyhydroxides such as ferrihydrite. The results of XANES measurements also showed that the Se(IV) sorbed onto chlorite was not reduced into Se(0) or Se(-II) even in the presence of Fe(II) ions in the solution because of the low Fe content of the chlorite although the mechanism was not clearly understood. (author)

  8. Removal of chlorite by reaction with ferrous iron

    OpenAIRE

    Iatrou, Angela

    1991-01-01

    The use of chlorine dioxide as an oxidant and/or disinfectant for drinking water treatment has been an alternative considered when utilities seek to control trihalomethane concentrations. However, concern regarding residual concentrations of chlorite and chlorate have resulted in limitations on applied chlorine dioxide dosages. This study describes the use of ferrous iron as a possible reducing agent for the elimination of residual chlorite from drinking water.

  9. Ideonella dechloratans: Investigation of the chlorite dismutase promoter

    OpenAIRE

    Goetelen, Thijs

    2015-01-01

    Chlorate and perchlorate pollutions have become a problem in the environment in the last decades. Studies have shown that some bacteria can degrade these substances into unharmful substances such as chloride and molecular oxygen. One of these chlorate degrading bacteria is Ideonella dechloratans that uses chlorate reductase and chlorite dismutase to process chlorate. In the promoter gene sequence of chlorite dismutase there might be regulator sequences such as fumarate and nitrate reductase r...

  10. 57Fe Moessbauer investigation of naturally oxidised chlorite

    International Nuclear Information System (INIS)

    The green chlorite, occurring as monomineralic mass in the Sukinda (India) area has been investigated by 57Fe Moessbauer spectroscopy together with IR, XRD and XRF analysis. The Moessbauer spectra (at RT and 100 K), split into four symmetric doublets, show hyperfine parameters suggesting Fe2+ at cis and brucite sites and Fe3+ at trans and cis sites. The results show that susceptibility to oxidation (Fe2+ → Fe3+) is highest in the trans site, moderate in the cis site, and least in the brucite site. (orig.)

  11. Approaches to the Low Grade Metamorphic History of the Karakaya Complex by Chlorite Mineralogy and Geochemistry

    Directory of Open Access Journals (Sweden)

    Sema Tetiker

    2015-04-01

    Full Text Available In this study, chlorite is used to investigate the diagenetic-metamorphic evolution and accurate geological history of the different units belonging to the Karakaya complex, Turkey. Primary and secondary chlorite minerals in the very low-grade metamorphic rocks display interference colors of blue and brown and an appearance of optical isotropy. Chlorites are present in the matrix, pores, and/or rocks units as platy/flaky and partly radial forms. X-ray diffraction (XRD data indicate that Mg-Fe chlorites with entirely IIb polytype (trioctahedral exhibit a variety of compositions, such as brunsvigite-diabantite-chamosite. The major element contents and structural formulas of chlorite also suggest these were derived from both felsic and metabasic source rocks. Trace and rare earth element (REE concentrations of chlorites increase with increasing grade of metamorphism, and these geochemical changes can be related to the tectonic structures, formational mechanics, and environments present during their generation.

  12. Ligand Binding to Chlorite Dismutase from Magnetospirillum sp.

    Science.gov (United States)

    De Schutter, Amy; Correia, Hugo D; Freire, Diana M; Rivas, María G; Rizzi, Alberto; Santos-Silva, Teresa; González, Pablo J; Van Doorslaer, Sabine

    2015-10-29

    Chlorite dismutase (Cld) catalyzes the reduction of chlorite to chloride and dioxygen. Here, the ligand binding to Cld of Magnetospirillum sp. (MaCld) is investigated with X-ray crystallography and electron paramagnetic resonance (EPR). EPR reveals a large heterogeneity in the structure of wild-type MaCld, showing a variety of low- and high-spin ferric heme forms. Addition of an axial ligand, such as azide or imidazole, removes this heterogeneity almost entirely. This is in line with the two high resolution crystal structures of MaCld obtained in the presence of azide and thiocyanate that show the coordination of the ligands to the heme iron. The crystal structure of the MaCld-azide complex reveals a single well-defined orientation of the azide molecule in the heme pocket. EPR shows, however, a pH-dependent heme structure, probably due to acid-base transitions of the surrounding amino-acid residues stabilizing azide. For the azide and imidazole complex of MaCld, the hyperfine and nuclear quadrupole interactions with the close-by (14)N and (1)H nuclei are determined using pulsed EPR. These values are compared to the corresponding data for the low-spin forms observed in the ferric wild-type MaCld and to existing EPR data on azide and imidazole complexes of other heme proteins. PMID:26287794

  13. Kinetics and Mechanism of Oxidation of Methimazole by Chlorite in Slightly Acidic Media.

    Science.gov (United States)

    Chipiso, Kudzanai; Simoyi, Reuben H

    2016-06-01

    The kinetics and mechanism of the oxidation of methimazole (1-methyl-3H-imidazole), MMI, by chlorite in mildly acidic environments were studied. It is a complex reaction that gives oligo-oscillations in chlorine dioxide concentrations in excess chlorite conditions. The stoichiometry is strictly 2:1, with the sulfur center being oxidized to sulfate and the organic moiety being hydrolyzed to several indeterminate species. In excess MMI conditions over chlorite, the sulfinic acid and sulfonic acid were observed as major intermediates. The sulfenic acid, which was observed in the electrochemical oxidation of MMI, was not observed with chlorite oxidations. Initial reduction of chlorite produced HOCl, an autocatalytic species in chlorite oxidations. HOCl rapidly reacts with chlorite to produce chlorine dioxide, which, in turn, reacts rapidly with MMI to produce more chlorite. The reaction of chlorine dioxide with MMI is competitive, in rate, with the chlorite-MMI and HOCl-ClO2(-) reactions. This explains the oligo-oscillations in ClO2 concentrations. PMID:27126471

  14. Low-temperature magnetic anisotropy in micas and chlorite

    DEFF Research Database (Denmark)

    Biedermann, Andrea R.; Bender Koch, Christian; Lorenz, Wolfram E A;

    2014-01-01

    use the magnetic anisotropy to understand a rock fabric, it is necessary to identify the minerals responsible for the magnetic anisotropy. Techniques have been developed to separate contributions of the ferrimagnetic, antiferromagnetic, paramagnetic, and diamagnetic susceptibilities to the anisotropy......Phyllosilicates, such as micas and chlorite, are common rock-forming minerals and often show preferred orientation in deformed rocks. In combination with single-crystal anisotropy, this leads to anisotropy of physical properties in the rock, such as magnetic susceptibility. In order to effectively...... of magnetic susceptibility. Because diamagnetic and paramagnetic susceptibility are both linearly dependent on field, separation of the anisotropic contributions requires understanding how the degree of anisotropy of the paramagnetic susceptibility changes as a function of temperature. Note that...

  15. Diagenetic alteration process of chlorite in Tyr Member sandstone, Siri Canyon, Danish North Sea

    DEFF Research Database (Denmark)

    Kazerouni, Afsoon Moatari; Friis, Henrik; Hansen, Jens Peter Vind

    zone and deeper, porous samples were later cemented by macro quartz, with larger amounts in the water zone. Chlorite is found in varying amounts in Rau 1A samples. It can be recognized in SEM as a platy or bladed precipitate, which is mostly rich in iron. Chlorite is present in most samples, although...... only in traceable amounts in the samples which are dominated by microquartz cement. There seem to be two chlorite phases: The first phase occurs as rosettes in a grain coating growth pattern. It is partially intergrown with microquartz or forms a dense mixture of small chlorite rosettes and scattered...... cement is more abundant and better developed in the lower parts of reservoir units, whereas it may be scarce and poorly developed in upper parts, especially within the oil zone. Below the oil-water contact, the growth of chlorite may have continued for a longer period, resulting in more dense coatings...

  16. Water incorporation in NAMs after antigorite and chlorite dehydration reactions

    Science.gov (United States)

    Padrón-Navarta, José Alberto; Hermann, Jörg

    2014-05-01

    Subduction zones play a fundamental role in the deep water cycle making the Earth unique among other terrestrial planets. Water is incorporated into hydrous minerals during seafloor alteration of the oceanic lithosphere. During subduction of the oceanic lithosphere, dehydration of these hydrous minerals produces a fluid phase. A part of this fluid phase will be recycled back to the Earth's surface through hydrothermal aqueous fluids or through hydrous arc magmas, whereas another part of the water will be transported to the deep mantle by Nominally Anhydrous Minerals (NAMs) such as olivine, pyroxene and garnet. The partitioning of water between these two processes is crucial for our understanding of the mantle-scale water recycling in the Earth. This can be investigated experimentally under water-saturated conditions because this situation is met during dehydration reactions. However relatively low temperature conditions for such reactions make challenging these experiments. An alternative can be found in the natural record. The Alpine Betic-Rif orogen together with Central and Western Alps offer an invaluable diversity of ultramafic lenses that record a significant range of pressure-temperature and cooling rates. Hence these samples portray an excellent data set of 24 samples to survey the transfer of fluids from hydrous phases (brucite, antigorite and chlorite) to NAMs (olivine, orthopyroxene, clinopyroxene and garnet). Well-studied samples from these localities have been selected for water measurement using FTIR spectroscopy. The selected suite comprises the following high-pressure peridotite outcrops: Malenco serpentinite, Cerro del Almirez (1.6-1.9 GPa and 680-710ºC), Alpe Arami (3.2 GPa and 840ºC), Cima di Gagnone (3.0 GPa and 750-800ºC) and Alpe Albion (0.6 GPa and 730ºC). The infrared signature of olivine in all localities contains water (hydroxyl groups) associated to intrinsic defects (mostly point defects related to Ti4+) and extrinsic submicroscopic

  17. Geochemistry of sericite and chlorite in well 14-2 Roosevelt Hot Springs geothermal system and in mineralized hydrothermal systems

    Energy Technology Data Exchange (ETDEWEB)

    Ballantyne, J.M.

    1980-06-01

    Chemical compositions of chlorite and sericite from one production well in the Roosevelt geothermal system have been determined by electron probe methods and compared with compositions of chlorite and sericite from porphyry copper deposits. Modern system sericite and chlorite occur over a depth interval of 2 km and a temperature interval of 250/sup 0/C.

  18. Approaches to the Low Grade Metamorphic History of the Karakaya Complex by Chlorite Mineralogy and Geochemistry

    OpenAIRE

    Sema Tetiker; Hüseyin Yalçın; Ömer Bozkaya

    2015-01-01

    In this study, chlorite is used to investigate the diagenetic-metamorphic evolution and accurate geological history of the different units belonging to the Karakaya complex, Turkey. Primary and secondary chlorite minerals in the very low-grade metamorphic rocks display interference colors of blue and brown and an appearance of optical isotropy. Chlorites are present in the matrix, pores, and/or rocks units as platy/flaky and partly radial forms. X-ray diffraction (XRD) data indicate that Mg-F...

  19. Manipulating Conserved Heme Cavity Residues of Chlorite Dismutase: Effect on Structure, Redox Chemistry, and Reactivity

    OpenAIRE

    Hofbauer, Stefan; Gysel, Kira; Bellei, Marzia; Hagmüller, Andreas; Schaffner, Irene; Mlynek, Georg; Kostan, Julius; Pirker, Katharina F.; Daims, Holger; Furtmüller, Paul G.; Battistuzzi, Gianantonio; Djinović-Carugo, Kristina; Obinger, Christian

    2013-01-01

    Chlorite dismutases (Clds) are heme b containing oxidoreductases that convert chlorite to chloride and molecular oxygen. In order to elucidate the role of conserved heme cavity residues in the catalysis of this reaction comprehensive mutational and biochemical analyses of Cld from “Candidatus Nitrospira defluvii” (NdCld) were performed. Particularly, point mutations of the cavity-forming residues R173, K141, W145, W146, and E210 were performed. The effect of manipulation in 12 single and doub...

  20. Investigation of chloritization of smectite. Document prepared by other institute, based on the trust contact

    International Nuclear Information System (INIS)

    The stability of smectite under the bulk composition of high iron content is as follows: (1) and (2). (1) In early burial diagenesis, the chemical variations of chlorite and dioctahedral smectite in Tertiary formations of Niigata prefecture. (2) The experiment of the stability of smectite in iron - rich bulk composition under oxygen fugacity. In the present study, the results are as follows: (1) Samples were taken from the cores and cuttings of exploratory test well of Oguni. The trioctahedral smectite in tertiary formation decreases with a depth. Below 3800m, Si content of chlorite increases with a depth. In the study, corrensite at 2700m depth has higher Si content, as compared to chlorite at 3800m. Mg/(Mg+Fe) ratios of chlorite/smectite interstratified mineral increase with increasing Si content regardless of the depth. (2) Chlorite/smectite interstratified mineral forms at 250degC on the compositions of the starting material of Mont:Mt=5:5. Chlorite did not crystallize by using of the starting material of Sap:Mt 5:5 at 250degC. At 400degC, montomorillonite did not decompose on the starting material composition with low iron content. The iron density is very important for the stability of smectite. (author)

  1. Characteristics of chlorites in seismogenic fault zones: the Taiwan Chelungpu Fault Drilling Project (TCDP core sample

    Directory of Open Access Journals (Sweden)

    H. Sone

    2008-02-01

    Full Text Available The iron content and the asymmetry of iron and magnesium ions in chlorites are examined for the Chelungpu Fault in Taiwan, which is a seismogenic fault. The samples are collected from the cores drilled for the Taiwan Chelungpu Fault Drilling Project (TCDP, borehole B. Three fault zones are recognized as candidates for the source of seismogenic materials. The fault zones are composed of fractured-damaged rocks, breccia, gray gouge, black gouge, and black material. Chlorite from each type of rock was analyzed by using X-ray diffraction (XRD. The iron content and asymmetry of the iron and magnesium ions in the chlorites were estimated from the XRD peak ratios. The hydroxide and silicate layers of chlorite in the black gouge and black material have low iron contents. Many studies have suggested that a temperature rise occurred at the fault zones. In addition, the temperature rise can result in the production of iron oxides such as magnetite or maghemite, as reported by other studies. However, the temperature rise cannot explain the low value of iron content in the chlorites. Another reason for the low value of iron content is the variation in the pH of the fluid, which can be controlled by radical reactions. Therefore, on the basis of chlorite characteristics, the reactions at the seismogenic fault are due not only to the thermal decomposition resulting from the temperature rise and but also to rock-fluid interactions.

  2. Sedimentary and diagenetic processes at the origin of chlorites formation inside silico-clastic reservoirs; Processus sedimentaires et diagenetiques a l'origine de la formation des chlorites dans les reservoirs silicoclastiques

    Energy Technology Data Exchange (ETDEWEB)

    Tinseau, E.

    2002-06-01

    Diagenetic chlorite in deeply buried petroleum reservoirs give to the formations relatively good reservoir properties. The purpose of this study is, by a multidisciplinary approach, to better understand how chlorites form and to put into evidence the factors which influence their formation. Four case studies have been chosen: the silici-clastic Mulichinco (Valanginian) and Tordillo (Kimmeridgian) formations of the Neuquen basin, Argentina, the Springhill Formation (Lower Cretaceous) of the Austral basin, Argentina, and the Mashirah Bay formation (Precambrian) from the Huqf-Haushi area, Oman. Sedimentological analyses have been combined to petrographical observations (optical microscope, SEM, TEM, HRTEM, Cathodoluminescence), to chemical analyses, to chlorite polytypicism study, and by fluid inclusions micro-thermometry in silicifications. These studies have allowed to precise the diagenetic sequence for each of these formations and to approach the conditions for the formation of diagenetic chlorites for each case, and to conclude the following points: (1) ferro-magnesian chlorites require precursor material such as volcano-clasts. Their presence is associated with continental environments. Their destabilization into chlorite, via smectite, is favoured at the water/sediment interface during marine transgression. (2) ferriferous chlorites formation can happen from glauconitic minerals which contain a 7 angstroms phase like berthierite, and 10-12 angstroms phase as smectite phase, under anoxic conditions. (3) polytypicism variations traduce two different mechanisms for the chlorite formation: ferro-magnesian chlorites form by dissolution-recrystallization process and re-equilibrate with burial, whereas ferriferous chlorite form from berthierite. (author)

  3. Characteristics of chlorites in seismogenic fault zones: the Taiwan Chelungpu Fault Drilling Project (TCDP core sample

    Directory of Open Access Journals (Sweden)

    Y. Hashimoto

    2007-07-01

    Full Text Available The iron content and the asymmetry of iron and magnesium ions in chlorites are examined for the Chelungpu Fault in Taiwan, which is a seismogenic fault. The samples are collected from the cores drilled for the Taiwan Chelungpu Fault Drilling Project (TCDP. Three fault zones are recognized as candidates for the source of seismogenic materials. The fault zones are composed of fractured-damaged rocks, breccia, gray gouge, black gouge, and black material. Chlorite from each type of rock was analyzed by using X-ray diffraction (XRD. The iron content and asymmetry of the iron and magnesium ions in the chlorites were estimated from the XRD peak ratios. The hydroxide and silicate layers in the black gouge and black material have low iron contents. Many studies have suggested that a temperature rise occurred at the fault zones. In addition, the temperature rise can result in the production of iron oxides such as magnetite or maghemite, as reported by other studies. However, the temperature rise cannot explain the low value of iron content in the chlorites. Another reason for the low value of iron content is the variation in the pH of the fluid, which can be controlled by radical reactions. Therefore, the reactions at the seismogenic fault are due to not only the thermal decomposition resulting from the temperature rise and but also rock-fluid interactions based on the chlorite characteristics.

  4. Cloning, expression, purification, crystallization and preliminary X-ray diffraction analysis of chlorite dismutase: a detoxifying enzyme producing molecular oxygen

    International Nuclear Information System (INIS)

    Preliminary X-ray data collection and analysis for crystals of chlorite dismutase, a haem-based enzyme that very effectively reduces chlorite to chloride while producing molecular oxygen, is reported to 2.1 Å resolution. Chlorite dismutase, a homotetrameric haem-based protein, is one of the key enzymes of (per)chlorate-reducing bacteria. It is highly active (< 2 kU mg−1) in reducing the toxic compound chlorite to the innocuous chloride anion and molecular oxygen. Chlorite itself is produced as the intermediate product of (per)chlorate reduction. The chlorite dismutase gene in Azospira oryzae strain GR-1 employing degenerate primers has been identified and the active enzyme was subsequently overexpressed in Escherichia coli. Chlorite dismutase was purified, proven to be active and crystallized using sitting drops with PEG 2000 MME, KSCN and ammonium sulfate as precipitants. The crystals belonged to space group P21212 and were most likely to contain six subunits in the asymmetric unit. The refined unit-cell parameters were a = 164.46, b = 169.34, c = 60.79 Å. The crystals diffracted X-rays to 2.1 Å resolution on a synchrotron-radiation source and a three-wavelength MAD data set has been collected. Determination of the chlorite dismutase structure will provide insights into the active site of the enzyme, for which no structures are currently available

  5. Influence of drinking water treatments on chlorine dioxide consumption and chlorite/chlorate formation.

    Science.gov (United States)

    Sorlini, Sabrina; Gialdini, Francesca; Biasibetti, Michela; Collivignarelli, Carlo

    2014-05-01

    Disinfection is the last treatment stage of a Drinking Water Treatment Plant (DWTP) and is carried out to maintain a residual concentration of disinfectant in the water distribution system. Chlorine dioxide (ClO2) is a widely used chemical employed for this purpose. The aim of this work was to evaluate the influence of several treatments on chlorine dioxide consumption and on chlorite and chlorate formation in the final oxidation/disinfection stage. A number of tests was performed at laboratory scale employing water samples collected from the DWTP of Cremona (Italy). The following processes were studied: oxidation with potassium permanganate, chlorine dioxide and sodium hypochlorite, coagulation/flocculation with ferric chloride and aluminum sulfate, filtration and adsorption onto activated carbon. The results showed that the chlorine dioxide demand is high if sodium hypochlorite or potassium permanganate are employed in pre-oxidation. On the other hand, chlorine dioxide leads to the highest production of chlorite and chlorate. The coagulation/flocculation process after pre-oxidation shows that chlorine dioxide demand decreases if potassium permanganate is employed as an oxidant, both with ferric chloride and aluminum sulfate. Therefore, the combination of these processes leads to a lower production of chlorite and chlorate. Aluminum sulfate is preferable in terms of the chlorine dioxide demand reduction and minimization of the chlorite and chlorate formation. Activated carbon is the most effective solution as it reduced the chlorine dioxide consumption by about 50% and the DBP formation by about 20-40%. PMID:24534637

  6. A chlorite mineral surface actively drives the deposition of DNA molecules in stretched conformations

    International Nuclear Information System (INIS)

    Muscovite mica is commonly used to immobilize DNA molecules onto a flat surface. This method, however, requires either the use of divalent cations in the buffer solution or the chemical modification of the surface. Here we show that DNA molecules have different binding affinities and assume different conformations when adsorbed to different layered minerals. In particular, the effect of biotite, muscovite, talc, brucite and chlorite upon DNA binding is investigated. Using atomic force microscopy it is possible to quantify the amount of DNA deposited onto a flat surface and it is experimentally confirmed that biotite, talc and brucite have a much higher affinity than muscovite (7-, 20- and 25-fold more volume of DNA deposited, respectively). The deposition of DNA onto chlorite presents areas (brucite-like) with high DNA coverage and areas (mica-like) where DNA molecules are absent. We regularly observed isolated DNA molecules that became stretched across these regions of low affinity. The stretching is not induced by the deposition procedure but is driven by the surface potential gradient between brucite-like and mica-like regions in chlorite. The active stretching of DNA on chlorite is a clear indication of the technological potential carried by these materials when used as substrates for biomolecules

  7. THE REACTIVITY OF PREHYDROLYZED SOFTWOOD KRAFT PULPS AFTER PROLONGED COOKING FOLLOWED BY CHLORITE DELIGNIFICATION

    Directory of Open Access Journals (Sweden)

    Ulf Germgard

    2011-05-01

    Full Text Available In a laboratory study high-quality spruce chips were prehydrolyzed to remove hemicelluloses and then kraft cooked to different kappa numbers by varying the cooking time. Each pulp sample was then chlorite delignified to selectively remove the remaining lignin. The reactivities of the pulp samples before and after chlorite delignification were determined by Fock’s test, which is supposed to measure the pulp’s reactivity in the conventional viscose process. A number of analyses were carried out to determine which parameters affected pulp reactivity, as, for example: intrinsic viscosity, kappa number, pulp yield, carbohydrate composition, levelling-off degree of polymerization (LODP, and alkali solubility. The results of the study showed that the pulp reactivity increased with decreasing kappa number, and the highest reactivity was obtained after total lignin removal using chlorite delignification. It was also found that the carbohydrate composition had no influence on the pulp reactivity, but lower intrinsic viscosity either obtained by prolonged cooking or chlorite delignification correlated with higher pulp reactivity. Finally, lower alkali solubility, i.e. higher R18, reduced the reactivity.

  8. Surface energy of talc and chlorite: Comparison between electronegativity calculation and immersion results.

    Science.gov (United States)

    Douillard, Jean-Marc; Salles, Fabrice; Henry, Marc; Malandrini, Harold; Clauss, Frédéric

    2007-01-15

    The surface energies of talc and chlorite is computed using a simple model, which uses the calculation of the electrostatic energy of the crystal. It is necessary to calculate the atomic charges. We have chosen to follow Henry's model of determination of partial charges using scales of electronegativity and hardness. The results are in correct agreement with a determination of the surface energy obtained from an analysis of the heat of immersion data. Both results indicate that the surface energy of talc is lower than the surface energy of chlorite, in agreement with observed behavior of wettability. The influence of Al and Fe on this phenomenon is discussed. Surface energy of this type of solids seems to depend more strongly on the geometry of the crystal than on the type of atoms pointing out of the surface; i.e., the surface energy depends more on the physics of the system than on its chemistry. PMID:17081554

  9. Nanoscale surface properties and interaction with fundamental biomolecules of chlorite and phlogopite

    OpenAIRE

    Moro, Daniele

    2014-01-01

    The surface properties of minerals have important implications in geology, environment, industry and biotechnology and for certain aspects in the research on the origin of life. This research project aims to widen the knowledge on the nanoscale surface properties of chlorite and phlogopite by means of advanced methodologies, and also to investigate the interaction of fundamental biomolecules, such as nucleotides, RNA, DNA and amino acid glycine with the surface of the selected phyllosilica...

  10. Redox Thermodynamics of High-Spin and Low-Spin Forms of Chlorite Dismutases with Diverse Subunit and Oligomeric Structures

    OpenAIRE

    Hofbauer, Stefan; Bellei, Marzia; Sündermann, Axel; Pirker, Katharina F.; Hagmüller, Andreas; Mlynek, Georg; Kostan, Julius; Daims, Holger; Furtmüller, Paul G.; Djinović-Carugo, Kristina; Oostenbrink, Chris; Battistuzzi, Gianantonio; Obinger, Christian

    2012-01-01

    Chlorite dismutases (Clds) are heme b-containing oxidoreductases that convert chlorite to chloride and dioxygen. In this work, the thermodynamics of the one-electron reduction of the ferric high-spin forms and of the six-coordinate low-spin cyanide adducts of the enzymes from Nitrobacter winogradskyi (NwCld) and Candidatus “Nitrospira defluvii” (NdCld) were determined through spectroelectrochemical experiments. These proteins belong to two phylogenetically separated lineages that differ in su...

  11. Mineralogy and geochemistry of laterites developed on chlorite schists in Tchollire region, North Cameroon

    Science.gov (United States)

    Banakeng, L. A.; Zame, P. Zo'o.; Tchameni, R.; Mamdem, L.; Bitom, D.

    2016-07-01

    Laterites developed from the weathering of chlorite schists have been studied in Tchollire region, North Cameroon. They include two profiles: a 5.5 m depth profile in Doudja site and a 12.3 m profile in Fimbe site. The chlorite schists have a lepidoblastic to lepidogranoblastic texture and are mainly composed of chlorite, muscovite, biotite, feldspars and quartz but that of Fimbe is marked by the presence of amphibole. It is felsic with a high SiO2 content (67%) and low Fe2O3 (5.8%) and MgO (2.4%) contents in Doudja site but has a lower content of SiO2 (46%) in the Fimbe site where it is mafic with higher contents in Fe2O3 (12.4%) and MgO (6.3%). The chlorite schists of Doudja show high contents in Zr, Sr, Ta, with moderate contents in Cr, V, U and Zn. That of Fimbe is particularly rich in Cr, V, Ni, Sr and Zn with a moderate Zr content. All chlorite schists have high barium contents (270-393 ppm) with LREE-enrichment. The soils are yellowish and, from bottom to top, are composed of a coarse saprolite, fine saprolite, loose clayey horizon and an organo mineral horizon. The main minerals are chlorite, muscovite, biotite, feldspars, quartz, smectites, vermiculite, kaolinite, hematite and goethite. In Doudja, SiO2 mainly decreases from the bottom to the top of the profile while, Al2O3 and Fe2O3 generally increase; in Fimbe, SiO2 and Al2O3 increase up the profile but Fe2O3 decreases; the general high Fe and corresponding decrease in Mg contents in the soils show that the smectite formed is nontronite. Chromium, V, Cu, Ba and Sr show high contents in the two studied profiles but Zr, U and Ta is higher in Doudja than in Fimbe. Copper generally has high contents in the loose clayey and organo mineral horizons. Nickel is higher in the Fimbe profile and probably issued from the Ni-rich mafic protolith. SiO2 has positive correlations with K2O, Zr, Li and Rb. Correlations of SiO2 with CaO, TiO2 and Cr are negative. Al2O3 and Fe2O3 have a positive correlation with Pb. Doudja

  12. Study of adsorption behaviors of Cs+ and Yb3+ on calcite, kaolinite, montmorillonite, chlorite and glauconite

    International Nuclear Information System (INIS)

    The adsorption behaviors of Cs+ and Yb3+ on five minerals including calcite, kaolinite, montmorillonite, chlorite and glauconite are simultaneously investigated by the static equilibrium batch experiments with radioactive tracer technique. The experimental results indicate that under same experimental conditions (initial solution acidity, initial ion concentration and liquid-solid phase ratio), the adsorption capacity (Q) in unit of mmol/g of montmorillonite towards Cs+ and/or Yb3+ are stronger than other 4 minerals, which display no evident difference of Q values. The Rd of Cs+ and Yb3+ on the five minerals decrease with increasing of their initial concentrations in solution. The uptakes of Cs+ are ordinary lower than Ya3+ except for the high c0. The adsorption isotherms of Cs+ and Yb3+ are all in fairly agreement with the Freundlich's equation. The adsorption mechanism of Cs+ and Yb3+ in the systems of kaolinite, montmorillonite and chlorite at the experimental pH range is likely attributed to the process of ion exchange

  13. Evaluation of experimental teat dip containing sodium chlorite and lactic acid by excised teat assay.

    Science.gov (United States)

    Schmidt, A L; Oliver, S P; Fydenkevez, M E

    1984-12-01

    An experimental teat dip containing sodium chlorite and lactic acid, diluted in water, was evaluated by excised teat protocol. The teat dip was tested against 21 microorganisms. Included were: Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus uberis, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Numerous strains were tested for strain differences. Environmental bacteria were included because of their increasing importance as a cause of bovine mastitis. All excised teats were dipped in a bacterial suspension containing about 1 X 10(8) cfu/ml. Negative control teats were not dipped in a germicidal compound. Positive controls were dipped in 1% iodophor. Effectiveness of the experimental teat dip was expressed as the percent reduction in mean log of bacteria recovered from dipped teats as compared to numbers recovered from control teats. The sodium chlorite - lactic acid dip caused a greater percent log reduction than iodophor for 14 of 21 strains tested. However, differences were generally slight. The experimental teat dip appeared effective against Gram-negative bacteria. Some differences in percent log reduction were observed between strains of the same species. Lowest effectiveness and greatest strain variation were observed with Staphylococcus aureus for both dips tested. PMID:6530497

  14. Dissimilatory perchlorate reduction linked to aerobic methane oxidation via chlorite dismutase

    Science.gov (United States)

    Oremland, R. S.; Baesman, S. M.; Miller, L. G.

    2013-12-01

    The presence of methane (CH4) in the atmosphere of Mars is controversial yet the evidence has aroused scientific interest, as CH4 could be a harbinger of extant or extinct microbial life. There are various oxidized compounds present on the surface of Mars that could serve as electron acceptors for the anaerobic oxidation of CH4, including perchlorate (ClO4-). We examined the role of perchlorate, chlorate (ClO3-) and chlorite (ClO2-) as oxidants linked to CH4 oxidation. Dissimilatory perchlorate reduction begins with reduction of ClO4- to ClO2- and ends with dismutation of chlorite to yield chloride (Cl-) and molecular oxygen (O2). We explored the potential for aerobic CH4 oxidizing bacteria to couple with oxygen derived from chlorite dismutation during dissimilatory perchlorate reduction. Methane (0.2 kPa) was completely removed within several days from the N2-flushed headspace above cell suspensions of methanotrophs (Methylobacter albus strain BG8) and perchlorate reducing bacteria (Dechloromonas agitata strain CKB) in the presence of 5 mM ClO2-. Similar rates of CH4 consumption were observed for these mixed cultures whether they were co-mingled or segregated under a common headspace, indicating that direct contact of cells was not required for methane consumption to occur. We also observed complete removal of 0.2 kPa CH4 in bottles containing dried soil (enriched in methanotrophs by CH4 additions over several weeks) and D. agitata CKB and in the presence of 10 mM ClO2-. This soil (seasonally exposed sediment) collected from the shoreline of a freshwater lake (Searsville Lake, CA) demonstrated endogenous CH4 uptake as well as perchlorate, chlorate and chlorite reduction/dismutation. However, these experiments required physical separation of soil from the aqueous bacterial culture to allow for the partitioning of O2 liberated from chlorite dismutation into the shared headspace. Although dissimilatory reduction of ClO4- and ClO3- could be inferred from the

  15. Evolution of chlorite composition in the Paleogene prototype basin of Jiyang Depression, Shandong, China, and its implication for paleogeothermal gradient

    Institute of Scientific and Technical Information of China (English)

    ZHAO; Ming; CHEN; XiaoMing; JI; JunFeng; ZHANG; Zhe; ZHANG; Yun

    2007-01-01

    The Dongying Basin,Huimin Basin,and Zhanhua Basin constitute the Jiyang Depression in Shandong Province.They are major oil and gas exploring districts within the depression.Through reconstructions of the paleotemperature of the three basins facilitated with the chlorite geothermometry,the thermal history of the Paleogene prototype basin in Jiyang Depression and its geologic significance were explored.This study reveals that the Si4+ component in chlorites reduces gradually as its buried depth increases,while the AlIV component increases accordingly.The chlorite type changes from silicon-rich diabantite to silicon-poor ferroamesite and prochlorite.The prochlorite in this district only appears in the deep buried depth,high temperature,and relatively old stratigraphies; while the diabantite appears in the shallower buried,low temperature,and newly formed strata; the ferroamesite exists in the conditions between prochlorite and diabantite formation.The diagenetic temperatures of the chlorites in these Paleogene basins are 171―238℃ for the Dongying Basin,160―202℃ for the Huimin Basin,and 135―180℃ for the Zhanhua Basin.The differences of the chlorite diagenetic temperatures in the three basins were controlled by the duration time of the structural depressing processes.Higher temperature indicates longer depression time.The relationship between the chlorite diagenetic temperature and its buried depth indicates that the average paleogeothermal gradient is about 38.3℃/km in the Paleogene prototype basin of Jiyang Depression.It was higher than the present geothermal gradient (29―30℃/km).This phenomenon was attributed to the evolution of the structural dynamics in the depression basin.

  16. Enhancement of the nanofibrillation of wood cellulose through sequential periodate-chlorite oxidation.

    Science.gov (United States)

    Liimatainen, Henrikki; Visanko, Miikka; Sirviö, Juho Antti; Hormi, Osmo E O; Niinimaki, Jouko

    2012-05-14

    Sequential regioselective periodate-chlorite oxidation was employed as a new and efficient pretreatment to enhance the nanofibrillation of hardwood cellulose pulp through homogenization. The oxidized celluloses with carboxyl contents ranging from 0.38 to 1.75 mmol/g could nanofibrillate to highly viscous and transparent gels with yields of 100-85% without clogging the homogenizer (one to four passes). On the basis of field-emission scanning electron microscopy images, the nanofibrils obtained were of typical widths of approximately 25 ± 6 nm. All of the nanofibrillar samples maintained their cellulose I crystalline structure according to wide-angle X-ray diffraction results, and the crystallinity index was approximately 40% for all samples. PMID:22512713

  17. Fe-SAPONITE and Chlorite Growth on Stainless Steel in Hydrothermal Engineered Barrier Experiments

    Science.gov (United States)

    Cheshire, M. C.; Caporuscio, F. A.; McCarney, M.

    2012-12-01

    The United States recently has initiated the Used Fuel Disposition campaign to evaluate various generic geological repositories for the disposal of high-level, spent nuclear fuel within environments ranging from hard-rock, salt/clay, to deep borehole settings. Previous work describing Engineered Barrier Systems (EBS) for repositories focused on low temperature and pressure conditions. The focus of this experimental work is to characterize the stability and alteration of a bentonite-based EBS with different waste container materials in brine at higher heat loads and pressures. All experiments were run at ~150 bar and 125 to 300 C for ~1 month. Unprocessed bentonite from Colony, Wyoming was used in the experiments as the clay buffer material. The redox conditions for each system were buffered along the magnetite-iron oxygen fugacity univariant curve using Fe3O4 and Feo filings. A K-Na-Ca-Cl-based salt solution was chosen to replicate deep groundwater compositions. The experimental mixtures were 1) salt solution-clay; 2) salt solution -clay-304 stainless steel; and 3) salt solution -clay-316 stainless steel with a water/bentonite ratio of ~9. Mineralogy and aqueous geochemistry of each experiment was evaluated to monitor the reactions that took place. No smectite illitization was observed in these reactions. However, it appears that K-smectite was produced, possibly providing a precursor to illitization. It is unclear whether reaction times were sufficient for bentonite illitization at 212 and 300 C or whether conditions conducive to illite formation were obtained. The more notable clay mineral reactions occurred at the stainless steel surfaces. Authigenic chlorite and Fe-saponite grew with their basal planes near perpendicular to the steel plate, forming a 10 - 40 μm thick 'corrosion' layer. Partial dissolution of the steel plates was the likely iron source for chlorite/saponite formation; however, dissolution of the Feo/Fe3O4 may also have acted as an iron source

  18. Ferrihydrite formation during the dissolution of chlorite and its effect on the sorption behavior of U(VI)

    International Nuclear Information System (INIS)

    During the dissolution of a Fe-rich chlorite spherical ferrihydrite particles are formed in neutral and alkaline solutions. The ferrihydrite particles are predominantly covering the {hk0} faces due to the reactivity of the edge surfaces of sheet silicates. Their huge specific surface area is significantly influencing the natural attenuation processes of contaminants, i.e. uranium. (orig.)

  19. Scales of equilibrium and disequilibrium during cleavage formation in chlorite and biotite-grade phyllites, SE Vermont

    Science.gov (United States)

    McWilliams, C.K.; Wintsch, R.P.; Kunk, M.J.

    2007-01-01

    Detailed electron microprobe analyses of phyllosilicates in crenulated phyllites from south-eastern Vermont show that grain-scale zoning is common, and sympathetic zoning in adjacent minerals is nearly universal. We interpret this to reflect a pressure-solution mechanism for cleavage development, where precipitation from a very small fluid reservoir fractionated that fluid. Multiple analyses along single muscovite, biotite and chlorite grains (30-200 ??m in length) show zoning patterns indicating Tschermakitic substitutions in muscovite and both Tschermakitic and di/trioctahedral substitutions in biotite and chlorite. Using cross-cutting relationships and mineral chemistry it is shown that these patterns persist in cleavages produced at metamorphic conditions of chlorite-grade, chlorite-grade overprinted by biotite-grade and biotite-grade. Zoning patterns are comparable in all three settings, requiring a similar cleavage-forming mechanism independent of metamorphic grade. Moreover, the use of 40Ar/ 39Ar geochronology demonstrates this is true regardless of age. Furthermore, samples with chlorite-grade cleavages overprinted by biotite porphyroblasts suggest the closure temperatures for the diffusion of Al, Si, Mg and Fe ions are greater than the temperature of the biotite isograd (>???400 ??C). Parallel and smoothly fanning tie lines produced by coexisting muscovite-chlorite, and muscovite-biotite pairs on compositional diagrams demonstrate effectively instantaneous chemical equilibrium and probably indicate simultaneous crystallization. These results do not support theories suggesting cleavages form in fluid-dominated systems. If crenulation cleavages formed in systems in which the chemical potentials of all major components are fixed by an external reservoir, then the compositions of individual grains defining these cleavages would be uniform. On the contrary, the fine-scale chemical zoning observed probably reflects a grain-scale process consistent with a

  20. Comparison of ion chromatography and flow injection analysis methods for monitoring chlorite and chlorate ions in drinking water

    OpenAIRE

    Ledder, Tracey

    1991-01-01

    Up-coming regulations on chlorine dioxide in drinking water treatment require low level measurement of chlorite ion (CI02-) and chlorate ion (CI03-). This research investigated analysis of CI02- and CI03-; in drinking water by flow injection analysis with iodometric detection (FIA) and ion chromatography with conductivity detection (IC). Both the FIA and IC methods were accurate for the determination of CIO2-; and CIO3-; in reagent water. The IC method was accurate in dr...

  1. Redox Interactions of Tc(VII), U(VI), and Np(V) with Microbially Reduced Biotite and Chlorite.

    Science.gov (United States)

    Brookshaw, Diana R; Pattrick, Richard A D; Bots, Pieter; Law, Gareth T W; Lloyd, Jonathan R; Mosselmans, J Fredrick W; Vaughan, David J; Dardenne, Kathy; Morris, Katherine

    2015-11-17

    Technetium, uranium, and neptunium are contaminants that cause concern at nuclear facilities due to their long half-life, environmental mobility, and radiotoxicity. Here we investigate the impact of microbial reduction of Fe(III) in biotite and chlorite and the role that this has in enhancing mineral reactivity toward soluble TcO4(-), UO2(2+), and NpO2(+). When reacted with unaltered biotite and chlorite, significant sorption of U(VI) occurred in low carbonate (0.2 mM) buffer, while U(VI), Tc(VII), and Np(V) showed low reactivity in high carbonate (30 mM) buffer. On reaction with the microbially reduced minerals, all radionuclides were removed from solution with U(VI) reactivity influenced by carbonate. Analysis by X-ray absorption spectroscopy (XAS) confirmed reductive precipitation to poorly soluble U(IV) in low carbonate conditions and both Tc(VII) and Np(V) in high carbonate buffer were also fully reduced to poorly soluble Tc(IV) and Np(IV) phases. U(VI) reduction was inhibited under high carbonate conditions. Furthermore, EXAFS analysis suggested that in the reaction products, Tc(IV) was associated with Fe, Np(IV) formed nanoparticulate NpO2, and U(IV) formed nanoparticulate UO2 in chlorite and was associated with silica in biotite. Overall, microbial reduction of the Fe(III) associated with biotite and chlorite primed the minerals for reductive scavenging of radionuclides: this has clear implications for the fate of radionuclides in the environment. PMID:26488884

  2. Chemical classification and geotermometry of chlorites from the cretaceous Santa Rosa and Lutitas de Macanal formations, eastern emerald belt, eastern cordillera, Colombia

    International Nuclear Information System (INIS)

    The study of the chemical composition of chlorites from the Santa Rosa and Lutitas de Macanal formations in the eastern emerald belt (eastern cordillera), are used to estimate the formation temperature of these minerals and the associated hydrothermal fluids. The chlorites were analyzed using the classification proposed by hey (1954), foster (1962), and Bailey (1980); and the formation temperature is calculated from empirical geothermometers from kranidiotis and Maclean (1987), Cathelineau (1988), Jowett (1991) and Xie et al. (1997). Chlorites in hydrothermally altered rocks associated with emerald mineralization of the Santa Rosa formation is classified as clinochlore and formed at temperatures of 354 Celsius degrade; this temperature is consistent with the fluid inclusions in emeralds of the same formation. Chlorites in veins from Lutitas de Macanal Formation are classified as chamosites and formed at lower temperatures between 210 to 225 Celsius degrade

  3. Paragenesis of Cr-rich muscovite and chlorite in green-mica quartzites of Saigaon–Palasgaon area, Western Bastar Craton, India

    Indian Academy of Sciences (India)

    K R Randive; M M Korakoppa; S V Muley; A M Varade; H W Khandare; S G Lanjewar; R R Tiwari; K K Aradhi

    2015-02-01

    Green mica (fuchsite or chromian-muscovite) is reported worldwide in the Archaean metasedimentary rocks, especially quartzites. They are generally associated with a suite of heavy minerals and a range of phyllosilicates. We report the occurrence of green-mica quartzites in the Saigaon–Palasgaon area within Bastar Craton in central India. Mineralogical study has shown that there are two types of muscovites; the chromium-containing muscovite (Cr2O3 0.84–1.84%) and muscovite (Cr2O3 0.00–0.22%). Chlorites are chromium-containing chlorites (Cr2O3 3.66–5.39%) and low-chromium-containing chlorites (Cr2O3 0.56–2.62%), and as such represent ripidolite–brunsvigite varieties. Back scattered electron images and EPMA data has revealed that chlorite occurs in two forms, viz., parallel to subparallel stacks in the form of intergrowth with muscovite and independent crystals within the matrix. The present study indicates that the replacement of chromium-containing chlorite by chromium-containing muscovite is found to be due to increasing grade of metamorphism of chromium-rich sediments. However, the absence of significant compositional gap between aforementioned varieties indicates disparate substitution of cations, especially chromium, within matrix chlorites. The chromium-containing muscovite and muscovite are two separate varieties having distinct paragenesis.

  4. Characterization of Zn-bearing chlorite by Moessbauer and infrared spectroscopy - occurrence associated to the Pb-Zn-Ag deposits of Canoas, PR, Brazil

    International Nuclear Information System (INIS)

    In order to provide new insights on mineralogical aspects of geochemical mapping/natural processes related to the chlorite formation (e.g. crystallochemistry and mechanisms of formation of these materials, which has been applied in different studies of environmental profiles), we investigated chlorite samples associated to the Pb-Zn-Ag sulfide ore from Canoas 1 deposit (Vale do Ribeira, state of Parana, Brazil). By means of Moessbauer (MS) and infrared (IV) spectroscopy, we addressed some issues as those related to the chloritization processes, as well as how Zn would be incorporated into its crystalline structure. Results carried out by ME and IV spectroscopy clearly pointed out for a chlorite occurrence, which in fact incorporates Zn into its structure and also alters the structural patterns for this mineral. Moreover, ME data sets indicated the presence of Fe which is located only in octahedral sites, in trans-configuration, and the Zn emplacement by the chloritization process also occurs in the brucite layer. (author)

  5. The dissolution of biotite and chlorite at 25°C in the near-neutral pH region

    Science.gov (United States)

    Malmström, Maria; Banwart, Steven; Lewenhagen, Jeanette; Duro, Lara; Bruno, Jordi

    1996-02-01

    We studied the dissolution of biotite and chlorite in laboratory systems with flow-through and batch reactors. The initial dissolution of biotite in the near-neutral pH region, under N 2(g) atmosphere is highly non-stoichiometric. A slow linear release of iron during a period of weeks indicates a surface-chemical-reaction-controlled mechanism of release for iron. The release of potassium is much faster than that of iron. A parabolic dependence of accumulated release with time suggests a diffusion-controlled mechanism of potassium release. The rates of magnesium, aluminium and silicon release are between those for potassium and iron and approach that of iron with time. There is no significant influence of (bi)carbonate or pH on biotite dissolution rate or stoichiometry in the pH region 7 < pH < 8.5. The release rates of elements from chlorite are close to stoichiometric and similar to the iron release rate from biotite. In closed batch reactors at near-basic pH the composition of test solutions in contact with biotite is apparently controlled by gibbsite (Al), kaolinite (Si) and Fe(III)-(hydr)oxide. We estimated a turn-over time (10 1-10 2 yr) for molecular oxygen and a time scale (10 months) to develop characteristic Fe(II) concentrations for a granitic groundwater.

  6. Single Molecule Investigation of Glycine-Chlorite Interaction by Cross-Correlated Scanning Probe Microscopy and Quantum Mechanics Simulations.

    Science.gov (United States)

    Moro, Daniele; Ulian, Gianfranco; Valdrè, Giovanni

    2015-04-21

    In this work, we studied the interaction of glycine with the (001) surface of chlorite mineral at a single molecule level by cross-correlating scanning probe microscopy (SPM) and ab initio quantum mechanics (QM) investigations. Chlorite mineral is particularly interesting and peculiar for the interaction with organic molecules because it presents an alternated stacking of brucite-like (hydrophobic) and talc-like (hydrophilic) layers of different polarities. Brucite-like is positive, whereas talc-like is negative. The experimental atomic force microscopy (AFM) observations show that glycine is stably and selectively adsorbed on the brucite-like layer, organized in monolayers with different patterns. The sizes of single molecules of glycine measured by AFM are in agreement with those calculated by QM. Glycine molecules were found to align both at the edges and on the terraces of the brucitic surface. QM simulations confirmed the AFM observations that glycine molecule is adsorbed with high adsorption energy preferentially with its plane parallel to the (001) brucite-like surface. QM also provided the geometry conformation of the molecule and the bonding scheme between glycine and brucite surface. This kind of data can be very helpful both to biotechnological applications of this substrate and to depict some important processes that might have been occurred in prebiotic environments. PMID:25830864

  7. Succession of Permian and Mesozoic metasomatic events in the eastern Pyrenees with emphasis on the Trimouns talc-chlorite deposit

    Science.gov (United States)

    Boutin, Alexandre; de Saint Blanquat, Michel; Poujol, Marc; Boulvais, Philippe; de Parseval, Philippe; Rouleau, Caroline; Robert, Jean-François

    2016-04-01

    Recent studies proposing pre-orogenic mantle exhumation models have helped renew the interest of the geosciences community in the Pyrenees, which should be now interpreted as a hyper-extended passive margin before the convergence between Iberia and Eurasia occurred. Unresolved questions of the Pyrenean geology, as well as the understanding of the formation of hyper-extended passive margins, are how the crust was thinned, and when, where and how the crustal breakoff occurred. The study of the Variscan and pre-Variscan Pyrenean basement is thus critical to document and understand this Cretaceous crustal thinning. In order to specify the timing of Mesozoic metasomatism and the associated deformation in the pre-Mesozoic basement of the Pyrenees, we carried out a U-Th-Pb laser ablation ICP-MS study on a large panel of REE and titanium-rich minerals (titanite and rutile) from talc-chlorite ores from the eastern Pyrenees, with a special emphasis on the Trimouns deposit, the world's largest talc quarry. Our results suggest that the Trimouns talc formation was restricted to the upper Aptian-Cenomanian time, while the talc and chlorite formation in the eastern Pyrenees occurred during several distinct Permian, Jurassic and Cretaceous episodes. These results give strong constraints on the tectonic setting of the Pyrenean domain during the transition between the Variscan and Alpine orogenic cycles, and particularly on when and how the upper crust was thinned before the crustal breakoff and the final mantle exhumation.

  8. Effectiveness of acidified sodium chlorite and other sanitizers to control Escherichia coli O157:H7 on tomato surfaces.

    Science.gov (United States)

    Inatsu, Yasuhiro; Kitagawa, Tomoko; Bari, Md Latiful; Nei, Daisuke; Juneja, Vijay; Kawamoto, Shinichi

    2010-06-01

    The use of a suitable sanitizer can reduce the risk of produce-related foodborne illnesses. We evaluated the effectiveness of several sanitizers to reduce inoculated Escherichia coli O157:H7 on the surface of cherry tomatoes (Solanum lycopersicum var. cerasiform). Depending on the method of inoculation (dipping/spotting), each of 80 g (eight tomatoes) of inoculated cherry tomatoes was washed in 400 mL of sanitizer solutions or 400 mL distilled water for 5 minutes. The effectiveness of sanitizers on spot-inoculated E. coli O157:H7 on tomato surfaces was found higher than on dip-inoculated tomatoes. Washing with water or chlorine water (0.1 g/L as free chlorine) could reduce 1.3 log CFU/g of E. coli O157:H7 in dip-inoculated (6.8 log CFU/g) tomatoes. Washing with lactic acid (LA) solution (1.0 g/L), phytic acid solution (1.0 g/L), calcinated seashells (oyster/sakhalin surf clam), and 1.0 g/L chitosan in 0.5 g/L LA (Chito) did not exhibit a significant higher effectiveness than that of water wash alone (1.0 log CFU/g). Acidified sodium chlorite (ASC) solution prepared from 0.5 g/L of sodium chlorite and 1.0 g/L LA or phytic acid reduced 3.5 log CFU/g of E. coli O157:H7 in dip-inoculated tomato surfaces. ASC (0.5 g/L of sodium chlorite and 1.0 g/L of LA) wash followed by a second wash with LA exhibited an additional sanitary effectiveness compared to a single wash with ASC. However, washing with ASC followed by a second wash with Chito exhibited an additional 1.0 log CFU/g reduction compared to a secondary wash with water. No significant difference of color, taste, and texture was observed among the washed cherry tomatoes. PMID:20113205

  9. A case of severe chlorite poisoning successfully treated with early administration of methylene blue, renal replacement therapy, and red blood cell transfusion : case report

    NARCIS (Netherlands)

    Gebhardtova, Andrea; Vavrinec, Peter; Vavrincova-Yaghi, Diana; Seelen, Mark; Dobisova, Anna; Flassikova, Zora; Cikova, Andrea; Henning, Robert H.; Yaghi, Aktham

    2014-01-01

    The case of a 55-year-old man who attempted suicide by ingesting <100 mL of 28% sodium chlorite solution is presented. On arrival in the intensive care unit, the patient appeared cyanotic with lowered consciousness and displayed anuria and chocolate brown serum.Initial laboratory tests revealed 40%

  10. Assessment of sodium hypochlorite and acidified sodium chlorite as antimicrobial agents to inhibit growth of Escherichia coli O157:H7 and natural microflora on shredded carrots

    Science.gov (United States)

    The influence of cold tap water, sodium hypochlorite (200 ppm) and acidified sodium chlorite (100, 250, 500 and 1000 ppm) washes on survival and growth of Escherichia coli O157:H7 inoculated onto shredded carrots was determined after treatment and 7 and 14 days of storage. Growth of total mesophilic...

  11. Thermal inactivation of Salmonella Enteritidis on chicken skin previously exposed to acidified Sodium chlorite or tri-sodium phosphate.

    Science.gov (United States)

    Karuppasamy, K; Yadav, Ajit S; Saxena, Gaurav K

    2015-12-01

    Thermal inactivation of normal and starved cells of Salmonella Enteritidis on chicken skin previously exposed to different concentrations of acidified sodium chlorite (ASC) or tri-sodium phosphate (TSP) was investigated. Inoculated skin was pretreated with different concentration of ASC or TSP, packaged in bags, and then immersed in a circulating water bath at 60 to 68 °C. The recovery medium was Hektoen enteric agar. D-values, determined by linear regression, for normal cells on chicken skin, were 2.79, 1.17 and 0.53 min whereas D-values for starved cells were 4.15, 1.83 and 0.66 at 60, 64 and 68 °C, respectively. z-values for normal cells were 3.54 and for starved cells were 2.29. Pretreatment of Salmonella Enteritidis cells with 0 to 200 ppm of ASC or 0 to 1.0 % TSP resulted in lower D-values at all temperatures. Sensory results indicated no significance differences for control and treatments. Thus, results of this study indicated that pretreatment of chicken skin with ASC or TSP increased sensitivity of Salmonella Enteritidis to heat without affecting organoleptic quality of chicken meat. PMID:26604399

  12. Expression of Chlorite Dismutase and Chlorate Reductase in the Presence of Oxygen and/or Chlorate as the Terminal Electron Acceptor in Ideonella dechloratans

    OpenAIRE

    Hellberg Lindqvist, Miriam; Johansson, Nicklas; Nilsson, Thomas; Rova, Maria

    2012-01-01

    The ability of microorganisms to perform dissimilatory (per)chlorate reduction is, for most species, known to be oxygen sensitive. Consequently, bioremediation processes for the removal of oxochlorates will be disturbed if oxygen is present. We measured the expression of chlorite dismutase and chlorate reductase in the presence of different terminal electron acceptors in the chlorate reducer Ideonella dechloratans. Enzyme activity assays and mRNA analyses by real-time quantitative reverse tra...

  13. Determination of chlorite, muscovite, albite and quartz in claystones and clay shales by infrared spectroscopy and partial least-squares regression

    Czech Academy of Sciences Publication Activity Database

    Ritz, M.; Vaculíková, Lenka; Plevová, Eva; Matýsek, D.; Mališ, J.

    2012-01-01

    Roč. 9, č. 4 (2012), s. 511-520. ISSN 1214-9705 R&D Projects: GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : claystone and clay shale * infrared spectroscopy * chemometrics * chlorite * muscovite Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 0.530, year: 2011 https://www.irsm.cas.cz/materialy/acta_content/2012_04/9.Ritz.pdf

  14. Kinetics and Mechanism of the Chlorite-Periodate System: Formation of a Short-Lived Key Intermediate OClOIO3 and Its Subsequent Reactions.

    Science.gov (United States)

    Baranyi, Nóra; Csekő, György; Valkai, László; Xu, Li; Horváth, Attila K

    2016-03-01

    The chlorite-periodate reaction has been studied spectrophotometrically in acidic medium at 25.0 ± 0.1 °C, monitoring the absorbance at 400 nm in acetate/acetic acid buffer at constant ionic strength (I = 0.5 M). We have shown that periodate was exclusively reduced to iodate, but chlorite ion was oxidized to chlorate and chlorine dioxide via branching pathways. The stoichiometry of the reaction can be described as a linear combination of two limiting stoichiometries under our experimental conditions. Detailed initial rate studies have clearly revealed that the formal kinetic orders of hydrogen ion, chlorite ion, and periodate ion are all strictly one, establishing an empirical rate law to be d[ClO2]/dt = kobs[ClO2(-)][IO4(-)][H(+)], where the apparent rate coefficient (kobs) was found to be 70 ± 13 M(-2) s(-1). On the basis of the experiments, a simple four-step kinetic model with three fitted kinetic parameters is proposed by nonlinear parameter estimation. The reaction was found to proceed via a parallel oxygen transfer reaction leading to the exclusive formation of chlorate and iodate as well as via the formation of a short-lived key intermediate OClOIO3 followed by its further transformations by a sequence of branching pathways. PMID:26849795

  15. Coupled Petrological and Geodynamic Models of Mantle Flow in Subduction Zones; the Importance of Chlorite in the Emergence of a Low-Viscosity Channel

    Science.gov (United States)

    Smith, P. M.; Baker, L. J.; Asimow, P. D.; Gurnis, M. C.

    2007-12-01

    Seismic velocity and attenuation studies have shown that 5-20 km thick low velocity layers exist above seismically fast slabs and are associated with broad zones of high attenuation in many subduction zones. These observations are generally interpreted as formation of hydrous phases by dehydration of the slab, although the impact of water in nominally anhydrous minerals (NAM) on seismic wave propagation is largely unknown. Recent petrological experiments on hydrous peridotite at subduction zone conditions suggest that chlorite will be stable adjacent to the subducting slab in sufficient quantities to be a significant water sink. We use a scheme that couples a petrological model (pHMELTS) with a 2-D thermal and variable viscosity flow model (ConMan) to model energy and mass transfer within a subduction zone. By varying input parameters including the convergence rate and slab dip we have developed models for cases in the Costa-Rica and Izu- Bonin-Marianas arc systems and are able to predict major and trace element compositions of primary melts, as well as geophysical observables, such as the topography and geoid. We find that the emergence of a slab- adjacent low-viscosity channel (LVC) is a natural consequence of the thermal and chemical controls on mantle dynamics and feedback between them. In our earlier models, as the LVC is dragged downwards by the subducting slab, hornblende breaks down at about 2.5 GPa and other hydrous phases such as serpentine are secondary in importance to the NAM water reservoir. The spatial limit of the LVC is the water-saturated solidus of the hydrated peridotite; the LVC thickens as the peridotite is progressively depleted by melting and the solidus migrates into the warmer wedge, despite water replenishment at depth. pHMELTS is a hybrid of the pMELTS model of Ghiorso and co-workers and includes amphiboles, serpentines and micas. Chlorite was lacking but we have recently rectified this omission. Following De Capitani and co- workers, we

  16. Precipitation of uraninite in chlorite-bearing veins of the hydrothermal alteration zone (argile de pile) of the natural nuclear reactor at Bangombe, Republic of Gabon

    International Nuclear Information System (INIS)

    This paper describes the mineralogy of a phyllosilicate/uraninite/galena-bearing vein located within the hydrothermal alteration halo associated with the Bangombe reactor. Phyllosilicates within the vein include a trioctahedral Al-Mg-Fe chlorite (ripidolite), Al-rich clay (kaolinite and/or donbassite) and illite. Textural relations obtained by backscattered-electron imaging suggest that ripidolite crystallized first among the sheet silicates. Uraninite is spatially associated with ripidolite and probably precipitated at a later time. While energy-dispersive X-ray analyses suggest that the uranium phase is predominantly uraninite, coffinite or other phases may also be present

  17. Efficacy of two acidified chlorite postmilking teat disinfectants with sodium dodecylbenzene sulfonic acid on prevention of contagious mastitis using an experimental challenge protocol.

    Science.gov (United States)

    Oura, L Y; Fox, L K; Warf, C C; Kempt, G K

    2002-01-01

    Two acidified sodium chlorite postmilking teat disinfectants were evaluated for efficacy against Staphylococcus aureus and Streptococcus agalactiae by using National Mastitis Council experimental challenge procedures. The effect of these teat dips on teat skin and teat end condition was also determined. Both dips contained 0.32% sodium chlorite, 1.32% lactic, and 2.5% glycerin. Dips differed in the amount of sodium dodecylbenzene sulfonic acid (0.53 or 0.27%) added as a surfactant. Both dips significantly reduced new intramammary infection (IMI) rates compared with undipped controls. The dip containing 0.53% dodecylbenzene sulfonic acid reduced new IMI by Staph. aureus by 72% and Strep. agalactiae by 75%. The dip containing 0.27% dodecylbenzene sulfonic acid reduced new IMI by Staph. aureus by 100% and by Strep. agalactiae by 88%. Changes in teat skin and teat end condition for treatment and control groups varied in parallel over time. Teats treated with either teat dip had higher mean teat skin and teat end scores than control teats at some weeks. However, teat skin and teat end condition did not tend to change from the start to the completion of the trial. Application of the two new postmilking teat dips was effective in reducing new IMI from contagious mastitis pathogens. (Key words: teat dip, contagious mastitis, chlorous acid) PMID:11860118

  18. High-dose stabilized chlorite matrix WF10 prolongs cardiac xenograft survival in the hamster-to-rat model without inducing ultrastructural or biochemical signs of cardiotoxicity

    DEFF Research Database (Denmark)

    Hansen, A; Kemp, K; Kemp, E;

    2001-01-01

    WF10 is a stabilized chlorite matrix with immunosuppressive effects. In vitro studies have demonstrated its ability to suppress T cells and delay or abolish antigen presentation. Hence, WF10 may prove useful to prolong graft survival after transplantation. In this study, we evaluated the use of...... high dose WF10 as a single drug regimen in the hamster-to-rat xenotransplantation model and searched for possible cardiotoxic side effects. WF10 prolonged cardiac xenograft survival, but did not induce tolerence or inhibit pathological signs of acute rejection. Hamsters from the donor population......, receiving high dose WF10 for 5 days, were compared with a matched control group. Ultrastructural examination of cardiac tissue as well as biochemical analysis of the cardiac enzymes troponin I, myoglobin and MB isoenzyme of creatine kinase showed no signs of damage. Thus, while prolonging graft survival...

  19. Synergistic Effect of Sodium Chlorite and Edible Coating on Quality Maintenance of Minimally Processed Citrus grandis under Passive and Active MAP.

    Science.gov (United States)

    Ban, Zhaojun; Feng, Jianhua; Wei, Wenwen; Yang, Xiangzheng; Li, Jilan; Guan, Junfeng; Li, Jiang

    2015-08-01

    Edible coating has been an innovation within the bioactive packaging concept. The comparative analysis upon the effect of edible coating, sodium chlorite (SC) and their combined application on quality maintenance of minimally processed pomelo (Citrus grandis) fruits during storage at 4 °C was conducted. Results showed that the combination of edible coating and SC dipping delayed the microbial development whereas the sole coating or dipping treatment was less efficient. The synergetic application of edible coating and SC treatment under modified atmosphere packaging (MAP, 10% O2 , 10% CO2 ) was able to maintain the total soluble solids level and ascorbic acid content, while reduce the weight loss as well as development of mesophiles and psychrotrophs. Nonetheless, the N, O-carboxymethyl chitosan solely coated samples showed significantly higher level of weight loss during storage with comparison to the untreated sample. Furthermore, the combined application of edible coating and SC dipping under active MAP best maintained the sensory quality of minimally processed pomelo fruit during storage. PMID:26147928

  20. 法国比利牛斯山Trimouns滑石-绿泥石矿床地质与成因%Geology and ore genesis of the Trimouns talc-chlorite ore deposit,Pyrénées,France

    Institute of Scientific and Technical Information of China (English)

    Ph de PARSEVAL; 蒋少涌; F FONTAN; 王汝成; F MARTIN; J FREEET

    2004-01-01

    位于法国比利牛斯山的nimouns矿床是世界上最大的滑石-绿泥石矿床之一.对该矿床形成的条件及滑石和绿泥石矿石的含量已较清楚.它是由不同类型的岩石通过热液交代蚀变而形成的,主要包括白云岩蚀变为滑石为主的矿石和硅铝质岩石(云母片岩和伟晶岩)蚀变为绿泥石为主的矿石.滑石矿石显示片理化结构(滑石片岩)或压实块状结构(块滑石).由伟晶岩蚀变而来的绿泥石矿石为呈绿色的球状矿体,而由云母片岩蚀变而来的绿泥石矿石呈块状或片理状、颜色为灰绿色和深灰色.本文对欧洲这个独一无二的滑石和绿泥石矿床的地质特征和成因进行了总结和讨论.流体包裹体研究表明成矿流体为高盐度(20 to30%eq.wt%NaCl)、中温(320℃)、压为为2.5kbars.磷钇矿和独居石的U-Pb定年结果表明,成矿年代为112~97Ma,成矿作用可能持续了16Ma以上.%The Trimouns deposit, in the French Pyr閚閑s, is one of the largest talc and chlorite exploitation in the world. The conditions of formation and concentration for talc and chlorite ores are now well known. The deposit consists the metasomatic alteration of various rocks, mainly dolostones altered into talc-dominant ore and silico-aluminous rocks (mica schists and pegmatites) into chlorite-dominant ore. The talc ore shows schisteous texture (talc schist) or in compact mass (steatite). The chlorite ore altered from pegmatite show green colors and ball bodies. The chlorite ores altered from mica schists are either massive or schisteous ores with graygreenish and dark gray colors. This paper summarizes the general geology and ore genesis of this exceptional talc and chlorite ore deposit in Europe. Fluid inclusion study shows high salinity of 20 to 30% eq. wt% NaCl, intermediate temperature of 320℃ and pressure of 2.5 kbars for the formation of Trimouns deposit. According to U-Pb dating on xenotime and monazite, the mineralization took

  1. Characterization of Zn-bearing chlorite by Moessbauer and infrared spectroscopy - occurrence associated to the Pb-Zn-Ag deposits of Canoas, PR, Brazil; Caracterizacao de clorita portadora de Zn por espectroscopia Moessbauer e espectroscopia infravermelho - uma ocorrencia associada ao deposito de Pb-Zn-Ag de Canoas, PR, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Imbernon, Rosely Aparecida Liguori [Universidade de Sao Paulo (EACH/USP), SP (Brazil). Escola de Artes, Ciencias e Humanidades; Blot, Alain [Institut de Recherche pour le Developpement (IRD), Paris (France); Pereira, Vitor Paulo [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Inst. de Geociencias; Franco, Daniel Ribeiro, E-mail: imbernon@usp.br, E-mail: brotalain@free.fr, E-mail: vitor.pereira@ufrgs.br, E-mail: drfranco@on.br [Observatorio Nacional do Brasil (COGE/ON), Rio de Janeiro, RJ (Brazil). Coordenacao de Geofisica

    2011-06-15

    In order to provide new insights on mineralogical aspects of geochemical mapping/natural processes related to the chlorite formation (e.g. crystallochemistry and mechanisms of formation of these materials, which has been applied in different studies of environmental profiles), we investigated chlorite samples associated to the Pb-Zn-Ag sulfide ore from Canoas 1 deposit (Vale do Ribeira, state of Parana, Brazil). By means of Moessbauer (MS) and infrared (IV) spectroscopy, we addressed some issues as those related to the chloritization processes, as well as how Zn would be incorporated into its crystalline structure. Results carried out by ME and IV spectroscopy clearly pointed out for a chlorite occurrence, which in fact incorporates Zn into its structure and also alters the structural patterns for this mineral. Moreover, ME data sets indicated the presence of Fe which is located only in octahedral sites, in trans-configuration, and the Zn emplacement by the chloritization process also occurs in the brucite layer. (author)

  2. 二氧化氯消毒饮用水中亚氯酸盐污染的初步研究%Priliminary Study on Chlorite Pollution of Drinking Water Disinfected by Chlorine Dioxide

    Institute of Scientific and Technical Information of China (English)

    施小平; 周明浩

    2000-01-01

    [Objective] To explore the status of chlorite pollution in drinking water due to chlorine dioxide , aswell as its causes and counter measures. [Methods]A water plant collecting surface water as raw water slightly pol-luted by organic compounds and B water plant collecting ground water without organic compounds pollution wereselected as observed objectives. Chlorine dioxide generators were used in both of A and B water plants, their rawmaterials was chlorite for A plant and chlorate for B plant. The levels of chlorite in treated water from these twowater plants were determined by amperometric titration. [Results]The levels of chlorite in treated water of A waterplant ranged 0.530~0.760 mg/L, 2.6~3.8 times of the standard value, with a over standard rate of 100%, thelevels of B water plant range 0.257~0.733 mg/L, 1.3~3.7 times of the standard value, with a over standard rateof 83.3%. [Conclusion] The treated water of A and B water plants presented higher pollution by chlorite, the by-product of chlorine dioxide disinfection.%[目的]了解二氧化氯消毒饮用水产生的亚氯酸盐(ClO2-)污染现状,并探讨其成因和对策。[方法]选择2个自来水厂,其中甲水厂以受轻度有机物污染的地面水为水源,乙水厂以未受有机物污染的地下水为水源,两个水厂均使用二氧化氯发生器,主要原料甲厂为亚氯酸盐,乙厂为氯酸盐。采用电流滴定仪法测定这2个水厂出厂水中ClO2-浓度。[结果]出厂水ClO2-浓度:甲厂0.530~0.760 mg/L,为标准值的2.6~3.8倍,超标率100%;乙厂0.100~0.733 mg/L,其中超标浓度值范围0.257~0.733 mg/L,为标准值的1.3~3.7倍,超标率83.3%。[结论]甲、乙自来水厂出厂水中由二氧化氯消毒产生的消毒副产物亚氯酸盐污染较严重。

  3. Clinical analysis of vitamin B(6): determination of pyridoxal 5'-phosphate and 4-pyridoxic acid in human serum by reversed-phase high-performance liquid chromatography with chlorite postcolumn derivatization.

    Science.gov (United States)

    Rybak, Michael E; Pfeiffer, Christine M

    2004-10-15

    A reversed-phase high-performance liquid chromatography (HPLC) method with fluorometric detection was developed for the routine determination of pyridoxal 5'-phosphate (PLP) and 4-pyridoxic acid (4-PA) in serum. Chlorite postcolumn derivatization was used to oxidize PLP to a more fluorescent carboxylic acid form. Sensitivity improved fourfold for PLP using chlorite postcolumn derivatization over traditional bisulfite postcolumn derivatization. The HPLC injection cycle was 15 min, facilitating a throughput of 60 patient samples (72 injections that included standards and quality control (QC) samples) in 18.5h. Method precision was evaluated using three serum QC pools with PLP and 4-PA concentrations of 11.5-34.8 nmol/L and 10.4-21.0 nmol/L, respectively. Within-run (n=7) repeatabilities were 0.6-1.2% for PLP and 0.9-1.8% for 4-PA. Run-to-run (n=23) reproducibilities were 3.6-6.7% for PLP and 3.7-5.6% for 4-PA. Relative detection (3sigma(0)) and quantitation (10sigma(0)) limits were 0.3 and 0.9 nmol/L, respectively, for both PLP and 4-PA using a 10-microl sample injection volume. Analytical recoveries ranged from 97 to 102%. Patient-matched serum and plasma specimens (n=25) were analyzed to evaluate specimen-type bias. Of the plasma types evaluated, heparinized plasma introduced the lowest relative bias for PLP (-5.3%) and minimal bias for 4-PA (-2.3%) compared with serum. Ethylenediaminetetraacetic acid (EDTA) plasma showed the lowest bias for 4-PA (0.7%) but a relatively high bias for PLP (13.0%) due to a chromatographic interference. Human serum samples from a non-representative population subset (n=303) were commensurate with values published for other vitamin B(6) HPLC methods. These values gave geometric means of 42.4 nmol/L for PLP and 27.3 nmol/L for 4-PA. Medians for PLP and 4-PA were 40.1 and 21.8 nmol/L, respectively. The high sensitivity, precision, and throughput of this method, combined with its minimal serum specimen (150 microl) and sample injection

  4. Validation of lactic acid bacteria, lactic acid, and acidified sodium chlorite as decontaminating interventions to control Escherichia coli O157:H7 and Salmonella Typhimurium DT 104 in mechanically tenderized and brine-enhanced (nonintact) beef at the purveyor.

    Science.gov (United States)

    Echeverry, Alejandro; Brooks, J Chance; Miller, Markus F; Collins, Jesse A; Loneragan, Guy H; Brashears, Mindy M

    2010-12-01

    After three different outbreaks were linked to the consumption of nonintact meat products contaminated with Escherichia coli O157:H7, the U.S. Food Safety and Inspection Service published notice requiring establishments producing mechanically tenderized and moisture-enhanced beef products to reassess their respective hazard analysis and critical control point systems, due to potential risk to the consumers. The objective of this study was to validate the use of lactic acid bacteria (LAB), acidified sodium chlorite (ASC), and lactic acid (LA) sprays when applied under a simulated purveyor setting as effective interventions to control and reduce E. coli O157:H7 and Salmonella Typhimurium DT 104 in inoculated U.S. Department of Agriculture (USDA) Choice strip loins (longissimus lumborum muscles) pieces intended for either mechanical blade tenderization or injection enhancement with a brine solution after an aging period of 14 or 21 days at 4.4°C under vacuum. After the mechanical process, translocation of E. coli O157:H7 and Salmonella Typhimurium DT 104 from the surface into the internal muscles occurred at levels between 1.00 and 5.72 log CFU/g, compared with controls. LAB and LA reduced internal E. coli O157:H7 loads up to 3.0 log, while ASC reduced the pathogen 1.4 to 2.3 log more than the control (P tenderization or enhancement of steaks should increase the safety of these types of products. PMID:21219733

  5. Biotite and chlorite weathering at 25 degrees C: the dependence of pH and (bi)carbonate on weathering kinetics, dissolution stoichiometry, and solubility; and the relation to redox conditions in granitic aquifers

    International Nuclear Information System (INIS)

    We have studied the kinetics and thermodynamics of biotite and chlorite weathering in the pH range 22-102 year); and 2. the development of characteristic Fe(III) concentrations (10-5 M in 10-1 years). The Fe(III)-bearing clay minerals formed during these experiments are similar to the fracture-filling-material observed at the Aespoe Hard Rock Laboratory. Such clays can provide reducing capacity to a repository. They can help maintain anoxic conditions by consuming oxygen that enters the repository during the construction and operation phases thereby helping maintain the redox stability of the repository regarding canister corrosion. The half-life of oxygen trapped in the repository at the time of closure depends on the rate of oxygen uptake by Fe(II) minerals, sulfide minerals and organic carbon. Fe(II)-clay minerals are important to the redox stability of a repository, as well as providing a sorption barrier to radionuclide migration. 107 refs, 52 figs, 35 tabs

  6. Toxicological effects of chlorine dioxide, chlorite and chlorate.

    OpenAIRE

    Couri, D; Abdel-Rahman, M S; Bull, R J

    1982-01-01

    Review of the available literature obtained from both acute and chronic experiments utilizing rats, mice and chickens treated with ClO2, ClO2- and ClO3-in drinking water has demonstrated alterations in hematologic parameters in all species tested. The effects were usually dose related and marked changes occurred only at the higher dosages (up to 1000 mg/l.). In chronic studies, rats have been given ClO2 at doses of up to 1000 mg/l., and NaClO2 or NaClO3 at up to 100 mg/l., in their drinking w...

  7. 21 CFR 173.325 - Acidified sodium chlorite solutions.

    Science.gov (United States)

    2010-04-01

    ... with current industry standards of good manufacturing practice. The additive is produced by mixing an... manufacturing practice. Applied as a dip or spray, the additive is used at levels that result in a sodium... industry standards of good manufacturing practice. Applied as a dip or a spray, the additive is used...

  8. Recovery modelling and water resources of the abandoned open-pit talc-chlorite-feldspar mine excavations at Lasasai-Bonucoro,Central Sardinia,Italy%意大利撒丁岛中部Lasasai-Bonucoro地区的废弃露天滑石-绿泥石-长石采矿场的水资源及其修复模式

    Institute of Scientific and Technical Information of China (English)

    Maddalena FIORI; Carlo MATZUZZI

    2004-01-01

    In the district of Orani, central Sardinia, several talc-chlorite-feldspar bodies, hosted in Palaeozoic metamorphic rocks and granites, have long been mined by open- pit operations. The mining activity has deeply modified the original landscape of the Lasasai-Bonucoro area. Thus the rearrangement of this area, in particular of the open-pit works that are now occupied by newly formed pools, filled with water from aquifers flowing along faults crossed by mining operations, should be considered as an overall project of landscape restoration. In the first phase of this work, the environmental and hydrogeological characterisation and the general definition of different zones characterised by different sets of intervention operations has already been made. The following step will include the detailed definition of the different technological interventions to be performed. In order to attain a rehabilitation of this area, first of all the interventions will include: 1) smoothing and re-modelling of local morphology in its still rough sites, namely a few points of the mine benches and dumps, by removing the volumes in excess and settling them again in the hollows, on the base of the indications obtained from opportunely plotted sections; 2) restoration of the removed soil covers, and rehabilitation of the newly formed surfaces after waste disposal, trough re-vegetation techniques including settlement of vegetal soil and nutrients, herbaceous essence hydrosowing, temporary automatic sprinkling; 3) rehabilitation of the corrected slopes, and in general of the remaining poorly vegetated surfaces, trough the above re-vegetation techniques.The above operations will result in a slightly modified plane-altimetrical and landscape arrangement. However these interventions will be sufficient to reach a new environmental qualification, characterised by several opportunities of exploitation. Particular conditions, such as the constant outflow of good-quality water and the amenity of

  9. Evaluation of the use of ferrous iron for chlorite removal under alkaline pH conditions

    OpenAIRE

    Hurst, Gregory H.

    1994-01-01

    Chlorine dioxide has gained much attention for use as a possible alternative disinfectant in water treatment plants due to concerns regarding trihalomethane formation in drinking waters which utilize chlorine as the primary disinfectant and the strict regulations regarding THM's and THMFP (MCL of 0.080 mg/L for TTHMs) (Pontius, 1993). Although the use of Cl02 as a disinfectant prevents the formation of THM's, concern exists regarding the potential health risks due to t...

  10. Controlled clinical evaluations of chlorine dioxide, chlorite and chlorate in man.

    OpenAIRE

    Lubbers, J R; Chauan, S; Bianchine, J. R.

    1982-01-01

    To assess the relative safety of chronically administered chlorine water disinfectants in man, a controlled study was undertaken. The clinical evaluation was conducted in the three phases common to investigational drug studies. Phase I, a rising dose tolerance investigation, examined the acute effects of progressively increasing single doses of chlorine disinfectants to normal healthy adult male volunteers. Phase II considered the impact on normal subjects of daily ingestion of the disinfecta...

  11. Preservation of giant anomalocaridids in silica-chlorite concretions from the early Ordovician of Morocco

    OpenAIRE

    Gaines, R.R.; Briggs, D.E.G; Orr, P.J.; Roy, P.

    2012-01-01

    The recently discovered Fezouata Biota, from the Early Ordovician (late Tremadocian to late Floian) of Morocco, preserves a diverse soft-bodied fauna. While preservation is mostly of Burgess Shale-type, giant anomalocaridids also occur in siliceous concretions. Petrographic and geochemical analyses of these concretions reveal their growth history and the circumstances that led to the fossilization of nonbiomineralized anatomy within them. The large (>1 m) concretions are homogeneous in compos...

  12. Computer simulation of Turing structures in the chlorite-iodide-malonic acid system

    DEFF Research Database (Denmark)

    Jensen, O.; Mosekilde, Erik; Borckmans, P.;

    1996-01-01

    develop from the noise infected homogeneous steady state is examined. In the region where they are both stable, the competition between Hopf oscillations and Turing stripes is studied by following the propagation of a front connecting the two modes. Examples are presented of the types of structures that...

  13. Effectiveness of acidified sodium chlorite and other sanitizers to control Escherichia coli O157:H7 on tomato surfaces

    Science.gov (United States)

    The use of a suitable sanitizer can reduce the risk of produce related food-borne illnesses. We evaluated the effectiveness of several sanitizers to reduce inoculated Escherichia coli O157:H7 on petit tomatoes. Depending on the method of inoculation (dipping / spotting), each of 80g of inoculated to...

  14. Metamorphic chlorite and "vermiculitic" phases in mafic dikes from the Maláguide Complex (Betic Cordillera, Spain)

    Czech Academy of Sciences Publication Activity Database

    Ruiz Cruz, M. D.; Novák, Jiří Karel

    2003-01-01

    Roč. 15, č. 1 (2003), s. 1-14. ISSN 0935-1221 Grant ostatní: Ministerio de Educación y Cultura (ES) BTE-2000-1150; Research Group(ES) RNM-199 Institutional research plan: CEZ:AV0Z3013912 Keywords : low-grade metamorphism * vermiculite * Betic Cordillera Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.185, year: 2003

  15. The role of paramagnetic minerals in clay sediments magnetic anisotropy: correlation between magnetic fabric and chlorite preferred orientation

    Czech Academy of Sciences Publication Activity Database

    Cifelli, F.; Mattei, M.; Chadima, Martin; Hirt, A. M.; Lenser, S.

    Geofyzikální ústav AV ČR, v. v. i.. Roč. 38, - (2006), s. 24-24 ISSN 0231-5548. [Castle Meeting New Trends in Geomagnetism, Paleo, Rock and Environmental Magnetism /10./. 03.09.2006-08.09.2006, Valtice] Institutional research plan: CEZ:AV0Z30130516 Keywords : magnetic anisotropy * neutron diffraction analysis * clay sediments Subject RIV: DB - Geology ; Mineralogy

  16. The heat capacities of osumilite from 298.15 to 1000 K, the thermodynamic properties of two natural chlorites to 500 K, and the thermodynamic properties of petalite to 1800 K.

    Science.gov (United States)

    Hemingway, B.S.; Robie, R.A.; Kittrick, J.A.; Grew, E.S.; Nelen, J.A.; London, D.

    1984-01-01

    Modifications to an automated low-T, adiabatic calorimeter are described. Thermodynamic data obtained with this instrument are reported for minerals from metamorphic terrains. (U.S. Bureau of Mines Report of Investigations 8451)-J.A.Z.

  17. Efficacy of chlorine, acidic electrolyzed water and aqueous chlorine dioxide solutions to decontaminate Escherichia coli O157:H7 from lettuce leaves

    Science.gov (United States)

    This study compared the efficacy of chlorine (20 – 200 ppm), acidic electrolyzed water (50 ppm chlorine, pH 2.6), acidified sodium chlorite (20 – 200 ppm chlorite ion concentration, Sanova), and aqueous chlorine dioxide (20 – 200 ppm chlorite ion concentration, TriNova) washes in reducing population...

  18. Perdas fermentativas e estabilidade aeróbia de silagens de cana-de-açúcar tratadas com cal virgem e cloreto de sódio Fermentation losses and aerobic stability of sugarcane silages treated with whitewash and sodium chlorite

    Directory of Open Access Journals (Sweden)

    A.V. Rezende

    2011-04-01

    Full Text Available Esta pesquisa foi realizada com o objetivo de determinar o efeito da inclusão de cal virgem e cloreto de sódio sobre as perdas fermentativas e a estabilidade aeróbia de silagens de cana-de-açúcar. O delineamento experimental utilizado foi o totalmente ao acaso em esquema de parcelas subdivididas com quatro repetições, de modo que os aditivos foram avaliados nas parcelas (silagem sem aditivo; silagens contendo 0,5; 1,0 e 2,0% de cloreto de sódio; e silagens contendo 0,5; 1,0 e 1,5% de cal virgem na matéria natural e os tempos de exposição ao oxigênio nas subparcelas. Após 75 dias da ensilagem, os silos foram abertos para determinação dos teores de matéria seca (MS e da perda de MS por efluente e gases e aferição da temperatura e do pH da silagem. A inclusão de cal nas silagens, independentemente da dose utilizada, proporcionou maior teor de MS e menor perda de MS. As menores temperaturas foram observadas nas silagens tratadas com cloreto de sódio. Os aditivos utilizados, sobretudo o cloreto de sódio, foram eficientes em manter a estabilidade aeróbia da silagem de cana.The objective of this work was to determine the inclusion of whitewash and sodium chloride on the fermentative losses and aerobic stability of sugarcane silages. It was used a completely randomized experimental design in split plot scheme with four replicates, so the additives were evaluated in the plots (silage without additive, silages containing 0.5; 1.0 and 2.0% of sodium chloride; and silages containing 0.5; 1.0 and 1.5% of whitewash, on the basis of natural matter and the time of exposition to oxygen was evaluated in the subplots. After 75 days from ensilage, silos were opened for determination of the contents of dry matter (DM and the loss of dry matter by effluent and gases and checking of temperature and pH of the silage. The addition of whitewash into silages, regardless to the dose utilized, provides greater DM content and smaller loss of DM. The lowest temperatures were found in the silages treated with sodium chloride. The additives utilized were efficient in keeping the aerobic stability of sugar cane silage, particularly sodium chloride.

  19. Optimization of dicarboxylic acid cellulose synthesis: reaction stoichiometry and role of hypochlorite scavengers.

    Science.gov (United States)

    Sirviö, Juho Antti; Liimatainen, Henrikki; Visanko, Miikka; Niinimäki, Jouko

    2014-12-19

    The reaction conditions in terms of reaction time, sodium chlorite stoichiometry, and the effect of hypochlorite scavengers on the chlorite oxidation of dialdehyde cellulose (DAC) was studied. The impact of storage on the reactivity of DAC fibers was also investigated. It was found that chlorite oxidation of DAC is a rapid reaction, resulting in oxidation of 71% of the aldehyde after only 8 min when 2.5 times excess of sodium chlorite compared to aldehyde groups was used. Reactivity of DAC was observed to decrease quickly during the storage and only 68% of the aldehyde groups reacted after two weeks storage compared to the reaction performed with freshly prepared DAC. Hydrogen peroxide and sulfamic acid were observed to increase the reaction efficiency of chlorite oxidation by reducing the amount of side-reactions between chlorite and hypochlorite. A minor amount of sulfamic acid can be used to replace acetic acid as a catalyst. PMID:25263866

  20. Clays at the natural nuclear reactor at Bangombe, Gabon: migration of actinides

    International Nuclear Information System (INIS)

    Clay minerals were examined from the natural nuclear reactor at Bangombe. The clay mineralogy of the reactor facies is: illite, kaolinite and minor chlorite (FB formation); illite with chlorite and kaolinite in hydrothermal veins (argile de pile); illite and chlorite (reactor core); and (i) chlorite and kaolinite ± illite ± smectite or (ii) illite in the underlying FA formation. Illite crystallinity values are in general highest in rocks that experienced the highest temperatures during reactor operation. Chlorite chemistry varies with respect to position around the reactor: both di-tri and trioctahedral chlorites are present in hydrothermal veins within the argile de pile, dioctahedral chlorites are present in the FA formation within cm of the reactor core, trioctahedral chlorites are present within a meter of the reactor. Chemical data for the argile de pile and the FB formation suggest that formation of the former unit occurred as a result of thermal metamorphism of the FB pelites, as opposed to large-scale dissolution of the sandstones of the FA formation. Autoradiography is used to study the sorptive characteristics of the clays for actinides. The results show that actinide sorption varies in the order: chlorite > illite ≅ kaolinite. (orig.)

  1. Late-Quaternary variations in clay minerals along the SW continental margin of India: Evidence of climatic variations

    Digital Repository Service at National Institute of Oceanography (India)

    Chauhan, O.S.; Sukhija, B.S.; Gujar, A.R.; Nagabhushanam, P.; Paropkari, A.L.

    Down-core variations in illite, chlorite, smectite and kaolinite (the major clays) in two sup(14)C-dated cores collected along the SW continental margin of India show that illite and chlorite have enhanced abundance during 20-17, 12.5, 11-9.5, and 5-4...

  2. Uranium deposits of the Grants, New Mexico mineral belt (II). [Genesis

    Energy Technology Data Exchange (ETDEWEB)

    Brookins, D.G.

    1979-07-01

    This is part of a study of the genesis of the U deposits of the Grants mineral belt. Enrichment of Mg in ore zones is frequently observed, with chlorite being a common product. Clay mineralogic studies argue for chlorite-illite-montmorillonite associations with ores. The methods include scanning electron microscopy, Eh-pH diagrams, activation analysis, and rare earth element studies. (DLC)

  3. Uranium deposits of the Grants, New Mexico mineral belt (II)

    International Nuclear Information System (INIS)

    This is part of a study of the genesis of the U deposits of the Grants mineral belt. Enrichment of Mg in ore zones is frequently observed, with chlorite being a common product. Clay mineralogic studies argue for chlorite-illite-montmorillonite associations with ores. The methods include scanning electron microscopy, Eh-pH diagrams, activation analysis, and rare earth element studies

  4. Chemistry, reaction mechanisms and micro-structures during retrograde metamorphism of gedrite-biotite-plagioclase bearing rocks from Bergslagen, south-central Sweden

    Science.gov (United States)

    Ferrow, Embaie A.; Ripa, Magnus

    1991-01-01

    The Proterozoic rhyolitic volcanics constituting the foot-wall rocks in the Stollberg ore-field, Bergslagen, south-central Sweden, locally contain gedrite altered to chlorite and serpentine, biotite altered to chlorite and plagioclase altered to epidote. The intergrowths between the host gedrite and the chlorite/serpentine inclusions are oriented with the a ∗ of gedrite parallel to the c ∗ of serpentine and chlorite. The biotite has been altered to chlorite by brucitization of both the K-interlayer and talc-like layer. In both cases the net change in volume during chloritization is small. The assumption that Al is conserved during alteration of gedrite and biotite agrees very well with the micro-structures and orientation relations observed by transmission electron microscopy. Normalizing the chlorite to 1.00 mole, the overall chemical change that took place during the retrograde metamorphism of the Stollberg rocks can be written as: 0.84Ged+0.14Bio+0.65Mg+4.76H 2O+0.42H=1.00Chl+0.57Alb+0.72Fe+0.01Na+0.12K+0.01Ti+0.05Mn+0.95H 4SiO 4 The reaction results in ca 9% increase in volume for the solid phases. Thus, a slightly acidic Mg-rich fluid started the reaction and, upon leaving the system, the metasomatic fluid was enriched in Na, Fe, K, and Si.

  5. Alligator Rivers Analogue project. Weathering and its effects on uranium redistribution

    International Nuclear Information System (INIS)

    In the vicinity of the uranium ore deposit at Koongarra, quartz-chlorite schist, the ore host rock, has been subjected to weathering. Although quartz is resistant to weathering, chlorite has been altered to clays and iron minerals. The chlorite weathering and the uranium association with the weathered minerals are the main topics of this study. In order to clarify the weathering of chlorite and its effects on the redistribution of uranium, the processes, mechanisms, and kinetics of the chlorite weathering, and the uranium concentrations in minerals were examined by various methods: X-ray diffraction analysis, scanning electron microscopy, electron microprobe analysis, transmission electron microscopy, autoradiography, visible spectroscopy, alpha and gamma spectrometry. The observed results were compared to those calculated, based on two different models developed for the present study. Water-rock interactions have resulted in the weathering of chlorite and precipitation and sorption of uranyl from the groundwaters with the weathering products. It is concluded that the chlorite weathering affects the uranium retardation factor, and thus uranium redistribution at Koongarra. 55 refs., 20 tabs., 120 figs

  6. Hydrothermal alteration studies of gabbros from northern central Indian ridge and their geodynamic implications

    Digital Repository Service at National Institute of Oceanography (India)

    Ray; Mevel, C.; Banerjee, R.

    assemblages: chlorite, albite, quartz and locally magnesio hornblende. Crystal plastic deformation resulted in mylonite formation and often porphyroclasts of plagioclase and clinopyroxene grains, while altered gabbro locally exhibits cataclastic texture...

  7. Aeolian deposition of Arabia and Somalia sediments on the southwestern continental margin of India

    Digital Repository Service at National Institute of Oceanography (India)

    Chauhan, O.S.

    Kaolinite, smectite, illite and chlorite as major clay minerals and palygorskite and gibbsite in minor quantities have been recorded from the slope of southwestern continental margin of India. Contribution of kaolinite, smectite and gibbsite is from...

  8. Provenance and distribution of clay minerals in the sediments of the western continental shelf and slope of India

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, V.P.; Rao, B.R.

    The distribution of clay minerals from 156 surficial sediments of the western continental margin of India, ranging from 17 to 2000 m water depth, indicate that there are three principal sources of sediments. The illite and chlorite-rich assemblage...

  9. COMBINING METHODS FOR THE REDUCTION OF OXYCHLORINE RESIDUALS IN DRINKING WATER

    Science.gov (United States)

    Previous investigations have shown ferrous iron application to be an effective and economically feasible method of removing residual chlorine dioxide and chlorite iron from drinking water. This treatment, however, was not effective in reducing concentrqations of chlorate iron. ...

  10. 18 Ka BP records of climatic changes, Bay of Bengal: Isotopic and sedimentological evidences

    Digital Repository Service at National Institute of Oceanography (India)

    Chauhan, O.S.; Suneethi, J.

    Based upon the oxygen isotopic records of Globigerinoide sacculifer, the clay mineral assemblages and aridity indicator chlorite/illite (C/I) ratio, the palaeoclimatic changes during the past 18 Ka BP have been archived. The results show intense...

  11. Analysis of mechanical behavior of soft rocks and stability control in deep tunnels

    Directory of Open Access Journals (Sweden)

    Hui Zhou

    2014-06-01

    Full Text Available Due to the weakness in mechanical properties of chlorite schist and the high in situ stress in Jinping II hydropower station, the rock mass surrounding the diversion tunnels located in chlorite schist was observed with extremely large deformations. This may significantly increase the risk of tunnel instability during excavation. In order to assess the stability of the diversion tunnels laboratory tests were carried out in association with the petrophysical properties, mechanical behaviors and water-weakening properties of chlorite schist. The continuous deformation of surrounding rock mass, the destruction of the support structure and a large-scale collapse induced by the weak chlorite schist and high in situ stress were analyzed. The distributions of compressive deformation in the excavation zone with large deformations were also studied. In this regard, two reinforcement schemes for the excavation of diversion tunnel bottom section were proposed accordingly. This study could offer theoretical basis for deep tunnel construction in similar geological conditions.

  12. Clay mineral distribution in the continental shelf and slope off Saurashtra, West coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, V.P.

    with relatively low values on the outer shelf. Illite and chlorite contents are high on the outer shelf. These variations are attributed to the influence of depositional environment and individual property of the clay minerals. Distinct differences in the nature...

  13. 長崎県耕地土壌粘土鉱物地図の作成と利活用

    OpenAIRE

    江頭, 和彦; 中島, 征志郎; 磯田, 雅子

    1997-01-01

    The clay mineralogical map of cultivated soils of Nagasaki prefecture was prepared based on the analytical data of the clay content and clay mineralogical composition of surface soils of paddy fields, upland fields, and lands under perennial crops throughout the prefecture. Following eight categories were used as mapping units: “smectite-dominant”, “smectite-abundant”, “chlorite/mica/vermiculite/intergrade mineral-type(I)“, “chlorite/mica/vermiculite/intergrade mineral-type(II)“, “kaolin mine...

  14. Influence of the Outer Surface Layers of Crystals on the X-Ray Diffraction Intensity of Basal Reflections

    OpenAIRE

    Sakharov, Boris A.; Plançon, Alain; Lanson, Bruno; Drits, Victor A.

    2004-01-01

    This study presents a mathematical formalism describing diffraction effects from periodic and mixed-layer minerals in which the outer surface layers of crystals differ from layers forming the core of the crystals. XRD patterns calculated for structure models of chlorite and irregular chlorite-smectites terminated on both sides of the crystals by either brucite-like or 2:1 layers show the strong influence that different outer surface layers make on the distribution of basal reflection intensit...

  15. Hidrólise enzimática de casca de arroz utilizando-se celulases: efeito de tratamentos químicos e fotoquímicos Enzymatic hydrolysis of rice hull using cellulases: effect of chemical and photochemical treatments

    OpenAIRE

    Juan Reyes; Patricio Peralta-Zamora; Nelson Durán

    1998-01-01

    In the present work we reported the study of rice hull enzymatic hydrolysis using a commercial cellulase preparation. The results showed that previous treatment with light and sodium chlorite inhibits the enzymatic process (31.4 and 11.8%, respectively) while hydrogen peroxide and ozone favoured the enzymatic production of reducing sugars (5.9 and 54.9%, respectively). Studies performed by quimiluminescence showed that the chlorite treatment produced the most significant change in the structu...

  16. Chlorine dioxide by-products in drinking water and their control by powdered activated carbon

    OpenAIRE

    Grabeel, Margaret N.

    1992-01-01

    The concentrations of chlorine dioxide (CI02), chlorine, chlorite (CIO2), and chlorate (CI03) were evaluated following pretreatment of raw water by CI02 at water treatment plants in New Castle, Pennsylvania; Charleston, West Virginia; Skagit, Washington; and Columbus, Georgia. Chlorite and chlorate concentrations were unaffected by any of the water treatment processes and did not vary as a function of time of travel in the distribution system. Chlorine dioxide, which was ana...

  17. 3D modelling of hydrothermal alteration associated with VHMS deposits in the Kristineberg area, Skellefte district, northern Sweden

    Science.gov (United States)

    Chmielowski, Riia M.; Jansson, Nils; Persson, Mac Fjellerad; Fagerström, Pia

    2016-01-01

    This contribution presents a 3D assessment of metamorphosed and deformed, hydrothermally altered volcanic rocks, hosting the massive sulphide deposits of the Kristineberg area in the 1.9 Ga Skellefte mining district in northern Sweden, using six calculated alteration parameters: the Ishikawa alteration index, the chlorite-carbonate-pyrite index and calculated net mass changes in MgO, SiO2, Na2O and Ba. The results, which are also available as film clips in the Supplementary data, confirm inferences from geological mapping; namely that the sericite- and chlorite-rich alteration zones have complex and cross-cutting geometries and that most of these zones are semi-regional in extent and range continuously from surface to over a kilometre deep. The major known massive sulphide deposits occur proximal to zones characterised by coincidence of high values for the alteration index and chlorite-carbonate-pyrite index and large MgO gains, which corresponds to zones rich in magnesian silicates. These zones are interpreted as the original chlorite-rich, proximal parts the alteration systems, and form anomalies extending up to 400 m away from the sulphide lenses. In addition, the stratigraphically highest VHMS are hosted by rocks rich in tremolite, talc, chlorite and dolomite with lesser clinozoisite, which have high chlorite-carbonate-pyrite index and low-medium alteration index values, reflecting a greater importance of some chlorite-carbonate alteration at this stratigraphic level. Vectoring towards massive sulphide deposits in this area can be improved by combining the AI and CCPI indexes with calculated mass changes for key mobile elements. Of the ones modelled in this study, MgO and SiO2 appear to be the most useful.

  18. Petrology of plagiogranite from Sjenica, Dinaridic Ophiolite Belt (southwestern Serbia)

    Science.gov (United States)

    Milovanović, Dragan; Srećković-Batoćanin, Danica; Savić, Marija; Popovic, Dana

    2012-04-01

    The Sjenica plagiogranite occurs in the southern part of the Dinaridic Ophiolite Belt, 5 km northwest of Sjenica. The main minerals are albite with strongly altered biotite (replaced with chlorite), with occasional amphibole (magnesio hornblende to tschermakite) and quartz. An enclave of fine-grained granitic rocks with garnet grains was noted too. Secondary minerals are calcite and chlorite (daphnite). Major, trace and REE geochemistry coupled with field observations support a model by which the Sjenica plagiogranite could be formed by fractional crystallization of mantle origin mafic magma in a supra-subduction zone setting. Occurrences of calcite and chlorite nests in the Sjenica plagiogranites revealed that these rocks underwent hydrothermal alteration due to intensive sea water circulation in a sub-sea-floor environment.

  19. Microbial metabolism of oxochlorates: a bioenergetic perspective.

    Science.gov (United States)

    Nilsson, Thomas; Rova, Maria; Smedja Bäcklund, Anna

    2013-02-01

    The microbial metabolism of oxochlorates is part of the biogeochemical cycle of chlorine. Organisms capable of growth using perchlorate or chlorate as respiratory electron acceptors are also interesting for applications in biotreatment of oxochlorate-containing effluents or bioremediation of contaminated areas. In this review, we discuss the reactions of oxochlorate respiration, the corresponding enzymes, and the relation to respiratory electron transport that can contribute to a proton gradient across the cell membrane. Enzymes specific for oxochlorate respiration are oxochlorate reductases and chlorite dismutase. The former belong to DMSO reductase family of molybdenum-containing enzymes. The heme protein chlorite dismutase, which decomposes chlorite into chloride and molecular oxygen, is only distantly related to other proteins with known functions. Pathways for electron transport may be different in perchlorate and chlorate reducers, but appear in both cases to be similar to pathways found in other respiratory systems. This article is part of a Special Issue entitled: Evolutionary aspects bioenergetic systems. PMID:22735192

  20. Modelling study on uranium migration in rocks under weathering condition

    International Nuclear Information System (INIS)

    A modelling study has been completed to understand the effect of rock alteration on uranium migration at the Koongarra ore deposit, Australia. The model considers the weathering process, the mechanism and rate of chlorite alteration, a major mineral of the host rock, and assumes the presence of reversible sorption sites of chlorite and the presence of reversible and irreversible sorption sites of the weathering products. One- and two-dimensional, calculated uranium concentrations were compared with those observed. Good agreement between the calculated and observed uranium concentration profiles was obtained only when an appropriate fraction of uranium is fixed to the irreversible sorption sites of Fe-minerals produced during weathering of chlorite. On the other hand, the conventional Kd model failed to estimate an adequate uranium concentration profile. The results suggest that the fixation of uranium to Fe-minerals has dominated the migration of uranium in the vicinity of the Koongarra ore deposit

  1. Uruguay geology contributions no. 4

    International Nuclear Information System (INIS)

    Sedimentary facies: the metasiltites and mela sandstones develop granoblastic textures. The present lepidoblastic textures in flexured bands of seri cite and/or chlorite, a fine qranoblastic matrix made by quartz-feldespaths. The carbonates develop mosaic textures with big crystals of calcites and dolomite, generally elongated following metamorphic foliation (seri cite/chlorite). The quartzites develop qranoblastic textures, with few minerals. Volcanics facies: the basic volcanics presents doleritic intersect al textural, that exist saussuritized plagioclase and albitic diabasa with diopside-augite beaches. Usually the pyroxenes develop poiquilitic textural. Present amphiboles of the acti note series and frequently sphene. Others basic rocks are microlitio porfiric, in intersect al or fluidal matrix, with albite microliters in epi dote-chlorite-acti note criploerislalline ground.The stability relationships of the diferents types of basic metavulcanites show low metamorphic facies, with temperatures under 530-550 grades C, being the most Irequenl association: albite+actinote+chlorite+epidote+opaques- opaques.The clastic faciest are integrated by monogenic breccia with elements of varied vulcanites and porfiric rnicrolitic texture. The matrix is made of line quartz and epidote aggregate. The basic volcanism present hyalo-porfiric textures with saussuritized plagiodase pheno crystals, and quartz in a micro lo criptocrystalline ground. Were also defined rocks with porfiric texture in a piromeritic ground as well as rocks with vacuolar microlitic texture.The clastic facies are made by breccias with sharp elements, with rare cement, integrated by pyroclastic products, The volcanics rocks present retrometamorphism of the phenocrystals and devitrification. The plagioclase are traslormated in fine aggregates of albite epidote. The regional metamorphism minerals are represented by the para genesis: quartz+albite+chlorite+epidote+(seri cite-actinole), subfacies quartz albite-chlorite

  2. The Management and Classification of the Typical Soils of the Yıldız Forest Ecosystem

    OpenAIRE

    Cangir, C.; D. Boyraz

    2009-01-01

    The soils of the Yıldız Mountain, namely Entisols, Mollisols, Inceptisols, Ultisols, and Spodosols, from Poyralı, Yeniceköy, Demirköy and northwest of Igneada that were developed on calcareous sandy sediments, chlorite schists, Pliocene sediments and alluvial materials were studied in this paper. Moreover, the Entisols and the Mollisols located at the Kırklareli, Koruköy, Dereköy and the land up to the Bulgarian border developed on metagranites, quartz-quartzitic sediments, chlorite schists, ...

  3. Luminescence and other spectroscopic properties of purple and green Cr-clinochlore

    Science.gov (United States)

    Czaja, Maria; Kądziołka-Gaweł, Mariola; Lisiecki, Radosław; Bodył-Gajowska, Sabina; Mazurak, Zbigniew

    2014-02-01

    For the first time ever, the luminescence spectra of Cr3+ centers in two chlorite crystals are presented. Chromium ions occupy the strong crystal-field site M4 in the brucite sheet and the intermediate crystal-field site in the inner octahedral sheet for purple and green chlorite, respectively. We discuss the influence of an effective positive charge on the Cr3+ ion and an effective negative charge of ligands on the differences in the values of the Dq and B parameters. It is concluded that the presence of Fe2+ ions and other point defects, as well as concentration quenching, causes the very short luminescence lifetimes of chromium ions.

  4. Mineralogical, IR-spectral and geochemical monitoring of hydrothermal alteration in a deformed and metamorphosed Jurassic VMS deposit at Arroyo Rojo, Tierra del Fuego, Argentina

    Science.gov (United States)

    Biel, C.; Subías, I.; Acevedo, R. D.; Yusta, I.; Velasco, F.

    2012-04-01

    The Arroyo Rojo Zn-Pb-Cu volcanogenic massive sulfide deposit is the main deposit of the Fin del Mundo District in the Fuegian Andes, Argentina. This deposit is hosted by a Middle Jurassic volcanic and volcanoclastic sequence forming the Lemaire Formation. The latter consists, from the base up, of the following: rhyolitic and dacitic porphyritic rocks, ignimbrite, tuff, and flow. It is underlain by a pre-Jurassic basement and overlain by the hyaloclastic andesites of the Yahgán Formation. The Arroyo Rojo consists of stacked lenticular lenses that are associated with disseminated mineralization in both the footwall and the hanging wall. The internal structure of the ore lenses is marked by the occurrence of massive, semi-massive and banded facies, along with stringer and brecciated zones and minor ore disseminations. The mineral assemblage comprises mainly pyrite and sphalerite, with minor amounts of galena and chalcopyrite and rare pyrrhotite, arsenopyrite, tetrahedrite and bournonite. The ores and the volcanic host rocks have metamorphosed to greenschist facies and were overprinted by a penetrative tectonic foliation, which led to the development of mylonitic, and cataclastic textures, recrystallization and remobilization. Primary depositional characteristics and regional and hydrothermal alteration patterns were preserved despite deformation and metamorphism. Therefore, primary banding was preserved between facies boundaries. In addition, some remnants of magmatic origin are recognizable in preserved phenocrysts and volcaniclastic phenoclasts. Most of the volcanic and volcaniclastic rocks of the host sequence show a rhyolitic to rhyo-dacitic composition. Regional seafloor alteration, characterized by the presence of clinozoisite, Fe-chlorite and titanite, along with quartz and albite, is partially obliterated by hydrothermal alteration. The hydrothermal alteration is stratabound with the following assemblages, which developed from the base to top: (1) Quartz-Chlorite

  5. Linking methane oxidation with perchlorate reduction: a microbial base for possible Martian life

    Science.gov (United States)

    Miller, L. G.; Carlstrom, C.; Baesman, S. M.; Coates, J. D.; Oremland, R. S.

    2011-12-01

    Recent observations of methane (CH4) and perchlorate (ClO4-) within the atmosphere and surface of Mars, respectively, provide impetus for establishing a metabolic linkage between these compounds whereby CH4 acts as an electron donor and perchlorate acts as an electron acceptor. Direct linkage through anaerobic oxidation of methane (AOM) has not been observed. However, indirect syntrophic oxygenase-dependent oxidation of CH4 with an aerobic methane oxidizer is feasible. The pathway for anaerobic dissimilatory perchlorate reduction includes 3 steps. The first 2 are sequential reductions of (1) perchlorate to chlorate and (2) chlorate to chlorite, mediated by perchlorate reductase. The third step is disproportionation of chlorite to chloride and molecular oxygen, mediated by chlorite dismutase. Utilization of thusly derived oxygen by hydrocarbon-degrading organisms in anoxic environments was first demonstrated by Coates et. al. (1998)1, however the link to aerobic methane oxidation was not examined at that time. Here, we systematically explore the potential for several species of aerobic methanotrophs to couple with chlorite during dissimilatory perchlorate reduction. In one experiment, 0.5 kPa CH4 was completely removed in one day from the headspace of combined cell suspensions of Dechloromonas agitata strain CKB and Methylococcus capsulatus in the presence of 5 mM chlorite. Oxidation of labeled 14CH4 to 14CO2 under similar conditions was later confirmed. Another experiment demonstrated complete removal of 0.2 kPa CH4 over several days by Methylobacter albus strain BG8 with strain CKB in the presence of 5 mM chlorite. Finally, we observed complete removal of 0.2 kPa CH4 in bottles containing natural soil (enriched in methanotrophs by CH4 additions over several weeks) and strain CKB and in the presence of 10 mM chlorite. This soil, collected from a pristine lake shoreline, demonstrated endogenous methane, perchlorate, chlorate and chlorite uptake. Other soil and

  6. Isotopic characteristics of two kinds of hydrothermal carbonation in the Maria Lazara gold deposit. Goias Estate of Central Brazil

    International Nuclear Information System (INIS)

    In the hydrothermal halo of the Maria Lazara gold deposit, two kinds of carbonation were identified: pervasive carbonation, which corresponds to the disseminations of calcite in the hydrothermal halo represented by the biotite-sulfide and carbonate-chlorite zones and, venular carbonation expressed by quartz and calcite veins inserted in the inner biotite-sulfide zone show an organic carbon component depleted in C. In the carbonate-chlorite zone the calcite isotopic behavior reflects the Co2 derived from the metamorphism o the basic host-rocks. (author)

  7. Clay vein and its implication for uranium exploration activity in the northern part of the Alligator Rivers Uranium Field, northern Australia

    International Nuclear Information System (INIS)

    Clay veins have been found by uranium exploration drilling around the Black Rock uranium prospect in the northern part of the alligator Rivers Uranium Field (ARUF), northern Australia. The mineralogical and chemical features are described to clarify relations with uranium mineralization, because it is not accompanied by uranium mineralization. X-ray diffraction and chemical analysis for major elements indicate that the clay vein consists mainly of chlorite (clinochlore to ferroan clinochlore) and lesser mica clay mineral (t-1M dominant). The clay vein is compared with the clay alteration zone around the uranium deposits in ARUF in terms of mode of occurrence, mineral and chemical compositions. Mineral composition of the clay vein is only in accordance with that of the inner alteration halo of the clay alteration zone. It is, however, different from mineral composition of the outer alteration halo in terms of lack of Fe chlorite in the clay vein. Chemical composition of the clay vein is similar to that of the clay alteration zone, except for lack in the vein of high iron content which is observed in some samples of the alteration zone. As a whole, the feature of the clay vein corresponds to the inner alteration zone around the uranium deposit in ARUF. The mode of occurrence of the clay vein is very different from that of the clay alteration zone. Mode of occurrence, and mineral and chemical compositions of the clay vein resemble a chlorite vein in the Lower to Middle Proterozoic sandstone above the Jabiluka deposit, one of major uranium deposit in the ARUF. Because of the similarity between the clay and the chlorite veins, the clay vein is regarded as marginal facies of an alteration zone. The fluid that formed the clay vein is estimated to have been oxidized, because of the existence of hematite and ubiquitous Mg chlorite. This nature is in accordance with the mineralizing fluid that formed the inner alteration zone in the Nabarlek deposit. In conclusion, the vein

  8. Indian summer monsoon and winter hydrographic variations over past millennia resolved by clay sedimentation

    Science.gov (United States)

    Chauhan, Onkar S.; Dayal, A. M.; Basavaiah, Nathani; Kader, U. Syed Abdul

    2010-09-01

    Reconstruction of century-scale Indian monsoon and winter hydrography is made from an AMS-dated core located in the unique region of the southeast Arabian Sea which lies in the pathways of the low-salinity Bay of Bengal Waters, advecting during winter northeast monsoon (NEM). Based upon clay mineral analyses in seawaters, we identify chlorite and kaolinite as specific clays supplied by the Bay of Bengal Waters and local fluvial flux (by the southwest monsoon (SWM) precipitation from the Peninsular India), respectively, along the southwest continental margin of India. An evaluation of clay flux and δ18O in G. ruber portrays century-scale weaker SWM precipitation events during ˜450-650 yr, ˜1000 yr, and 1800-2200 cal yr BP. Kaolinite wt % and flux were found to be low during all these events, though chlorite had a persistent or enhanced flux. From the enhanced flux of chlorite and reduced kaolinite/chlorite ratio, during weaker phases of SWM, we deduce a stronger NEM (winter hydrography), implying an inverse coupling between the summer and the winter monsoon.

  9. Clay mineral stratigraphy of Miocene to recent marine sediments in the central Mediterranean

    NARCIS (Netherlands)

    Visser, J.P. de

    1992-01-01

    X-ray diffraction analyses were made of the smaller than 2 J..Lm fraction from about 1250 samples of the central Mediterranean Miocene to Recent and the southeastern North-Atlantic Miocene in order to reconstruct climatic changes. Relative quantities of the clay minerals chlorite, illite, pyrophylli

  10. Geochemistry of the Cambrian Sirius Passet Lagerstätte, Northern Greenland

    DEFF Research Database (Denmark)

    Le Boudec, Ange; Ineson, Jon; Rosing, Minik Thorleif;

    2014-01-01

    broken down into variable proportions of two inputs, a dry felsic component and a hydrous mafic component (smectite or chlorite). Zircons U-Pb ages indicate multiple sources, the local Proterozoic basement of Northern Greenland (1250–2400 Ma) and Pan-African felsic magmas (620–650 Ma) from across the...

  11. Provenance of Holocene sediment on the Chukchi-Alaskan margin based on combined diffuse spectral reflectance and quantitative X-Ray Diffraction analysis

    Science.gov (United States)

    Ortiz, J.D.; Polyak, L.; Grebmeier, J.M.; Darby, D.; Eberl, D.D.; Naidu, S.; Nof, D.

    2009-01-01

    Sediment clay and silt mineral assemblages provide an excellent means of assessing the provenance of fine-grained Arctic sediment especially when a unique mineral assemblage can be tied to specific source areas. The diffuse spectral reflectance (DSR) first derivative measurements and quantitative X-Ray Diffraction (qXRD) on a high-resolution sediment core from the continental slope north of Alaska constrain the sediment mineralogy. DSR results are augmented by measurements on several adjacent cores and compared to surface sediment samples from the northern Alaskan shelf and slope. Using Principal Component Analysis (PCA), we infer that the three leading DSR modes relate to mixtures of smectite + dolomite, illite + goethite, and chlorite + muscovite. This interpretation is consistent with the down core qXRD results. While the smectite + dolomite, and illite + goethite factors show increased variability down core, the chlorite + muscovite factor had highest positive loadings in the middle Holocene, between ca. 6.0 and 3.6??ka. Because the most likely source of the chlorite + muscovite suite in this vicinity lies in the North Pacific, we argue that the oscillations in chlorite + muscovite values likely reflect an increase in the inflow of Pacific water to the Arctic through the Bering Strait. The time interval of this event is associated in other parts of the globe with a non-linear response of the climate system to the decrease in insolation, which may be related to changes in water exchange between the Pacific and Arctic Ocean. ?? 2009 Elsevier B.V.

  12. Development of chlorine dioxide releasing film and its application in decontaminating fresh produce

    Science.gov (United States)

    A feasibility study was conducted to develop chlorine dioxide releasing packaging films for decontaminating fresh produce. Sodium chlorite and citric acid powder were incorporated into polylactic acid (PLA) polymer. Films made with different amount of PLA (100 & 300 mg), percentage of reactant (5-60...

  13. Petrofabrics, microtextures and dislocation substructures of olivine in a peridotite mylonite (Alpe Arami, Switzerland)

    NARCIS (Netherlands)

    Buiskool Toxopeus, J.M.A.

    1978-01-01

    The development of preferred crystallographic orientation and dimensional fabric of olivine in relation to deformation were investigated in a thin, continuous chlorite peridotite mylonite rim around the garnet peridotite body of Alpe Arami, Ticino, Switzerland. The mylonite is a foliated rock contai

  14. Lability of soil organic carbon in tropical soils with different clay minerals

    DEFF Research Database (Denmark)

    Bruun, Thilde Bech; Elberling, Bo; Christensen, Bent Tolstrup

    2010-01-01

    of SOC in tropical soils with contrasting clay mineralogy (kaolinite, smectite, allophane and Al-rich chlorite). Soil was sampled from A horizons at six sites in humid tropical areas of Ghana, Malaysian Borneo and the Solomon Islands and separated into fractions above and below 250 µm by wet sieving...

  15. Radiochemical studies of the sorption behavior of strontium and barium

    International Nuclear Information System (INIS)

    The sorption behavior strontium and barium on kaolinite, bentonite and chlorite-illite mixed clay was studied by radioanalytical techniques using the batch method. 90Sr(29.1 y) and 133Ba(10.5y) were used as radiotracers. Characterization of the solid matrices was done by FTIR and XRD spectrometers and specific surface area measurements. Synthetic groundwater was used as the aqueous phase. The variation of the distribution ratio Rd, as a function of metal ion loading was examined. The sorption isotherms were fitted to various iso term models. The sorption energies were calculated to be in the range of 8-10kJ/mol suggesting an ion exchange type of sorption mechanism. In detailed experiments, chlorite-illite mixed clay was first presatured with K+, Sr2+, Ca2+ and Al 3= ions, respectively, prior to sorption studies with Ba2+ ions. The results of Ca2+ pretreated chlorite-illite were very similar to those of natural chlorite-illite, suggesting that the Ba2+ ion exchanges primarily with the Ca2+ ion on the clay minerals. (author). 15 refs., 3 figs., 5 tabs

  16. 40 CFR 141.132 - Monitoring requirements.

    Science.gov (United States)

    2010-07-01

    ... discretion. (2) Chlorite. Community and nontransient noncommunity water systems using chlorine dioxide, for... water from a single aquifer as one treatment plant for determining the minimum number of TTHM and HAA5..., taking into account number of persons served, different sources of water, and different treatment...

  17. Identification of a Perchlorate Reduction Genomic Island with Novel Regulatory and Metabolic Genes ▿

    OpenAIRE

    Melnyk, Ryan A.; Engelbrektson, Anna; Clark, Iain C.; Carlson, Hans K.; Byrne-Bailey, Kathy; Coates, John D.

    2011-01-01

    A comparative analysis of the genomes of four dissimilatory (per)chlorate-reducing bacteria has revealed a genomic island associated with perchlorate reduction. In addition to the characterized metabolic genes for perchlorate reductase and chlorite dismutase, the island contains multiple conserved uncharacterized genes possibly involved in electron transport and regulation.

  18. Identification of a perchlorate reduction genomic island with novel regulatory and metabolic genes.

    Science.gov (United States)

    Melnyk, Ryan A; Engelbrektson, Anna; Clark, Iain C; Carlson, Hans K; Byrne-Bailey, Kathy; Coates, John D

    2011-10-01

    A comparative analysis of the genomes of four dissimilatory (per)chlorate-reducing bacteria has revealed a genomic island associated with perchlorate reduction. In addition to the characterized metabolic genes for perchlorate reductase and chlorite dismutase, the island contains multiple conserved uncharacterized genes possibly involved in electron transport and regulation. PMID:21856823

  19. Chemical petrology of polymetamorphic ultramafic rocks from Galicia, NW Spain

    NARCIS (Netherlands)

    Maaskant, P.

    1970-01-01

    The investigated polymetamorphic peridotites occur associated with metabasic rocks in several complexes of probably Precambrian age in the northern part of the Hesperian massif (Iberian peninsula). Spinel-clinopyroxene-, spinel-pargasite-, spinel-hornblende- and chlorite-amphibole-peridotites, wehrl

  20. Petrographic characteristics of rocks with magnetite deposits of Vrbno (Jesieniki - Czech Republic

    Directory of Open Access Journals (Sweden)

    Miłosz A. Huber

    2011-11-01

    Full Text Available Introduction: The subject of this paper is a study the metamorphite shists from the old mines around the Mala Moravka-Karlova Studianka in which is magnetite ore, with ferrous chlorites present.Materials and methods: Samples were taken directly from the reservoir and the surrounding of the ore, then the samples were observed in the microscope in transmitted and reflected light, and were carried out X-ray analysis of XRD and SEM-EDS.Results: In the quartz-chlorite slates occur fibroblastic structure with numerous microfolds. X-ray analysis of rocks indicates the presence of calcite, quartz and ferrous chlorites of magnesium-ferrous group. The ore has a steel-gray color, granoblastic structure, layered, compact texture, sometimes with microfolds and deformations. The ore has a lenticular layers of quartz. Background of the ore are doubly and triply twinned magnetite and hematite idioblasts in some cases.Conclusions: The ore zone analysis indicates hydrothermal origin of the ore, which escaped to the earth surface by means of exhalations was deposited as sediment in clayey material. These deposits were metamorphosed in the chlorite facies.

  1. A note on incipient spilitisation of central Indian basin basalts

    Digital Repository Service at National Institute of Oceanography (India)

    Karisiddaiah, S.M.; Iyer, S.D.

    of chlorite, epidote and opaques. The oxide variation plots indicate a mid-ocean ridge basalt trend for the samples, which have been spilitised to varying degrees. It is suggested that the basalts formed as a result of a fissure type of eruption along...

  2. A new occurrence of ambient inclusion trails from the ~1900-million-year-old Gunflint Formation, Ontario: nanocharacterization and testing of potential formation mechanisms.

    Science.gov (United States)

    Wacey, D; Saunders, M; Kong, C; Kilburn, M R

    2016-09-01

    Ambient inclusion trails (AITs) are tubular microstructures thought to form when a microscopic mineral crystal is propelled through a fine-grained rock matrix. Here, we report a new occurrence of AITs from a fossilized microbial mat within the 1878-Ma Gunflint Formation, at Current River, Ontario. The AITs are 1-15 μm in diameter, have pyrite as the propelled crystal, are infilled with chlorite and have been propelled through a microquartz (chert) or chlorite matrix. AITs most commonly originate at the boundary between pyrite- and chlorite-rich laminae and chert-filled fenestrae, with pyrite crystals propelled into the fenestrae. A subset of AITs originate within the fenestrae, rooted either within the chert or within patches of chlorite. Sulphur isotope data ((34) S/(32) S) obtained in situ from AIT pyrite have a δ(34) S of -8.5 to +8.0 ‰, indicating a maximum of ~30 ‰ fractionation from Palaeoproterozoic seawater sulphate (δ(34) S ≈ +20 ‰). Organic carbon is common both at the outer margins of the fenestrae and in patches of chlorite where most AITs originate, and can be found in smaller quantities further along some AITs towards the terminal pyrite grain. We infer that pyrite crystals now found within the AITs formed via the action of heterotrophic sulphate-reducing bacteria during early diagenesis within the microbial mat, as pore waters were becoming depleted in seawater sulphate. Gases derived from this process such as CO2 and H2 S were partially trapped within the microbial mat, helping produce birds-eye fenestrae, while rapid microquartz precipitation closed porosity. We propose that propulsion of the pyrite crystals to form AITs was driven by two complementary mechanisms during burial and low-grade metamorphism: firstly, thermal decomposition of residual organic material providing CO2 , and potentially CH4 , as propulsive gases, plus organic acids to locally dissolve the microquartz matrix; and secondly, reactions involving clay minerals that

  3. Geochemical and Mineralogical Characteristics of Pleistocene Lignites and Associated Sediments of Marathousa Coal Field,Central Peloponnese,Greece

    Institute of Scientific and Technical Information of China (English)

    A.E.KELEPERTSIS; E.KONTIS

    1997-01-01

    The mineralogy and geochemistry data are presented for thirty-seven shales,four concretions,two carbonate sediments and seven lignites from the Marathousa coal field of the Megalopolis Basin in Greece.The argillaceous rocks consist of chlorite,illite,kaolinte,albite,quartz.opal-A,calcite and dolomite;the concretions of aragonite,gypsum and pyrite;and the carbonate rocks of calcite,quartz and illite.The mineral matter in the lignites consists of gypsum,quartz,albite,chlorite,illite,opal-A,dolomite,pyrite,and rarely calcite and kaolinite Athree-factor model explains the total variaition of major and trace elements in the argillaceous sediments.The first factor is an aluminosilicate factor and involves the following elements:Al,Si,Mg,Na,K,Ti,Mn,Nb,Y,Rb,Zn,Cu,Ni,Cr,Nband V,associated with chlorite,albite and illite.The second factor involves the elements Ca,Sr,Ba,Znand Sc and is related to carbonate lithology and mainly the carbonate concretions with gypsum.The third factor involves Fe and Ce with a weak association with Mn.The diagenesis of the Marathousa sediments and lignites was not very advanced as indicated by (a) the total thickness of the sequence (500m),(b) the presence of biogenic silica(opal-A) and (c) the age of the deposit(Pleistocene).FOr these reasons the rpresence of chlorite,illite and kaolinite in the sediments and lignite is due not to diagenetic reactions but to weathering of the flysch and metamorphic rocks at the edges of the Megalopolis Basin and transport of the weathering products(illite,chlorite,kaolinite)into the basin of deposition.The diagenetic minerals of the Marathousa sequence include pyrite,gypsum,dolomite and aragonite.

  4. The origin and age of the metamorphic sole from the Rogozna Mts., Western Vardar Belt: New evidence for the one-ocean model for the Balkan ophiolites

    Science.gov (United States)

    Borojević Šoštarić, S.; Palinkaš, A. L.; Neubauer, F.; Cvetković, V.; Bernroider, M.; Genser, J.

    2014-04-01

    This study brings new geochronological and petrochemical data from the metamorphic sole beneath the Rogozna Mts., Western Vardar ophiolite belt. The Rogozna metamorphic sole is located at the base of a serpentinite nappe and consists of amphibolites and talc-chlorite schists. The Rogozna amphibolites are medium- to fine-grained rocks with nematoblastic texture and pronounced foliation. They consist of green amphibole (~ 70 vol.%) with variable silica contents (6.4 to 7.8 Si apfu), as well as Mg# (molMg/[Mg + Fetot]; 0.53 to 0.77) and variably albitized plagioclase (~ 30 vol.%; Ab24-Ab98). Amphibolites are overprinted by a retrograde assemblage containing actinolite, epidote, clinoclore, sericite, chlorite, and magnetite. The amphibolites formed due to metamorphism of two basaltic suites: subalkaline/tholeiitic and alkaline. Subalkaline/tholeiitic amphibolites possess low Zr, Nb, Y, Th, Hf, TiO2, and P2O5 values and a LREE-depleted pattern, typical for the N-MORB (normal mid ocean ridge basalt) to BAB (back-arc basalt) origin. Alkaline amphibolites show elevated concentrations of Zr, Nb, Y, Th, Hf, TiO2, and P2O5 with a LREE-enriched pattern typically displayed by OIB (ocean island basalt). Amphibolites were crystallized during intra-oceanic thrusting at temperatures between 685 °C and 765 °C and at a depth of 12-17 km. 40Ar/39Ar cooling ages of amphibole, ranging from 165 to 170 Ma, slightly postdate the sole formation. Talc-chlorite schists are related to retrograde greenschist-facies metamorphism. They consist of Fe-rich talc and Cr-rich chlorite (peninite-diabantite) pseudomorphs after amphibole and MORB-type Cr-Al spinel, surrounded by Al- and Mg-poor ferrit chromite. The occurrence of ferrit chromite is related to earlier, amphibolite facies metamorphism. Chlorite pseudomorphs after amphibole were formed at 300-410 °C.

  5. CLAY MINERAL ASSEMBLAGES AND THEIR IMPLICATIONS IN SHIHEZI FORMATION FROM THE HUAIBEI COAL-BEARING STRATA

    Institute of Scientific and Technical Information of China (English)

    黄文辉; 许光泉; 刑军

    1998-01-01

    Clay mineral assemblages in Shihezi Formation of Huaibei coal-bearing strata are determined by X-ray diffraction and Differential Thermal Analyzer, that is restated to the sedimentfaces and climatic changes in the source area, and to a lesser extent, alterations during burial diagenesis. In the Upper Shihezi Formation, the clay fraction is dominated by kaolinite in norther npart of the coal field, which was formed in alluvial sediment environment. But in the South ofHuaibei coal field, the clay mineral assemblage consists of mainly illite that reflects the influenceof sea water. The predominately kaolinite and sederite composition of the clay fraction in the lower Shihezi Formation sediments documents less relief and gentle erosion of kaolinite rich soils developing under warm source area. In the lower part of Shihezi Formation, some chlorite is detected, which suggests transformation of illite or kaolinite to chlorite under conditions of burial diagenesis.

  6. Rodingitization and carbonization processes in Triassic ultramafic cumulates and lavas, Othris Mt, Central Greece

    Science.gov (United States)

    Koutsovitis, Petros; Magganas, Andreas; Economou, Georgios

    2016-04-01

    A Triassic magmatic sequence from the south Othris region is comprised of early stage basaltic pillow lavas, as well as late stage ultramafic rocks, lava flows, high-Mg doleritic dykes and pyroclastic tuffs. The ultramafic rocks include slightly serpentinized wehrlites and lavas consisting of cumulate olivine, variably textured clinopyroxene (cumulate, quench, hollow, skeletal or blade shaped), magnesiohornblende, tremolite, phlogopite, spinel, chlorite, garnet, serpentine, calcite and devitrified glass[1]. Part of their secondary mineralogy developed due to percolation of metasomatic fluids during rodingitization and carbonization processes. In ultramafic rocks from Agia Marina and Mili, rodingitization was rather penetratively and expressed with crystallization of hydrogarnets, accompanied by secondary diopside and chlorite. Hydrogarnets are characterized by their low Ti-contents (recycling thermal carbonated seawater, leached from the rifted Triassic platform carbonates. References. [1] Koutsovitis, Magganas, Ntaflos 2012: Lithos 144-145, 177-193; [2] Koutsovitis, Magganas, Pomonis, Ntaflos 2013: Lithos 172-173, 139-157.

  7. Super absorbent materials from lignocellulosic materials by phosphorylation. Lignocellulose no rinsan esuteruka ni yoru kokyusuisei zairyo

    Energy Technology Data Exchange (ETDEWEB)

    Saito, N.; Seki, K.; Aoyama, M. (Hokkaido Forest Products Research Institute, Hokkaido (Japan))

    1991-05-10

    Hydrogels were prepared from oxidized wood meals and chemical pulps through phosphorylation using phosphoric acid and urea. A transparent hydrogel, which was prepared from wood meals by oxidation with chlorite followed by phosphorylation, exhibited a capability of absorbing 115g of water for 1g of sample. As an oxidant, peracetic acid and ozone were also applied to the pretreatment. Brownish colored hydrogels were obtained from phosphorylated kraft and sulfite pulps. Phosphorylated kraft pulp showed the water absorbency of 66gH {sub 2} O/g, while phosphorylated sulfite pulp showed that of 29gH {sub 2} O/g. Wood meals phosphorylated without oxidation and the chemical pulps absorbed only several times individual weights of water. These results indicated that the pretreatment with chlorite would be the most effective for the hydrogelation. 24 refs., 2 tabs.

  8. Radiochemical studies of the sorption behaviour of strontium and barium in various clays

    International Nuclear Information System (INIS)

    The sorption of strontium and barium on kaolinite, bentonite, and chlorite-illite mixed clay was studied by radioanalytical techniques using the batch method. The variation of the distribution ratio as a function of the metal ion loading is reported. The maximum uptake of Ba2+ was observed for the chlorite-illite clays. The experimental data were fitted to Freundlich and Dubinin-Raduskevich isotherm models. The effect of the pH on the sorption process was studied. No significant changes in the sorption behaviour of Ba2+ and Sr2+ were measured in the pH range between 3.0 and 8.5. At pH-values of 11.0 and higher however, Rd values increase, probably due to the formation of carbonate complexes

  9. Chlorine dioxine DBPs (disinfection by-products in drinking water

    Directory of Open Access Journals (Sweden)

    C. Lasagna

    2013-01-01

    Full Text Available Since the 1970s it has been well known that, though water for human consumption is generally disinfected before being distributed along the network, the use of chemicals results in the formation of many different Disinfection By-Products (DBPs. In the case of chlorine dioxide, the most important and represented DBPs are chlorite and chlorate: after an introduction concerning the current Italian regulation on this subject, in the experimental part the results of a 7-year minitoring campaign, concerning water of different origin collected from taps in various Italian regions, are shown. The analytical technique used for the determination of chlorite and chlorate was Ion Chromatography. The result obtained are finally discussed.

  10. Maritime Antarctica soils studied by Moessbauer spectroscopy and other methods

    International Nuclear Information System (INIS)

    Soil samples from the King george Island, Antarctica, have been studied by 57 Fe Moessbauer spectroscopy, X-ray diffractometry, radiometry,neutron activation analysis and chemical analytical methods. X-ray diffractometry measurements have identified soils containing different volume ratios of quartz, feldspar, chlorite as well as hematite. The difference in the phase composition and in the iron distribution among the crystallographic sites of iron bearing minerals (chlorite, magnetite and hematite) of samples from two different depths was derived from the complex Moessbauer spectra. The differences in the mineral composition, iron distribution, concentration of water soluble salts, pH and radioactivity of certain radionuclides indicate the occurrence of chemical weathering of minerals. (author)

  11. CLAY MINERALOGY OF INSOLUBLE RESIDUES IN MARINE EVAPORITES.

    Science.gov (United States)

    Bodine, Marc W., Jr.

    1985-01-01

    Insoluble residues from three sequences of Paleozoic marine evaporites (Retsof salt bed in western New York, Salado Formation in south-eastern New Mexico, and Paradox Member of the Hermosa Formation in southeastern Utah) are rich in trioctahedral clays. Chlorite (clinochlore), corrensite (mixed-layer chlorite-trioctahedral smectite), talc, and illite (the only dioctahedral clay) are the dominant clay minerals; serpentine, discrete trioctahedral smectite (saponite), and interstratified talc-trioctahedral smectite are sporadically abundant. These clay-mineral assemblages differ chemically and mineralogically from those observed in most continental and normal marine rocks, which commonly contain kaolinite, dioctahedral smectite (beidellite-montmorillonite), illite, mixed-layer illite-dioctahedral smectite, and, in most cases, no more than minor quantities of trioctahedral clay minerals. The distinctive clay mineralogy in these evaporite sequences suggests a largely authigenic origin. These clay minerals are thought to have formed during deposition and early diagenesis through interaction between argillaceous detritus and Mg-rich marine evaporite brines.

  12. Significance of saturation index of certain clay minerals in shallow coastal groundwater, in and around Kalpakkam, Tamil Nadu, India

    Indian Academy of Sciences (India)

    S Chidambaram; U Karmegam; P Sasidhar; M V Prasanna; R Manivannan; S Arunachalam; S Manikandan; P Anandhan

    2011-10-01

    The saturation index of clay minerals like Gibbsite, Kaolinite, Illite, Montmorillonite and Chlorite in groundwater were studied in detail by collecting 29 groundwater samples from the shallow coastal aquifers in and around Kalpakkam. The samples collected were analysed for major cations, anions and trace elements by using standard procedures. The study reveals that pH has a significant role in the saturation index (SI) of minerals. It also shows that the relationship of electrical conductivity to the SI of these minerals is not significant than that of the ionic strength, log pCO2 values, and alumina silica ratio have significant relation to the SI of these clay minerals. The SI of these clay minerals was spatially distributed to identify the areas of higher SI. Silica has good correlation to SI of Kaolinite, Gibbsite and Montmorillonite and Al has good correlation to SI of all the minerals except to that of Chlorite.

  13. Hydrothermal alteration at the Roosevelt Hot Springs thermal area, Utah: characterization of rock types and alteration in Getty Oil Company well Utah state 52-21

    Energy Technology Data Exchange (ETDEWEB)

    Ballantyne, G.H.

    1978-11-01

    Getty Oil Company well 52-21 in the Roosevelt Hot Springs thermal area was drilled to 7500 feet in predominantly upper amphibolite facies metamorphic rocks. All lithologies in the drill hole are pervasively but weakly altered: the alteration assemblage is chlorite + sericite + clays with occasional traces of calcite, above 2300 feet, and chlorite + sericite + clays + calcite +- epidote below 2500 feet. A zone of increased alteration intensity from approximately 1800 feet to 2300 feet occurs within and adjacent to a dacite dike which cuts the metamorphic rocks. A second zone of stronger alteration extends from 6000 feet to the bottom of the drill hole. The drill hole which is located approximately 5000 feet south of the center of the silica apron known as the Opal Mound was apparently drilled beyond the influence of acid, high-sulfate brines such as have affected the upper portions of drill holes 72-16, 76-1 and University of Utah 1A and 1B.

  14. Petrographic report on clay-rich samples from Permian Unit 4 salt, G. Friemel No. 1 well, Palo Duro Basin, Deaf Smith County, Texas: unanalyzed data

    International Nuclear Information System (INIS)

    This report presents the results of mineralogic and petrographic analyses performed on five samples of clay-rich rock from salt-bearing Permian strata sampled by drill core from G. Friemel No. 1 Well, Deaf Smith County, Texas. Five samples of clay-rich rock from depths of about 2457, 2458, 2521, 2548, and 2568 feet were analyzed to determine the amounts of soluble phase (halite) and the amounts and mineralogy of the insoluble phases. The amounts of halite found were 59, 79, 47, 40, and 4 weight percent, respectively, for the samples. The insoluble minerals are predominately clay (20 to 60 volume percent) and anhydrite (up to 17 volume percent), with minor (about 1.0%) and trace amounts of quartz, dolomite, muscovite, and gypsum. The clays include illite, chlorite, and interstratified chlorite-smectite. The results presented in this petrographic report are descriptive, uninterpreted data. 2 references, 7 tables

  15. X-ray diffraction analysis of clay stones, Muglad Sedimentary Basin, Sudan

    International Nuclear Information System (INIS)

    This study deals with the theoretical and experimental aspects of X-ray diffraction (XRD) technique. Moreover the XRD technique has been used to investigate the clay mineral types and their distribution for samples obtained from exploration wells in the Mugald Sedimentary Basin in Western Sudan. The studied samples range in depth from 1524 m to 4572 m. The XRD analysis of samples shows that they consist of kaolinite, smectite, illite, chlorite and the mixed-layer smectite/illite. Kaolinite has higher abundance (15 - 72 %) followed by illite (7 - 34 %), smectite (11 - 76 %) and the less abundance of chlorite and the mixed-layer smectite/illite. Non-clay minerals found include quartz and cristabolite. The clay mineral types and their vertical distribution reflect various controls such as environmental, burial diagenesis, source rocks and climatic influences in the Muglad Sedimentary Basin. (author). 19 refs., 11 figs., 3 tabs

  16. Diagenetic effect on permeabilities of geothermal sandstone reservoirs

    DEFF Research Database (Denmark)

    Weibel, Rikke; Olivarius, Mette; Kristensen, Lars;

    The Danish subsurface contains abundant sedimentary deposits, which can be utilized for geothermal heating. The Upper Triassic – Lower Jurassic continental-marine sandstones of the Gassum Formation has been utilised as a geothermal reservoir for the Thisted Geothermal Plant since 1984 extracting...... and permeability is caused by increased diagenetic changes of the sandstones due to increased burial depth and temperatures. Therefore, the highest water temperatures typically correspond with the lowest porosities and permeabilities. Especially the permeability is crucial for the performance of the geothermal......-line fractures. Continuous thin chlorite coatings results in less porosity- and permeability-reduction with burial than the general reduction with burial, unless carbonate cemented. Therefore, localities of sandstones characterized by these continuous chlorite coatings may represent fine geothermal reservoirs...

  17. Petrographic report on clay-rich samples from Permian Unit 4 salt, G. Friemel No. 1 well, Palo Duro Basin, Deaf Smith County, Texas: unanalyzed data

    Energy Technology Data Exchange (ETDEWEB)

    Fukui, L M

    1983-09-01

    This report presents the results of mineralogic and petrographic analyses performed on five samples of clay-rich rock from salt-bearing Permian strata sampled by drill core from G. Friemel No. 1 Well, Deaf Smith County, Texas. Five samples of clay-rich rock from depths of about 2457, 2458, 2521, 2548, and 2568 feet were analyzed to determine the amounts of soluble phase (halite) and the amounts and mineralogy of the insoluble phases. The amounts of halite found were 59, 79, 47, 40, and 4 weight percent, respectively, for the samples. The insoluble minerals are predominately clay (20 to 60 volume percent) and anhydrite (up to 17 volume percent), with minor (about 1.0%) and trace amounts of quartz, dolomite, muscovite, and gypsum. The clays include illite, chlorite, and interstratified chlorite-smectite. The results presented in this petrographic report are descriptive, uninterpreted data. 2 references, 7 tables.

  18. COMPOSITION OF MINERAL PHASES OF THE GHIDIRIM DIATOMITE

    OpenAIRE

    Vasile Rusu; Aliona Vrînceanu; Igor Polevoi

    2007-01-01

    Studies of the mineralogical composition of diatomite from the Ghidirim location of RM, as well as of the extracted clay phase are presented. The mineral phase of the diatomite contains a number of clay minerals, like montmorillonite (in a mixture with insignificant quantities of slightly chloritized montmorillonite), illite and kaolinite. Diatomite contains also non-clay components as fine-dispersed quartz and amorphous material, the more probable sources of which are opal, amorphous alumosi...

  19. Distribution of clay minerals in drift sediments on the continental rise west of the Antarctic Peninsula, ODP Leg 178, Sites 1095 and 1096

    OpenAIRE

    Hillenbrand, C.-D.; W. Ehrmann

    2001-01-01

    The clay mineral compositions of upper Miocene to Quaternary sediments recovered at Ocean Drilling Program (ODP) Leg 178, Sites 1095 and 1096, from the continental rise west of the Antarctic Peninsula were analyzed in order to reconstruct the Neogene and Quaternary Antarctic paleoclimate and ice dynamics. The clay mineral assemblages are dominated by smectite, illite, and chlorite. Kaolinite occurs only in trace amounts. Analysis of a surface-sample data set facilitates the assignment of thes...

  20. Origine de la sédimentation dans le delta de l'Orénoque et le golfe de Paria (Venezuela) : impact du système dispersif amazonien

    OpenAIRE

    Pujos, M.; Monente, J; Latouche, C.; Maillet, N.

    1997-01-01

    The suspended matter transported by the Orinoco to the Orinoco delta originates mainly in the Colombian Andes. The four clayey minerals (kaolinite, chlorite, illite and smectite) are always present in the deltaic suspensions, the delta deposits and the gulf of Paria. Illite contents are always dominant except in those regions of the gulf of Paria situated far from the mouths of the Orinoco tributaries characterized by smectites. In the delta, illite contents which are minimal during the dry s...

  1. Mineralogy and chemistry of archaeological ceramic fragments from archaeological Dark Earth site in Colombian Amazon Mineralogia e química de fragmentos cerâmicos arqueológicos em sítio com Terra Preta da Amazônia Colombiana

    OpenAIRE

    Marcondes Lima da Costa; Gaspar Morcote Rios; Mônia Maria Carvalho da Silva; Glayce Jholy da Silva; Uliana Molano-Valdes

    2011-01-01

    Several Archaeological Dark Earth (ADE) sites have been already found in the Colombian Amazon forest showing high content of archaeological ceramic fragments similarly to those in the Brazilian Amazon represented by Quebrada Tacana site. Their fragments are yellow to grey colour, display a burned clayey matrix which involves fragments of cariapé and coal and ash particles, besides grains of quartz and micas. The clay matrix is made of metakaolinite, quartz, and some mica flakes, chlorite and ...

  2. Status of natural analogue studies

    International Nuclear Information System (INIS)

    This report is based on the materials for the meeting at the Nuclear Safety Commission of Japan held on September 1993. Details are as follows: Alteration of glass as the study of alteration of natural minerals; alteration of uranium minerals, migration of uranium and thorium series radionuclides, alteration of chlorite, fixation of uranium alteration of minerals and migration of uranium as the study of alligator rivers analogue project held at Koongarra uranium deposit, Australia. (author)

  3. Mineralogy, geochemistry, genesis, and industrial application of silica in Arefi area, south of Mashhad

    OpenAIRE

    Mohammad Hassan Karimpour; Azadeh Malekzadeh Shafaroudi; Saeid Saadat

    2014-01-01

    Introduction Arefi quartz-bearing conglomerate (Middle Jurassic) is situated within Binalud structural zone. The unit is trending NW-SE located 25 km south of Mashhad. More than 97% of the pebbles are quartz as mono-crystalline, poly-crystalline, and minor fragments of chert, quartzite, and mica schist. Less that 3% of the remaining minerals are feldspar, mica, chlorite, hornblende, tourmaline, zircon, sphene, and opaque minerals. The cement is mainly silica. Hashemi (Hashemi, 2004) sugges...

  4. Chlorine dioxide and by-products in water distribution systems

    OpenAIRE

    Ferreira, Francisco Cardoso

    1991-01-01

    Chlorine dioxide is used as both a pre-oxidant and/or a post-disinfectant in several water treatment plants in the United States. Chlorine dioxide is associated with its byproducts chlorite and chlorate. Chlorine dioxide, chlorine, chlori te and chlorate were sampled in four distribution systems where chlorine dioxide is used for disinfection purposes: Charleston, WV, Columbus, GA, New Castle, PA, and Skagit, WA. The fate of chlorine dioxide and its by-products in dist...

  5. Disinfecting capabilities of oxychlorine compounds.

    OpenAIRE

    Noss, C I; Olivieri, V P

    1985-01-01

    The bacterial virus f2 was inactivated by chlorine dioxide at acidic, neutral, and alkaline pH values. The rate of inactivation increased with increasing pH. Chlorine dioxide disproportionation products, chlorite and chlorate, were not active disinfectants. As chlorine dioxide solutions were degraded under alkaline conditions, they displayed reduced viricidal effectiveness, thereby confirming the chlorine dioxide free radical as the active disinfecting species.

  6. Permeability of sheeted dykes beneath oceanic ridges: Strain experiments coupled with 3D numerical modeling of the Troodos Ophiolite, Cyprus

    OpenAIRE

    Coelho, Gabriel; Branquet, Yannick; Sizaret, Stanislas; Arbaret, Laurent; Champallier, Rémi; Rozenbaum, Olivier

    2015-01-01

    Permeability laboratory measurements under in-situ pressures, temperature and strain have been performed on three different diabase alteration facies (metadiabase, chloritized diabase, epidosite) from the Troodos Ophiolite, Cyprus. This aims to study the relations between hydrodynamics, deformation and hydrothermal reaction in the sheeted dyke complex beneath oceanic ridges. The use of water as pore fluid in these experiments favors hydrothermal fluid-rock interactions. All experiments, perfo...

  7. Perchlorate reduction by microbes inhabiting oil reservoirs

    Science.gov (United States)

    Liebensteiner, Martin; Stams, Alfons; Lomans, Bart

    2014-05-01

    Microbial perchlorate and chlorate reduction is a unique type of anaerobic respiration as during reduction of (per)chlorate chlorite is formed, which is then split into chloride and molecular oxygen. In recent years it was demonstrated that (per)chlorate-reducing bacteria may employ oxygenase-dependent pathways for the degradation of aromatic and aliphatic hydrocarbons. These findings suggested that (per)chlorate may be used as oxygen-releasing compound in anoxic environments that contain hydrocarbons, such as polluted soil sites and oil reservoirs. We started to study perchlorate reduction by microbes possibly inhabiting oil reservoirs. One of the organisms studied was Archaeoglobus fulgidus. This extremely thermophilic archaeon is known as a major contributor to souring in hot oil reservoirs. A. fulgidus turned out to be able to use perchlorate as terminal electron acceptor for growth with lactate (Liebensteiner et al 2013). Genome based physiological experiments indicated that A. fulgidus possesses a novel perchlorate reduction pathway. Perchlorate is first reduced to chlorite, but chlorite is not split into chloride and molecular oxygen as occurs in bacteria. Rather, chlorite reacts chemically with sulfide, forming oxidized sulfur compounds, which are reduced to sulfide in the electron transport chain by the archaeon. The dependence of perchlorate reduction on sulfur compounds could be shown. The implications of our findings as novel strategy for microbiological enhanced oil recovery and for souring mitigation are discussed. Liebensteiner MG, Pinkse MWH, Schaap PJ, Stams AJM and Lomans BP (2013) Archaeal (per)chlorate reduction at high temperature, a matter of abiotic-biotic reactions. Science 340: 85-87

  8. Alteration of podzolized tills by acid load near Ni-Cu smelters at Monchegorsk, Kola Peninsula, Russia

    Directory of Open Access Journals (Sweden)

    Räisänen, M.L.

    1994-06-01

    Full Text Available Mineralogy and geochemistry of podzolized tills was studied in the area of dieback forest near the Ni-Cu smelters at Monchegorsk, and less extensively forest damage near by Apatity and Kirovsk in the Russian Kola Peninsula. The abundances of main elements (Si, Al, Fe, Mg, Ca, K, Na in the <64 μm fraction were determined by the hot aqua regia digestion method and inductively coupled plasma spectrometry. The clay mineralogy of the silt plus clay fraction was examined by X-ray diffraction after selective extraction and heating treatments. At all study sites, trioctahedral mica and chlorite were totally weathered from the silt and clay fraction (<64 μm of the eluvial layer, leaving behind interstratified mica-vermiculite-smectite clays. In general, the mixed-layer clay of the eluvial layer had low levels of hydroxy interlayering. Illuviated layers were characterized by hydroxy interlayered vermiculite-chlorite. The abundance of chlorite and mica was greater, and the degree of interlayering lower, in parent tills than in the overlying illuviated layers. Regardless of differences in bedrock and till geochemistry, the weathering sequence throughout the podzolized till profile was coherent at most of the sampling sites. Exceptionally, in a few profiles sampled at the totally destroyed forest site, the swelling mixed-layer clay of the eluvial layer displayed a neochloritized structure. On the basis of XRD patterns and geochemistry of the samples, it was inferred that a short-term decomposition of plagioclase had promoted, via inputs of Al-hydroxides, the transformation of mica-vermiculite-smectite to a poorly crystalline interstratification of chlorite-aluminous montmorillonite. The accelerated weathering occurring occasionally in exposed places was probably activated by the strongly acidic load in the vicinity of the smelters and the city of Monchegorsk.

  9. The first data on paleomagnetism of Palaeoproterozoic rocks of the Serpovidny structure (the Kola region, northeastern Baltic Shield

    Directory of Open Access Journals (Sweden)

    Matyushkin A. V.

    2016-03-01

    Full Text Available The orientation of natural magnetization vector components in amphibolites and amphibole schists (magnetite up to 10 % coincides with that of the modern magnetic field vector. Different orientations have been discovered only in quartzitic gneiss (magnetite ≤ 2 % and regressively changed chlorite-amphibole schist. The palaeopole position determined for these rocks corresponds on the apparent pole wander path to ages of 1.95 Ga and ~1.80 Ga, respectively

  10. Evidence for low-grade metamorphism, hydrothermal alteration, and diagenesis on mars from phyllosilicate mineral assemblages

    Science.gov (United States)

    Ehlmann, B.L.; Mustard, J.F.; Clark, R.N.; Swayze, G.A.; Murchie, S.L.

    2011-01-01

    The enhanced spatial and spectral resolution provided by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on the Mars Reconnaissance Orbiter (MRO) has led to the discovery of numerous hydrated silicate minerals on Mars, particularly in the ancient, cratered crust comprising the southern highlands. Phases recently identified using visible/near-infrared spectra include: smectite, chlorite, prehnite, high-charge phyllosilicates (illite or muscovite), the zeolite analcime, opaline silica, and serpentine. Some mineral assemblages represent the products of aqueous alteration at elevated temperatures. Geologic occurrences of these mineral assemblages are described using examples from west of the Isidis basin near the Nili Fossae and with reference to differences in implied temperature, fluid composition, and starting materials during alteration. The alteration minerals are not distributed homogeneously. Rather, certain craters host distinctive alteration assemblages: (1) prehnite-chlorite-silica, (2) analcime-silica-Fe,Mg-smectite-chlorite, (3) chlorite-illite (muscovite), and (4) serpentine, which furthermore has been found in bedrock units. These assemblages contrast with the prevalence of solely Fe,Mg-smectites in most phyllosilicate-bearing terrains on Mars, and they represent materials altered at depth then exposed by cratering. Of the minerals found to date, prehnite provides the clearest evidence for subsurface, hydrothermal/metamorphic alteration, as it forms only under highly restricted conditions (T = 200 400??C). Multiple mechanisms exist for forming the other individual minerals; however, the most likely formation mechanisms for the characteristic mineralogic assemblages observed are, for (1) and (2), low- grade metamorphism or hydrothermal (400??C has not been found.

  11. Purification and Characterization of (Per)Chlorate Reductase from the Chlorate-Respiring Strain GR-1

    OpenAIRE

    Kengen, Servé W. M.; Rikken, Geoffrey B.; Hagen, Wilfred R.; van Ginkel, Cees G.; Stams, Alfons J. M.

    1999-01-01

    Strain GR-1 is one of several recently isolated bacterial species that are able to respire by using chlorate or perchlorate as the terminal electron acceptor. The organism performs a complete reduction of chlorate or perchlorate to chloride and oxygen, with the intermediate formation of chlorite. This study describes the purification and characterization of the key enzyme of the reductive pathway, the chlorate and perchlorate reductase. A single enzyme was found to catalyze both the chlorate-...

  12. The effects of retrograde reactions and of diffusion on 39Ar-40Ar ages of micas

    DEFF Research Database (Denmark)

    Allaz, Julien; Engi, Martin; Berger, Alfons;

    2011-01-01

    Effects of metamorphic reactions occurring during decompression were explored to understand their influence on 39Ar-40Ar ages of micas. Monometamorphic metasediments from the Lepontine Alps (Switzerland) were studied. Collected samples reached lower amphibolite facies during the Barrovian...... retrograde chlorite formation. We conclude that even very minor chloritisation of biotite is apparently a more effective parameter than temperature in resetting the Ar clock, as is the formation of plagioclase from paragonite decomposition. Multi-equilibrium thermobarometry is necessary to ensure that...

  13. Zoning and contamination rate of magnesium and heavy metals of iron, zinc and copper in the north and northwest aquifer of Khoy (Zourabad) based on GIS and determining the contaminated source

    OpenAIRE

    Fariborz Khodadadi; Abdolnaser Fazlnia; Hossein Pirkharrati

    2015-01-01

    Introduction Heavy metals are the most toxic pollutants in aquatic ecosystems. This contamination can result from the release of heavy metal elements during alteration and weathering of ultramafic and mafic rocks (ophiolite zones). Among the important metals and pollutants in the ophiolite; chromium, cobalt, nickel, iron, magnesium, manganese, zinc and copper could be noted. Basically, a mass of serpentine consists of serpentine, amphibole, talc, chlorite, magnetite, and the remainder of o...

  14. Zeta Potential Measurements on Three Clays from Turkey and Effects of Clays on Coal Flotation

    Science.gov (United States)

    Hussain; Dem&idot;rc&idot;; özbayoğlu

    1996-12-25

    There is a growing trend of characterizing coal and coal wastes in order to study the effect of clays present in them during coal washing. Coarse wastes from the Zonguldak Coal Washery, Turkey, were characterized and found to contain kaolinite, illite, and chlorite. These three clays, obtained in almost pure form from various locations in Turkey, have been subjected to X-ray diffraction (XRD) analysis to assess their purity and zeta potential measurements in order to evaluate their properties in terms of their surface charge and point of zero charge (pzc) values. It was found from XRD data that these clays were almost pure and their electrokinetic potential should therefore be representative of their colloidal behavior. All three clay minerals were negatively charged over the range from pH 2.5 to 11. Chlorite and illite have pzc at pH 3 and pH 2.5, respectively, whereas kaolinite has no pzc. The effect of these clays in Zonguldak coal, wastes, and black waters on coal flotation was studied by floating artificial mixtures of Zonguldak clean coal (4.5% ash) and individual clay. The flotation tests on coal/individual clay revealed that each clay influences coal flotation differently according to its type and amount. Illite had the worst effect on coal floated, followed by chlorite and kaolinite. The loss of yield in coal was found to be 18% for kaolinite, 20% for chlorite, and 28% for illite, indicating the worst effect of illite and least for kaolinite during coal flotation. PMID:8978557

  15. Clay mineralogy and isotope geochemistry of the alteration halo at the Cigar Lake uranium deposit

    International Nuclear Information System (INIS)

    The clay-size fraction of the alteration halo associated with the Cigar Lake uranium deposit consists of illite with subordinate kaolinite, sudoite (Al-chlorite), Fe-chlorite, hematite, and traces of an illite-chlorite mixed-layer mineral. The Kuebler Index of illite crystallinity ranges from 2.0 to 6.7; the most-altered samples average 4.0. These data indicate that high-grade diagenetic to anchizonal conditions have been reached within the alteration halo. Intensity ratios of the 002 and 001 illite reflections (I(002)/I(001)) are generally greater than 0.4, the phengite-muscovite boundary, reflecting aluminum-rich illites; illite composition approaches hydromuscovite. K-Ar dates for illite-rich samples, from 1255 to 1148 Ma, could reflect variable resetting of the K-Ar system during hydrothermal fluid circulation after or during main-stage ore formation. The sudoite-illite assemblage from an altered basement sample yield a date of 815 Ma, unlike the clay-rich ore sample which contains no radiogenic argon. The younger date of the basement sample and the lack of radiogenic 40Ar in the ore sample may result from alteration. Average δD and δ18O values for illite-rich samples are -82 and +10, respectively. Samples that contain sudoite are enriched in D, but the ore sample containing Fe-chlorite is depleted in D and 18O relative to the illite-rich samples. 72 refs., 12 figs., 6 tabs

  16. Mantle metasomatism for metaperidotite from Shuanggou ophiolite of Yunnan Province by proton microprobe

    International Nuclear Information System (INIS)

    This study shows that olivine, serpentine and ortho pyroxene are enriched with compatible element Ni; clinopyroxene with Ni and Y; spinel strongly with Ni, Zn, Ga, Ge, As and Zr; chlorite with Ni, Zn, Sr and Zr. However, Grossularite is poor in all of these trace elements, except Sr. The trace element composition and distribution in the minerals are heterogeneous. The distributions of trace elements in the minerals further demonstrate that they result from mantle metasomatism under open system

  17. Chemical composition of Kiscellian silty sediment (sivica from the Trobni Dol area, Eastern Slovenia

    Directory of Open Access Journals (Sweden)

    Miha Mišič

    2003-06-01

    Full Text Available Kiscellian marine silt termed »sivica« is widely developed in Tertiary basins of Eastern Slovenia. Chemical composition is rather uniform and reflects the dominance of filosilicates (mainly illite/muscovite, chlorite and montmorillonite and carbonates. PAAS normalised REE and Y abundances are slightly depleted for La, Ce, Pr and Nd, very close to PAAS for Sm, Eu, Gd and Tb, and depleted for Y, Ho, Er, Tm, Yb and Lu.

  18. Improving Settling Dynamics of Activated Sludge by Adding Fine Talc Powder

    DEFF Research Database (Denmark)

    Rasmussen, Michael R.; Larsen, Torben; Clauss, F.

    1996-01-01

    The effect of adding varying mixtures of talc and chlorite powder to activated sludge in order to improve the settling characteristic has been studied. The powder is found to improve the settling velocity of the sludge, strictly by increasing the average density of the sludge floc aggregate. The...... settling velocity was measured with a recirculated settling column under different concentrations and turbulence levels. Numerical simulation of a secondary settling tank indicates that adding fine powder will improve the overall performance considerably....

  19. High resolution characterization of ectomycorrhizal fungal-mineral interactions in axenic microcosm experiments

    OpenAIRE

    Saccone, Loredana; Gazzè, Salvatore A.; Duran, Adele L.; Leake, Jonathan R; Banwart, Steven A.; Ragnarsdóttir, Kristín Vala; Smits, Mark M; McMaster, Terence J.

    2012-01-01

    Microcosms with Pinus sylvestris seedlings in symbiosis with the fungus mycorrhizal Paxillus involutus were established, and atomic force microscopy (AFM) was used to characterise plant photosynthate-driven fungal interactions with mineral surfaces. Comparison of images of the same area of the minerals before and after mycorrhizal fungal colonization showed extensive growth of hyphae on three different mineral surfaces - hornblende, biotite and chlorite. A layer of biological exudate, or biol...

  20. Tonmineral-Neubildung und Paläosalinität im Unteren Muschelkalk des südlichen Germanischen Beckens

    OpenAIRE

    Ruegner, Oliver

    2000-01-01

    Die Nichtkarbonatfraktion des Unteren Muschelkalks (Mittlere Trias) wurde anhand von sechs Bohrprofilen aus dem südlichen Germanischen Becken mittels konventioneller und isotopen-geochemischer Methoden analysiert. Die Tonfraktion besteht im wesentlichen aus der Mineralphase Illit, daneben kommen Illit-Smektit, Kaolinit und Chlorit vor. In der Tonfraktion wurden Borkonzentrationen zwischen 150 und 275 ppm gemessen. Innerhalb der Muschelkalk-Abfolge lassen sich charakteristische Verteilungsmust...

  1. The first data on paleomagnetism of Palaeoproterozoic rocks of the Serpovidny structure (the Kola region, northeastern Baltic Shield)

    OpenAIRE

    Matyushkin A. V.; Balagansky V. V.

    2016-01-01

    The orientation of natural magnetization vector components in amphibolites and amphibole schists (magnetite up to 10 %) coincides with that of the modern magnetic field vector. Different orientations have been discovered only in quartzitic gneiss (magnetite ≤ 2 %) and regressively changed chlorite-amphibole schist. The palaeopole position determined for these rocks corresponds on the apparent pole wander path to ages of 1.95 Ga and ~1.80 Ga, respectively

  2. High and intermediate sulphidation environment in the same hydrothermal deposit: the example of Au-Cu Palai???Islica deposit, Carboneras (Almer??a)

    OpenAIRE

    Carrillo-Ros??a, Javier; Morales-Ruano, Salvador; Boyce, Adrian J.; Fallick, Anthony E.

    2003-01-01

    Two epithermal environments have been identified in the Miocene Palai???Islica Au???Cu deposit: A) Intermediate sulphidation, hosted mainly in quartz veins, comprises pyrite, chalcopyrite, sphalerite and galena as the major sulphides, which are accompanied by a variety of Ag-bearing accessory minerals. Au???Ag alloys are the only gold-bearing phase. The veins are enclosed by sericitic and chloritic alteration. Fluid inclusions in quartz, sphalerite and calcite give Th between 118???453 ??C, a...

  3. Geological and geochemical implications of the genesis of the Qolqoleh orogenic gold mineralisation, Kurdistan Province (Iran)

    OpenAIRE

    Taghipour Batoul; Ahmadnejad Farhad

    2015-01-01

    The Qolqoleh gold deposit is located in the northwestern part of the Sanandaj–Sirjan Zone (SSZ), within the NE–SW trending Qolqoleh shear zone. Oligocene granitoids, Cretaceous meta-limestones, schists and metavolcanics are the main lithological units. Chondrite-normalised REE patterns of the ore-hosting metavolcanics indicate REE enrichment relative to hanging wall (chlorite-sericite schist) and footwall (meta-limestone) rocks. The pattern also reflects an enrich -ment in LREE re...

  4. Electron transport in microbial chlorate respiration

    OpenAIRE

    Smedja Bäcklund, Anna

    2009-01-01

    Several bacterial species are capable to use perchlorate and/or chlorate as an alternative electron acceptor in absence of oxygen. Microbial respiration of oxochlorates is important for biotreatment of effluent from industries where oxochlorates are produced or handled. One of these species, the Gram-negative Ideonella dechloratans, is able to reduce chlorate but not perchlorate. Two soluble enzymes, chlorate reductase and chlorite dismutase, participate in the conversion of chlorate into chl...

  5. Characterization of (per)chlorate-reducing bacteria

    OpenAIRE

    Wolterink, A.F.W.M.

    2004-01-01

    Some bacteria can use (per)chlorateas terminal electron acceptor for growth. These bacteria convert perchlorate via chlorate and chlorite into chloride and molecular oxygen. Oxygen formation in microbial respiration is unique. In this study two chlorate-reducing strains belonging to the species Pseudomonas chloritidismutans and a (per)chlorate-reducing strain Dechloromonas hortensis were isolated. The characterization of the chlorate-reducing strain AW-1, which was isolated from a bioreactor ...

  6. Transposon and Deletion Mutagenesis of Genes Involved in Perchlorate Reduction in Azospira suillum PS

    OpenAIRE

    Melnyk, Ryan A.; Clark, Iain C.; Liao, Annette; Coates, John D.

    2013-01-01

    ABSTRACT Although much work on the biochemistry of the key enzymes of bacterial perchlorate reduction, chlorite dismutase, and perchlorate reductase has been published, understanding of the molecular mechanisms of this metabolism has been somewhat hampered by the lack of a clear model system amenable to genetic manipulation. Using transposon mutagenesis and clean deletions, genes important for perchlorate reduction in Azospira suillum PS have been identified both inside and outside the previo...

  7. Physiological and Genetic Description of Dissimilatory Perchlorate Reduction by the Novel Marine Bacterium Arcobacter sp. Strain CAB

    OpenAIRE

    Carlström, Charlotte I.; Wang, Ouwei; Melnyk, Ryan A.; Bauer, Stefan; Lee, Joyce; Engelbrektson, Anna; Coates, John D.

    2013-01-01

    ABSTRACT A novel dissimilatory perchlorate-reducing bacterium (DPRB), Arcobacter sp. strain CAB, was isolated from a marina in Berkeley, CA. Phylogenetically, this halophile was most closely related to Arcobacter defluvii strain SW30-2 and Arcobacter ellisii. With acetate as the electron donor, strain CAB completely reduced perchlorate (ClO4 −) or chlorate (ClO3 −) [collectively designated (per)chlorate] to innocuous chloride (Cl−), likely using the perchlorate reductase (Pcr) and chlorite di...

  8. Identification, Characterization, and Classification of Genes Encoding Perchlorate Reductase

    OpenAIRE

    Bender, Kelly S.; Shang, Ching; Chakraborty, Romy; Belchik, Sara M.; Coates, John D.; Achenbach, Laurie A.

    2005-01-01

    The reduction of perchlorate to chlorite, the first enzymatic step in the bacterial reduction of perchlorate, is catalyzed by perchlorate reductase. The genes encoding perchlorate reductase (pcrABCD) in two Dechloromonas species were characterized. Sequence analysis of the pcrAB gene products revealed similarity to α- and β-subunits of microbial nitrate reductase, selenate reductase, dimethyl sulfide dehydrogenase, ethylbenzene dehydrogenase, and chlorate reductase, all of which are type II m...

  9. Fluid flow and polymetallic sulfide mineralization in the Kettara shear zone (Jebilet Massif, Variscan Belt, Morocco)

    Science.gov (United States)

    N'diaye, I.; Essaifi, A.; Dubois, M.; Lacroix, B.; Goodenough, K. M.; Maacha, L.

    2016-07-01

    The Kettara shear zone is a regional wrench shear zone within the Jebilet massif of Western Morocco, part of the Variscan orogenic belt. This massif is characterized by bimodal magmatism, largely intrusive, and by a number of polymetallic massive sulfide deposits. A syntectonic mafic-ultramafic intrusion and an adjacent, deformed pyrrhotite-rich massive sulfide deposit are located within a 'compressional jog' of the shear zone. Hydrothermal alteration in both the intrusion and the wall rocks adjacent to the deposit is characterized by syntectonic replacement processes leading to formation of chlorite-schists and quartz ± calcite veins. Fluid inclusions in mineralized (pyrrhotite-bearing) quartz veins from the wall rocks adjacent to the deposit and in veins associated with chlorite-schists within the intrusion indicate a prevalence of H2O-CO2-CH4-N2 and H2O-salt fluid systems. In the mineralized veins the fluid shows reducing conditions, with gas dominated by CH4 and N2 and salinities around 7.5 wt% NaCl, whereas in the chlorite shear zones fluid is CO2 dominated and salinities are higher than 23 wt% NaCl. Hydrogen and oxygen isotopic compositions of chlorite and quartz are similar and demonstrate involvement of metamorphic water in both the deposit and the intrusion. The data are consistent with a regional metamorphic fluid flow through the Kettara shear zone. The migrating metamorphic fluids were reduced in the organic matter-rich host rocks leading to deposition of sulfides in the mineralized veins. There are two possible hypotheses for the origin of these mineralized veins: either they were formed during deformation and remobilization of a syn-sedimentary massive sulfide deposit, or they were formed synchronously with the sulfide deposit during development of the Kettara shear zone.

  10. Effect of Different Sanitizers on Microbial, Sensory and Nutritional Quality of Fresh-Cut Jalapeno Peppers

    OpenAIRE

    Saul Ruiz-Cruz; Emilio Alvarez-Parrilla; de la Rosa, Laura A.; Alejandra I. Martinez-Gonzalez; Jose D.J. Ornelas-Paz; Ana M. Mendoza-Wilson; Gustavo A. Gonzalez-Aguilar

    2010-01-01

    Problem statement: Sanitation is a critical step to insure safety of fresh-cut produce. The inadequacies of chlorine, currently used as a sanitizer, have stimulated interest in finding safer, more effective sanitizers, however little is known on the impact of these novel sanitizers on sensory and nutrimental quality of the treated products. Approach: The effect of four sanitizers: Sodium hypochlorite (OCl), Peroxiacetic Acid (PA), Acidified Sodium Chlorite (ASC) and carvacrol on microbiologic...

  11. Alteration mineralogy of Home Plate and Columbia Hills—Formation conditions in context to impact, volcanism, and fluvial activity

    Science.gov (United States)

    Filiberto, Justin; Schwenzer, Susanne P.

    2013-10-01

    The Mars Exploration Rover Spirit investigated the igneous and alteration mineralogy and chemistry of Home Plate and its surrounding deposits. Here, we focus on using thermochemical modeling to understand the secondary alteration mineralogy at the Home Plate outcrop and surrounding Columbia Hills region in Gusev crater. At high temperatures (300 °C), magnetite occurs at very high W/R ratios, but the alteration assemblage is dominated by chlorite and serpentine over most of the W/R range. Quartz, epidote, and typical high-T phases such as feldspar, pyroxene, and garnet occur at low W/R. At epithermal temperatures (150 °C), hematite occurs at very high W/R. A range of phyllosilicates, including kaolinite, nontronite, chlorite, and serpentine are precipitated at specific W/R. Amphibole, with garnet, feldspar, and pyroxene occur at low W/R. If the CO2 content of the system is high, the assemblage is dominated by carbonate with increasing amounts of an SiO2-phase, kaolinite, carpholite, and chlorite with lower W/R. At temperatures of hydrous weathering (13 °C), the oxide phase is goethite, silicates are chlorite, nontronite, and talc, plus an SiO2-phase. In the presence of CO2, the mineral assemblage at high W/R remains the same, and only at low W/R, i.e., with increasing salinity, carbonate precipitates. The geochemical gradients observed at Home Plate are attributed to short-lived, initially high (300 °C) temperature, but fast cooling events, which are in agreement with our models and our interpretation of a multistage alteration scenario of Home Plate and Gusev in general. Alteration at various temperatures and during different geological processes within Gusev crater has two effects, both of which increase the habitability of the local environment: precipitation of hydrous sheet silicates, and formation of a brine, which might contain elements essential for life in diluted, easily accessible form.

  12. Abiotic CO2 reduction during geologic carbon sequestration facilitated by Fe(II)-bearing minerals

    Science.gov (United States)

    Nielsen, L. C.; Maher, K.; Bird, D. K.; Brown, G. E.; Thomas, B.; Johnson, N. C.; Rosenbauer, R. J.

    2012-12-01

    Redox reactions involving subsurface minerals and fluids and can lead to the abiotic generation of hydrocarbons from CO2 under certain conditions. Depleted oil reservoirs and saline aquifers targeted for geologic carbon sequestration (GCS) can contain significant quantities of minerals such as ferrous chlorite, which could facilitate the abiotic reduction of carbon dioxide to n-carboxylic acids, hydrocarbons, and amorphous carbon (C0). If such reactions occur, the injection of supercritical CO2 (scCO2) could significantly alter the oxidation state of the reservoir and cause extensive reorganization of the stable mineral assemblage via dissolution and reprecipitation reactions. Naturally occurring iron oxide minerals such as magnetite are known to catalyze CO2 reduction, resulting in the synthesis of organic compounds. Magnetite is thermodynamically stable in Fe(II) chlorite-bearing mineral assemblages typical of some reservoir formations. Thermodynamic calculations demonstrate that GCS reservoirs buffered by the chlorite-kaolinite-carbonate(siderite/magnesite)-quartz assemblage favor the reduction of CO2 to n-carboxylic acids, hydrocarbons, and C0, although the extent of abiotic CO2 reduction may be kinetically limited. To investigate the rates of abiotic CO2 reduction in the presence of magnetite, we performed batch abiotic CO2 reduction experiments using a Dickson-type rocking hydrothermal apparatus at temperatures (373 K) and pressures (100 bar) within the range of conditions relevant to GCS. Blank experiments containing CO2 and H2 were used to rule out the possibility of catalytic activity of the experimental apparatus. Reaction of brine-suspended magnetite nanoparticles with scCO2 at H2 partial pressures typical of reservoir rocks - up to 100 and 0.1 bars respectively - was used to investigate the kinetics of magnetite-catalyzed abiotic CO2 reduction. Later experiments introducing ferrous chlorite (ripidolite) were carried out to determine the potential for

  13. Study of corrosion resistance of chromium-nickel steel in calcium-hypochlorite solution part 2: Steels Č 4574 and Č 4583

    Directory of Open Access Journals (Sweden)

    Tošković D.

    2003-01-01

    Full Text Available This paper shows the results of investigations of corrosion resistance of different samples of chromium-nickel steels Č 4574 and Č 4583 in calcium-hypochlorite solution, by potentiodynamic method. The paper presents continuation of investigations on steels URANUS B6 and Č 4578 published in reference [1]. In this paper comparison of the obtained results is carried out, too, in order to detect steel, which quality is the best choice for calcium hypo chlorite solution requirements.

  14. Determination of refractory organic matter in marine sediments by chemical oxidation, analytical pyrolysis and solid-state 13C nuclear magnetic resonance spectroscopy

    OpenAIRE

    Rosa Arranz, José M. de la; González-Pérez, José Antonio; Hatcher, Patrick G; Knicker, Heike; González-Vila, Francisco Javier

    2008-01-01

    Seeking to quantify the amount of refractory organic matter (ROM), which includes black carbon-like material (BC), in marine sediments, we have applied a two-step procedure that consists of a chemical oxidation with sodium chlorite of the demineralized sediments followed by integration of the aromatic C region in the remaining residues by solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. The efficacy for lignin removal was tested by analytical pyrolysis in the presence of tetrame...

  15. Investigation of alteration zones, geochemistry and petrogenesis of the Chahshaljami prospect, Easthern Iran

    OpenAIRE

    Arjmandzadeh, R.; M. H. Karimpour; Mazaheri, S. A.; Santos, J. F.; Medina, J. M.; Homam, S.M.

    2010-01-01

    Chahshalghami mineral index is located 190 km to the south of Birjand in the Lut Block volcanic-plutonic belt. Intrusive rocks of Chahshalghami include quartz monzonite, monzonite, granodiorite and diorite and classified as volcanic arc granites, high-K calc alkaline to shoshonite rocks. Processing Aster Satellite image has detected alteration minerals such as alunite, jarusite, chlorite, dickite, sericite, montmorillonite, quartz and iron oxide. Silicic, sulfide and stockwork zones show anom...

  16. Surficial clay mineral distribution on the southwestern continental margin of India: Evidence of input from the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Chauhan, O.S.; Gujar, A.R.

    are also present in significant quantities on the slope with traces of gibbsite and palygorskite in some samples. The high contents of illite and chlorite (clay minerals which are not abundant in the soils and estuarine sediments of this region...) in the southern region of the study area are evidence for sediment contribution from the Bay of Bengal waters (BBW), which enter this region after the SW monsoon. Distribution trends of kaolinite, smectite, gibbsite, and laterite granules on the slope...

  17. Clay mineralogy of the Boda Claystone Formation (Mecsek Mts., SW Hungary

    Directory of Open Access Journals (Sweden)

    Németh Tibor

    2016-04-01

    Full Text Available Boda Claystone Formation (BCF is the host rock of the planned site for high level nuclear waste repository inHungary. Samples representing the dominant rock types of BCF were studied: albitic claystone, claystone with high illite content, and analcime bearing claystone. Clay minerals in these three rock types were characterized by Xray powder diffraction (XRD, transmission electron microscopy (TEM and thermal analysis (DTA-TG, and the results were discussed from the point of view of the radionuclide sorption properties being studied in the future. Mineral compositions of bulk BCF samples vary in wide ranges. In the albitic sample, besides the dominant illite, few percent of chlorite represents the layer silicates in the clay fraction. Illite is the dominating phase in the illitic sample, with a few percent of chlorite. HRTEM study revealed that the thickness of illite particles rarely reaches 10 layers, usually are of 5-6 TOT layer thick. Illite crystals are generally thicker in the albitic sample than in the illitic one. The significant difference between the clay mineral characterisitics of the analcimous and the other two samples is that the former contains regularly interstratified chlorite/smectite beside the dominant illite.

  18. Clay mineral records of East Asian monsoon evolution during late Quaternary in the southern South China Sea

    Institute of Scientific and Technical Information of China (English)

    LIU Zhifei; C. Colin; A. Trentesaux; D. Blamart

    2005-01-01

    High-resolution clay mineral records combined with oxygen isotopic stratigraphy over the past 190 ka during late Quaternary from core MD01-2393 off the Mekong River in the southern South China Sea are reported to reconstruct a history of East Asian monsoon evolution.The dominating clay mineral components indicate a strong glacial-interglacial cyclicity, with high glacial illite, chlorite, and kaolinite contents and high interglacial smectites content. The provenance analysis indicates the direct input of clay minerals via the Mekong River drainage basin.Illite and chlorite derived mainly from the upper reach of the Mekong River, where physical erosion of meta-sedimentary rocks is dominant. Kaolinite derived mainly from active erosion of inhered clays from reworked sediments in the middle reaches. Smectites originated mainly through bisiallitic soils in the middle to lower reaches of the Mekong River. The smectites/(illite+chlorite)and smectites/kaolinite ratios are determined as mineralogical indicators of East Asian monsoon variations. Relatively high ratios occur during interglacials and indicate strengthened summer-monsoon rainfall and weakened winter-monsoon winds; relatively lower ratios happened in glacials, indicating intensified winter monsoon and weakened summer monsoon. The evolution of the summer and winter monsoons provides an almost linear response to the summer insolation of the Northern Hemisphere, implying an astronomical forcing of the East Asian monsoon evolution.

  19. Multicomponent reactive transport modeling of acid neutralization reactions in mine tailings

    Science.gov (United States)

    Jurjovec, Jasna; Blowes, David W.; Ptacek, Carol J.; Mayer, K. Ulrich

    2004-11-01

    Multicomponent reactive transport modeling was conducted to analyze and quantify the acid neutralization reactions observed in a column experiment. Experimental results and the experimental procedures have been previously published. The pore water geochemistry was described by dissolution and precipitation reactions involving primary and secondary mineral phases. The initial amounts of the primary phases ankerite-dolomite, siderite, chlorite, and gypsum were constrained by mineralogical analyses of the tailings sample used in the experiment. Secondary gibbsite was incorporated into the model to adequately explain the changes in pH and concentration changes of Al in the column effluent water. The results of the reactive transport modeling show that the pH of the column effluent water can be explained by dissolution reactions of ankerite-dolomite, siderite, chlorite, and secondary gibbsite. The modeling results also show that changes in Eh can be explained by dissolution of ferrihydrite during the experiment. In addition, the modeling results show that the kinetically limited dissolution of chlorite contributes the largest mass of dissolved Mg and Fe (II) in the effluent water, followed by ankerite-dolomite, which contributes substantially less. In summary, reactive transport modeling based on detailed geochemical and mineralogical data was successful to quantitatively describe the changes in pH and major ions in the column effluent.

  20. Carboxymethylcellulose Obtained by Ethanol/Water Organosolv Process Under Acid Conditions

    Science.gov (United States)

    Ruzene, Denise S.; Gonçalves, Adilson R.; Teixeira, José A.; Pessoa de Amorim, Maria T.

    Sugar cane bagasse pulps were obtained by ethanol/water organosolv process under acid and alkaline conditions. The best condition of acid pulping for the sugarcane bagasse was 0.02 mol/L sulfuric acid at 160°C, for 1h, whereas the best condition for alkaline pulping was 5% sodium hydroxide (base pulp) at 160°C, for 3h. For the residual lignin removal, the acid and alkaline pulps were submitted to a chemical bleaching using sodium chlorite. Pulps under acid and alkaline conditions bleached with sodium chlorite presented viscosities of 3.6 and 7.8 mPas, respectively, and μ-kappa numbers of 1.1 and 2.4, respectively. The pulp under acid condition, bleached with sodium chlorite was used to obtain carboxymethylcellulose (CMC). CMC yield was 35% (pulp based), showing mass gain after the carboxymethylation reaction corresponding to 23.6% of substitution or 0.70 groups-CH2COONa per unit of glucose residue. The infrared spectra showed the CMC characteristic bands and by the infrared technique it was possible to obtain a substitution degree (0.63), similar to the substitution degree calculated by mass gain (0.70).

  1. Nature of uranium mineralization and associated wall rock alteration in the White's East area of the Embayment, Rum Jungle, Northern Territory

    International Nuclear Information System (INIS)

    The uranium mineralisation in the White's East area of The Embayment is hosted by Lower Proterozoic schists of the Masson formation which have undergone polyphase deformation and upper greenschist metamorphism. Significant mineralisation is also present in apatite rocks. The ore zones occur near an unconformity with overlying Middle Proterozoic sandstone and breccia conglomerate. Kink breccias and fracture systems related to post Middle Proterozoic reverse faults are the controls for mineralising fluid migration. Pitchblende is the main uranium mineral and it occurs as fine disseminated grains, fibrous webs, clusters composed of botryoidal aggregates and locally as veins. Two generations of uranium mineralisation are present. The first generation (pitchblende I) occurs as fine grained inclusions within chlorite II, and the second (pitchblende II) as hydraulic fracture networks and massive veins intimately associated with sericite-hematite-chlorite III. Two hydrothermal alteration phases have affected both Lower Proterozoic and Middle Proterozoic sequences. The most extensive alteration mineral is chlorite, of which a number of varieties has been identified

  2. Spectral properties and ASTER-based alteration mapping of Masahim volcano facies, SE Iran

    Science.gov (United States)

    Tayebi, Mohammad H.; Tangestani, Majid H.; Vincent, Robert K.; Neal, Devin

    2014-10-01

    This study applies Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data and the Mixture Tuned Matched Filtering (MTMF) algorithm to map the sub-pixel distribution of alteration minerals associated with the Masahim volcano, SE Iran for understanding the spatial relationship between alteration minerals and volcano facies. Investigations of the alteration mineralogy were conducted using field-spectroscopy, X-ray diffraction (XRD) analysis and ASTER Short Wave Infrared (SWIR) spectral data. In order to spectrally characterize the stratovolcano deposits, lithological units and alteration minerals, the volcano was divided into three facies: the Central, Proximal, and Medial-distal facies. The reflectance spectra of rock samples show absorption features of a number of minerals including white mica, kaolinite, montmorillonite, illite, goethite, hematite, jarosite, opal, and chlorite. The end-members of key alteration minerals including sericite (phyllic zone), kaolinite (argillic zone) and chlorite (propylitic zone) were extracted from imagery using the Pixel Purity Index (PPI) method and were used to map alteration minerals. Accuracy assessment through field observations was used to verify the fraction maps. The results showed that most prominent altered rocks situated at the central facies of volcano. The alteration minerals were discriminated with the coefficient of determination (R2) of 0.74, 0.81, and 0.68 for kaolinite, sericite, and chlorite, respectively. The results of this study have the potential to refine the map of alteration zones in the Masahim volcano.

  3. Proterozoic seawater — felsic volcanics interaction W. Bergslagen, Sweden. Evidence for high REE mobility and implications for 1.8 Ga seawater compositions

    Science.gov (United States)

    Baker, James H.; de Groot, Pier A.

    1983-06-01

    Mg enrichment in diffusely bounded, schistose alteration zones occurring in Proterozoic submarine felsic volcanics NE of Hjulsjö, W. Bergslagen is shown to result from felsic rock-seawater interaction in a sub-seafloor hydrothermal system. The alteration is apparently in two stages, feldspar being altered first to a kaolinite-type clay which is then replaced by Mg-chlorite. Major and trace element data are presented for the schist and sheridanite (chlorite). Relative to the least altered felsic volcanics, and for negligible volume change, the schist shows strong addition of Mg and to a lesser extent Si; K, Al and Rb are apparently conserved, while most other elements are strongly depleted, including the REEs which are removed for ˜75%, indicating a high degree of mobility. The chlorite, with its HREE enriched pattern, is considered to have equilibrated with the hydrothermal fluid, which consisted predominantly of seawater. Comparison with modern seawater leads to the tentative conclusion that the Proterozoic seawater HREE composition was not drastically different from that of modern seawater.

  4. Monochloramine and chlorine dioxide for controlling Legionella pneumophila contamination: biocide levels and disinfection by-product formation in hospital water networks.

    Science.gov (United States)

    Marchesi, Isabella; Ferranti, Greta; Bargellini, Annalisa; Marchegiano, Patrizia; Predieri, Guerrino; Stout, Janet E; Borella, Paola

    2013-12-01

    Legionella colonization in hospital hot water distribution networks was evaluated following 36 months of continuous treatment with monochloramine and compared with chlorine dioxide. Nitrite, nitrate, chlorite, chlorate, bromide, trihalomethanes and haloacetic acids as well as the biocide concentration at sampled points were measured. Only 8/84 samples treated with monochloramine were found contaminated and after the first 8 months of treatment no Legionella was isolated. Chlorine dioxide was associated with a strong reduction in Legionella contamination compared to pre-treatment, but differences according to the device were observed. Monochloramine between 2 and 3 mg l(-1) and chlorine dioxide between 0.50 and 0.70 mg l(-1) were needed to control Legionella colonization. Comparing no- and post-flush samples, a higher frequency of no-flush positive samples was noted using chlorine dioxide, suggesting an increased risk for patients when they open the tap. No increase in chlorite levels and no water nitrification occurred by using monochloramine. Chlorite at levels exceeding the limit requested for drinking water was measured when chlorine dioxide was applied. In conclusion, we highlight that continuous injection of monochloramine should be considered as an effective alternative to chlorine dioxide in controlling legionellae contamination inside hospital water distribution systems. PMID:24334848

  5. Preliminary study on features of mineralogical zoning of epigenetic alteration at sandstone-type uranium deposit, Dongsheng area, Ordos basin

    International Nuclear Information System (INIS)

    Sandstone-type uranium deposits located in Dongsheng area, northern Ordos basin, occur in Zhiluo Formation, Middle Jurassic. The Zhiluo Formation is divided into two members. The lower member is further divided into two submembers. The lower submember is dominantly composed of grey sandstone being the ore-hosting horizon; the upper submember consists of grey-green sandstone and mudstone. The upper member of Zhiluo Formation is made of mottled medium-fine grained sandstone and mudstone. Through the microscopic observation and study on sandstones of Zhiluo Formation, authors have established a vertical zonation of epigenetic alteration (from the top to the bottom): the limonitization + clayization + carbonation in the mottled fine-grained sandstone of the upper member of Zhiluo Formation; the green alteration (II) (mainly the chloritization of biotite, as well as the chloritization and epidotization of feldspar) + clayization + carbonation in the grey-green sandstone of the upper submember of the lower member of Zhiluo Formation; and the green alteration (I) (mainly the epidotization of feldspar) + carbonation in grey, grey-white sandstone of the lower submember. The epigenetic alteration basically occurs in grey-green sandstone. The sandstone shows grey-green color because it contains much green biotite (not chlorite). The epigenetic alteration in sandstone layer is closely associated with the uranium ore-formation

  6. Germicidal persistence of teat dips by modified excised teat procedure.

    Science.gov (United States)

    Schmidt, A L; Oliver, S P; Fydenkevez, M E

    1985-01-01

    An excised teat protocol was modified to evaluate persistence of germicidal activity of teat dips over 8 h. Five teat dip formulations, iodophor (1%), chlorhexidine gluconate (.55%), linear dodecyl benzene sulfonic acid (1.94%), sodium chlorite-lactic acid in a water base, and sodium chlorite-lactic acid in a gel base were tested against Escherichia coli and Klebsiella oxytoca. Iodophor and chlorhexidine had high germicidal activity throughout 8 h, whereas dodecyl benzene sulfonic acid had little activity. Germicidal activity of both sodium chlorite-lactic acid teat dips was high initially but declined with time. The gel base dip, however, remained more germicidal than the water base dip. Results were similar for either organism for most teat dips. However, chlorhexidine was less effective and the gel base dip more effective against Klebsiella oxytoca than Escherichia coli. Standard errors often appeared higher for Klebsiella oxytoca than for Escherichia coli. These assays may prove useful for laboratory screening of teat dips to determine germicidal persistence over time. PMID:3884679

  7. Biotite weathering in podzolic soil under conditions of a model field experiment

    Science.gov (United States)

    Sokolova, T. A.; Tolpeshta, I. I.; Topunova, I. V.

    2010-10-01

    The biotite changes in the 1-5 μm fraction after its occurrence in the F, H, AE, and E horizons of a pale-podzolic soil for five years under conditions of a model field experiment were assessed by X-ray diffraction analysis. It was found that the main changes of the biotite in all the horizons included the degradational transformation of its crystal lattice to interstratified mica-vermiculite structures and vermiculite. The intensity of this process gradually decreased from the F horizon down the profile in parallel with the decrease in the amount of roots and the abundance and activity of microbiota. Chloritized structures were present among the products of the biotite weathering in the H, AE, and E horizons; the degree of chloritization gradually increased from the H horizon to the E horizon. The main identified products of the biotite weathering in the AE and E horizons formed during the 5 years of the model experiment were identified in the clay and fine-silt fractions from these horizons of the native pale-podzolic soils. Therefore, the vermiculite, soil chlorite, and mixed-layer illite-vermiculite minerals in the soils studied could be considered as products of the recent soil functioning. The obtained results and literature data showed that the weathering of biotite resulted in the formation of K- and Al-buffer systems.

  8. Comparative study of microfacies variation in two samples from the Chittenango member, Marcellus shale subgroup, western New York state, USA

    Energy Technology Data Exchange (ETDEWEB)

    Balulla, Shama, E-mail: shamamohammed77@outlook.com; Padmanabhan, E., E-mail: eswaran-padmanabhan@petronas.com.my [Department of Geoscience, Faculty of Geosciencs and Petroleum Engineering Universiti Teknologi PETRONAS, Tronoh (Malaysia); Over, Jeffrey, E-mail: over@geneseo.edu [Department of geological sciences, Geneseo, NY (United States)

    2015-07-22

    This study demonstrates the significant lithologic variations that occur within the two shale samples from the Chittenango member of the Marcellus shale formation from western New York State in terms of mineralogical composition, type of lamination, pyrite occurrences and fossil content using thin section detailed description and field emission Scanning electron microscope (FESEM) with energy dispersive X-Ray Spectrum (EDX). This study is classified samples as laminated clayshale and fossiliferous carbonaceous shale. The most important detrital constituents of these shales are the clay mineral illite and chlorite, quartz, organic matter, carbonate mineral, and pyrite. The laminated clayshale has a lower amount of quartz and carbonate minerals than fossiliferous carbonaceous shale while it has a higher amount of clay minerals (chlorite and illite) and organic matter. FESEM analysis confirms the presence of chlorite and illite. The fossil content in the laminated clayshale is much lower than the fossiliferous carbonaceous shale. This can provide greater insights about variations in the depositional and environmental factors that influenced its deposition. This result can be compiled with the sufficient data to be helpful for designing the horizontal wells and placement of hydraulic fracturing in shale gas exploration and production.

  9. Microbial respiration with chlorine oxyanions: diversity and physiological and biochemical properties of chlorate- and perchlorate-reducing microorganisms.

    Science.gov (United States)

    Liebensteiner, Martin G; Oosterkamp, Margreet J; Stams, Alfons J M

    2016-02-01

    Chlorine oxyanions are valuable electron acceptors for microorganisms. Recent findings have shed light on the natural formation of chlorine oxyanions in the environment. These suggest a permanent introduction of respective compounds on Earth, long before their anthropogenic manufacture. Microorganisms that are able to grow by the reduction of chlorate and perchlorate are affiliated with phylogenetically diverse lineages, spanning from the Proteobacteria to the Firmicutes and archaeal microorganisms. Microbial reduction of chlorine oxyanions can be found in diverse environments and different environmental conditions (temperature, salinities, pH). It commonly involves the enzymes perchlorate reductase (Pcr) or chlorate reductase (Clr) and chlorite dismutase (Cld). Horizontal gene transfer seems to play an important role for the acquisition of functional genes. Novel and efficient Clds were isolated from microorganisms incapable of growing on chlorine oxyanions. Archaea seem to use a periplasmic Nar-type reductase (pNar) for perchlorate reduction and lack a functional Cld. Chlorite is possibly eliminated by alternative (abiotic) reactions. This was already demonstrated for Archaeoglobus fulgidus, which uses reduced sulfur compounds to detoxify chlorite. A broad biochemical diversity of the trait, its environmental dispersal, and the occurrence of relevant enzymes in diverse lineages may indicate early adaptations of life toward chlorine oxyanions on Earth. PMID:26104311

  10. Formation Rule of Chlorine Dioxide Disinfection By-products%二氧化氯消毒副产物的生成规律研究

    Institute of Scientific and Technical Information of China (English)

    张盛军; 张大钰; 董燕; 王永芳

    2013-01-01

    According to chlorite excessive phenomenon in chlorine dioxide sterilization of drinking water, Xiaoqinghe River and Darning Lake water were selected to study the relationship between chlorine dioxide consumption and chlorite production in the disinfection process. The removal of COD by chlorine dioxide was assessed. The results showed that chlorite production was positively correlated with chlorine dioxide consumption, and had no direct relation with chlorine dioxide dosage and COD concentration in water.%针对二氧化氯在饮用水消毒过程中出现的副产物亚氯酸盐超标现象,以小清河水和大明湖水为处理对象,研究了在消毒过程中二氧化氯的消耗量与亚氯酸盐的产生量之间的关系,同时测定了二氧化氯对COD的去除情况.结果表明,副产物亚氯酸盐的产生量与二氧化氯的消耗量呈正相关关系,而与二氧化氯的投加量及水体中的COD浓度没有直接关系.

  11. The Management and Classification of the Typical Soils of the Yıldız Forest Ecosystem

    Directory of Open Access Journals (Sweden)

    C. Cangir

    2009-01-01

    Full Text Available The soils of the Yıldız Mountain, namely Entisols, Mollisols, Inceptisols, Ultisols, and Spodosols, from Poyralı, Yeniceköy, Demirköy and northwest of Igneada that were developed on calcareous sandy sediments, chlorite schists, Pliocene sediments and alluvial materials were studied in this paper. Moreover, the Entisols and the Mollisols located at the Kırklareli, Koruköy, Dereköy and the land up to the Bulgarian border developed on metagranites, quartz-quartzitic sediments, chlorite schists, talc schists, dolomites, cyanites, have been studied as the soils in between the forest areas for their agricultural potentials. The clay mineral assemblages of the soils located at the west of the Yıldız Mountains revealed the presence of illite, vermiculite, smectite, chlorite and kaolinite that have indicated their influence on the fertility of these soils. Thus, the soils of the area are in need of appropriate management plans. The typical properties of the soils studied are: the absence of salinity and carbonate contents, the low amounts of organic matter, the deficiency in P and K which most probably is due to the leaching under acid conditions, the dominantly loamy textures and the pH varying from weakly to strong acid. The priority in the management of these soils should therefore be the application of an appropriate fertilization programme along with soil liming. In addition, some soils may need deep ripping and tillage.

  12. Comparative study of microfacies variation in two samples from the Chittenango member, Marcellus shale subgroup, western New York state, USA

    International Nuclear Information System (INIS)

    This study demonstrates the significant lithologic variations that occur within the two shale samples from the Chittenango member of the Marcellus shale formation from western New York State in terms of mineralogical composition, type of lamination, pyrite occurrences and fossil content using thin section detailed description and field emission Scanning electron microscope (FESEM) with energy dispersive X-Ray Spectrum (EDX). This study is classified samples as laminated clayshale and fossiliferous carbonaceous shale. The most important detrital constituents of these shales are the clay mineral illite and chlorite, quartz, organic matter, carbonate mineral, and pyrite. The laminated clayshale has a lower amount of quartz and carbonate minerals than fossiliferous carbonaceous shale while it has a higher amount of clay minerals (chlorite and illite) and organic matter. FESEM analysis confirms the presence of chlorite and illite. The fossil content in the laminated clayshale is much lower than the fossiliferous carbonaceous shale. This can provide greater insights about variations in the depositional and environmental factors that influenced its deposition. This result can be compiled with the sufficient data to be helpful for designing the horizontal wells and placement of hydraulic fracturing in shale gas exploration and production

  13. Evaluation of uranium anomalies in the McCaslin Syncline, northeastern Wisconsin

    International Nuclear Information System (INIS)

    On the basis of this investigation, the McCaslin area does not demonstrate sufficient recognition criteria to be considered favorable for the occurrence of uranium deposits that are analogous to quartz-pebble conglomerate deposits or unconformity-related deposits. Neither model is applicable because: (1) More often than not the conglomeratic lenses of the McCaslin Quartzite are polymictic. (2) Pyrite and chlorite are essentially lacking; (3) Pervasive chloritic and hematitic alteration are not present in the McCaslin district; (4) The maximum estimated age of the McCaslin is 1.9 b.y.; (5) The notable absence of anomalous uranium values in the basal McCaslin Quartzite, and especially where known faulting intersects the McCaslin, suggests that a process for concentrating uranium has not been effective in the area; (6) The Waupee Volcanics are not known to contain any extensive graphitic or chloritic schists, nor do they have more than normal amounts of uranium; (7) Uranium anomalies in stream-water, stream-sediment, and aerial surveys may be explained by uranium derived from the relatively uraniferous Hager Rhyolite, or other granitic intrusives related to the Wolf River batholith. The McCaslin area warrants no further investigation; it will not contribute any significant new potential the the NURE resource base. 3 figures, 3 tables

  14. Comparative study of microfacies variation in two samples from the Chittenango member, Marcellus shale subgroup, western New York state, USA

    Science.gov (United States)

    Balulla, Shama; Padmanabhan, E.; Over, Jeffrey

    2015-07-01

    This study demonstrates the significant lithologic variations that occur within the two shale samples from the Chittenango member of the Marcellus shale formation from western New York State in terms of mineralogical composition, type of lamination, pyrite occurrences and fossil content using thin section detailed description and field emission Scanning electron microscope (FESEM) with energy dispersive X-Ray Spectrum (EDX). This study is classified samples as laminated clayshale and fossiliferous carbonaceous shale. The most important detrital constituents of these shales are the clay mineral illite and chlorite, quartz, organic matter, carbonate mineral, and pyrite. The laminated clayshale has a lower amount of quartz and carbonate minerals than fossiliferous carbonaceous shale while it has a higher amount of clay minerals (chlorite and illite) and organic matter. FESEM analysis confirms the presence of chlorite and illite. The fossil content in the laminated clayshale is much lower than the fossiliferous carbonaceous shale. This can provide greater insights about variations in the depositional and environmental factors that influenced its deposition. This result can be compiled with the sufficient data to be helpful for designing the horizontal wells and placement of hydraulic fracturing in shale gas exploration and production.

  15. Metamorphic modifications of the Muremera mafic-ultramafic intrusions, eastern Burundi, and their effect on chromite compositions

    Science.gov (United States)

    Evans, David M.

    2015-01-01

    The Muremera mafic-ultramafic intrusions were emplaced into metasedimentary rocks of the Karagwe-Ankole Belt in eastern Burundi, as part of the Mesoproterozoic Kibaran tectonomagmatic event. Igneous minerals of the Muremera intrusions have been partly altered to hydrous and carbonated metamorphic assemblages, although in most cases, the original igneous textures are well-preserved. Rounded, subhedral cumulus olivine has been partially and pseudomorphically replaced by lizardite-magnetite mesh-rim and lizardite-brucite mesh-centre assemblages, while anhedral interstitial plagioclase has been replaced by chlorite-tremolite. A later and localized event results in prograde alteration to antigorite-magnetite-chlorite-talc-carbonate and talc-carbonate-chlorite assemblages. The rocks are inferred to have undergone at least three separate metamorphic/alteration events resulting in: AS1 - an early alteration assemblage (mesh-rim lizardite-magnetite) characterized by very low fluid/rock ratios and widespread distribution; AS2 - a later, widespread low-temperature retrogressive (mesh-centre lizardite-brucite) assemblage associated with abundant close-spaced parallel veins; AS3 - later, prograde (antigorite-magnetite) and AT4 (talc-chlorite-carbonate) assemblages associated with more localized shearing and higher fluid/rock ratios. The AS1 assemblage most likely represents deuteric alteration that occurred soon after intrusion and cooling. The AS2 assemblage may relate to a continuation of this cooling, or may be correlated with the regional upright D2 folding event, while the AS3 and AT4 alteration assemblages are most likely correlated with the N-S oriented D3 faulting episode linked to the distal East African Orogeny. Euhedral to subhedral chromite grains are essentially unaltered where enclosed in primary unaltered olivine, pyroxene or plagioclase, as well as in AS1 lizardite-magnetite and AS2 lizardite-brucite altered olivine or pyroxene. In samples which show alteration

  16. Enhanced chlorine dioxide decay in the presence of metal oxides: Relevance to drinking water distribution systems

    KAUST Repository

    Liu, Chao

    2013-07-19

    Chlorine dioxide (ClO2) decay in the presence of typical metal oxides occurring in distribution systems was investigated. Metal oxides generally enhanced ClO2 decay in a second-order process via three pathways: (1) catalytic disproportionation with equimolar formation of chlorite and chlorate, (2) reaction to chlorite and oxygen, and (3) oxidation of a metal in a reduced form (e.g., cuprous oxide) to a higher oxidation state. Cupric oxide (CuO) and nickel oxide (NiO) showed significantly stronger abilities than goethite (α-FeOOH) to catalyze the ClO2 disproportionation (pathway 1), which predominated at higher initial ClO2 concentrations (56-81 μM). At lower initial ClO2 concentrations (13-31 μM), pathway 2 also contributed. The CuO-enhanced ClO2 decay is a base-assisted reaction with a third-order rate constant of 1.5 × 10 6 M-2 s-1 in the presence of 0.1 g L -1 CuO at 21 ± 1 C, which is 4-5 orders of magnitude higher than in the absence of CuO. The presence of natural organic matter (NOM) significantly enhanced the formation of chlorite and decreased the ClO 2 disproportionation in the CuO-ClO2 system, probably because of a higher reactivity of CuO-activated ClO2 with NOM. Furthermore, a kinetic model was developed to simulate CuO-enhanced ClO 2 decay at various pH values. Model simulations that agree well with the experimental data include a pre-equilibrium step with the rapid formation of a complex, namely, CuO-activated Cl2O4. The reaction of this complex with OH- is the rate-limiting and pH-dependent step for the overall reaction, producing chlorite and an intermediate that further forms chlorate and oxygen in parallel. These novel findings suggest that the possible ClO2 loss and the formation of chlorite/chlorate should be carefully considered in drinking water distribution systems containing copper pipes. © 2013 American Chemical Society.

  17. The Geology and Petrography of Yücebelen and Surrounding Area, Torul-Gümüşhane

    Science.gov (United States)

    Doǧacan, Özcan; Özpınar, Yahya

    2013-04-01

    The study area is located in the tectono-stratigraphic zone named "Eastern Pontide Zone" from the northeastern part of Turkey. Eastern Pontides were formed by the subduction of Tethys Ocean under the Eurasian plate, during the Early Cretaceous - Late Eocene. Eastern Pontide orogenic zone can be divided in two tectono-stratigraphic subgroups as the northern and southern zones. The study area is located very close to border of these two subgroups but located in northern zone. In this project, the first geological map of the study area at the scale 1:5000 was made. Subsequently, detailed geological maps at the scale 1:2000 were made for the areas rich in ores. In the study area, Upper Cretaceous volcanic rocks consisting of basalts and basaltic andesites take place at the bottom of the rock sequence. Basalts and basaltic andesites with hyaloophitic, vitrophiric and microporphyric texture comprise plagioclase +pyroxene +chlorite +calcite ±epidote ±chalcedony ±opaque minerals. They are overlain by concordant pyroclastic and dacitic-rhyodacitic rocks. Quarts + K-feldispar ±plagioclase? ±biotite ±chlorite ±calcite ±chalcedony minerals are determined as a result of microscope investigation on samples taken from these rocks. These rocks are overlain by sedimentary rocks intercalated with pyroclastic rocks. All those units mentioned above, were intruded by granitoids of supposed Upper Cretaceous-Eocene age. Granitoids that crop out in the area were classified in terms of Q-ANOR parameters as granodiorites (Adile Hamlet occurrence - investigated in detail), diorites (Tuzlak Hill occurrence- eastern-part of study area) and quartz monzodiorites (İstavroma Hill occurrence- northern part of study area). Adile Hamlet granodiorites comprise plagioclase +pyroxene +chlorite +calcite ±quarts ±epidote +opaque minerals. A sequence of quarts +orthoclase +plagioclase ±chlorite ±epidote ±calcite ±opaque minerals have been determined after investigation of the rock samples

  18. Mobility of gold during metamorphism of the Dalradian in Scotland

    Science.gov (United States)

    Pitcairn, I. K.; Skelton, A. D. L.; Wohlgemuth-Ueberwasser, C. C.

    2015-09-01

    Mobility of Au and related metals during metamorphism has been suggested to be the source of metals enriched in orogenic Au deposits. This study investigates the mobility of Au, As, and Sb during metamorphism of the Dalradian metasedimentary rocks of Scotland. The metamorphic processes in the Dalradian of Scotland are extremely well studied, and the terrane is an ideal area to investigate mobility of these metals. Our results show that of the 25 major and trace elements analysed, only Au, As, Sb, S and volatile contents as shown by loss on ignition (LOI) values show systematic variation with the metamorphic grade of the samples. Average Au concentrations decrease from 1.1 ± 0.55 ppb and 0.72 ± 0.34 ppb in chlorite and biotite zone rocks down to 0.4 ± 0.22 ppb and 0.34 ± 0.13 ppb in kyanite and sillimanite zone rocks. Average As concentrations decrease from 4.8 ppm (range 0.5 to 17.8 ppm) and 1.96 ± 1.9 ppm in chlorite and biotite zone rocks down to 0.24 ± 0.15 ppm and 0.2 ± 0.12 ppm in kyanite and sillimanite zone rocks. Average Sb concentrations decrease from 0.18 ± 0.15 ppm and 0.11 ± 0.10 ppm in chlorite and biotite zone rocks down to 0.04 ± 0.02 ppm in both kyanite and sillimanite zone rocks. Sulphur and LOI concentrations also show significant decreases. Mass balance calculations indicate that compared to chlorite and biotite zone samples, sillimanite zone samples have an average mass loss of 62 ± 14%, 94 ± 4% and 74 ± 14% for Au, As, and Sb respectively. Every 1 km3 of chlorite-biotite zone mixed psammitic-pelitic protolith rock that is metamorphosed to sillimanite zone conditions would release 1.5 t Au, 8613 t As, 270 t Sb, and 1.02 Mt S. The mobility of these elements is strongly controlled by the paragenesis of sulphide minerals. Pyrite, sphalerite, galena and cobaltite (as well as gersdorffite) decrease in abundance with increasing metamorphic grade in the Dalradian metasedimentary rocks. A critical aspect of the sulphide paragenesis is the

  19. Microstructural studies of rocks from the 25 S oceanic core complex, along the Central Indian Ocean Ridge

    Science.gov (United States)

    Soda, Yusuke; Sawaguchi, Takashi; Enomoto, Tsubasa; Takagi, Hideo; Neo, Natsuki; Morishita, Tomoaki; Kumagai, Hidenori

    2010-05-01

    This study shows the microstructural development of rocks from the 25° S oceanic core complex (OCC) along the Central Indian Ocean Ridge, located near the Rodriguez Triple Junction. The samples described here are recovered by three submersible SHINKAI 6500 dives (Kumagai et al., 2008, Morishita et al., 2009). Characteristic foliated rocks with slickenline are recognized at a top surface of OCC, making up platy landform. Attitudes of those rocks are striking NE-SW and dipping to the NW and SE at moderate angle (20-30° ). Direction of lineation structures is perpendicular to the divergence ridge axis. We collect 55 samples during the three dives, and evaluate 10 samples as deformed rocks based on hand specimen scale structures on the shipboard. Deformed rocks distributed around the OCC surface consist of peridotite, gabbro, basalt, breccia and those altered rocks. Although almost olivine grains in peridotite are altered and replaced by talc, which forms anastmosing texture, olivine remnants show mylonitic texture characterized by undulose extinction and grain size reduction. Orthopyroxene grains are also elongated. Serpentine with platy shape makes up foliation, showing serpentinite mylonite texture. Olivine and serpentine are replaced by talc following mylonitization. Talc occurs as two different textures. One is static replacing primary minerals, and the other is syn-tectonic deformation textures such as foliated with shape preferred orientations, comprising talc schist. Gabbro also shows mylonitic structures featured by grain size reduction of plagioclase. Tremolite/actinolite is dominant facies in well foliated and altered gabbro in which has porphyroclasts of hornblende and plagioclase. Deformation of basalt is inhomogeneous and accompanying chloritization. Some part of basalt keeps plagioclase with basaltic textures, glassy texture and pseudomorph texture of them. Chlorite-rich basalt develops penetrative foliation and alters to chlorite schist. Breccia is

  20. Environment of ore deposition in the Creede mining district, San Juan Mountains, Colorado; Part IV, source of fluids, from oxygen, hydrogen, and carbon isotope studies

    Science.gov (United States)

    Bethke, P.M.; Rye, R.O.

    1979-01-01

    The hydrogen isotopic composition of fluids responsible for formation of the near-surface silver-base metal vein deposits at Creede was measured by direct analysis of inclusion fluids in sphalerite, quartz, and rhodochrosite and was estimated from analyses of illite and chlorite. The oxygen isotopic composition was determined directly on inclusion fluids in sphalerite and was estimated from analyses of quartz, illite, rhodochrosite, siderite, and adularia. The carbon isotopic composition was estimated from analyses of rhodochrosite and siderite. The ranges in isotopic composition for water and CO2 in the fluids associated with the formation of each of the minerals is given below (number of determinations given in parentheses):Mineral delta D (sub H2) O ppm delta 18 O (sub H2) O ppm delta 13 C (sub CO2) ppmSphalerite -81 to -54 (4) -10.1 to -4.5 (4)Quartz -97 to -86 (4) -5.9 to 1.8 (18)Illite -62 to -50 (8) -1.6 to 1.2(7)Chlorite -64 to -55 (10) -2.2 to 0.8 (10)Adularia 4.2 (1)Rhodochrosite -82 to -78 (2) 4.2 to 9.4 (9) -5.7 to -4.2 (9)Siderite 4.9 to 9.9 (6) -6.9 to -2.7 (6)The delta D (sub H2) O and delta 18 O (sub H2) O values of fluids associated with the formation of sphalerite, quartz, illite/chlorite, and carbonate minerals differ substantially from one another, and these differences appear to have been maintained throughout the depositional history, regardless of the positions of the minerals in the paragenetic sequence.The data suggest that waters from three coexisting reservoirs fed the vein system alternately and episodically during vein formation, and apparently there was little mixing of the fluids from the different reservoirs. The hydrogen, oxygen, and carbon isotope data suggest that the carbonate waters were deep seated, probably dominantly magmatic, in origin. The sphalerite and illite/chlorite waters must have been dominantly meteoric in origin and substantially oxygen shifted by exchange with the volcanic country rocks. The quartz waters were

  1. Deposition of talc - kerolite-smectite - smectite at seafloor hydrothermal vent fields: Evidence from mineralogical, geochemical and oxygen isotope studies

    Science.gov (United States)

    Dekov, V.M.; Cuadros, J.; Shanks, Wayne C.; Koski, R.A.

    2008-01-01

    Talc, kerolite-smectite, smectite, chlorite-smectite and chlorite samples from sediments, chimneys and massive sulfides from six seafloor hydrothermal areas have been analyzed for mineralogy, chemistry and oxygen isotopes. Samples are from both peridotite- and basalt-hosted hydrothermal systems, and basaltic systems include sediment-free and sediment-covered sites. Mg-phyllosilicates at seafloor hydrothermal sites have previously been described as talc, stevensite or saponite. In contrast, new data show tri-octahedral Mg-phyllosilicates ranging from pure talc and Fe-rich talc, through kerolite-rich kerolite-smectite to smectite-rich kerolite-smectite and tri-octahedral smectite. The most common occurrence is mixed-layer kerolite-smectite, which shows an almost complete interstratification series with 5 to 85% smectitic layers. The smectite interstratified with kerolite is mostly tri-octahedral. The degree of crystal perfection of the clay sequence decreases generally from talc to kerolite-smectite with lower crystalline perfection as the proportion of smectite layers in kerolite-smectite increases. Our studies do not support any dependence of the precipitated minerals on the type/subtype of hydrothermal system. Oxygen isotope geothermometry demonstrates that talc and kerolite-smectite precipitated in chimneys, massive sulfide mounds, at the sediment surface and in open cracks in the sediment near seafloor are high-temperature (> 250????C) phases that are most probably the result of focused fluid discharge. The other end-member of this tri-octahedral Mg-phyllosilicate sequence, smectite, is a moderate-temperature (200-250????C) phase forming deep within the sediment (??? 0.8??m). Chlorite and chlorite-smectite, which constitute the alteration sediment matrix around the hydrothermal mounds, are lower-temperature (150-200????C) phases produced by diffuse fluid discharge through the sediment around the hydrothermal conduits. In addition to temperature, other two

  2. Change of iron species and iron solubility in Asian dust during the long-range transport from western China to Japan

    Directory of Open Access Journals (Sweden)

    Y. Takahashi

    2011-11-01

    Full Text Available In the North Pacific, transport and deposition of mineral dust from Asia appear to be one of major sources of iron which can regulate growth of phytoplankton in the ocean. In this process, it is essential to identify chemical species of iron contained in Asian dust, because bioavailability of iron in the ocean is strongly influenced by the solubility of iron, which in turn is dependent on iron species in the dust. Here, we report that clay minerals (illite and chlorite in the dusts near the source collected at Aksu (western China can be transformed into ferrihydrite by atmospheric chemical processes during their long-range transport to eastern China (Qingdao and Japan (Tsukuba based on the speciation by X-ray absorption fine structure (XAFS and other methods such as X-ray diffraction and chemical extraction. As a result, Fe molar ratio in Aksu (illite : chlorite : ferrihydrite = 70 : 25 : 5 was changed to that in Tsukuba (illite : chlorite : ferrihydrite = 65 : 10 : 25. Moreover, leaching experiments were conducted to study the change of iron solubility. It was found that the iron solubility for the dust in Tsukuba (soluble iron fraction: 11.8 % and 1.10 % for synthetic rain water and seawater, respectively was larger than that in Aksu (4.1 % and 0.28 %, respectively, showing that iron in the dust after the transport becomes more soluble possibly due to the formation of ferrihydrite in the atmosphere. Our findings suggested that secondary formation of ferrihydrite during the transport should be considered as one of important processes in evaluating the supply of soluble iron to seawater.

  3. Fluid inclusion and phase equilibrium studies at the Cannivan Gulch molybdenum deposit, Montana, USA: Effect of CO 2 on molybdenite-powellite stability

    Science.gov (United States)

    Darling, Robert S.

    1994-01-01

    The molybdenum deposit at Cannivan Gulch is characterized by both stockwork- and skarn type mineralization. The vein mineral assemblages, however, differ considerably between the various host rocks. In the Cannivan stock, molybdenite occurs in typical quartz + K-feldspar or quartz + muscovite veins. In the country rocks, molybdenite occurs in chlorite + pyrite + magnetite veins containing variable amounts of quartz, calcite, and epidote. Primary fluid inclusions in quartz and fluorite contain aqueous liquid, CO 2 liquid, and CO 2 vapor (average XCO2 = 0.05). Microthermometric and Laser Raman microspectrographic analyses indicate CO 2 is the principal volatile phase. First melting temperatures in the aqueous portion indicate the dissolved salt is principally NaCl. Final CO 2-clathrate melting temperatures indicate NaCl contents ranging from 2 to 7 wt% relative to H 2O. Homogenization temperatures range from 196 to 272°C. Four chlorite temperatures from two samples range from 296 to 319°C. In P- T space, the four chlorite univariants intersect four fluid inclusion isochores (from the same samples) at temperatures of 300 ± 20° C and 1500 ± 300 bars, which are the inferred P and T of molybdenite formation. Mineral equilibria in vein assemblages from country rocks at Cannivan Gulch indicate fO2 and fS2 conditions of molybdenite formation between the pyrite-pyrrhotite-magnetite and pyrite-magnetite-hematite buffers. Formation of a calcite-molybdenite assemblage over powellite suggests that even small amounts of CO 2 ( XCO2 = 0.05) in an ore fluid greatly extend the stability field of molybdenite to higher oxygen fugacities.

  4. A study on the ground water flow and hydrogeochemical interaction in fractured rock masses

    International Nuclear Information System (INIS)

    A study site, the Precambrian gneiss complex in the vincinity of Chungyang has been investigated by geologic surface mapping, tunnel mapping and core drilling with chemical analysis and microscopic observation of rock samples and fracture filling materials. Four boreholes at depths between 50 and 200m were drilled. They are located in a potential fracture zone, which was selected based on the topographic characterisitcs and the fracture survey data. The hydraulic characteristics are described based on the results of constant pressure injection test and cross hole test. In the single hole test, the test sections varied between 1 and 5 m. The hydraulic conductivity of local fracture zones ranges from 1xlO-5 to lxlO-7 m/sec whereas that of the intact rock within the depth of 50 m is in the range of 7xlO-8 to 8xlO-9 m/sec. The field dispersivity values obtained from an injection phase range from 0.15 to 4.5 m at varying depths. The whole thickness dispersivity on the 18 m section obtained from a withdrawal phase is 0.4 m. The dispersion test in two well non-circulation mode was carried out along a single fracture set at depth between 11.5-14.5m. The longitudinal dispersivity obtained from the two well test is 8.14 m. The identified minerals of host rocks are quartz, K-feldspar,plagioclase, biotite, muscovite, sericite, chlorite, calcite, pyrite, zircon and opaque minerals. The primary minerals such as feldspar and biotite are highly altered into sericite and chlorite respectively. The fracture-filling materials from core samples identified by as calcite, kaolinite, smectite, chlorite, illitite, quartz, pyrite with fe- and Mn-oxides. (Author)

  5. Formation of disinfection byproducts upon chlorine dioxide preoxidation followed by chlorination or chloramination of natural organic matter.

    Science.gov (United States)

    Yang, Xin; Guo, Wanhong; Lee, Wontae

    2013-06-01

    Chlorine dioxide (ClO2) is often used as an oxidant to remove taste, odor and color during water treatment. Due to the concerns of the chlorite formation, chlorination or chloramination is often applied after ClO2 preoxidation. We investigated the formation of regulated and emerging disinfection byproducts (DBPs) in sequential ClO2-chlorination and ClO2-chloramination processes. To clarify the relationship between the formation of DBPs and the characteristics of natural organic matter (NOM), changes in the properties of NOM before and after ClO2 oxidation were characterized by fluorescence, Fourier transform infrared spectroscopy (FTIR), and size and resin fractionation techniques. ClO2 preoxidation destroyed the aromatic and conjugated structures of NOM and transformed large aromatic and long aliphatic chain organics to small and hydrophilic organics. Treatment with ClO2 alone did not produce significant amount of trihalomethanes (THMs) and haloacetic acids (HAAs), but produced chlorite. ClO2 preoxidation reduced THMs, HAAs, haloacetonitriles (HANs) and chloral hydrate (CH) during subsequent chlorination, but no reduction of THMs was observed during chloramination. Increasing ClO2 doses enhanced the reduction of most DBPs except halonitromethanes (HNMs) and haloketones (HKs). The presence of bromide increased the formation of total amount of DBPs and also shifted DBPs to more brominated ones. Bromine incorporation was higher in ClO2 treated samples. The results indicated that ClO2 preoxidation prior to chlorination is applicable for control of THM, HAA and HAN in both pristine and polluted waters, but chlorite formation is a concern and HNMs and HKs are not effectively controlled by ClO2 preoxidation. PMID:23312737

  6. Clay mineralogy of the Boda Claystone Formation (Mecsek Mts., SW Hungary)

    Science.gov (United States)

    Németh, Tibor; Máthé, Zoltán; Pekker, Péter; Dódony, István; Kovács-Kis, Viktória; Sipos, Péter; Cora, Ildikó; Kovács, Ivett

    2016-04-01

    Boda Claystone Formation (BCF) is the host rock of the planned site for high level nuclear waste repository inHungary. Samples representing the dominant rock types of BCF were studied: albitic claystone, claystone with high illite content, and analcime bearing claystone. Clay minerals in these three rock types were characterized by Xray powder diffraction (XRD), transmission electron microscopy (TEM) and thermal analysis (DTA-TG), and the results were discussed from the point of view of the radionuclide sorption properties being studied in the future. Mineral compositions of bulk BCF samples vary in wide ranges. In the albitic sample, besides the dominant illite, few percent of chlorite represents the layer silicates in the clay fraction. Illite is the dominating phase in the illitic sample, with a few percent of chlorite. HRTEM study revealed that the thickness of illite particles rarely reaches 10 layers, usually are of 5-6 TOT layer thick. Illite crystals are generally thicker in the albitic sample than in the illitic one. The significant difference between the clay mineral characterisitics of the analcimous and the other two samples is that the former contains regularly interstratified chlorite/smectite beside the dominant illite. Based on the structural and chemical data two illite type minerals are present in the BCF samples: 1M polytype containing octahedral Fe and Mg besides Al, 2M polytype illite generally is free of Fe andMg. Close association of very thin illite plates and nanosized hematite crystals is typical textural feature for BCF. The goal of this study is to provide solid mineralogical basis for further studies focusing on radionuclide sorption properties.

  7. Desalination impacts on the coastal environment: Ash Shuqayq, Saudi Arabia

    International Nuclear Information System (INIS)

    Ash Shuqayq (Saudi Red Sea coast) is approximately 28 km long and characterised by narrow rocky headlands with intermittent pocket beaches. Fifty-two sediment samples from six different environments (beach, dune, sabkha, tidal/lagoon, offshore and wadi) were analysed. Testing showed that beach and dune sands are mainly medium to fine grained, with some very coarse sand (MZ = − 0.59ø). Both beach and dune sands are moderately well to moderately sorted, although some are poorly sorted due to an influx of wadi sediments. Sediment source together with littoral reworking contributed to grain size variation. Carbonate content varied between 1.5% and 23%, whilst the organic content varied between 1.1% and 13%. Spatial analysis showed increasing southward carbonate and organic content, with both correlated (r = 0.57). Sabkha sediments had significantly higher carbonate percentages (t = 2.898; df = 18; p < 0.01) and results suggested origins are similar for both UAE Arabian Sea and Saudi Arabian Red Sea coasts. X-ray diffractions show beach and dune sediments are mainly composed of detrital quartz and plagioclase feldspar with uncommon amounts of chlorites. Analysis of sediment characteristics, composition and shoreline distribution alongside coastal processes, indicate that high chlorite levels are probably caused by desalination processes. Due to human and ecosystem health consequences and the likely increased demand for desalination plants, similar analyses should be undertaken elsewhere, e.g. the Mediterranean. - Highlights: ► New and previously unpublished Red Sea sediment information. ► Sediment chemical and spatial variations established. ► Sabkha origins are similar for both UAE Arabian Sea and Saudi Arabian Red Sea coasts. ► Desalination plant shown as cause of increased marine sediment chlorite levels.

  8. Fluid–rock interaction across the South Tibetan Detachment, Garhwal Himalaya (India): Mineralogical and geochemical evidences

    Indian Academy of Sciences (India)

    Anubhooti Saxena; Himanshu K Sachan; Pulok K Mukherjee; Dilip K Mukhopadhya

    2012-02-01

    The Malari Leucogranite in the Garhwal Himalaya is cut across by a continental-scale normal fault system called the South Tibetan Detachment (STD). A mineralogical, geochemical and fluid inclusion study of samples from the fault zone of the Malari Granite was performed to reveal the imprints of fluid–rock interaction. Fluid inclusion assemblages observed in the alteration zone indicate the presence of NaCl-dominated aqueous fluids with varied salinity of 6 –16 wt.% of NaCl equivalent. Mineralogical changes include the alteration of feldspar to muscovite and muscovite to chlorite. This alteration took place at temperatures of 275°–335°C and pressures between 1.9 and 4.2 kbars as revealed by the application of chlorite thermometry, fluid isochores, and presence of K-feldspar+muscovite+chlorite+quartz mineral assemblage. Geochemical mass-balance estimates predict 32% volume loss during alteration. An estimated fluid/rock ratio of 82 is based on loss of silica during alteration, and reveals presence of a moderately low amount of fluid at the time of faulting. Results of fluid inclusion and alteration mineralogy indicate that the Malari Leucogranites were exhumed due to normal faulting along the STD and erosion from mid-crustal levels. Most of the leucogranites in the Himalayas occur along the STD and possibly a regional-scale fluid flow all along the STD might have caused similar alteration of leucogranites along this tectonic break. Regional fluid flow was probably concentrated along the STD and channelized through mesoscopic fractures, microcracks and grain boundaries.

  9. Animal-sediment interactions: the effect of ingestion and excretion by worms on mineralogy

    Science.gov (United States)

    Needham, S. J.; Worden, R. H.; McIlroy, D.

    2004-09-01

    By controlled experiments that simulate marine depositional environments, it is shown that accelerated weathering and clay mineral authigenesis occur during the combined process of ingestion, digestion and excretion of fine-grained sediment by two species of annelid worms. Previously characterized synthetic mud was created using finely ground, low-grade metamorphic slate (temperature approximately 300°C) containing highly crystalline chlorite and muscovite. This was added to experiment and control tanks along with clean, wind-blown sand. Faecal casts were collected at regular intervals from the experimental tanks and, less frequently, from the control tanks. Over a period of many months the synthetic mud (slate) proved to be unchanged in the control tanks, but was significantly different in faecal casts from the experimental tanks that contained the worms Arenicola marina and Lumbricus terrestris. Chlorite was preferentially destroyed during digestion in the gut of A. marina. Both chlorite and muscovite underwent XRD peak broadening with a skew developing towards higher lattice spacing, characteristic of smectite formation. A neoformed Fe-Mg-rich clay mineral (possibly berthierine) and as-yet undefined clay minerals with very high d-spacing were detected in both A. marina and L. terrestris cast samples. We postulate that a combination of the low pH and bacteria-rich microenvironment in the guts of annelid worms may radically accelerate mineral dissolution and clay mineral precipitation processes during digestion. These results show that macrobiotic activity significantly accelerates weathering and mineral degradation as well as mineral authigenesis. The combined processes of sediment ingestion and digestion thus lead to early diagenetic growth of clay minerals in clastic sediments.

  10. Lithologic characteristics and diagenesis of the Devonian Jauf sandstone at Ghawar Field, Eastern Saudi Arabia

    Energy Technology Data Exchange (ETDEWEB)

    Al Ramadan, K.A.; Hussain, M. [King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia). Dept. of Earth Sciences; Imam, B. [Dhaka Univ. (Bangladesh). Dept. of Geology; Saner, S. [King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia). Research Inst.

    2004-12-01

    The Lower Devonian Jauf Formation in Saudi Arabia is an important hydrocarbon reservoir. However, in spite of its importance as a reservoir, published studies on the Jauf Formation more specifically on the reservoir quality (including diagenesis), are very few. This study, which is based on core samples from two wells in the Ghawar Field, northeastern Saudi Arabia, reports the lithologic and diagenetic characteristics of this reservoir. The Jauf reservoir is a fine to medium-grained, moderate to well-sorted quartz arenite. The diagenetic processes recognized include compaction, cementation (calcite, clay minerals, quartz overgrowths, and a minor amount of pyrite), and dissolution of the calcite cements and of feldspar grains. The widespread occurrences of early calcite cement suggest that the Jauf reservoir lost a significant amount of primary porosity at a very early stage of its diagenetic history. Early calcite cement, however, prevented the later compaction of the sandstone, thus preserving an unfilled part of the primary porosity. Based on the framework grain-cement relationships, precipitation of the early calcite cement was either accompanied or followed by the development of part of the pore-lining and pore-bridging clay cement. Secondary porosity development occurred due to partial to complete dissolution of early calcite cements and feldspar. Late calcite cement occurs as isolated patches, and has little impact on reservoir quality of the sandstones. In addition to calcite, several different clay minerals including illite and chlorite occur as pore-filling and pore-lining cements. While the pore-filling illite and chlorite resulted in a considerable loss of porosity, the pore-lining chlorite may have helped in retaining the porosity by preventing the precipitation of syntaxial quartz overgrowths. Illite, which largely occurs as hair-like rims around the grains and bridges on the pore throats, caused a substantial deterioration to permeability of the

  11. Structure and geochemistry of the Rise and Shine Shear Zone mesothermal gold system, Otago Schist, New Zealand

    International Nuclear Information System (INIS)

    The Rise and Shine Shear Zone is a late metamorphic deformation zone developed in biotite zone Textural Zone 4 schist in Central Otago. The shear zone has been hydrothermally altered, with addition of gold associated with replacement of schist minerals by pyrite and arsenopyrite. Hydrothermal alteration of schist during mineralisation involved replacement of titanite by rutile, recrystallisation of metamorphic quartz, muscovite and chlorite, and addition of ankerite. Mineralised schist has abundant microshears that have developed parallel and subparallel to the pervasive schist foliation, and these microshears contain much of the hydrothermal sulfides and gold. Microshears have been deformed locally by upright syn-mineralisation brittle reverse faults and angular folds that have a southerly axial trend. These more brittle deformation zones are confined to the Rise and Shine Shear Zone. Gold-bearing veins and mineralised breccias, made up of quartz, albite, pyrite, arsenopyrite, calcite, and chlorite, fill extensional sites associated with upright fold zones. Calcite delta18OVSMOW from these late-stage mineralised veins ranges from +7 to +15 per mille and δ13CPDB from -5.3 to -6.6 per mille, are similar to many other gold-bearing vein systems in Otago, but are distinctly different from the Macraes deposit. Mineralisation occurred near to the brittle/ductile transition, at 200-400 degrees C. The upper part of the shear zone was truncated by a shallow northeast-dipping normal fault, the Thomsons Gorge Fault, which juxtaposed shear zone rocks against unmineralised Textural Zone 3 chlorite zone rocks in the middle Cretaceous. The Rise and Shine Shear Zone has some structural and geochemical features in common with the Hyde-Macraes Shear Zone, but also some important differences, and is not a simple strike-extension of that structure. (author). 46 refs., 9 figs., 3 tabs

  12. Blueschist metamorphism and its tectonic implication of Late Paleozoic-Early Mesozoic metabasites in the mélange zones, central Inner Mongolia, China

    Science.gov (United States)

    Zhang, Jinrui; Wei, Chunjing; Chu, Hang

    2015-01-01

    Blueschists in central Inner Mongolia are distributed as layers and blocks in mélanges including the southern zone in Ondor Sum area and the northern zone in Manghete and Naomuhunni areas. They have been attributed to the subduction of Early Paleozoic oceanic crust. Blueschists from Ondor Sum and Naomuhunni are characterized by occurrence of sodic amphibole coexisting with epidote, albite, chlorite, calcic amphibole (in Ondor Sum) and muscovite (in Naomuhunni). Blueschists in Manghete contain porphyroblastic albite with inclusions of garnet and epidote in a matrix dominated by calcic-sodic amphibole, epidote, chlorite, albite and muscovite. Phase equilibria modeling for three blueschist samples using pseudosection suggest that the AlM2 contents in sodic amphibole can be used as a good barometer in the limited assemblage involving sodic amphibole + actinolite + epidote + chlorite + albite + quartz under pressures 7-10 kbar. In the sodic amphibole-bearing assemblages, the NaM4 contents in sodic amphibole mainly decrease as temperature rises, being a potential thermometry. The calculated pseudosections constrain the P-T conditions of blueschists to be 3.2-4.2 kbar/355-415 °C in Ondor Sum, 8.2-9.0 kbar/455 °C-495 °C in Manghete and 6.6-8.1 kbar/420-470 °C in Naomuhunni. These P-T estimates indicate a rather high geothermal gradient of 18-25 °C/km for the blueschist metamorphism, being of intermediate P/T facies series. Available zircon U-Pb age data suggests that the protoliths of blueschists were formed later than Late Paleozoic-Early Mesozoic and metamorphosed soon afterwards. An alternative interpretation for the tectonic implication of blueschists in central Inner Mongolia is that they may be a new type attributed to closure of limited ocean basins and do not represent a tectonic regime occurred in conventional subduction setting.

  13. Hydrothermal alterations and O, H, C isotopic characterization of fluids and minerals in uraniferous massif of Saint Sylvestre (France). Extension to other French intragranitic uranium deposits

    International Nuclear Information System (INIS)

    Petrographical, mineralogical, geochemical and stable isotope (18O/16O, D/H, 13C/12C) studies have been performed on the leucogranitic massif of St Sylvestre (Limousin, Massif Central francais), particularly on the different hydrothermal alterations. The oxygen isotope geochemistry of granites confirms the unicity of the different facies and their sialic origin (delta18O whole rocks = +11.0 +- 0.5 per mill), with a major contribution of detritic sediments rich in organic matter and poor in carbonate (delta13C magm. CO2 = -10.6 per mill). Late lamprophyres have a deep-seated origin (delta18O = + 6 per mill). The pervasive chloritization of granitic biotites occurs during the convective circulation of a fluid of meteoric origin, at temperatures around 350-4500C. The chemical composition of chlorite which is buffered by that of biotite and the large 18O-shift of fluid towards high delta values indicate that water-rock ratio was not very high. Chloritization takes place in high permeability zones. In regions where porosity is generally low, fluids are ''canalised'' in localised micro-fissured zones. Very high water/rock ratios lead to the dissolution of quartz, and the formation of the ''feldspathic episyenite'' alteration facies. The isotopic features of this fluid (delta18O approximately - 8 per mill, deltaD approximately - 50 per mill) indicate an elevated altitude. An isotopically similar fluid is responsible for the later ''micaceous episyenite'' alteration facies, found in fractured zones. Mixing of this fluid with a sedimentary fluid (delta18O approximately + 10 per mill, deltaD approximately - 30 per mill, delta13C approximately - 18 per mill) yielded the conditions necessary for the deposit of primary economic ore. Such fluids, sedimentary or metamorphic in origin, have been recognized in most hercynian intragranitic U and Sn-W deposits

  14. Lithological nature of the subduction channel: Insights from the Karabakh suture zone (Lesser Caucasus) and general comparisons

    Science.gov (United States)

    Hässig, Marc; Rolland, Yann; Sosson, Marc; Avagyan, Ara

    2016-05-01

    The lithological nature of major interplate boundaries is estimated by a field analysis of a well preserved exhumed subduction channel in the Caucasus Karabakh region. From this field example the subduction channel is a narrow geological object of about 500 m width formed at approximate depth of 10 km along an Andean-type subduction zone. It is comprised by an upper 'sedimentary' channel formed by an upper section of detrital and volcanic rocks thrusted on top of pelagic sediments scrapped off the oceanic floor. This sedimentary mélange is thrusted on top of an intensely deformed tectonic mélange. The tectonic mélange comprises blocks of basalt from the oceanic floor and a focussed deformation zone 50-100 m in width. This zone is mainly formed by mud-supported conglomerates exhibiting a chlorite + carbonate matrix with blocks of basalt, cross-cut by numerous chlorite-carbonate-epidote-albite veins. It overlies an undeformed ocean floor section. Superposed chlorite- and calcite-bearing veins in the mélange evidence high fluid:rock ratios of 0.3-2.3, with varied δ18O and δ13C isotopic ratios (+17 reservoirs along the subduction interface. These data show that the several fluid reservoirs situated along the interplate boundary could have been connected by high-magnitude co-seismic displacements along the subduction zone. These subduction channel features are confronted to other similar fossil examples and current settings, such as the Andes accretionary prism to propose a reconstructed geometry of the interplate contact zone from the surface to the base of the crust.

  15. Mineralogía y génesis de las arcillas de las unidades del Campo de Gibraltar. IV. Unidad de Facinas

    Directory of Open Access Journals (Sweden)

    Ruiz Cruz, M. O.

    1989-08-01

    Full Text Available The Facinas Unit consists of a clayed flysch facies with quartzite and sandstone centimeter layers. According to paleontological data, two beds are distinguished, one lower of Albian-Aptian age, and another, hígher, Upper Cretaceous-Paleocene in age. The mineralogy of the Facinas Unit is very monotonous through all the sequences studied, especially for the concerning to less than 2 fraction. This unít is characterized by an abundance of chlorites of different composition and genesis: Authigenic chlorites are mainly Fe-rich members, whereas chlorites of inherited origin are magnesian. On the other hand, this míneralogical study reveals a common origin and/or evolution for the two beds of the Facinas Unít.Se recogen en este trabajo los resultados obtenidos a partir del estudio mineralógico de la Unidad de Facinas, que presenta dos tramos, uno inferior Albo-Aptense y otro superior Cretácico Superior-Paleoceno. Las secuencias estudiadas muestran una gran similitud litológica y, si bien en las muestras totales se observan ciertas diferencias mineralógicas, la fracción menor de 2 micras es muy homogénea. Caracterizan a esta Unidad la abundancia de cloritas de diferente composición y génesis: cloritas autigénicas, predominantemente ferrosas y cloritas heredadas, magnesianas. Por otra parte, este estudio mineralógico permite indicar un origen y/o evolución común para los dos tramos de la Unidad de Facínas.

  16. Mineral types of hydrothermal alteration zones in the Dukat ore field and their relationships to leucogranite and epithermal gold-silver ore, northeastern Russia

    Science.gov (United States)

    Filimonova, L. G.; Trubkin, N. V.; Chugaev, A. V.

    2014-05-01

    The paper considers the localization of potassic and propylitic hydrothermal alteration zones in the domal volcanic-plutonic structure controlling the position of the Dukat ore field with the eponymous unique epithermal Au-Ag deposit. Comprehensive mineralogical and geochemical data on rocks and minerals in hydrothermal alteration zones and associated intrusions have shown that quartz-jarosite-sericite, quartz-pyrite-sericite, and quartz-adularia-chlorite alterations were formed with the participation of fluid flows related to a fingerlike projection of a high-K leucogranite porphyry intrusion with large phenocrysts. These hydrothermal alterations developed in the rifted graben under conditions of divergent plate boundaries, whereas quartz-clinozoisite-calcite, epidote-chlorite, and garnet-calcite-chlorite alterations were linked to K-Na leucogranite intrusive bodies and developed under conditions of convergent plate boundaries reactivated as a result of formation of the marginal Okhotsk-Chukotka volcanic belt. Phase separation and coagulation of specific portions of ascending fluids resulted in the formation and stabilization of small-sized particles of native silver and other ore components, which enabled involvement in flows of secondary geothermal solutions and ore-forming fluids. The Sr, Nd, and Pb isotopic compositions of rocks and minerals from the hydrothermal alteration zones, associated intrusions, and economic orebodies at the Dukat deposit indicate that their components have been derived from the juvenile continental crust, which was altered in pre-Cretaceous periods of endogenic activity. The components of gangue minerals of potassic and propylitic hydrothertmal alterations and associated intrusions have been taken from deep sources differing in 87Sr/86Sr and 143Nd/144Nd at similar U/Pb and Th/Pb ratios. Chalcophile lead in products of hydrothermal activity and melanocratic inclusions in leucogranite has been taken from regions with elevated U/Pb and

  17. Chromite Composition and Accessory Minerals in Chromitites from Sulawesi, Indonesia: Their Genetic Significance

    Directory of Open Access Journals (Sweden)

    Federica Zaccarini

    2016-05-01

    Full Text Available Several chromite deposits located in the in the South and Southeast Arms of Sulawesi, Indonesia, have been investigated by electron microprobe. According to the variation of the Cr# = Cr/(Cr + Fe3+, the chromite composition varies from Cr-rich to Al-rich. Small platinum-group minerals (PGM, 1–10 μm in size, occur in the chromitites. The most abundant PGM is laurite, which has been found included in fresh chromite or in contact with chlorite along cracks in the chromite. Laurite forms polygonal crystals, and it occurs as a single phase or in association with amphibole, chlorite, Co-pentlandite and apatite. Small blebs of irarsite (less than 2 μm across have been found associated with grains of awaruite and Co-pentlandite in the chlorite gangue of the chromitites. Grains of olivine, occurring in the silicate matrix or included in fresh chromite, have been analyzed. They show a composition typical of mantle-hosted olivine. The bimodal composition and the slight enrichment in TiO2 observed in some chromitites suggest a vertical zonation due to the fractionation of a single batch magma with an initial boninitic composition during its ascent, in a supra-subduction zone. This observation implies the accumulation of Cr-rich chromitites at deep mantle levels and the formation of the Al-rich chromitites close or above the Moho-transition zone. All of the laurites are considered to be magmatic in origin, i.e., entrapped as solid phases during the crystallization of chromite at temperature of around 1200 °C and a sulfur fugacity below the sulfur saturation. Irarsite possibly represents a low temperature, less than 400 °C, exsolution product.

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

    International Nuclear Information System (INIS)

    The present study deals with the petrographical, mineralogical and geochemical characteristics of the alteration facies zones recognized around the shear zone at Gabal El-Missikat area, Central Eastern Desert, Egypt. Petrographically, the fresh granitic samples are composed mainly of quartz, K-feldspars (microcline and microcline perthite), plagioclase, biotite. The secondary minerals are sericite, kaolinite, muscovite, chlorite and epidote as well as zircon, apatite, fluorite, titanite and iron oxides as accessory minerals. Two alteration facies zones are recognized and namely as propylitic and advanced argillic. The propylitic facies zone is composed mainly of sericite with minor kaolinite, muscovite, quartz, relics of plagioclases, chlorite and rare epidote as well as zircon, hematite, goethite, magnetite, ilmenite, ilmenorutile, rutile, titanite, apatite, columbite and fluorite and secondary uranium minerals, the advanced argillic facies zone is composed mainly of kaolinite with minor sericite, quartz, muscovite, chlorite and rare epidote as well as zircon, hematite, goethite, magnetite, ilmenite, ilmenorutile, rutile, titanite, apatite and garnet of spessartine type as accessory minerals. The identified minerals in the studied two alteration facies zones can be grouped into three mineral groups which are: the primary minerals (pyrite, magnetite, galena, columbite and gold), the secondary minerals (uranophane, kasolite and wulfenite) and the gangue minerals (anhydrite, barite, celestine, hematite, goethite and fluorite). The identified mineral assemblage of the studied propylitic alteration facies zone may be attributed to strongly alkaline hydrothermal solutions at ph value of more than 7 with temperature varying between 350 and 450°C, while the advanced argillic alteration facies zone is essentially associated with strongly acidic hydrothermal solutions at ph value less than 7 with temperature varying between 150 and 400°C

  19. Activity diagrams for calcium/hydrogen, sodium/hydrogen, and potassium/hydrogen, and H4SiO4 and their relation to reactions in systems containing radioactive waste forms, cement, and rock in the presence of water

    International Nuclear Information System (INIS)

    In order to identify reactions which can occur in systems containing nuclear waste forms, cement, and repository rock in the presence of water, activity diagrams were calculated from free energies for aluminosilicates and calcium silicates. Groundwater compositions from candidate repository sites in the Palo Duro Basin of Texas, the Delaware Basin of New Mexico, and the Nevada Test Site were plotted on these diagrams. Essentially all of these are shown to be in the calcium zeolite field as shown on the diagram for calcium in the absence of other cations. Chlorite is shown to be stable in this region at the Mg and pH level of the Ogallala if the chlorite is high in iron, and at the Mg and pH level of the Wolfcamp low- or high-Fe chlorites are stable. Potassium and sodium mineral relationships fall in two categories, dilute waters and saline waters. Boreholes at Yucca Flat and Mercury Valley at the Nevada Test Site, and shallow ground water from the Rolling Plains north and east of the Palo Duro Basin are in equilibrium with kaolinite. The brines from the Salado and Rustler formations are in equilibrium with kaolinite and possibly also with sodium-potassium zeolite and illite. Leachates of cement and water, and cement, waste, and water were plotted on the calcium silicate activity diagram. These solutions are in equilibrium with calcium silicate hydrate hydrolysis reactions, with grossular and possibly with Ca-zeolites. Among the calcium silicates, calcium-silicate-hydrate gel (C-S-H gel) and tobermorite are the most likely candidates, but the thermodynamic data are not adequate to distinguish all the possibilities. 37 references, 4 figures, 3 tables

  20. Clay minerals assemblage in the Neogene fluvial succession of the Pishin Belt, Pakistan

    DEFF Research Database (Denmark)

    Kasi, Aimal Khan; Kassi, Akhtar Muhammad; Friis, Henrik;

    2014-01-01

    indicate derivation of material from the Pre-Miocene sedimentary and meta-sedimentary terrains of the Pishin Belt. X-ray diffraction (XRD) analyses indicate that clay minerals in various mudstones and sandstone samples are identical and detrital in nature and include smectite, chlorite, illite, serpentine...... sedimentary and metasedimentary successions. The source of kaolinite seems to be pedogenic or lateritic. The clay minerals assemblage in mudstones and sandstones of the Dasht Murgha group, Malthanai formation and Bostan formation appears to have been derived from the nearby-exposed Pre-Miocence mafic...

  1. 福岡県水田土壌粘土鉱物地図の作成

    OpenAIRE

    江頭, 和彦; 田中, 有希

    1997-01-01

    Fukuoka prefecture has 78,800 ha of paddy soils occupying 15.9% of the whole prefectural area. Analytical data of clay mineralogical composition of paddy soils was used for the preparation of a map of clay mineral distribution. Based on the mineral index and the magnitude of specific surface area, 288 paddy soil samples were classified into 6 categories. Namely, “smectite-dominant”, “smectite-abundant”, “smectite-fair”, “chlorite-type”, “kaolin mineral-type”, and “noncrystalline/layersilicate...

  2. Clay mineral distribution in surface sediments of the South China Sea and its significance for in sediment sources and transport

    Institute of Scientific and Technical Information of China (English)

    刘建国; 陈木宏; 陈忠; 颜文

    2010-01-01

    Clay minerals of surface sediments in the South China Sea (SCS) are analyzed with X-ray diffraction, and their transport is explored with a grain size trend analysis (GSTA) model. Results show that clay mineral types in various sedimentary environments have different sediment sources and transport routes. Sediments in the northern SCS (north of 20°N) between the southwest of Taiwan Island and the outer mouth of the Pearl River have high contents of illite and chlorite, which are derived mainly from sediment...

  3. Active silica sources in the Sele formation and quartz cementation in mudstone-Examples from the Siri Canyon, Danish North Sea

    DEFF Research Database (Denmark)

    Kazerouni, Afsoon Moatari; Friis, Henrik; Svendsen, Johan B.

    depths, related to the dissolution of opal-CT and zeolite.  At these processes, the shale may have been active silica exported.  Reported sandstone cementation patterns indicate the earlier phase is related to major export of silica, whereas the shale itself was the major consumer during the intermediate...... phase.  Late phase mobilization of silica (smectite to chlorite transformation) is at an initial stage and has not contributed significantly to the massive late-stage quartz cementation of the interbeded sandstones. The Sele Formation in the Siri Canyon has not been influence by illite formation, even...

  4. Geothermal alteration of clay minerals and shales: diagenesis

    International Nuclear Information System (INIS)

    The objective of this report is to perform a critical review of the data on the mineral and chemical alterations that occur during diagenesis and low-grade metamorphism of shale and other clay-rich rocks - conditions similar to those expected from emplacement of heat-producing radioactive waste in a geologic repository. The conclusions drawn in this document are that the following type of alterations could occur: smectite alteration, ion mobilization, illitic shales, kaolinite reactions, chlorite reactions, organic reactions, paleotemperatures, low temperature shales, high temperature shales, and phase equilibrium changes

  5. Metabolism and pharmacokinetics of alternate drinking water disinfectants.

    OpenAIRE

    Abdel-Rahman, M S; Couri, D; Bull, R J

    1982-01-01

    The chlorination of surface waters is known to elevate trihalomethanes; consequently, chlorine dioxide (ClO2) is being considered as an alternative disinfectant. The primary products resulting from ClO2 disinfection of waters are chlorites (ClO2-) and chlorates (ClO3-). Studies in rats revealed that ClO2 is converted to chloride (Cl-), ClO2- and ClO3-. ClO2- and ClO3- are excreted as Cl-, ClO2- and Cl-, ClO2-, ClO3-, respectively. Radioactivity was rapidly absorbed from the gastrointestinal t...

  6. Hyperspectral imaging spectroscopy of a Mars analogue environment at the North Pole Dome, Pilbara Craton, Western Australia

    CERN Document Server

    Brown, Adrian J; Cudahy, Thomas

    2014-01-01

    A visible and near infrared (VNIR) to shortwave infrared (SWIR) hyperspectral dataset of the Early Archaean North Pole Dome, Pilbara Craton, Western Australia, has been analysed for indications of hydrothermal alteration. Occurrence maps of hydrothermal alteration minerals were produced. It was found that using a spatial resolution on the ground of approximately 5 m and spectral coverage from 0.4 to 2.5 mm was sufficient to delineate several hydrothermal alteration zones and associated veins, including phyllic, serpentinitic and chloritic alteration. These results suggest this level of spectral and spatial resolution would be ideal for localising shallow epithermal activity, should such activity have existed, on the surface of Mars.

  7. Experimental and theoretical investigation of the production of HCl and some metal chlorides in magmatic/hydrothermal systems. Annual report, 1991--1992

    Energy Technology Data Exchange (ETDEWEB)

    1992-12-31

    In the calculations we have assumed that all apatites are magmatic. The presence of chlorite and altered plagioclase within the granite and quartz-monzodiorite suggests that alteration may play a role in leading to erroneous estimates of initial melt Cl and F for 2 reasons: (1) the apatites may in fact not be magmatic in origin, but are hydrothermal, and (2) the halogen signature of magmatic apatite may be changed due to subsolidus exchange with a hydrothermal fluid. We are currently endeavoring to develop criteria for determining whether apatite composition represents earlier or later stages of magmatic-hydrothermal development.

  8. Effets thermique et hydrothermal de la coulée de basalte triasico-liasique sur les argiles du bassin d'Argana (Maroc)Thermal and hydrothermal effects of Triassic Liassic basalt flow deposition on clays (Agana Basin, Morocco)

    Science.gov (United States)

    Daoudi, Lahcen; Pot de Vin, Jean-Luc

    Thermal and hydrothermal effects of Triassic-Liassic basalt flow deposition on sedimentary series of the Argana Basin are responsible for major modifications in detrital clays, until 20 m in depth. It expressed by transformation of detrital smectite to corrensite and moreover to chlorite, and by increasing illite crystallinity. On the 2 m of sediments located immediately under the flow, magnesium-rich hydrothermal fluids have caused precipitation of new mineral phases. To cite this article: L. Daoudi, J.-L. Pot de Vin, C. R. Geoscience 334 (2002) 463-468.

  9. Petrography of auriferous conglomerates in the Fortuna formation of the group Aguapei in Pau-A-Pique deposits in the Mato Grosso district, in the centre of Brazil

    International Nuclear Information System (INIS)

    Gold anomalies in the Pau a-Pique deposits are present in anastomossed shear zones near the contact between the Group Aguapei conglomerates and the Tonalito Alvorada. These high-strain zones are subparallel to the regional shearing NW - SE, and they have a brittle-ductile structures. The gold ore is exploted from veins and disseminations in the conglomerates that were affected by hydrothermal alteration. The main hydrothermal minerals in the mineralized layer are quartz, tourmaline, pyrite, biotite, chlorite and white mica. These hydrothermal minerals present textures that indicate their post-tectonic growth due the circulation of mineralizing fluids in the late shearing stages. (author)

  10. Spatial distribution and longitudinal variation of clay minerals in the Central Indian Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Valsangkar, A.

    1). Further, the average clay content gradually increases from 60 to 70 % particularly along either side of the 76.5 o fracture zone (fz; Table 1). Similar small increase in clay is also observed along the 73 o fz, but along 74.5 o E the clay... fz in the western CIB, smectite and illite decrease slightly (16 to 15 %, and 50 to 49 % respectively), and kaolinite and chlorite increase (17 to 18 %, and 16 to 19 % respectively, Table 2). Similarly, along 74.5 o E, smectite and kaolinite...

  11. The geology and mineralogy of the uranium occurrence at Hoehensteinweg near Poppenreuth (NE Bavaria) - a model of its mode of formation

    International Nuclear Information System (INIS)

    The uranium mineralization consists of U oxides, U titanates, U silicates and secondary U minerals, arranged roughly in order of crystallization. These ores are associated with muscovite, chlorite and smectite. The non-uranium mineralization consists of scheelite, arsenopyrite, native gold, pyrite/chalcopyrite, Bi/Pb-selenides, sulphides and iron sulphides. Scheelite only occurs in the outermost part of the granite (e.g. at Tirschenreuth). Isotope disequilibria show that further redeposition of uranium minerals probably took place in joints and alteration zones in recent or sub-recent times. The uranium mineralization is, on the basis of its geological setting, comparable with the Spanish deposits of Iberian type. (orig./HP)

  12. Petrophysics of shale intervals in the Skjold Field, Danish North Sea

    DEFF Research Database (Denmark)

    Mbia, Ernest Ncha; Fabricius, Ida Lykke; Oji, C. O.

    2011-01-01

    interval 6 is mainly shale. X-ray diffraction analysis reveals the dominance of inter-layered smectite/illite in interval 1–3 and upper part of interval 4, whereas illite dominates interval 5 and 6. Other minerals include kaolinite, chlorite, quartz, calcite, Opal-CT, dolomite and plagioclase....... Mineralogical variation is reflected in cation exchange capacity, BET specific surface, and grain density. Shales vary in total organic carbon, radioactivity, carbonate content, porosity and modeled permeability. Cross plots of logging data splits intervals according to mineralogy, porosity, modeled...

  13. The sorption of Eu(III) on Opalinus Clay at elevated temperatures and in presence of organics

    International Nuclear Information System (INIS)

    Presently, argillaceous rock formations are under investigation as potential host rocks for nuclear waste repositories. In addition to diffusion the sorption of radionuclides on mineral phases is an important physicochemical process. Concerning the required long-term safety and risk assessment of the storage of high level radioactive waste the understanding of these processes is essential. Opalinus Clay (OPA) is a complex argillaceous rock with illite, chlorite, kaolinite, quartz, calcite, pyrite and siderite as main components and a very low content of natural organic matter (small organic molecules, humic acids). This natural occurring clay rock is discussed as host rock formation for nuclear waste repositories. (orig.)

  14. Effect of nitrate on microbial perchlorate reduction

    Science.gov (United States)

    Sun, Y.; Coates, J. D.

    2007-12-01

    Over the last decade perchlorate has been recognized as an important emerging water contaminant that poses a significant public health threat. Because of its chemical stability, low ionic charge density, and significant water solubility microbial remediation has been identified as the most feasible method for its in situ attenuation. Our previous studies have demonstrated that dissimilatory perchlorate reducing bacteria (DPRB) capable of the respiratory reduction of perchlorate into innocuous chloride are ubiquitous in soil and sedimentary environments. As part of their metabolism these organisms reduce perchlorate to chlorite which is subsequently dismutated into chloride and molecular oxygen. These initial steps are mediated by the perchlorate reductase and chlorite dismutase enzymes respectively. Previously we found that the activity of these organisms is dependent on the presence of molybdenum and is inhibited by the presence of oxygen and to different extents nitrate. However, to date, there is little understanding of the mechanisms involved in the regulation of perchlorate reduction by oxygen and nitrate. As a continuation of our studies into the factors that control DPRB activity we investigated these regulatory mechanisms in more detail as a model organism, Dechloromonas aromatica strain RCB, transitions from aerobic metabolism through nitrate reduction to perchlorate reduction. In series of growth transition studies where both nitrate and perchlorate were present, preference for nitrate to perchlorate was observed regardless of the nitrate to perchlorate ratio. Even when the organism was pre-grown anaerobically in perchlorate, nitrate was reduced prior to perchlorate. Using non-growth washed cell suspension, perchlorate- grown D. aromatica was capable of reducing both perchlorate and nitrate concomitantly suggesting the preferentially utilization of nitrate was not a result of enzyme functionality. To elucidate the mechanism for preferential utilization of

  15. Growth of Pseudomonas chloritidismutans AW-1(T) on n-alkanes with chlorate as electron acceptor.

    OpenAIRE

    Mehboob, Farrakh; Junca, Howard; Schraa, Gosse; Alfons J. M. Stams

    2009-01-01

    Microbial (per)chlorate reduction is a unique process in which molecular oxygen is formed during the dismutation of chlorite. The oxygen thus formed may be used to degrade hydrocarbons by means of oxygenases under seemingly anoxic conditions. Up to now, no bacterium has been described that grows on aliphatic hydrocarbons with chlorate. Here, we report that Pseudomonas chloritidismutans AW-1(T) grows on n-alkanes (ranging from C7 until C12) with chlorate as electron acceptor. Strain AW-1(T) al...

  16. Growth of Pseudomonas chloritidismutans AW-1(T) on n-alkanes with chlorate as electron acceptor

    OpenAIRE

    Mehboob, F.; Junca, H.; Schraa, G.; Stams, A.J.M.

    2009-01-01

    Microbial (per)chlorate reduction is a unique process in which molecular oxygen is formed during the dismutation of chlorite. The oxygen thus formed may be used to degrade hydrocarbons by means of oxygenases under seemingly anoxic conditions. Up to now, no bacterium has been described that grows on aliphatic hydrocarbons with chlorate. Here, we report that Pseudomonas chloritidismutans AW-1(T) grows on n-alkanes (ranging from C7 until C12) with chlorate as electron acceptor. Strain AW-1(T) al...

  17. On the possibilities of occurrence of structure controlled unconformity-proximal uranium mineralization in Madhawanpalli - Rayalgandi Sector, Srisailam Sub-Basin, Cuddapah Basin, Andhra Pradesh

    International Nuclear Information System (INIS)

    The northern margin of Srisailam Sub-basin is well known for its potential to host unconformity proximal uranium mineralization and so far three deposits have been established at Lambapur, Peddagattu and Chitrial. Recent exploration in Madhawanpalli-Rayalgandi sector and follow up sub-surface exploration has indicated uranium mineralization in the granites beneath the cover of Srisailam sediments. The host rock is characterized by intense fracturing, brecciation, cataclasism and alterations like chloritization, illitization and silicification signifying the role of basement structures in uranium mineralization near the unconformity surface. (author)

  18. Petrological studies of plutonic rocks of Ecuador

    International Nuclear Information System (INIS)

    The feldspars of many tonalitic plutonic rocks in the coastal regions and West Andean regions are zoned. This leads to the conclusion that they are relatively flat intrusions and to some extent transition rocks in the subvulcanite direction. This is in accordance with the genetic and chronological relationship between plutonites and the surrounding vulcanites of the Basic Igreous Complex (BIC). The composition of representative minerals, e.g. alkali feldspar, plagioclase feldspar, biotite, chlorite, and amphibole has been determined as well as the age of plutonite samples by the K/Ar dating method. (DG)

  19. Fluvial influx and weathering history of the Himalayas since Last Glacial Maxima - Isotopic, sedimentological and magnetic records from the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Chauhan, O.S.; Patil, S.K.; Suneethi, J.

    augmented the fluvial influx of the Himalayan rivers. These events are also coeval with melt water pulses 1A and IB observed in sea - level r e- cords in which global sea - level had risen by 24 and 28 m respectively 17 . We, ther e fore, suggest... that augmented chlorite is produced under arid, cold climate due to higher magnitude of physical weathering. With increase in the precipitation, production of smectite ? illite ? kaolinite ? gibbsite in the increasing order is observed 35 . In the bay...

  20. Interstratified vermiculite-mica in the gneiss-metapelite-serpentinite rocks at Hafafit area, Southern Eastern Desert, Egypt: From metasomatism to weathering

    Science.gov (United States)

    Harraz, H. Z.; Hamdy, M. M.

    2010-09-01

    The Hafafit vermiculite in the Southern Eastern Desert of Egypt at the contact of the metapelite and serpentinite rocks with the pegmatites and gneisses of the Hafafit uplift is the only known deposit in the Arabian-Nubian Shield (ANS) rocks of the Eastern Desert (ED). It is distinctively interstratified with mica. The mineralogy and mineral chemistry of this vermiculite at four sites (HV1, HV2, HV3 and HV4) were studied to better understand its origin, which might refers to a specific geologic setting retained to Hafafit area. The vermiculite at Hafafit forms with phlogopite, actinolite-tremolite, asbestos-anthophyllite-talc and talc zones that are arranged from pegmatite and gneisses to the metapelite and serpentinite rocks. These zones were probably formed by metasomatism that related to the intrusion of the granitoid rocks and the connected pegmatites in the upper Pan-African. The XRD and EMPA studies of the interstratified vermiculite-mica concluded that vermiculitization took place through a layer-by-layer transformation of original micas. This formed, in decreasing abundance, mixed-layer phases of biotite/vermiculite (hydrobiotite), phlogopite/vermiculite (hydrophlogopite) and chlorite/vermiculite (corrensite) and discrete phases of vermiculite, chlorite and smectite. A model is suggested, in which chemical weathering by the moving downward meteoric water led to replacement of the interlayer K, in biotite from gneiss and in phlogopite from metasomatic zones, by H 2O molecules, Fe 2+ was oxidized and (OH) - replaced O 2- forming hydrobiotite and hydrophlogopite. By more K remove, Fe was replaced by Mg with the introduction of more layers of H 2O molecules leading to formation of the vermiculite. Weathering formed corrensite mixed-layer and chlorite expandable minerals on the expense of chlorite. Formation of the incomplete smectite-like layers and Al-hydroxy interlayers (13.97 Ǻ) took place at the expense of vermiculite, replacing the Mg interlayer cations

  1. Zinc-rich clays in supergene non-sulfide zinc deposits

    OpenAIRE

    Choulet, Flavien; Buatier, M.; Barbanson, Luc; Guégan, Régis; Ennaciri, A.

    2015-01-01

    The nature and the origin of zinc clays are poorly understood. With the example of the Bou Arhous Zn-Pb ore deposit in the Moroccan High Atlas, this study presents new data for the mineralogical and chemical characterization of barren and zinc clays associated with non-sulfide zinc ores. In the field, white to ocher granular clays are associated with willemite (Zn2SiO4), while red clays fill karst-related cavities cutting across the non-sulfide ore bodies. Red clays (kaolinite, chlorite, illi...

  2. Quality of fresh-cut avocado (Persea americana Mill.) stored under different temperatures Qualidade de abacates (Persea americana Mill.) minimally processados armazenados sob diferentes temperaturas

    OpenAIRE

    Ana Carla Marques Pinheiro; Eduardo Valério de Barros Vilas Boas; Lucas Carvalho e Silva; Alessandra de Paiva Alves; Marcelo La Selva; Adimilson Bosco Chitarra

    2009-01-01

    The goal of this work was to evaluate the effect of different storage temperatures on the quality maintenance of fresh-cut 'Fortuna' avocado (Persea americana Mill.). The fruit was selected, washed and sanitized with sodium hypochlorite solution (190 ppm total residual chlorinee) for 15 minutes. After that, the tip was cut and the fruit was also cut in halves, peeled and the pit removed, manually. Then the halves were immersed in 0.5% calcium chlorite + 0.5% cysteine solution for 2 minutes, t...

  3. Arc Magma Genesis from Melting of Mélange Diapirs

    Science.gov (United States)

    Cruz-Uribe, A. M.; Marschall, H.; Gaetani, G. A.

    2015-12-01

    Alkaline basalts occur in many subduction-related volcanic settings, including the Sunda, Izu-Bonin, Honshu, Aeolian, and Aleutian arcs, yet their origin continues to be debated. Recent studies have suggested that buoyant material (mélange) from the slab-wedge interface may rise into the hot corner of the mantle wedge as low-density plumes or diapirs, where it will melt or induce mantle melting due to dehydration. High-pressure mélange rocks represent a mixture of mafic, ultramafic, and sedimentary components, and are often dominated by chlorite. Mélange rocks are also enriched in accessory phases such as monazite, zircon, and rutile, which host a variety of trace elements. We present results from experimental melting of chlorite-rich mélange material at mantle wedge conditions that reproduce many of the compositional features of subduction-related lavas. Piston cylinder experiments were performed at conditions appropriate for mantle wedge diapirs (1030-1280 °C, 1.5-2.5 GPa) using natural mélange rocks from Syros, Greece. Experimental melts derived from omphacite-epidote-phengite bearing chlorite schists range in composition from basaltic trachyandesites to trachydacites to more alkaline melt compositions (50.7-60.73 wt% SiO2, 7.48-12.93 wt% Na2O+K2O). All of the experimental melts are characterized by high alumina contents (16.79-21.36 wt% Al2O3). Minerals coexisting with these melts include clinopyroxene, amphibole (at lower T) or olivine (at higher T), garnet (at higher P), ilmenite and/or rutile, and zircon. Trace element patterns in our experimentally produced melts are similar to those from arc volcanoes worldwide. Experimental melts are enriched in large ion lithophile elements (Cs, Rb, Ba, K, Pb, Sr) and depleted in high field strength elements (Nb, Ta, and Ti). Zirconium and Hf are enriched relative to the rare earth elements (REE), which show flat to heavy REE depleted patterns depending on the presence of residual garnet. Thorium is fractionated

  4. Uranium speciation as a function of depth in contaminated hanford sediments--a micro-XRF, micro-XRD, and micro- and bulk-XAFS study.

    Science.gov (United States)

    Singer, David M; Zachara, John M; Brown, Gordon E

    2009-02-01

    The distribution and speciation of U and Cu in contaminated vadose zone and aquifer sediments from the U.S. DOE Hanford site (300 Area) were determined using a combination of synchrotron-based micro-X-ray fluorescence (microXRF) imaging, micro-X-ray absorption near edge structure (microXANES) spectroscopy, and micro-X-ray diffraction (microXRD) techniques combined with bulk U LIII-edge X-ray absorption fine structure (XAFS) spectroscopy. Samples were collected from within the inactive North Process Pond (NPP2) at 8 ft (2.4 m, NPP2-8) depth and 12 ft (3.7 m, NPP2-12) depth in the vadose zone, and fines were isolated from turbid groundwater just below the water Table (12-14 ft, approximately 4 m, NPP2-GW). microXRF imaging, microXRD, and microXANES spectroscopy revealed two major U occurrences within the vadose and groundwater zones: (1) low to moderate concentrations of U(VI) associated with fine-textured grain coatings that were consistently found to contain clinochlore (referred to here as chlorite) observed in all three samples, and (2) U(VI)-Cu(II) hotspots consisting of micrometer-sized particles associated with surface coatings on grains of muscovite and chlorite observed in samples NPP2-8' and NPP2-GW. In the aquifer fines (NPP2-GW), these particles were identified as cuprosklodowskite (cps: Cu[(UO2)(SiO2OH)]2 x 6H2O) and metatorbernite (mtb: Cu(UO2)2(PO4)2 x 8H2O). In contrast, the U-Cu-containing particles in the vadose zone were X-ray amorphous. Analyses of U LIII-edge XAFS spectra by linear-combination fitting indicated that U speciation consisted of (1) approximately 75% uranyl sorbed to chlorite and approximately 25% mtb-like X-ray amorphous U-Cu-phosphates (8 ft depth), (2) nearly 100% sorbed uranyl (12 ft depth), and (3) approximately 70% uranyl sorbed to chlorite and approximately 30% cps/mtb (groundwater zone). These findings suggest that dissolution of U(VI)-Cu(II)-bearing solids as well as desorption of U(VI), mainly from phyllosilicates, are

  5. Carboxymethylcellulose obtained by ethanol/water organosolv process under acid conditions

    OpenAIRE

    Ruzene, Denise S.; A.R. Gonçalves; J. A. Teixeira; Amorim, M. T. Pessoa de

    2007-01-01

    Sugar cane bagasse pulps were obtained by ethanol/water organosolv process under acid and alkaline conditions. The best condition of acid pulping for the sugarcane bagasse was 0.02 mol/L sulfuric acid at 160°C, for 1 h, whereas the best condition for alkaline pulping was 5% sodium hydroxide (base pulp) at 160°C, for 3 h. For the residual lignin removal, the acid and alkaline pulps were submitted to a chemical bleaching using sodium chlorite. Pulps under acid and alkaline conditions bleached w...

  6. Characteristics and genesis of clay minerals in the northern margin of the Qaidam Basin

    Institute of Scientific and Technical Information of China (English)

    Wang Linlin; Jiang Bo; Peng Dehua; Yin Chengming; Zeng Chunlin

    2011-01-01

    In order to develop appropriate reservoir protection measures in the northern margin of the Qaidam Basin and improve its oil and gas recovery efficiency, characteristics of clay minerals from eleven clay rock samples from the northern margin of the Qaidam Basin were investigated using X-ray diffraction analysis, the Scanning Electron Microscope (SEM) and energy spectrum analysis. Clay mineral composition and distribution characteristics of the main hydrocarbon reservoirs, I.e., from the Jurassic and Paleogene-Neogene, were explored. We analyzed the main factors which affected these attributes. The results show that the major clay minerals in the northern margin are chlorite, kaolinite, illite, smectite and illite/smectite inter-stratified minerals, Illite is the most widely spread clay mineral in this area.Chlorite is mainly found in the entire Neogene and in shallow horizons of the Paleogene. Smectite is enriched in the shallow Paleogene-Neogene. There are large amounts of kaolinite and illite/smectite inter-stratified minerals in the Jurassic. The major factors affecting the different development of clay minerals in the region are properties of parent rocks, paleoclimate and paleowater media conditions,diagenesis transformation, tectonic and terrain conditions.

  7. Clay-mineral suites, sources, and inferred dispersal routes: Southern California continental shelf

    Science.gov (United States)

    Hein, J.R.; Dowling, J.S.; Schuetze, A.; Lee, H.J.

    2003-01-01

    Clay mineralogy is useful in determining the distribution, sources, and dispersal routes of fine-grained sediments. In addition, clay minerals, especially smectite, may control the degree to which contaminants are adsorbed by the sediment. We analyzed 250 shelf sediment samples, 24 river-suspended-sediment samples, and 12 river-bed samples for clay-mineral contents in the Southern California Borderland from Point Conception to the Mexico border. In addition, six samples were analyzed from the Palos Verdes Headland in order to characterize the clay minerals contributed to the offshore from that point source. The clay-mineral suite for the entire shelf sediment data set (26% smectite, 50% illite, 24% kaolinite+chlorite) is closely comparable to that for the mean of all the rivers (31% smectite, 49% illite, 20% kaolinite+chlorite), indicating that the main source of shelf fine-grained sediments is the adjacent rivers. However, regional variations do exist and the shelf is divided into four provinces with characteristic clay-mineral suites. The means of the clay-mineral suites of the two southernmost provinces are within analytical error of the mineral suites of adjacent rivers. The next province to the north includes Santa Monica Bay and has a suite of clay minerals derived from mixing of fine-grained sediments from several sources, both from the north and south. The northernmost province clay-mineral suite matches moderately well that of the adjacent rivers, but does indicate some mixing from sources in adjacent provinces.

  8. SEM/EDS characterisation of dusty deposits in precipitation and assessment of their origin

    Directory of Open Access Journals (Sweden)

    Miloš Miler

    2014-07-01

    Full Text Available Detailed scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS analysis of dusty material in rainfall residue, deposited and collected on February 19th 2014 in Ljubljana, was carried out with the intention to characterise it according to its chemical and mineral composition and to assess its origin. The material consists of poorly sorted and sharp-edged particles of mostly very fine-grained silt and clay fractions, which is consistent with long-range aerial transport. Particles are represented by illite, chlorite and kaolinite group clay minerals, quartz, feldspars, carbonates, accessory minerals and secondary Fe-oxy-hydroxide minerals. Quantities of minerals and illite/ kaolinite ratio (4.5 correspond to dusts in rainfall residues originating from Moroccan Atlas, while chlorite/kaolinite ratio (2.8 agrees better with dust from central Libya. The element ratios Al/Si, Ca/Al, K/Ca, Mg/Al, Fe/Al and (Ca+Mg/Fe in the studied dusty deposit are in good agreement with ratios in dusts from rainfall residues originating from Morocco and northern Mauritania. This was also confirmed by the trajectories of cloud movement that caused precipitation with dusty deposit, although the back trajectory HYSPLIT simulation of air masses indicated northern Mauritania, central Niger, southern Algeria, southwestern and central Libya as the most possible source regions.

  9. Mineralogy of Holocene Sediments from the Southwestern Black Sea Shelf (Turkey) in Relation to Provenance, Sea-level and Current Regimes

    Institute of Scientific and Technical Information of China (English)

    Emel BAYHAN; Mustafa ERG(I)N; Abidin TEMEL; Seref KESK(I)N

    2005-01-01

    Grain size and mineral composition of core sediments were used to investigate influences of various terrestrial and marine conditions,which have prevailed on the southwestern Black Sea shelf during the Holocene.Siliciclastic mud with small amounts of sand and gravel from nearby coastal hinterland is the principal sediment type,whereas sediments deposited near the shelf edge and the (I)stanbul Strait and off the Duru Lake (a paleo-river mouth)constitued large quantities of sand and gravel of both biogenic and terrigenic origin.Variable amounts of aragonite,1 nm-micas,quartz,feldspars,calcite and dolomite constitute the dominant non-clay minerals in bulk sediments.The clay mineral assemblage in the < 2 μm fraction is made up of smectite,illite,kaolinite and chlorite.Aragonite and calcite are mainly derived from benthic accumulations,whereas feldspars (mainly plagioclase) and smectite reflect magmaticvolcanic provenance and the distribution of 1 nm-micas and chlorite correlate with nearby metamorphic sources onland.Nevertheless,grain size and mineral distribution generally indicate a combination of effects of wind and wave climate,longshore and offshore cyclonic currents,changing sea-level stands and nearby source rock and morphological conditions.It is also suggested that at least part of clay minerals could be derived from the northwesterly Danube River input.

  10. Distribution of clay minerals in marine sediments off Chennai, Bay of Bengal, India:Indicators of sediment sources and transport processes

    Institute of Scientific and Technical Information of China (English)

    Subramanian VEERASINGAM; Ramdoss VENKATACHALAPATHY; Thirunavukkarasu RAMKUMAR

    2014-01-01

    Clay mineralogy, texture size and statistical analyses were carried out on surface sediments from the continental shelf of Chennai, Bay of Bengal, India. The purpose of this study is to characterize the clay mineral distribution and its relation to the hydrodynamics off Chennai to identify the sources and transport pathways of the marine sediments. Characterization of clay minerals in coastal sediments by Fourier Transform Infrared (FTIR) spectroscopy has provided the association of quartz, feldspar, kaolinite, chlorite, illite and iron oxides (magnetite and hematite) derived from river catchments and coastal erosion. Kaolinite, chlorite, illite, iron oxides, and organic matter are the dominant minerals in Cooum, and Adayar region. High quartz and feldspar zones were identified in Marina, which are being confined the sand zone and paralleling the coast. The strong relationships among the wave energy density, sand, quartz and carbonate revealed that wave induced littoral drift system play a dominant role in transportation and deposition of sediments in the Chennai coast. The sediment texture and minerals data are in agreement well with the previous results of hydrodynamics and littoral drift models in this region. Multivariate statistical analyses (correlation, cluster and factor analyses) were carried out and obtained results suggested that clay minerals and organic matter are trapped in silt and clay particles, whereas quartz, feldspar and carbonate are associated with sand particles. Results of sediment sources and transport processes from this study will be useful to predict the fate of the pollutants released from land or the potential change in sediment delivery to coastal areas.

  11. Dispersibility of Amphibious Montmorillonite

    Science.gov (United States)

    Yeh, Meng-Heng; Hwang, Weng-Sing; Kuo, Wuei-Jueng

    2005-09-01

    The objective of this study is to develop a suitable method to convert hydrophilic montmorillonite into amphibious montmorillonite by replacing the sodium ions normally found in clay with poly(oxyethylene) (POE)-amide chlorite cations. Amphibious montmorillonite has a high d-spacing and good dispersion characteristics in many different types of solutions, including those having an intermediate hydrophilic lipophilic balance (HLB) value. Four different modifying cations are tested and X-ray diffraction analysis is performed to measure the resulting changes in the d-spacing of the MMT. Scanning electron microscopy is employed to investigate the morphology of the modified clays. A laser-doppler particle analyzer is used to measure the particle size of the clays in various solutions. Dobrat’s method is applied to calculate the dispersibility of each clay and Stoke’s law is used to evaluate the settling rate. The results indicate that the d-spacing of the POE-amide chlorite cation modified montmorillonite increases from 1.28 to 3.51 nm. The amphibious montmorillonite demonstrates good dispersion characteristics in eight commonly employed coating solutions with intermediate HLB values.

  12. Mineralogical study on volcanic ash of the eruption on September 27, 2014 at Ontake volcano, central Japan: correlation with porphyry copper systems

    Science.gov (United States)

    Minami, Yusuke; Imura, Takumi; Hayashi, Shintaro; Ohba, Tsukasa

    2016-04-01

    The volcanic ash of the eruption on September 27, 2014 at Ontake volcano consists mostly of altered rock fragments. The ash contains partly altered volcanic rock fragments consisting of primary igneous minerals (plagioclase, orthopyroxene, titanomagnetite, and feldspars) and volcanic glass accompanied by alteration minerals to some extents, and contains no juvenile fragments. These features indicate that the eruption was a non-juvenile hydrothermal eruption that was derived from the hydrothermal system developed under the crater. The major minerals derived from hydrothermal alteration zones are silica mineral, kaolin-group mineral, smectite, pyrophyllite, muscovite, alunite, anhydrite, gypsum, pyrite, K-feldspar, albite, and rutile. Minor chlorite, biotite, and garnet are accompanied. Five types of alteration mineral associations are identified from observations on individual ash particles: silica-pyrite, silica-pyrite ± alunite ± kaolin, silica-pyrophyllite-pyrite, silica-muscovite ± chlorite, and silica-K-feldspar ± albite ± garnet ± biotite. The associations indicate development of advanced argillic, sericite, and potassic alteration zones under the crater. Occurrence of anhydrite veinlet and the set of alteration zones indicate hydrothermal alteration zones similar to late-stage porphyry copper systems. Comparing the mineral associations with the geologic model of the late-stage porphyry copper systems, the source depths of mineral associations are estimated to range from near surface to >2 km. The depths of advanced argillic alteration, sericite, and potassic zones are 0 to ~2, ~1.5 to ~2, and >2 km, respectively.

  13. Mechanisms of hydrothermal alteration in a granitic rock. Consequences for high-level radioactive waste disposal

    International Nuclear Information System (INIS)

    The study of hydrothermal alteration in the Auriat granitic rock (France, Massif-Central) has evidenced three main events: - a pervasive chloritisation of biotites in some parts of the drill-core, - an alteration localized around subvertical cracks and superimposed on previously chloritized or unaltered granite, - an alteration localized around subhorizontal cracks cross-cutting the preceding ones. The second type of alteration, produced by a geothermal system, gives the most interesting results to be applied to the nuclear radwaste disposal problem. Among primary minerals of granite, only biotite (or chlorite) and oligoclase are intensively altered. Therefore, the chemical composition of these minerals induces the nature of secondary parageneses. These, associated to the subvertical cracks network, indicate a thermal gradient of 150 C/Km. The geochemical code has allowed to corroborate that the thermal gradient was responsible for the occurrence of different parageneses with depth. Moreover, it was shown that the variable mineralogy around cracks was due to a thermal profile established at equilibrium between the rock and the fluid. Therefore, the extent of the alteration was proportional to the thermal power of the fluid. A dissolution and next a precipitation phase of new minerals characterize hydrothermal alteration, which is due to the thermal power emitted by radioactive waste and linked with the evolution of temperature during time. This alteration provokes two favourable events to storage: decrease of rock porosity and increase of sorption capacity

  14. 3D modelling and sheath folding at the Falun pyritic Zn-Pb-Cu-(Au-Ag) sulphide deposit and implications for exploration in a 1.9 Ga ore district, Fennoscandian Shield, Sweden

    Science.gov (United States)

    Kampmann, Tobias C.; Stephens, Michael B.; Weihed, Pär

    2016-06-01

    Altered and mineralized rocks at the Falun pyritic Zn-Pb-Cu-(Au-Ag) sulphide deposit, situated in the Palaeoproterozoic Bergslagen ore district in the south-western part of the Fennoscandian Shield, have been metamorphosed at low-pressure, amphibolite-facies conditions and affected by ductile deformation. Using combined surface mapping of lithology and structure, drill core logging and microstructural work, the polyphase (D1 and D2) ductile deformation is demonstrated and a 3D model for the deposit created. Mineral associations include quartz, biotite, cordierite, anthophyllite, and minor almandine, andalusite and chlorite in silicate-rich altered rock, calcite or dolomite in marble and tremolite-actinolite or diopside-hedenbergite in skarn. The silicate minerals show varying growth patterns during the different phases of the tectonothermal evolution, with considerable static grain growth occurring between D1 and D2, and even after D2. F2 sheath folding along axes that plunge steeply to the SSE, parallel to a mineral stretching lineation and the dip direction of the S2 foliation, is suggested as a key deformation mechanism forming steeply plunging, cone- to rod-shaped mineralized bodies. This contrasts with a previous structural model invoking fold interference. A major shear zone with talc-chlorite-(quartz-biotite) mineral association separates the northern and southern structural domains at the deposit and bounds the polymetallic massive sulphides to the north.

  15. Diagenetic fluids evolution and genetic mechanism of tight sandstone gas reservoirs in Upper Triassic Xujiahe Formation in Sichuan Basin, China

    Institute of Scientific and Technical Information of China (English)

    ZHU RuKai; ZOU CaiNeng; ZHANG Nai; WANG XueSong; CHENG Rong; LIU LiuHong; ZHOU ChuanMin; SONG LiHong

    2008-01-01

    The reservoirs of the Upper Triassic Xujiahe Formation in Sichuan Basin have the characteristics of low compositional maturity, low contents of cements and medium textural maturity.The general physical properties of the reservoirs are poor, with low porosity and low permeability, and there are only a few reservoirs with medium porosity and low permeability in local areas.Based on the diagenetic mineral association, a diagenetic sequence of cements is established: early calcites (or micrite siderites)→ first quartz overgrowth→chlorite coatings→dissolution of feldspars and debris→chlorite linings→ second quartz overgrowth (quartz widen or filled in remain intergranular pores and solution pores→ dissolution→third quartz overgrowth (quartz filled in intergranular and intragranular solution pores)→ intergrowth (ferro) calcites→dolomites→ferro (calcites) dolomites→later dissolution→veins of quartz and calcites formation.Mechanical compaction is the main factor in making the reservoirs tight in the basin, followed by the second and third quartz overgrowth.In a long-term closed system, only feldspars and some lithic fragments are dissolved by diagenetic fluids, while intergranular cements such as quartz and calcit are not dissolved and thus have little influence on the porosity of the Xujiahe Formation.This is the third factor that may have kept the sandstones of Xujiahe Formation tight finally.The hydrocarbon was extensively generated from organic materials after the second quartz overgrowth, and selectively entered favorable reservoirs to form tight sandstone gas reservoirs.

  16. Diagenetic fluids evolution and genetic mechanism of tight sandstone gas reservoirs in Upper Triassic Xujiahe Formation in Sichuan Basin, China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The reservoirs of the Upper Triassic Xujiahe Formation in Sichuan Basin have the characteristics of low compositional maturity, low contents of cements and medium textural maturity. The general physical properties of the reservoirs are poor, with low porosity and low permeability, and there are only a few reservoirs with medium porosity and low permeability in local areas. Based on the diagenetic mineral association, a diagenetic sequence of cements is established: early calcites (or micrite siderites) →first quartz overgrowth→chlorite coatings→dissolution of feldspars and debris→chlorite linings→ second quartz overgrowth (quartz widen or filled in remain intergranular pores and solution pores)→dissolution→third quartz overgrowth (quartz filled in intergranular and intragranular solution pores)→intergrowth (ferro) calcites→dolomites→ferro (calcites) dolomites→later dissolution→veins of quartz and calcites formation. Mechanical compaction is the main factor in making the reservoirs tight in the basin, followed by the second and third quartz overgrowth. In a long-term closed system, only feld-spars and some lithic fragments are dissolved by diagenetic fluids, while intergranular cements such as quartz and calcit are not dissolved and thus have little influence on the porosity of the Xujiahe Formation. This is the third factor that may have kept the sandstones of Xujiahe Formation tight finally. The hydrocarbon was extensively generated from organic materials after the second quartz overgrowth, and selectively entered favorable reservoirs to form tight sandstone gas reservoirs.

  17. Sorption of radioiodine on organic rich soil, clay minerals and alumina

    International Nuclear Information System (INIS)

    Batch method was used to investigate the sorption behavior of radioiodine on organic rich soil, alumina, chlorite-illite clay mixture and bentonite. 131 I was used as tracer. The grain sizes of the samples used were all below 38μm. A rather slow kinetics was observed for the adsorption of radioiodine on organic rich soil. The distribution ratio increased with increasing solution/solid (V/m) ratio, and the contact time. The pH of the synthetic groundwater did not change the distribution ratio appreciably. The soil biomass however, showed a striking effect on the adsorption of radioiodine. Among the clay minerals, the highest distribution ratio value was found for chlorite-illite clay mixture. All the values were however well below those of the organic rich soil. The sorption data were fitted to Freundlich and Dubinin-Radushkevich type isotherms. Mean energies of adsorption, as well as the affinity ratios of the sorption sites to iodine and chlorine were calculated. (author) 13 refs.; 6 figs.; 6 tabs

  18. Experimental investigation on the combined use of C1O2 and NaC1O for drinking water treatment

    International Nuclear Information System (INIS)

    In Italy, most of the plants producing water for human consumption, use Chlorine Dioxide (C1O2) and Sodium Hypochlorite (NaC1O) for the oxidation and disinfection treatments. These chemical disinfectants, which are very effective as regards the oxidation power, the disinfection capability and the bacteriostatic action, produce by-products harmful for human health: Chlorite and Trihalomethanes (THMs) respectively. The Italian Regulations (D.Lgs. 31/2001) sets very restrictive limits for the maximum concentration of these by-products in drinking water. Moreover, from December 2006, the limit for chlorite will be even more restrictive and, with present treatment process, the compliance with the regulation will be very difficult. Therefore the experimentation of alternative treatment techniques and products is of great interest. This article presents an experimental investigation on the combined use of C1O2 and NaC1O in the treatment of final water from two different plants producing drinking water in Florence. The main objective of this investigation was to evaluate the use of these two products in combination so as to keep the advantages (disinfection efficiency and stability in water) and to minimize the disadvantages (by-products formation) present when using this products separately. Positive results achieved in the experimental phase were used to evaluate the possible applications on real drinking water treatment conditions

  19. Well log responses in metamorphic rocks near Maribor

    Directory of Open Access Journals (Sweden)

    1995-12-01

    Full Text Available In the Stražun forest at Pobrežje near Maribor, (Eastern Slovenia six boreholes have been drilled from 860 to 1600m deep. The paper describes geological conditions in mentioned boreholes, as well as in wider surroundings of Maribor with stress on metamorphic rocks. Based on pétrographie analysis of the rocks cuttings and well logs the upper phyllitic part ant the lower Pohorje series of themetamorphic complex could be separated. The first one includes phyllites with phyllitic quartzites and silicate marmorized limestones. The Pohorje series is represented by two-mica gneiss and schist, mainly with inclusions of amphibolite and eclogite, and subordinately retrograde chlorite-amphibole schist. The welllog responses for particular lithological sequences of metamorphic complex have been distinguished on the basis of conventional electrologs and gamma ray measurements.The problem of lithological interpretation of well logs in these rocks is described. Two fields of well log responses are distinguishable, as separated by the degree of natural radioactivity. Apart from veined quartzite, all rocks fromthe phyllitic part of the metamorphic complex are highly radioactive. In the Pohorje series gneiss, schist and diaphtorite-phyllonite are highly radioactive, while amphibolite, eclogite and retrograde chlorite-amphibole schist have low radioactivity.Finally, typical well log responses in lithological sequences of the discussed metamorphic rocks are presented.

  20. Geology and geochemistry of palaeoproterozoic low-grade metabasic volcanic rocks from Salumber area, Aravalli Supergroup, NW India

    Indian Academy of Sciences (India)

    L S Shekhawat; M K Pandit; D W Joshi

    2007-12-01

    The Palaeoproterozoic Aravalli Supergroup in Salumber region includes a basal unit of metabasic volcanic rocks (Salumber volcanic rocks) overlain by a volcaniclastic/conglomerate one. Although these volcanic rocks have been metamorphosed to green-schist facies, some primary volcanic features are still preserved. This metabasic volcanic sequence can be further differentiated on the basis of textural variations, and the mineral assemblages are: (a) oligoclase + actinolite + chlorite + epidote; and (b) oligoclase + hornblende+ chlorite + biotite + Fe-Ti oxides. The SiO2 content ranges from ∼47.7 to 55.8% and MgO from ∼4.2 to 12.8%. Geochemical characteristics allow their subdivision into high Mg and Fe tholeiites. Inverse relationship of MgO with silica, alkalis and Zr is generally consistent with fractionation mechanism, also suggested by a change in colour of the rocks from dark greenish to light greenish towards the upper parts of the sequence. These metabasic volcanic rocks are enriched in incompatible trace elements and LREE (La = 30 − 40 × chondrite, Lu = 2 − 5 × chondrite), and demonstrate affinity mainly with MORB and within plate settings in geochemical tectonic discrimination schemes. The geochemical characteristics suggest a complex evolutionary history envisaging derivation of the melt from an enriched heterogeneous lithospheric source.

  1. Fissure fillings from the Klipperaas study site

    International Nuclear Information System (INIS)

    The Klipperaas study site is located within the Smaaland-Vaermland granitoid belt in southern Sweden. The area investigated can be subdivided into blocks with different hydraulic character and fracture frequency of the rocks. A fissure filling, study has been carried out within the area. This includes identification of the minerals, mineral frequency, textures within the fissures and isotope analyses of calcites. Four generation of fissure fillings, within the time space c. 1600 M.a. to present, has been distinguished. These are 1) quartz; 2) epidote + muscovite and adularia + hematite; 3) calcite + chlorite +/hematite; 4) calcite, clay minerals and Fe-oxyhydroxide. It is observed that the surface water affect the uppermost part of the bedrock resulting in calcite dissolution, break down of pyrite and precipitation of Fe-oxyhydroxide. It is also obvious from the fracture calcite frequency that calcite dissolution is more intensive close to and within the fracture zones. There, Fe-oxyhydroxide can be found down to at least 400 m depth. This gives valuable information about the physic-chemical character of the groundwater within the bedrock. Several fracture zones have been reactivated. It is also suspected that relatively late movements have taken place causing crushing of the rock and only a slight cementation of the crushed material is visible. Some of the fracture zones correspond to mafic dikes. These zones exhibit lower hydraulic conductivity than other zones due to fracture sealing by clay minerals but also by chlorite and calcite. (author)

  2. On the geology of the uranium mineralization in the Swiss Alps

    International Nuclear Information System (INIS)

    Numerous radiometric anomalies and several uranium occurrences were found in the Swiss Alps by systematic prospecting of selected areas carried out between 1957 and 1984. Most of the uranium indications lie in a rather narrow belt that follows roughly the valleys of the Rhone und of the Rhine Anterior, from Martigny onto Ilanz and extending northwards towards the Lake of Walenstadt. The uranium occurrences were found in the following geological environments: - permocarboniferous continental, variably metamorphosed series, belonging either to the formation of the 'Verrucano' or to the Penninic St. Bernhard nappe; - muscovite-chlorite-albite gneisses belonging to the pre-Westphalian basement of the St. Bernhard nappe; - muscovite-chlorite gneisses and phyllites of the Hercynian Tavetsch massiv; - muscovite-biotite gneisses within the southern border of the Aar massif; - Vallorcine granite of the Auguilles-Rouges massiv and polymetamorphic biotite gneisses along its northwestern contact zone. The possible geological (or 'in situ') resources are estimated to be 50-250 tonnes uranium in each one of the investigated mineralization zones of some importance; the respective estimated grades are 50-250 ppm U. Therefore the occurrences are actually of no economic value. (author) 25 figs., 1 tab., refs

  3. Tectonic hydrothermal gold mineralisation in the outboard zone of the Southern Alps, New Zealand

    International Nuclear Information System (INIS)

    Gold-bearing veins cut a belt of low-grade (pumpellyite-actinolite/greenschist facies) schist in the Ben Ohau Range to the east of the Main Divide, in the outboard zone of the Southern Alps continental collisional zone, New Zealand. The schist has been exposed along the currently active Ostler Fault system, which has had c. 5 km of reverse motion since the Pliocene. The veins consist of quartz, ankerite, calcite, chlorite, and pyrite, with minor chalcopyrite and galena. Hydrothermal chlorite contains about 490 ppm Zn, and the gold contains 3-5 wt% Ag. Hydrothermal alteration of host rock is minor apart from Sr enrichment (up to four times background). Fluid inclusions in quartz are aqueous with minor dissolved CO2 and salts (18O = +10 to +14; δ13C = -6 to -10 per thousand) are similar to data from economic metamorphogenic Au deposits of the nearby Otago Schist, but minor meteoric incursion may have occurred. Isotopic data are also similar to veins formed in the inboard zone of the Southern Alps orogen. The Ben Ohau veins demonstrate that gold can be concentrated in low-grade schists distant from the most active part of the hydrothermal system driven by continental collision. (author). 45 refs., 6 figs., 3 tabs

  4. Provenance and depositional age of metavolcano-sedimentary sequences of the Santa Terezinha de Goias, based on Sm-Nd and U-Pb zircon single grain; Proveniencia e idade deposicional de sequencias metavulcano-sedimentares da regiao de Santa Terezinha de Goias, baseada em dados isotopicos Sm-Nd e U-Pb em monocristal de zircao

    Energy Technology Data Exchange (ETDEWEB)

    Dantas, Ellton Luiz; Jost, Hardy; Fuck, Reinhardt A.; Brod, Jose Afonso; Pimentel, Marcio Martins; Meneses, Paulo Roberto [Brasilia Univ., DF (Brazil). Inst. de Geociencias]. E-mail: elton@unb.br

    2001-09-01

    Supracrustal rocks of the Santa Terezinha de Goias region, Central Brazil, presumably represent a southern extension of the Mara Rosa magmatic arc tectonically juxtaposed to Archean terrains and consist of a meta volcanic unit and a meta sedimentary unit. The aim of the paper is to present and discuss the first U-Pb and Sm-Nd data of rocks belonging to both units of that region. U-Pb data of zircons from a felsic meta volcanic rock inter layered with chlorite-rich schists (metandesites?) yield a concordant age of of 660 My, while the Sm-Nd model age of a variety of chlorite-schists indicate a juvenile age between 1.1 and 1.3 Ga. These data indicate that the meta volcanic rocks are Neo proterozoic in age and may be correlated with rocks of the Mara Rosa magmatic arc. On the other hand, the prevailing provenance of rocks belonging to the meta sedimentary unit indicate a Paleoproterozoic, or older, source. Thus, the deposition of both units are explained by means of the erosion of source-areas of variable age. (author)

  5. Experimental research on hydrophilic characteristics of natural soft rock at high stress state

    Institute of Scientific and Technical Information of China (English)

    Guo Hongyun; Lei Xiangyang; Zhang Yumei; Yang Guoxing; Niu Zhang

    2015-01-01

    In order to study features of rock–water interaction, a self-developed experimental system called Intelligent Testing System for Water Absorption in Deep Soft Rocks (ITSWADSR) was utilized to analyze the hydrophilic behaviors of natural soft rock at high stress state. Combining X-ray diffraction and mer-cury injection test, main influencing factors on hydrophilic characteristics were studied. According to the results, it could be concluded as the following:(1) the effective porosity, and the content of illite, illite/smectite formation (S=5%) and kaolinite have positive correlation with the water absorption capacity of rock;meanwhile, the initial moisture content, fractal dimension of effective pores, illite/smectite forma-tion (S=30%) and chlorite present negative correlation; (2) among the positive factors, the ascending order is kaolinite, illite/smectite formation (S=5%) and illite;(3) the descending order among the nega-tive factors are chlorite, illite/smectite formation (S=30%) and fractal dimension of the effective pores;(4) influence of effective porosity on the pressurized water absorbing capacity of rock is minimal, while it is maximal in the process of no pressurized water absorption.

  6. X-Ray Diffraction (XRD and X-Ray Fluorescence (XRF Analysis of Proto-historic Votive Tablets from Chawas Cave, Hulu Kelantan, Malaysia

    Directory of Open Access Journals (Sweden)

    Zuliskandar Ramli

    2014-02-01

    Full Text Available This research was conducted to determine the origin of votive tablets found in prehistoric and proto-historic site of Chawas Cave in Hulu Kelantan. The votive tablets found in Chawas Cave showed several Buddhist images which are associated with the Srivijaya Kingdom which existed from 7th century AD until 12th century AD. To determine if the votive tablets were produced by communities that lived in Hulu Kelantan, hence the study of the chemical composition of the votive tablets should be carried out. Two techniques were employed in this research, namely the X-Ray Diffraction (XRD and X-Ray Fluorescence (XRF techniques. The techniques will determine the mineral content as well as the major and trace element content of the votive tablets. Analysis showed that all the votive tablet samples have mineral known as clinochlore. Clinochlore is one of the chlorites, namely a group of phyllosilicate minerals. Chlorite is commonly found in igneous rocks as an alteration product of mafic minerals such as pyroxene, amphibole and biotite. The votive tablets were found in a cave which consisted of limestone cave formation and it showed that the votive tablets were not produced by the local community of Hulu Kelantan. Major elements also showed that the chemical composition of the votive tablets is not similar to the composition of clay samples taken from several rivers in Hulu Kelantan.

  7. Graft copolymerization of glycidyl methacrylate onto delignified kenaf fibers through pre-irradiation technique

    International Nuclear Information System (INIS)

    Glycidyl methacrylate grafted kenaf (GMA-g-Kenaf) was prepared by pre-irradiation grafting technique. Kenaf fibers were treated with different concentration of sodium chlorite solution before used as trunk polymer. Treated kenaf fibers were irradiated by electron beam followed by grafting reaction in GMA/water emulsion system. The degree of grafting was determined as a function of absorbed dose, reaction time, reaction temperature and concentration of monomer. The results showed that the lignin content was decreased from 14.3% to as low as 3.3% with the increased of sodium chlorite concentration. This was evidenced by SEM pictures which show the surface of treated kenaf fibers was cleaner and smoother compared to that of untreated one. The degree of grafting increased with the increase of absorbed dose, reaction temperature, reaction time and monomer concentration as well as with decreasing lignin content. Formation of graft copolymer was confirmed with SEM, FTIR analysis. The structural investigation by XRD showed that degree of crystallinity of graft copolymers decreased with the increase in degree of grafting. - Highlights: • We used kenaf fibers for radiation induce graft copolymerization with GMA. • Kenaf fibers was treated to remove lignin in order to increase grafting yield. • Treated kenaf fibers were graft copolymerize through preirradiation technique. • Optimum conditions for graft copolymerization of kenaf fibers were established. • Formation of graft copolymer is also confirmed with SEM, FTIR and XRD

  8. X-ray diffraction analysis of mudstone from nw sudan

    International Nuclear Information System (INIS)

    This study deals with the theoretical and experimental aspects of the x-ray diffraction technique (XRD). The XRD technique is used to investigate fine structure of matter, and it is most efficient method for the determination of the mineralogical composition of rocks. The XRD technique is used also to investigate the clay mineralogical of mud-stones of the Nubian sandstones of north western Sudan. The XRD results revealed that the mud-stone samples are composed, in decreasing abundance's of kaolinite, smectite, chlorite and illite. Non-clay minerals reported include quartz, feldspars and geothite. Kaolinite dominates in most of samples with percentages ranging between 78-96%. Smectite comes second in abundance and ranges between 10-24%, followed by chlorite and illite which showed the lowest abundance's. The dominance of kaolinite over smectite indicates that intense chemical weathering and leaching occurred under warm humid climate interrupted by dry periods. Most probably these clay minerals were produced by inheritance and partly by neo formation. The variation of the chemical composition of these mud stones is due basically to differences in clay mineralogy which was controlled by source rock geology, weathering physicochemical behavior of elements, local environment and climatic condition in the past. (Author)

  9. Genesis of the low-permeability reservoir bed of upper Triassic Xujiahe Formation in Xinchang gas field,western Sichuan Depression

    Institute of Scientific and Technical Information of China (English)

    Xu Zhangyou; Zhang Xiaoyu; Wu Shenghe; Zhao Yan

    2008-01-01

    The genesis of a reservoir is a result of the combined action of deposition,diagenesis,tectonic reworking,and interaction of rock and fluid and the evolutionary environment.We discuss the genetic and evolution mechanism of a low-permeability reservoir bed of the Xujiahe Formation in the western Sichuan Depression on the basis of the study of diagenesis,diagenetic reservoir facies and the diagenetic evolution sequence.The research indicated that this reservoir bed can be divided into five types of diagenetic reservoir facies,namely strong dissolution,chlorite-lined intergranular pores,compaction and pressure solution,carbonate cementation and secondary quartz increase.There are,however,just two diagenetic reservoir facies which provide low-permeability reservoir beds,namely strong dissolution and chlorite-lined intergranular pores.We also analyzed their diagenetic evolution sequences and the origin of the low-permeability reservoir bed.Besides,it was also indicated that the composition and structure of sandstones,types of sedimentary microfacies,diagenesis history as well as the tectonic reworking in later periods are the main factors controlling the formation of the low-permeability reservoir bed.The above mentioned factors establish the foundation for the forecasting the distribution of high quality reservoir beds.

  10. 3D modelling and sheath folding at the Falun pyritic Zn-Pb-Cu-(Au-Ag) sulphide deposit and implications for exploration in a 1.9 Ga ore district, Fennoscandian Shield, Sweden

    Science.gov (United States)

    Kampmann, Tobias C.; Stephens, Michael B.; Weihed, Pär

    2016-01-01

    Altered and mineralized rocks at the Falun pyritic Zn-Pb-Cu-(Au-Ag) sulphide deposit, situated in the Palaeoproterozoic Bergslagen ore district in the south-western part of the Fennoscandian Shield, have been metamorphosed at low-pressure, amphibolite-facies conditions and affected by ductile deformation. Using combined surface mapping of lithology and structure, drill core logging and microstructural work, the polyphase (D1 and D2) ductile deformation is demonstrated and a 3D model for the deposit created. Mineral associations include quartz, biotite, cordierite, anthophyllite, and minor almandine, andalusite and chlorite in silicate-rich altered rock, calcite or dolomite in marble and tremolite-actinolite or diopside-hedenbergite in skarn. The silicate minerals show varying growth patterns during the different phases of the tectonothermal evolution, with considerable static grain growth occurring between D1 and D2, and even after D2. F2 sheath folding along axes that plunge steeply to the SSE, parallel to a mineral stretching lineation and the dip direction of the S2 foliation, is suggested as a key deformation mechanism forming steeply plunging, cone- to rod-shaped mineralized bodies. This contrasts with a previous structural model invoking fold interference. A major shear zone with talc-chlorite-(quartz-biotite) mineral association separates the northern and southern structural domains at the deposit and bounds the polymetallic massive sulphides to the north.

  11. Provenance and depositional age of metavolcano-sedimentary sequences of the Santa Terezinha de Goias, based on Sm-Nd and U-Pb zircon single grain

    International Nuclear Information System (INIS)

    Supracrustal rocks of the Santa Terezinha de Goias region, Central Brazil, presumably represent a southern extension of the Mara Rosa magmatic arc tectonically juxtaposed to Archean terrains and consist of a meta volcanic unit and a meta sedimentary unit. The aim of the paper is to present and discuss the first U-Pb and Sm-Nd data of rocks belonging to both units of that region. U-Pb data of zircons from a felsic meta volcanic rock inter layered with chlorite-rich schists (metandesites?) yield a concordant age of of 660 My, while the Sm-Nd model age of a variety of chlorite-schists indicate a juvenile age between 1.1 and 1.3 Ga. These data indicate that the meta volcanic rocks are Neo proterozoic in age and may be correlated with rocks of the Mara Rosa magmatic arc. On the other hand, the prevailing provenance of rocks belonging to the meta sedimentary unit indicate a Paleoproterozoic, or older, source. Thus, the deposition of both units are explained by means of the erosion of source-areas of variable age. (author)

  12. Analytical and mineralogical studies of ore and impurities from a chromite mineral using X-ray analysis, electrochemical and microscopy techniques.

    Science.gov (United States)

    Sánchez-Ramos, S; Doménech-Carbó, A; Gimeno-Adelantado, J V; Peris-Vicente, J

    2008-02-15

    A wide analytical study of South African chromite ore, material with high interest in ceramic industry, has been carried out. With this purpose, an accurate chemical identification and mineralogical characterization of the mineral and the gangue have been performed using X-ray fluorescence (XRF), voltammetry, X-ray diffraction (XRD), light microscopy (LM), and scanning electron microscopy (SEM/EDX). The elemental composition of the sample (ore and gangue) has been obtained by XRF. The voltammetric analysis has allowed to demonstrate that iron in the sample was as Fe(II). The main compound of the chromite ore was a spinel (magnesiochromite ferroan), identified by XRD from the sample, which constitutes the chromite ore. This technique has also been useful to characterize some silicates as impurities in the chromite ore sample. Light microscopy has allowed the detection of the spinel and the identification of a silicate impurity (chrome chlorite), by means of their colouration. On the other hand, the other silicate impurity was identified as labradorite by means of X-ray microscopy by SEM/EDX. Finally, a strategy was developed to calculate the composition of each mineral in the unknown sample. The obtained results were: chromite spinel 82.89%, chlorite 12.79% and labradorite 4.32%. PMID:18371822

  13. Clay mineralogy and geochemistry of the soils derived from metamorphic and mafic igneous parent rocks in Lahijan area

    International Nuclear Information System (INIS)

    The mineralogical and geochemical composition of the soils of three representative pedons formed on basaltic andesite, andesitic basalt and phyllite were investigated. Results by x-ray diffraction showed that progressive weathering of rocks have been marked by gradual accumulation of Al, Fe, Ti, Mg, H3O+ and depletion of Na, K, Ca and Si in the soil; although, predominant clay, loss and gain trend of elements was different on the various rocks. Based on x-ray diffraction analysis, minerals in basaltic andesite and andesitic basalt were similar but, the intensity of mica to smectite or vermiculite transformation for latter was relatively higher than the former. This process revealed the degradation mineral because of two reasons: (i) - smectite and vermiculite increased whereas mica decreased in surface horizons. (i i)-Irregular mixed layer of mica-smectite or vermiculite was present in deeper part (170 cm) of the soils from andesitic basalt but shallower depth (75 em) of the soils from basaltic andesite. Clay minerals in phyllite were mica and chlorite that stratified with vermiculite. However, the absence of smectite in phyllite might be attributed to more acidic condition or position of the Fe ion in the mineral lattice of chlorite (higher Fe in the interlayer hydroxide sheet)

  14. Mineralogy and petrography of samples of Permo-Triassic sedimentary strata from Cumbria

    International Nuclear Information System (INIS)

    The mineralogy and petrography of Permo-Triassic sediments from Cumbria are described. The samples are duplicates of those selected for sorption experiments by Harwell Laboratory and are considered representative of Permo-Triassic strata underlying the BNFL Sellafield site. The regional geological context of the samples is briefly discussed. X-ray diffraction analysis indicates that the St Bees Sandstone and Eden Shales samples are predominantly composed of quartz with minor feldspar, gypsum and hematite. The clay assemblage is formed of dioctahedral mica and trioctahedral chloride with minor kaolinite. Diagnostic testing also reveals the presence of corrensite, a regularly interstratified chlorite-smectite, in one of the samples. Possible diagenetic processes responsible for corrensite formation, including the alteration of originally deposited smectite by magnesium-rich pore waters, are discussed. Modelling of the diffraction profile indicates that the chlorite and corrensite are iron-rich species. Back scattered electron microscopy shows the samples to be typical red bed sediments exhibiting framework grain dissolution, the breakdown and replacement of unstable ferromagnesian minerals being accompanied by the precipitation of hematite and anatase. Particle-size analysis shows similar distributions for the St Bees Sandstone samples but a greater proportion of clay material in the Eden Shales. (author)

  15. Bentonite alteration due to thermal-hydro-chemical processes during the early thermal period in a nuclear waste repository

    Energy Technology Data Exchange (ETDEWEB)

    Xu, T.; Senger, R.; Finsterle, S.

    2011-02-01

    After closure of an underground nuclear waste repository, the decay of radionuclides will raise temperature in the repository, and the bentonite buffer will resaturate by water inflow from the surrounding host rock. The perturbations from these thermal and hydrological processes are expected to dissipate within hundreds to a few thousand years. Here, we investigate coupled thermal-hydro-chemical processes and their effects on the short-term performance of a potential nuclear waste repository located in a clay formation. Using a simplified geometric configuration and abstracted hydraulic parameters of the clayey formation, we examine geochemical processes, coupled with thermo-hydrologic phenomena, and potential changes in porosity near the waste container during the early thermal period. The developed models were used for evaluating the mineral alterations and potential changes in porosity of the buffer, which can affect the repository performance. The results indicate that mineral alteration and associated changes in porosity induced by early thermal and hydrological processes are relatively small and are expected to not significantly affect flow and transport properties. Chlorite precipitation was obtained in all simulation cases. A maximum of one percent volume fraction of chlorite could be formed, whose process may reduce swelling and sorption capacity of bentonite clay, affecting the performance of the repository. llitisation process was not obtained from the present simulations.

  16. Petrology of metabasites in the south of Arousan, northeastern Isfahan province

    Directory of Open Access Journals (Sweden)

    Fereshteh Bayat

    2012-10-01

    Full Text Available Metagabbro, metadiabase and metabasalt of the Chah Palang and Me'raji mountains associated with Lower Paleozoic metamorphites are situated in the south of Arousan. Metabasites of these areas are relatively similar in terms of mineralogy and geochemical characteristics. Rock-forming minerals of the Me'raji metabasites are feldspar, amphibole, biotite, sphene, epidote, chlorite ± calcite. Metagabbro and metadiabase of the Chah Palang area are similar to the Me'raji metabasites in mineralogy and geochemistry. Volcanic rocks are overlain by metagabbros and consist of plagioclase, biotite, sphene, sanidine, chlorite, epidote and iron oxides. The rigid dykes, which are found in the volcanic units are associated with metagabbros and mineralogically are similar to the metavolcanics. Amphibolitic dykes are composed of amphibole, plagioclase and biotite with preferred orientation. Metabasites show limited range of differentiation. Me'raji metabasites are basalt and trachy-basalt in composition, whereas the Chah Palang ones present basalt and trachy-basalt composition. Similar to metabasites of the other parts of Iran, the studied basic rocks demonstrate alkaline to transitional chemical characteristic and are formed in an extensional environment by low-degree partial melting of a garnet-spinel peridotite. Metamorphic episodes have changed the studied rocks to amphibolite and greenschist, but the primitive igneous textures are preserved.

  17. Mineralogy of a perudic Andosol in central Java, Indonesia

    Energy Technology Data Exchange (ETDEWEB)

    Van Ranst, Eric; Utami, S. R.; Verdoodt, A.; Qafoku, Nikolla

    2008-02-15

    We studied the mineralogy of a perudic Andosol developed on the Dieng Tephra Sequence in central Java, Indonesia. The objective was to confirm the presence and determine the origin and stability of 2:1 and interlayered 2:1 phyllosilicates in well-drained Andosols. This was and still is a debated topic in the literature. Total elemental and selective dissolution, as well as microscopic and X-ray diffraction analyses, were performed on the soil samples collected from this site. These analyses confirmed that andic properties were present in the soil samples. The allophane content determined by selective dissolution was 3-4% in the A horizons, and increased to 12-18% in the deeper subsoil horizons. In addition, the clay fraction contained dioctahedral smectite, hydroxy-Al-interlayered 2:1 minerals (HIS), Al-chlorite, kaolinite, pyrophyllite, mica, cristobalite and some gibbsite. The silt and sand fractions were rich in plagioclase and pyroxene. The 2:1 minerals (smectite and pyrophyllite), as well as chlorite and kaolinite were of hydrothermal origin and were incorporated in the tephra during volcanic eruption. Besides desilication during dissolution of unstable minerals, Al interlayering of 2:1 layer silicates was most likely the most prominent pedogenic process. Although hydroxy-Al polymeric interlayers would normally stabilize the 2:1 clay phases, the strong weakening, and even disappearance of the characteristic XRD peaks, indicated instability of these minerals in the upper A horizons due to the perudic and intensive leaching conditions.

  18. Significant mineral variations in the Lower Karoo deposits of the Mid-Zambezi Basin, Zimbabwe, and their palaeoenvironmental implications

    International Nuclear Information System (INIS)

    Mineralogical composition of Lower Karoo deposits from the Mid-Zimbabwe Basin, Zimbabwe, have been established by means of X-ray diffractometry to evaluate mineralogical variables as possible palaeoenvironment indicators. Mineral variations are stratigraphically controlled. Dwyka tillites are composed of quartz, K-feldspar and plagioclase. Varvites contain additional calcite. The clay fraction is dominated by kaolinite in the northwestern part of the study area while in the southwest only subordinate proportions of kaolinite occur associated with approximately equal amounts of mica, chlorite, smectite, and interstratifications. The overlying Ecca sediments are characterized by a high kaolinite content, traces of K-feldspar, mica and occasional pyrite. In mudstones of the uppermost Ecca, the kaolonite proportion decreases in favour of mica and chlorite. The mineral composition of Beaufort mudstones differs significantly with considerable amounts of plagioclase and a more than sporadic presence of analcime which is restricted to this stratigraphic unit. The clay fraction is dominated by either kaolinite, mica, or smectite. Within the geotectonical setting discussed by this paper the kaolinite dominance in Ecca sediments corresponds well with freshwater depositional conditions deduced from sedimentological and palaeontological evidence. However, the abundance of 2:1 phyllosilicates and especially analcime prevalence in the Beaufort section indicates an alkaline palaeoenvironment. 10 figs., 29 refs

  19. Petrographical properties of shales from Campos Basin

    Energy Technology Data Exchange (ETDEWEB)

    Rabe, Claudio; Araujo, Ewerton M.P.; Fontoura, Sergio A.B. da [Pontificia Univ. Catolica do Rio de Janeiro, RJ (Brazil). Dept. de Engenharia Civil. Grupo de Tecnologia e Engenharia de Petroleo (GTEP)

    2004-07-01

    This paper presents a petrographical characterization of shales from Albacora, Marlim and Marlim Sul fields (offshore Campos Basin, Brazil). The characterization program included petrography analysis of thin section of undisturbed shale samples, scanning electron microscope (SEM) images and energy dispersive spectrometry (EDS) analysis. The tests were realized with the purpose of obtaining information to observe the nature of the rock microstructure. From the results presented herein, the shales can be described as silty and calciferous. The description of the thin sections indicated that all the shale samples are very similar from the compositional and textural point of view. The samples are rich in clay minerals, that show small size grains and seem homogeneous, and carbonatic cement. The samples are constituted by calcite, quartz, kaolinite, smecite, illite, illite/smectite, kaolinite/illite/smectite, feldspar, plagioclase, dolomite, chlorite and pyrite. The samples showed a great amount of calcium, resultant from the microfossils, that covers partially the clay minerals. Pyrite is also observed as small grains disperse throughout the sample with form of agglomerated pyrite framboids, cubo-octahedral and octahedral crystals. The EDS show the presence of picks of Si, Al, Mg, K and Na particles, indicating the presence of clay minerals, calcite, pyrite and chlorite. (author)

  20. Statistical analysis of results from the quantitative mapping of fracture minerals in Laxemar. Site descriptive modelling - complementary studies

    International Nuclear Information System (INIS)

    Within the Laxemar site investigation campaign, quantitative mapping of different fracture minerals has been performed. This has been done by studying fracture surfaces of drill core sections from many different boreholes at the Laxemar site /Eklund and Mattsson 2008/. The drill core mapping was focused on the rock in the vicinity of flow anomalies detected by the Posiva Flow Log (PFL). The quantitative mapping was performed only on open fractures. The fracture minerals that were mapped are calcite, chlorite, clay minerals (as a group), hematite, and pyrite. In this present report, data from the quantitative mineral mapping campaign are refined, sorted into different data subsets, and analysed by parametric and non-parametric statistical methods. The data subsets are associated with 17 different rock volumes, representing different elevations, rock domains, fracture domains, and groups of deformation zones. In total 1,852 fractures were mapped at the site, and the most frequent mineral was calcite. Its amount could be quantitatively estimated in 51% of the mapped fractures. Of the other minerals, chlorite was quantitatively estimated in 46%, pyrite in 19%, clay minerals in 16%, and hematite in 0.05% of the mapped fractures. For fractures where the averaged fracture mineral thickness, dmean [mm], and visible coverage, Cvis [%], could be quantitatively estimated, the following arithmetic means were found: calcite = 0.25 mm and 22%, chlorite = 0.29 mm and 41%, pyrite =1.3 μm and 0.2%, and clay minerals = 0.15 mm and 35%. These quantities are based on visual inspection of fracture surfaces and do not include the contribution from non-consolidated fracture fillings. It is shown that there is significant spatial variability of dmean and Cvis within the examined rock volumes. Furthermore, the non-parametric analyses indicate that there are differences in dmean and Cvis between the different rock volumes. Even so, the differences are generally shown to be small and if

  1. Static and fault-related alteration in the lower ocean crust, IODP Expedition 345, Hess Deep

    Science.gov (United States)

    McCaig, Andrew; Faak, Kathrin; Marks, Naomi; Nozaka, Toshio; Python, Marie; Wintsch, Robert; Harigane, Yumiko; Titarenko, Sofya

    2014-05-01

    IODP Expedition 345 drilled the first holes in the lower plutonic crust at a fast-spreading ridge, recovering primitive layered gabbros (Gillis et al 2014). Alteration can be subdivided into two series: 1) a largely static pseudomorphic alteration affecting predominantly olivine. This began in the amphibolite facies with minor secondary cinopyroxene and hornblendic amphibole replacing primary pyroxene, and sporadically developed corona textures with tremolite and chlorite replacing olivine and plagioclase respectively, but was predominantly in the greenschist and sub-greenschist facies with talc, serpentine, clay minerals,oxides andsulphides replacing olivine, and prehnite and locally other calcsilicates replacing plagioclase, commonly in micro-vein networks. Albitic plagioclase is sporadically developed, and locally zeolite and carbonate. 2) An overprinting metasomatic alteration under sub-greenschist or perhaps lowermost greenschist conditions(zeolite. This alteration is spatially related to cataclastic fault zones and macroscopic veins. Comminuted plagioclase in cataclasites is commonly completely replaced by prehnite, while chlorite may completely pseudomorph olivine, locally with textures suggesting replacement of previous secondary minerals such as talc and serpentine. Chlorite also ubiquitously occurs as patches replacing plagioclase along grain boundaries, locally associated with carbonate and amphibole needles. Metamorphosed dykes show chilled margins within the cataclasites, and are affected by cataclastic deformation. Faults, dykes and overprinting alteration are all inferred to be related to the westward propagation of Cocos-Nazca spreading that formed Hess Deep. Samples of different alteration and cataclastic domains were cut out of this section chips for isotopic analysis. 87Sr/86Sr ratios of cataclasites and dyke rocks are in the range 0.7037 - 0.7048, indicating alteration by seawater at moderate integrated fluxes. The highest values were in

  2. 四川周公山-汉王场地区峨眉山玄武岩中流体类型及活动期次%Fluid types and activities of Emeishan basalt in Zhougong mountain-Hanwang field of Sichuan Province.

    Institute of Scientific and Technical Information of China (English)

    侯明才; 王文楷; 张本健; 王维; 李秀华; 邓敏; 裴森奇; 杨毅

    2013-01-01

    来自汉王场-周公山地区周公2井和汉6井峨眉山玄武岩钻井岩心样品显示峨眉山玄武岩有:隐晶玄武岩、杏仁状玄武岩,凝灰岩,火山角砾岩,凝灰角砾岩,绿帘石岩,赤铁矿染玄武岩,红土化玄武岩和脉岩等九种岩石类型.其中发育的杏仁体成分有:赤铁矿杏仁体、绿帘石杏仁体、石英-绿泥石杏仁体、蛋白石-赤铁矿杏仁体、磁铁矿-赤铁矿杏仁体、榍石-玉髓杏仁体、绿帘石-葡萄石-绿泥石杏仁体、钛铁矿-玉髓-绿泥石-玉髓杏仁体等8种,脉体有:长石脉、赤铁矿脉、石英脉、绿帘石脉、绿泥石、榍石脉、方解石脉、玉髓-水铝英石脉、方解石-赤铁矿脉、方解石-绿泥石脉、石英-方解石脉、石英-绿帘石脉、石英-沥青脉、赤铁矿-玉髓-绿泥石脉、绿帘石-绿泥石-玉髓脉等15种.这些脉体和杏仁体形成于峨眉山玄武岩形成演化的不同阶段,喷溢期流体受岩浆原生组分影响,大气降水影响程度低,温度属高-中温,脉体包裹体盐度-温度为正相关,代表性产物为赤铁矿脉;风化期流体主要来源于大气降水,氧化作用和水解作用对脉体的发育产生了很大影响,这一时期δ13C为低-中负值,包裹体盐度、温度低,以水铝英石脉最为典型;进入埋藏期以后,上覆地层水和深部的卤水对岩石进行改造,这一时期的流体属低-中温,包裹体盐度与温度呈负相关,受有机质影响,δ13C呈高负值,以绿帘石脉最为典型.%Samples from Zhougong 2 well and Han 6 well in Zhougong mountain-Hanwang field show that the Emeishan basalt can be divided into 9 types,cryptocrystalline basalt,amygdaloidal basalt,tuff,volcanic breccia,tuff-breccia,epidosite rock,hematitedbasalt,weathered basalt and vein rock.Minerals and with their combinations such as hematite,epidote,quartz-chlorite,opalhematite,magnetite-hematite,sphene-chalcedony,epidote-prehnite-chlorite,and ilmenite-chalcedony-chlorite

  3. Fate of gold and base metals during metamorphic devolatilization of a pelite

    Science.gov (United States)

    Zhong, Richen; Brugger, Joël; Tomkins, Andrew G.; Chen, Yanjing; Li, Wenbo

    2015-12-01

    Scavenging of gold during metamorphic devolatilization is a widely accepted model for fluid and metal sourcing in orogenic gold deposits. In order to further constrain this process and quantify the capacity of autogenous fluids to release metals from pelites, we investigated the behaviors of S, Au, As, Cu, Pb, and Zn during pelite metamorphic devolatilization using thermodynamic modeling within the Al-As-Au-Cl-Cu-Fe-H-K-Mg-Na-O-Pb-S-Si-Ti-Zn system over a P-T range of 350-650 °C and 0.8-5 kbar. The model revealed that S, Au and base metals are predominantly released via partitioning into the fluid phase during reactions that liberate H2O: the dehydration of chlorite and muscovite, and to a lesser extent, the replacement of pyrite by pyrrhotite. Negligible sulfur is liberated during the pyrite-pyrrhotite transition, because the excess sulfur reacts with Fe in chlorite and muscovite to form pyrrhotite. The sulfidation of chlorite/muscovite releases water, so that a significant amount of Au can be liberated from S-rich pelites at the pyrite to pyrrhotite transition: up to 0.5 ppb Au (as a proportion of bulk rock) can be stripped from a pelite containing 1 wt.% sulfur, whereas only trace amounts of base metals can be mobilized under these conditions. Chlorite dehydration is the most important process in metal extraction; up to 2 ppb Au, 1.5 ppm Cu, 1 ppm Pb and 2 ppm Zn (as proportions of bulk rock) can be extracted from a pelite by autogenous fluids upon crossing the greenschist-amphibolite facies boundary. In comparison, an average pelite contains ∼3 ppb Au, indicating that most Au within an average pelite can be scavenged as a result of the breakdown of chlorite. Prograde metamorphism is an efficient mechanism for generating Au-bearing ore fluids: most Au can be extracted during chlorite dehydration from a source rock of average pelitic composition. In contrast, only a small portion of base metals can be released in autogenous fluids, and therefore only minor

  4. Unbiased isotope equilibrium factors from partial isotope exchange experiments in 3-exchange site systems

    Science.gov (United States)

    Agrinier, Pierre; Javoy, Marc

    2016-09-01

    Two methods are available in order to evaluate the equilibrium isotope fractionation factors between exchange sites or phases from partial isotope exchange experiments. The first one developed by Northrop and Clayton (1966) is designed for isotope exchanges between two exchange sites (hereafter, the N&C method), the second one from Zheng et al. (1994) is a refinement of the first one to account for a third isotope exchanging site (hereafter, the Z method). In this paper, we use a simple model of isotope kinetic exchange for a 3-exchange site system (such as hydroxysilicates where oxygen occurs as OH and non-OH groups like in muscovite, chlorite, serpentine, or water or calcite) to explore the behavior of the N&C and Z methods. We show that these two methods lead to significant biases that cannot be detected with the usual graphical tests proposed by the authors. Our model shows that biases originate because isotopes are fractionated between all these exchanging sites. Actually, we point out that the variable mobility (or exchangeability) of isotopes in and between the exchange sites only controls the amplitude of the bias, but is not essential to the production of this bias as previously suggested. Setting a priori two of the three exchange sites at isotopic equilibrium remove the bias and thus is required for future partial exchange experiments to produce accurate and unbiased extrapolated equilibrium fractionation factors. Our modeling applied to published partial oxygen isotope exchange experiments for 3-exchange site systems (the muscovite-calcite (Chacko et al., 1996), the chlorite-water (Cole and Ripley, 1998) and the serpentine-water (Saccocia et al., 2009)) shows that the extrapolated equilibrium fractionation factors (reported as 1000 ln(α)) using either the N&C or the Z methods lead to bias that may reach several δ per mil in a few cases. These problematic cases, may be because experiments were conducted at low temperature and did not reach high

  5. Fluid-related inclusions in Alpine high-pressure peridotite reveal trace element recycling during subduction-zone dehydration of serpentinized mantle (Cima di Gagnone, Swiss Alps)

    Science.gov (United States)

    Scambelluri, Marco; Pettke, Thomas; Cannaò, Enrico

    2015-11-01

    Serpentinites release at sub-arc depths volatiles and several fluid-mobile trace elements found in arc magmas. Constraining element uptake in these rocks and defining the trace element composition of fluids released upon serpentinite dehydration can improve our understanding of mass transfer across subduction zones and to volcanic arcs. The eclogite-facies garnet metaperidotite and chlorite harzburgite bodies embedded in paragneiss of the subduction melange from Cima di Gagnone derive from serpentinized peridotite protoliths and are unique examples of ultramafic rocks that experienced subduction metasomatism and devolatilization. In these rocks, metamorphic olivine and garnet trap polyphase inclusions representing the fluid released during high-pressure breakdown of antigorite and chlorite. Combining major element mapping and laser-ablation ICP-MS bulk inclusion analysis, we characterize the mineral content of polyphase inclusions and quantify the fluid composition. Silicates, Cl-bearing phases, sulphides, carbonates, and oxides document post-entrapment mineral growth in the inclusions starting immediately after fluid entrapment. Compositional data reveal the presence of two different fluid types. The first (type A) records a fluid prominently enriched in fluid-mobile elements, with Cl, Cs, Pb, As, Sb concentrations up to 103 PM (primitive mantle), ∼102 PM Tl, Ba, while Rb, B, Sr, Li, U concentrations are of the order of 101 PM, and alkalis are ∼2 PM. The second fluid (type B) has considerably lower fluid-mobile element enrichments, but its enrichment patterns are comparable to type A fluid. Our data reveal multistage fluid uptake in these peridotite bodies, including selective element enrichment during seafloor alteration, followed by fluid-rock interaction along with subduction metamorphism in the plate interface melange. Here, infiltration of sediment-equilibrated fluid produced significant enrichment of the serpentinites in As, Sb, B, Pb, an enriched trace

  6. Geochemical and fluid zonation in the skarn environment at the tomboy-minnie gold deposits, Lander County, Nevada

    Science.gov (United States)

    Theodore, T.G.; Howe, S.S.; Blake, D.W.; Wotruba, P.R.

    1986-01-01

    The Tomboy-Minnie gold deposits are related to the middle Tertiary porphyry copper system centered at Copper Canyon. Gold-silver ores in the deposits occur mostly in a pyrrhotite- and pyrite-rich basal 30-m-thick sequence of altered calcareous conglomerate belonging to the Middle Pennsylvanian Battle Formation. The entire mineralized system contained at least 3.3 million troy oz gold before large-scale mining operations began. Alteration in the Tomboy-Minnie deposits includes actinolite- and chlorite-dominant assemblages, in marked contrast to the skarn, potassic, and phyllic assemblages characterizing the copper-gold-silver deposits of the system. Introduction of gold occurred penecontemporaneously with replacement of early diopside-alteration assemblages by actinolite and chlorite. Metals are zoned strongly in the Copper Canyon system: the West and East ore bodies occur in a copper-gold-silver zone that is followed outward by a gold-silver zone which includes the Tomboy deposit and in turn, is succeeded by a lead-zinc-silver zone. Locations of drill holes that have Au/Ag assay ratios of ??? 1 clearly outline the Tomboy-Minnie deposits within an area of rocks with Au/Ag ratios of ??? 0.5. Fluid-inclusion studies suggest wide variations in temperature and chemistry prevailed in the fluids associated with mineralization at the Tomboy. Early fluids associated with diopsidequartz assemblages probably were dominantly CaCl2-rich brines and were boiling at temperatures higher than 500??C. These fluids were progressively enriched in sodium and potassium over time, and during the hydrosilicate stages, temperatures probably ranged from 320 to 500??C at the time actinolite formed, and from 220 to 320??C at the time chlorite was dominant. Sulfur isotopic data suggest that sulfur, mostly from a magmatic or deep-seated crustal source, was transported by hydrothermal fluids as aqueous H2S with a ?? 34S of about 4 ?? 1??? to the West, East, and Tomboy deposits. ?? 1986.

  7. The Marianas-San Marcos vein system: characteristics of a shallow low sulfidation epithermal Au-Ag deposit in the Cerro Negro district, Deseado Massif, Patagonia, Argentina

    Science.gov (United States)

    Vidal, Conrado Permuy; Guido, Diego M.; Jovic, Sebastián M.; Bodnar, Robert J.; Moncada, Daniel; Melgarejo, Joan Carles; Hames, Willis

    2016-08-01

    The Cerro Negro district, within the Argentinian Deseado Massif province, has become one of the most significant recent epithermal discoveries, with estimated reserves plus resources of ˜6.7 Moz Au equivalent. The Marianas-San Marcos vein system contains about 70 % of the Au-Ag resources in the district. Mineralization consists of Upper Jurassic (155 Ma) epithermal Au- and Ag-rich veins of low to intermediate sulfidation style, hosted in and genetically related to Jurassic intermediate composition volcanic rocks (159-156 Ma). Veins have a complex infill history, represented by ten stages with clear crosscutting relationships that can be summarized in four main episodes: a low volume, metal-rich initial episode (E1), an extended banded quartz episode with minor mineralization (E2), a barren waning stage episode (E3), and a silver-rich late tectonic-hydrothermal episode (E4). The first three episodes are interpreted to have formed at the same time and probably from fluids of similar composition: a 290-230 °C fluid dominated by meteoric and volcanic waters (-3‰ to -0‰ δ18Owater), with precipitated at the beginning of vein formation (episode 1) due to a combination of boiling at ˜600 to 800 m below the paleowater table, and associated mixing/cooling processes, as evidenced by sulfide-rich bands showing crustiform-colloform quartz, adularia, and chlorite-smectite banding. During episodes 2 and 3, metal contents progressively decrease during continuing boiling conditions, and veins were filled by quartz and calcite during waning stages of the hydrothermal system, and the influx of bicarbonate waters (-6 to -8.5 ‰ δ18Owater). Hydrothermal alteration is characterized by proximal illite, adularia, and silica zone with chlorite and minor epidote, intermediate interlayered illite-smectite and a distal chlorite halo. This assemblage is in agreement with measured fluid inclusion temperatures. A striking aspect of the Marianas-San Marcos vein system is that the high

  8. Characteristics of Clay Minerals in the Northern South China Sea and Its Implications for Evolution of East Asian Monsoon since Miocene

    Institute of Scientific and Technical Information of China (English)

    Wan Shiming; Li Anchun; Xu Kehui; Yin Xueming

    2008-01-01

    Clay mineral assemblages, crystallinity, chemistry, and micromorphology of clay particles in sediments from ODP Site 1146 in the northern South China Sea (SCS) were analyzed, and used to trace sediment sources and obtain proxy records of the past changes in the East Asian monsoon climate since the Miocene, based on a multi-approach, including X-ray diffraction (XRD) and scanning electron microscopy combined with energy dispersive X-ray spectrometry (SEM-EDS). Clay minerals consist mainly of illite and smectite, with associated chlorite and kaolinite. The illite at ODP Site 1146 has very well-to-well crystallinity, and smectite has moderate-to-poor crystallinity. In SEM the smectite particles at ODP Site 1146 often appear cauliflower-like, a typical micromorphology of volcanic smecites. The smectite at ODP Site 1146 is relatively rich in Si element, but poor in Fe, very similar to the smectite from the West Philippine Sea. In contrast, the chemical composition of illite at ODP Site 1146 has no obvious differences from those of the Loess plateau, Yellow River, Yangtze River, and Pearl River. A further study on sediment source indicates that smectite originates mainly from Luzon, kaolinite from the Pearl River, and illite and chlorite from the Pearl River, Taiwan and/or the Yangtze River. The clay mineral assemblages at ODP Site 1146 were not only controlled by continental eathering regimes surrounding the SCS, but also by the changing strength of the transport processes. The ratios of (illite+chlorite)/smectite at ODP Site 1146 were adopted as proxies for the East Asian monsoon evolution. Relatively higher ratios reflect strongly intensified winter monsoon relative to summer monsoon, in contrast, lower ratios indicate a strengthened summer monsoon relative to winter monsoon. The consistent variation of this clay proxy from those of Loess plateau, eolian deposition in the North Pacific, planktonic, benthic foraminifera, and black carbon in the SCS since 20 Ma shows

  9. Hydrothermal alteration styles in ancient and modern orogenic gold deposits, New Zealand

    International Nuclear Information System (INIS)

    Orogenic hydrothermal systems in the South Island of New Zealand were active during Mesozoic and late Cenozoic collisional deformation and metamorphism of greywacke/schist terranes. Observations on the currently active mountain-building environment yield insights on processes occurring in the upper 5-15 km of the crust, and observations on an adjacent lithologically identical exhumed ancient mountain belt provide information on processes at 10-20 km in the crust. Hydrothermal fluids were mainly derived from metamorphic dehydration reactions and/or circulating topographically driven meteoric water in these mountain belts. Three geochemically and mineralogically different types of hydrothermal alteration and vein mineralisation occurred in these orogenic belts, and gold enrichment (locally economic) occurred in some examples of each of these three types. The first type of alteration involved fluids that were in or near chemical equilibrium with their greenschist facies host rocks. Fluid flow was controlled by discontinuous fractures, and by microshears and grain boundaries in host rocks, in zones from metres to hundreds of metres thick. Vein and alteration mineralogy was similar to that of the host rocks, and included calcite and chlorite. The second type of alteration occurred where the fluids were in distinct disequilibrium with the host rocks. Fracture permeability was important for fluid flow, but abundant host rock alteration occurred as well. The alteration zones were characterised by decomposition of chlorite and replacement by ankeritic carbonate in zones up to tens of metres thick. The mineralising fluid was deep-sourced and initially rock-equilibrated, with some meteoric input. The third type of mineralisation was controlled almost exclusively by fracture permeability, and host rock alteration was minor (centimetre scale). This mineralisation type commonly involved calcite and chlorite as vein and alteration minerals, and mineralisation fluids had a major

  10. 鄂尔多斯盆地罗庞塬地区长8储层成岩相及其对物性的控制作用%Diagenetic facies and its control over physical property of Chang 8 reservoir in Luopangyuan area of Ordos Basin

    Institute of Scientific and Technical Information of China (English)

    张彬; 屈红军; 李敏; 杨欢; 王力; 郑艳荣

    2013-01-01

    罗庞塬地区长8油层组是定边油田重要的产油层段之一,但总体研究程度较低.文中综合利用物性分析、铸体薄片、扫描电镜、压汞等资料对罗庞塬地区的成岩相及其对物性的影响做了详细研究,得出以下结论:研究区长8油层组主要发育四种成岩相,绿泥石环边胶结—长石溶蚀相、长石溶蚀—铁方解石胶结相、铁方解石连晶胶结相和泥质胶结压实相.储层的物性分布规律明显受成岩相控制,绿泥石环边胶结—长石溶蚀相区储层物性最好,为最有利储集层发育的相带;长石溶蚀—铁方解石胶结相区储层物性稍差,为较有利储集层发育的相带.%Chang 8 oil-bearing layer in Luopangyuan area is one of the important oil producing intervals in Dingbian oil field, but is in low exploration extent. Based on data of physical property analyses, cast-slice, SEM analyses and mercury injection, the paper investigated diagenetic facies in Luopangyuan area and its control over physical property. Draw the following conclusions; the Chang 8 oil-bearing layer of the study area was divided into four diagenetic types of facies combination, including rim cementation-corrosion of chlorites, corrosion and carbonate cementation, poikilitic cementation of calcites and dense-mudstone compaction. The distribution of reservoir quality was obviously controlled by diagenetic facies. The reservoir quality of chlorite-rim cementation-corrosion belts are the best, which were proposed to be the most favorable places for reservoir development. The reservoir quality of corrosion and carbonate cementation is less than chlorite-rim cementation-corrosion belts, which is more favorable places for reservoir development.

  11. Retrograde metasomatic effects on phase assemblages in an interlayered blueschist-greenschist sequence (Coastal Cordillera, Chile)

    Science.gov (United States)

    Halama, Ralf; Konrad-Schmolke, Matthias

    2015-02-01

    Interlayered blueschists and greenschists of the Coastal Cordillera (Chile) are part of a Late Palaeozoic accretionary complex. They represent metavolcanic rocks with oceanic affinities based on predominantly OIB-type REE patterns and immobile trace element ratios. Both rock types have similar mineralogies, albeit with different mineral modal abundances. Amphibole is the major mafic mineral and varies compositionally from glaucophane to actinolite. The presence of glaucophane relicts as cores in zoned amphiboles in both blueschists and greenschists is evidence for a pervasive high-pressure metamorphic stage, indicating that tectonic juxtaposition is an unlikely explanation for the cm-dm scale interlayering. During exhumation, a retrograde greenschist-facies overprint stabilized chlorite + albite + winchitic/actinolitic amphibole + phengitic white mica ± epidote ± K-feldspar at 0.4 ± 0.1 GPa. Geochemical variability can be partly ascribed to primary magmatic and partly to secondary metasomatic processes that occurred under greenschist-facies conditions. Isocon diagrams of several adjacent blueschist-greenschist pairs with similar protolith geochemistry were used to evaluate metasomatic changes due to retrograde fluid-rock interaction. The most important geochemical changes are depletion of Si and Na and addition of water in the greenschists compared to the blueschists. Transition metals and LILE are mobilized to varying degrees. The unsystematic deviations from magmatic fractionation trends suggest open system conditions and influx of an external fluid. Pseudosection and water isopleth calculations show that the rocks were dehydrating during most of their exhumation history and remained at water-saturated conditions. The mineralogical changes, in particular breakdown of blue amphibole and replacement by chlorite, albite and calcic/sodic-calcic amphibole, are the prime cause for the distinct coloring. Pseudo-binary phase diagrams were used as a means to link bulk

  12. Physiological and genetic description of dissimilatory perchlorate reduction by the novel marine bacterium Arcobacter sp. strain CAB.

    Science.gov (United States)

    Carlström, Charlotte I; Wang, Ouwei; Melnyk, Ryan A; Bauer, Stefan; Lee, Joyce; Engelbrektson, Anna; Coates, John D

    2013-01-01

    A novel dissimilatory perchlorate-reducing bacterium (DPRB), Arcobacter sp. strain CAB, was isolated from a marina in Berkeley, CA. Phylogenetically, this halophile was most closely related to Arcobacter defluvii strain SW30-2 and Arcobacter ellisii. With acetate as the electron donor, strain CAB completely reduced perchlorate (ClO4(-)) or chlorate (ClO3(-)) [collectively designated (per)chlorate] to innocuous chloride (Cl(-)), likely using the perchlorate reductase (Pcr) and chlorite dismutase (Cld) enzymes. When grown with perchlorate, optimum growth was observed at 25 to 30°C, pH 7, and 3% NaCl. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) preparations were dominated by free-swimming straight rods with 1 to 2 polar flagella per cell. Strain CAB utilized a variety of organic acids, fructose, and hydrogen as electron donors coupled to (per)chlorate reduction. Further, under anoxic growth conditions strain CAB utilized the biogenic oxygen produced as a result of chlorite dismutation to oxidize catechol via the meta-cleavage pathway of aerobic catechol degradation and the catechol 2,3-dioxygenase enzyme. In addition to (per)chlorate, oxygen and nitrate were alternatively used as electron acceptors. The 3.48-Mb draft genome encoded a distinct perchlorate reduction island (PRI) containing several transposases. The genome lacks the pcrC gene, which was previously thought to be essential for (per)chlorate reduction, and appears to use an unrelated Arcobacter c-type cytochrome to perform the same function. IMPORTANCE The study of dissimilatory perchlorate-reducing bacteria (DPRB) has largely focused on freshwater, mesophilic, neutral-pH environments. This study identifies a novel marine DPRB in the genus Arcobacter that represents the first description of a DPRB associated with the Campylobacteraceae. Strain CAB is currently the only epsilonproteobacterial DPRB in pure culture. The genome of strain CAB lacks the pcrC gene found in all

  13. Hydrothermal alteration products of gabbros help accommodate exhumation-related deformation in mantle-derived ultramafics exposed at the Mid-Atlantic Ridge

    Science.gov (United States)

    Picazo, S.; Cannat, M.; Escartin, J.; Gibert, B.; Delacour, A.; Silantyev, S.

    2011-12-01

    Outcrops of deeply-derived ultramafic rocks and gabbros are widespread along slow spreading ridges but the rheology and dynamics of the exhumation faults and of their uplifted footwalls are still poorly known. Previous studies of samples collected within meters of exposed exhumation fault surfaces in the Atlantic have shown that a gabbroic component was added to the primarily ultramafic material in the fault zone, allowing for the growth of abundant amphibole, chlorite and talc. The nature of this component (altered magmatic intrusions or metasomatic hydrothermal fluids) could not, however, be ascertained in the pervasively sheared fault material. In this abstract we report on a set of 474 samples collected at the Mid-Atlantic Ridge (MAR) during the Serpentine cruise (2007; RV Pourquoi Pas? PI Y. Fouquet) next to the ultramafic-hosted Ashadze (13°N) and Logatchev (14°45'N) vent fields. Most of these 474 samples are weakly to moderately deformed and are interpreted as representing the upper few hundred meters below their respective exhumation fault zone, rather than the fault zone itself. The large number of samples, and their overall moderate degree of deformation gives us a chance to propose a semi-statistical study of plastic, brittle-plastic and brittle deformation in ultramafic rocks next to a MAR exhumation system, in relation with the magmatic and hydrothermal history. Our primary finding is that significant brittle-plastic deformation systematically involves amphibole±chlorite±talc-bearing ultramafic lithologies. Serpentine is commonly present in these deformed assemblages, but we did not find serpentine-only shear zones. Amphibole (in successive generations ranging from hornblende to tremolite) and chlorite occur in veins, many of which also contain zircon and some relict plagioclase, indicating a magmatic origin. Relicts of primary peridotite minerals in the most amphibole-rich samples indicate that magmatic injection followed on an episode of

  14. Fracture-zone conditions on a recently active fault: insights from mineralogical and geochemical analyses of the Hirabayashi NIED drill core on the Nojima fault, southwest Japan, which ruptured in the 1995 Kobe earthquake

    Science.gov (United States)

    Matsuda, Tatsuo; Omura, Kentaro; Ikeda, Ryuji; Arai, Takashi; Kobayashi, Kenta; Shimada, Koji; Tanaka, Hidemi; Tomita, Tomoaki; Hirano, Satoshi

    2004-01-01

    -rock interaction. In the fracture zone at about 1800 m depth, H 2O+ and CO 2 were very enriched throughout the interval, as in the fracture zone at about 1140 m depth. However, smectite was absent and chlorite was present, indicating the occurrence of chloritization, which requires a temperature of more than 200 °C. Only smectite can form under the present conditions in these fracture zones. The chloritization probably occurred in the past when the fracture zone was deeper than it is now. These observations suggest that among the three fracture zones, that at about 1140 m depth was the most activated at the time of the 1995 Hyogo-ken Nanbu (Kobe) earthquake.

  15. Transient Hydrothermal Alteration in Fault Zones Cutting the Lower Oceanic Crust, Hess Deep Rift

    Science.gov (United States)

    McCaig, Andrew; Titarenko, Sofya; Cliff, Robert; Ivan, Savov; Adrian, Boyce

    2015-04-01

    IODP Expedition 345 drilled the first holes in the lower plutonic crust at a fast-spreading ridge, recovering primitive layered gabbros [1]. Alteration occurred as: 1) a largely static pseudomorphic alteration, predominantly in the greenschist and sub-greenschist facies with mainly talc and serpentine replacing olivine, and prehnite replacing plagioclase. Talc sometimes overprints serpentine mesh texture. 2) an overprinting metasomatic alteration, spatially related to cataclastic fault zones and macroscopic veins, dominated by prehnite and chlorite. Secondary clinopyroxene and epidote locally overprint the prehnite-chlorite assemblage, but the last events are veins of prehnite and zeolite. Metamorphosed dykes show chilled margins within the cataclasites, and are themselves affected by cataclastic deformation. Faults, dykes and overprinting alteration are all inferred to be related to the westward propagation of Cocos-Nazca spreading forming Hess Deep. 87Sr/86Sr ratios of small whole rock samples of cataclasites and dyke rocks are in the range 0.7037 - 0.7048, indicating alteration by seawater at moderate integrated fluxes. The highest values were in cataclasites overprinted by prehnite. Sampling of individual minerals has been undertaken using a microscope mounted drill, and shows that alteration is mainly affecting secondary minerals, with late prehnite veins ranging up to Sr isotope ratios of 0.7054. δ18O values range from +1 to + 6 per mil. Combined with metamorphic data this indicates alteration at temperatures between 200 and 400 °C. Secondary clinopyroxene and talc replacing serpentine are interpreted to indicate transient prograde hydrothermal events. Preliminary modelling using Comsol Multiphysics suggests that the temperatures of the overprinting alteration, as well as transient prograde events, could be achieved in a permeable fault slot cutting through crust 0.5 to 1 m.y. old. The prehnite-chlorite assemblage is predicted to be important in off

  16. Hydration of the lithospheric mantle by the descending plate in a continent-continent collisional setting and its geodynamic consequences

    Science.gov (United States)

    Massonne, Hans-Joachim

    2016-05-01

    At the beginning of continent-continent collision the descending plate dehydrates. The influence of this dehydration on the adjacent lithospheric mantle was studied. For this reason, pressure (P), temperature (T) and T-H2O pseudosections were calculated for an average mantle composition using the computer software PERPLE_X. These pseudosections were contoured by isopleths, for instance, for volumes of amphibole, chlorite, and serpentine. In addition, P-T pseudosections were considered for four psammopelitic rocks, common in the upper portion of the continental crust, in order to quantify the release of H2O in these rocks during prograde metamorphism. At pressures around 1 GPa, a maximum of slightly more than 10 vol.% chlorite, almost 20 vol.% amphibole, and some talc but no serpentine forms when only 1.8 wt.% H2O is added to the dry ultrabasite at temperatures of 600 °C. For example, hydrous phases amount to about 35 vol.% serpentine and 10 vol.% each of chlorite and amphibole at 1 GPa, 550 °C, and 5 wt.% H2O. The modelled psammopelitic rocks can release 0.8-2.5 wt.% H2O between 450 and 650 °C at 0.8-1.4 GPa. On the basis of the above calculations, different collisional scenarios are discussed highlighting the role of hydrated lithospheric mantle. In this context a minimum hydration potential of the front region of the descending continental plate is considered, which amounts to 4.6 × 1016 kg releasable H2O for a 1000 km wide collisional zone, due to a thick sedimentary pile at the continental margin. Further suggestions are that (1) the lower crustal plate in a continent-continent collisional setting penetrates the lithospheric mantle, which is hydrated during the advancement of this plate, (2) the maximum depths of the subduction of upper continental crust is below 70 km and (3) hydrated mantle above the descending crustal plate is thrust onto this continental crust.

  17. Smart Clays: SAFOD Samples Confirm the Key Role of Newly-formed Clays in Shallow Fault Zones

    Science.gov (United States)

    Schleicher, A.; van der Pluijm, B.; Warr, L. N.

    2013-12-01

    Analysis of fault rocks from drill-cores of the San Andreas Fault Observatory at Depth (SAFOD) project in Parkfield (CA) confirm our original hypothesis that active clay growth can occur locally at shallow conditions and that such clay localization affect fault mechanics and fault creep in particular. SAFOD fault rocks contain a variety of newly formed clay minerals including smectite, illite-smectite and chlorite-smectite, as well as illite and chlorite. Brecciated host rock fragments are abundantly coated by polished and/or striated thin-films of hydrated clay minerals, creating an interconnected and pervasive network of displacement surfaces. Ar encapsulation dating of mixed-layer nanocoatings demonstrates recent crystallization and reveal an 'older' fault strand (~8 Ma) at 3066 m measured depth and a 'younger' fault strand (~4 Ma) at 3296 m measured depth. Today, the younger strand is the site of active creep behavior, demonstrating continued (re)activation of clay-weakened zones. Recent experimental work on aseismically creeping segments of SAFOD samples showed frictional strengths that are significantly weaker than neighboring wall rocks, offering independent validation of our model. Using a range of analytical methods that include X-ray diffraction, X-ray goniometry, elemental analysis and electron microscopy, we determined the location and nature of smectitic clay minerals in borehole samples, to assess the extent of smectitic phases in space and depth, any fault zone fabric development, and the swelling behavior of smectitic phases within the fault zone. Beyond the occurrence of illite-smectite in these relatively shallow fault rocks, the localized concentration of chlorite-smectite can extend the role of smectitic clays to depths down to ~10 km. We conclude that ultrathin hydrous clay films, or nanocoatings, on displacement surfaces play a key role in influencing weak fault and creep behavior along the San Andreas Fault at Parkfield, and likely in shallow

  18. Clay Mineralogy Investigation In The Soils Of Arid Almanaqil Ridge Gezira State Sudan Using Xrd Diffractograms

    Directory of Open Access Journals (Sweden)

    Elhag A.M.H

    2015-07-01

    Full Text Available Abstract Clay mineralogy was studied in the soils of Arid Almanaqil Ridge. The soils are classified according to the American System Keys to Soil Taxonomy 2010 in the fallowing families Fine loamy mixed isohyperthermic TypicHaplustepts unit1 sample A1 and A2 Fine mont superactive Isohyperthermic VerticHaplocambids unit2 sample A3 and Fine mont superactive isohyperthermic TypicHaploustert unit3 sample A4. Representative soil samples were collected from these units. These samples were samples A1 and A2 for unit1 sample A3 for unit 2 and sample A4 for uint3 respectively. Those samples were compared with samples from outside the study area from north of the study area sample A5 and A6 and from the alluvium of the Blue Nile sample A7 according to their lithology topographic position soil types and soil mapping units. Clay mineralogy of the samples was studied using X-ray diffractograms XRD techniques. The XRD diffractograms indicated the presence of smectite chlorite illite and kaolinite as the major clay minerals in the soil of the study area and outside of the study area. The major clay minerals in these soils Chlorite illite and kaolinite could have originated from parent material. Smectite showed an increasing trend in samples A7 outside of study area and sample A4 unit 3. The CEC of clay minerals in unit 1 and 2 were less than 50 Cmolkg which indicated that minerals with low CEC were dominant this result conformed with the XRD results that showed dominance of Chlorite illite and Kaolinite. Higher CEC values more than 50 Cmolkg of the clay were encountered in soils samples from unit3 A4 and those from outside study area Sample A7 XRD results showed that the samples were dominated by smectite. Moreover the CEC values of clay minerals were consistent with results of XRD. The X-ray mineralogy indicated that the Vertisols and Aridisols of the study area had the same origin as that of the Gezira soils.

  19. Modelling Iron-Bentonite Interactions

    Science.gov (United States)

    Watson, C.; Savage, D.; Benbow, S.; Wilson, J.

    2009-04-01

    The presence of both iron canisters and bentonitic clay in some engineered barrier system (EBS) designs for the geological disposal of high-level radioactive wastes creates the potential for chemical interactions which may impact upon the long-term performance of the clay as a barrier to radionuclide migration. Flooding of potential radionuclide sorption sites on the clay by ferrous ions and conversion of clay to non-swelling sheet silicates (e.g. berthierine) are two possible outcomes deleterious to long-term performance. Laboratory experimental studies of the corrosion of iron in clay show that corrosion product layers are generally thin ( 250 °C) are dominated by chlorite, whereas lower temperatures produce berthierine, odinite, cronstedtite, or Fe-rich smectite. Unfortunately, the inevitable short-term nature of laboratory experimental studies introduces issues of metastability and kinetics. The sequential formation in time of minerals in natural systems often produces the formation of phases not predicted by equilibrium thermodynamics. Evidence from analogous natural systems suggests that the sequence of alteration of clay by Fe-rich fluids will proceed via an Ostwald step sequence. The computer code, QPAC, has been modified to incorporate processes of nucleation, growth, precursor cannibalisation, and Ostwald ripening to address the issues of the slow growth of bentonite alteration products. This, together with inclusion of processes of iron corrosion and diffusion, has enabled investigation of a representative model of the alteration of bentonite in a typical EBS environment. Simulations with fixed mineral surface areas show that berthierine dominates the solid product assemblage, with siderite replacing it at simulation times greater than 10 000 years. Simulations with time-dependent mineral surface areas show a sequence of solid alteration products, described by: magnetite -> cronstedtite -> berthierine -> chlorite. Using plausible estimates of mineral

  20. The differences in clay minerals between the northern and southern Chelungpu fault, Taiwan

    Science.gov (United States)

    Hashimoto, Y.

    2004-12-01

    In 1999, we obtained a detailed data about motion of fault from the Taiwan Chi-Chi earthquake. The motion represents the high frequency of acceleration and small slip distance in southern part, and low frequency of acceleration and large slip distance in the northern part. Those differences in the fault motion between the southern and northern parts are coincidence with occurrences of deformation textures of rocks which were sampled by drilling of shallow parts (a few hundreds meter) of the fault in 2000. In the southern core, a relatively strong deformation structure is preserved in total, and gouge containing fragments of pseudotachylytes and ultracataclasites is observed at the Chi-Chi- earthquake fault, which indicates that the main deformation mechanisms for the southern part of the fault was brittle. On the other hands, in the northern part, sand layer with much amount of water is found at the Chi-Chi- earthquake fault zone, and no breakage of sand grain is observed, which suggests that the deformation mechanism for northern part is independent particulate flow. The purpose of this study is to reveal the differences in clay minerals between the southern and northern part of the Chi-Chi earthquake fault. And then, we discuss about rock-fluid interaction and frictional heating characterized in seismogenic fault system. We analyzed clay minerals by X-ray diffract meter (XRD) after classification of rock types such as sandstone, alteration of sandstone and mudstone, breccia, and gouge. 1.33 micron meter of grains are obtained. Oriented sample was made. XRD analysis was conducted under following condition; 35kV, 15mA, 1 degree per minute of scan rate, and 0.02 degree of scan step. Range of 2 theta was from 2 degree to 35 degree. At first, air-dried condition of samples was measured. After that, ethylene glycol solvated samples were measured. The result represents that all samples contain smectite, illite, chlorite. No difference in components of clay mineral is

  1. Correlation of Cadmium Distribution Coefficients to Soil Characteristics

    DEFF Research Database (Denmark)

    Holm, Peter Engelund; Rootzen, Helle; Borggaard, Ole K.;

    2003-01-01

    values for Cd ranged from 5 to 3000 L kg(-1). The soils were described pedologically and characterized in detail (22 parameters) including determination of contents of the various minerals in the clay fraction. Correlating parameters were grouped and step-wise regression analysis revealed that the...... organic carbon content was a significant variable at both pH values. Cation exchange capacity (CEC) and gibbsite were important at the low pH (5.3) while iron oxides also were important at the high pH (6.7). None of the other clay minerals present in the soils (illite, smectite, kaolinite, hydroxy...... interlayered clay minerals [HIM], chlorite, quartz, microcline, plagioclase) were significant in explaining the Cd distribution coefficient....

  2. Analysis of mixed-layer clay mineral structures

    Science.gov (United States)

    Bradley, W.F.

    1953-01-01

    Among the enormously abundant natural occurrences of clay minerals, many examples are encountered in which no single specific crystallization scheme extends through a single ultimate grain. The characterization of such assemblages becomes an analysis of the distribution of matter within such grains, rather than the simple identification of mineral species. It having become established that the particular coordination complex typified by mica is a common component of many natural subcrystalline assemblages, the opportunity is afforded to analyze scattering from random associations of these complexes with other structural units. Successful analyses have been made of mixed hydration states of montmorillonite, of montmorillonite with mica, of vermiculite with mica, and of montmorillonite with chlorite, all of which are variants of the mica complex, and of halloysite with hydrated halloysite.

  3. Features of Clay Minerals in the YSDP102 Core on the Continental Shelf of the Southeast Yellow Sea

    Institute of Scientific and Technical Information of China (English)

    JIANG Xuejun; QU Gaosheng; LI Shaoquan

    2004-01-01

    Ninety-eight clay mineral samples from the YSDP102 core were analyzed by x-ray diffractometer to study the four clay minerals: illite, chlorite, kaolinite and smectite. Twenty-eight samples had been analyzed on the laser particle-size analyzer to reveal the particle features of the sediments. Distribution of the clay minerals and the particle characteristics in the YSDP102 core show that the core experienced three different depositional periods and formed three different sedimentary intervals due to different sediment sources and different depositional environments. Features of the clay minerals and the heavy minerals in the YSDP102 core indicate that coarse-grained sediments and fine-grained sediments result from different sources. The Yellow Sea Warm Current has greatly influenced the sedimentary framework of this region since the current's formation.

  4. Reversed flow injection spectrophotometric determination of low residuals of chlorine dioxide in water using chlorophenol red

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A novel,simple,rapid,sensitive and highly selective flow injection procedure for the spectrophotometrie determination of chlorine dioxide in the presence of other chlorine species,viz,free chlorine,chlorite,chlorate and hypoehlorite,is developed.The method is based on the discoloration reaction between chlorine dioxide and chlorophenol red and can overcome the shortcomings existed in direct speetrophotometrie determination for chlorine dioxide owing to the serious interference of free and combined chlorine.The procedure gave a linear calibration graph over the range 0-0.71 mg/L of chlorine dioxide.With a detection limit of 0.024 mg/L and a sample throughput of 60 samples/h.

  5. Geochemical modelling for the unconformity-related uranium mineralization. A case study from Baskati area, Madhya Pradesh, India

    International Nuclear Information System (INIS)

    Signatures of concealed unconformity-related uranium mineralization at the contact of Chhotanagpur Granite Gneissic Complex (CGGC)/Mahakoshal and Lower Vindhyan Semri sequence have come to light at Baskati, in Vindhyan-Mahakoshal Basin, following a multiprolonged exploratory efforts. Systematic lithogeochemical sampling brought out uranium halos with concentration sufficiently above the normal background along reactivated faults/fractures occurring parallel and oblique to the unconformity contact. Alteration features like haematitization, chloritization and illitization have also been observed in surroundings of these reactivated faults/fractures. Geochemical modelling indicates a hypogene source for mineralizing fluids. Based on geochemical modelling supported by geology, structure and lithogeochemistry, unconformity-related U mineralization model has been envisaged and the target area has been narrowed down for sub-surface exploration. (author)

  6. A field trip guidebook to the type localities of Marland Billings' 1935 Paleozoic bedrock stratigraphy near Littleton, New Hampshire

    Science.gov (United States)

    Rankin, Douglas W.; Rankin, Mary B.

    2014-01-01

    Marland Billings' classic paper published in 1937 in the Geological Society of America Bulletin established a succession of six stratigraphic units in rocks of low metamorphic grade near Littleton, New Hampshire. The two youngest units are fossiliferous in the area, with ages established at the time as “middle” Silurian and Early Devonian. Billings and students mapped the same stratigraphic section in adjacent areas of progressively higher regional metamorphic grade. This work laid the foundation upon which a major part of subsequent work in New England has been directly or indirectly built. This guidebook was written for a field trip held in March 2013 to visit roadcuts that are as close as possible in March to the type localities or areas of Billings’ six-fold stratigraphic succession. Ten stops are in rocks of chlorite grade of Acadian(?) metamorphism; the final stop visits amphibolite of the Ammonoosuc Volcanics. Fieldwork by the authors over the past 20 years confirms Billings’ broad conclusions.

  7. Petrology and geochemistry of greywackes of Middle Aravalli supergroup, NW India: evidence for active margin processes

    International Nuclear Information System (INIS)

    Aravalli Mountain Belt (AMB) of Northwestern, India represents one of the major Proterozoic accretionary orogens of the world, preserving two Wilson cycles; viz. Paleoproterozoic Aravalli Supergroup and Mesoproterozoic Delhi Supergroup. Although two gross Wilson cycles involving opening and closing of Paleoproterozoic Aravalli ocean and Mesoproterozoic Delhi ocean are recognized, the finer details of the evolution of the orogen are still poorly understood. We have carried out geochemical and petrological study of the well-preserved greywacke horizon of the 'Middle Aravalli Supergroup' in order to place constraints on early evolution of the Aravalli basin. These greywackes are enriched in Fe, Mg and K; and depleted in Na in comparison to normal greywackes and can be classified as ferroan potassic sandstone. Petrographic examination indicate that the greywacke samples contain about 30 to 50% matrix that is mainly composed of biotite/chlorite and interspersed with fine Fe-Ti rich opaque mineral phases

  8. Experimental study of gold activation-transportation in the process of potash metasomatism-alteration——North China platform gold deposit taken as an example

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Chemical reactions of plagioclase, biotite and their singleminerals, as well as a mineral mixture of (plagioclase +biotite+quartz), with KCl and (KCl+KHCO3) solutions were carried out at 150400℃ and 5080 MPa. Experiments show that alkaline fluid promotes plagioclase’s changing into potash feldspar, while acid fluid helps plagioclase, potash feldspar and biotite alteration form chlorite and sericite. After chemical reaction the acidity-alkalinity of solutions often changes reversely. It was observed that gold dissolved from the tube wall and recrystallized on the surfaces of biotite and pyrite. Therefore the transportation and enrichment of gold are related to the elementary effect of the fluid-mineral interfaces. Fe3+-Fe2+, as an oxidition-reduction agent, and volatile components Cl? and CO2 play important roles in the reaction process.

  9. Experimental study of gold activation-transportation in the process of potash metasomatism-alteration ——North China platform gold deposit taken as an example

    Institute of Scientific and Technical Information of China (English)

    WANG; Yurong; HU; Shouxi

    2001-01-01

    Chemical reactions of plagioclase, biotite and their single minerals, as well as a mineral mixture of (plagioclase +biotite+quartz), with KCl and (KCl+KHCO3) solutions were carried out at 150400℃ and 5080 MPa. Experiments show that alkaline fluid promotes plagioclase’s changing into potash feldspar, while acid fluid helps plagioclase, potash feldspar and biotite alteration form chlorite and sericite. After chemical reaction the acidity-alkalinity of solutions often changes reversely. It was observed that gold dissolved from the tube wall and recrystallized on the surfaces of biotite and pyrite. Therefore the transportation and enrichment of gold are related to the elementary effect of the fluid-mineral interfaces. Fe3+-Fe2+, as an oxidition-reduction agent, and volatile components Cl? and CO2 play important roles in the reaction process.

  10. The blueschits from the Kopina Mt., West Sudetes, Poland - what do they tell us about accretion of the Variscides?

    Science.gov (United States)

    Majka, Jarosław; Mazur, Stanisław; Kośmińska, Karolina; Dudek, Krzysztof

    2015-04-01

    Blueschists are tracers of sutures, thus marking fossil subduction zones at convergent plate boundaries and providing important constraints on plate tectonic reconstructions. Their occurrences are scarce in the Variscan belt owing to a strong collisional overprint but just because of that each locality deserves particular attention. The Variscan blueschists must have formed during the early stage of the Variscan Orogeny and may represent a vestige of missing marginal basins fringing the Rheic Ocean at the onset of subduction. The studied rocks from the Kopina Mt. consist mainly of garnet, glaucophane, clinozoisite-epidote, chlorite-I, titanite, hematite and quartz. The original high-pressure assemblage is overprinted by later, lower pressure paragenesis, which comprises mostly Ca-amphiboles, chlorite-II, albite and K-feldspar. The latter occurs in polymineral inclusions in other phases together with albite and chlorite that are interpreted as phengite breakdown products. Garnet shows chemical compositional variation from Alm54Prp3Grs30Sps13 in the cores to Alm66Prp4Grs29Sps1 in the rims. The almandine zoning is bowl-shaped, whereas spessartine profiles show bell-shaped trends. The grossular and pyrope contents are generally constant throughout the grain. Rather gradual changes in the chemical zoning suggest a progressive, one-step garnet growth pattern. Glaucophane, although commonly well preserved, in some cases disintegrates to the albite-chlorite assemblage. The pressure-temperature (P-T) conditions were estimated using the phase equilibrium modelling in the NCKFMMnASHTO system using the PerpleX software. The compositional isopleths cross cut in the stability field of Grt+Gln+Ep+Chl+Pheng+Ttn+Hem+Q. P-T estimates indicate that the peak conditions occur at c. 14-17 kbar and 470-500°C, which corresponds to quite a low geothermal gradient in the range of 8-10°C/km. The P-T conditions estimated lie on a low temperature geotherm that is typical for a relatively

  11. The effect of non-structural components and lignin on hemicellulose extraction.

    Science.gov (United States)

    Liu, Kai-Xuan; Li, Hong-Qiang; Zhang, Jie; Zhang, Zhi-Guo; Xu, Jian

    2016-08-01

    As the important structural component of corn stover, hemicellulose could be converted into a variety of high value-added products. However, high quality hemicellulose extraction is not an easy issue. The present study aims to investigate the effects of non-structural components (NSCs) and lignin removal on alkaline extraction of hemicellulose. Although NSCs were found to have a minimal effect on hemicellulose dissolution, they affected the color values of the hemicellulose extracts. The lignin limited the hemicellulose dissolution and increased the color value by binding to hemicellulose molecules and forming lignin-carbohydrate complexes. Sodium chlorite method can remove about 90% lignin from corn stover, especially the lignin connected to hemicellulose through p-coumaric and ferulic acids. Which increased the hemicellulose dissolution ratio to 93% and reduced the color value 14-28%, but the cost is about 20% carbohydrates lost. PMID:27213576

  12. Petrology, composition, and age of intrusive rocks associated with the Quartz Hill molybdenite deposit, southeastern Alaska.

    Science.gov (United States)

    Hudson, T.; Smith, James G.; Elliott, R.L.

    1979-01-01

    A large porphyry molybdenum deposit (Quartz Hill deposit) was recently discovered in the heart of the Coast Range batholithic complex about 70 km E of Ketchikan, SE Alaska. Intrusive rocks associated with the mineral deposit form two composite epizonal to hypabyssal stocks and many dikes in country rocks. All observed metallization and alteration is within the Quartz Hill stock. Molybdenite forms fracture coatings and occurs in veins with quartz. Alteration is widespread and includes development of secondary quartz, pyrite, K-feldspar, biotite, white mica, chlorite, and zeolite. Field relations indicate that the stocks were emplaced after regional uplift and erosion of the Coast Range batholithic complex, and K-Ar data show that intrusion and alteration took place in late Oligocene time, about 27 to 30 Ma ago. Data from the Ketchikan quadrangle indicate that porphyry molybdenum metallization in the Coast Range batholithic complex is associated with regionally extensive but spotty, middle Tertiary or younger, felsic magmatism. -from Authors

  13. Rayleigh-type parametric chemical oscillation

    International Nuclear Information System (INIS)

    We consider a nonlinear chemical dynamical system of two phase space variables in a stable steady state. When the system is driven by a time-dependent sinusoidal forcing of a suitable scaling parameter at a frequency twice the output frequency and the strength of perturbation exceeds a threshold, the system undergoes sustained Rayleigh-type periodic oscillation, wellknown for parametric oscillation in pipe organs and distinct from the usual forced quasiperiodic oscillation of a damped nonlinear system where the system is oscillatory even in absence of any external forcing. Our theoretical analysis of the parametric chemical oscillation is corroborated by full numerical simulation of two well known models of chemical dynamics, chlorite-iodine-malonic acid and iodine-clock reactions

  14. Soap-stone in architecture of North European cities. A nomination as a candidate for a Global Heritage Stones Resource

    Science.gov (United States)

    Bulakh, Andrey

    2016-04-01

    Soap stone represents soft Proterozoic rock type from the deposit Nunnalahti situated on the western shore of the big Lake Pielinen in Eastern Finland. It consists of talc (40 - 50 %), magnesite MgCO3 (40 - 50 %), chlorite (5 - 8 %), dolomite, calcite, etc. The colour of the stone is very spectacular and varies from yellow and brownish-yellow to grey, greenish grey. The soft stone is a highly workable material for a sculptor's chisel. It was one of the most popular ornamental rocks used architecture of the Modern style in St Petersburg, Helsinki, Turku, Tampere and other North European cities lately in the XIX-th centuries. Examples are given and discussed. References: Bulakh, A.G., Abakumova, N.B., and Romanovsky, J.V. St Petersburg: a History in Stone. 2010. Print House of St Petersburg State University. 173 p. (In English).

  15. METARHYOLITES OF VRANICA MOUNTAIN IN PALEOZOIC OF CENTRAL BOSNIA

    Directory of Open Access Journals (Sweden)

    Vladimir Majer

    2001-12-01

    Full Text Available Metharyolites of Vranica mountain are roks of emphasized porphyritic texture containing phenocrysts of quartz, K.feldspar and very rarely albite. The groundmass is microcrystallinic, characterized by finegrained phengite, biotite and area consisting of granophyric intergrowths of quartz and feldspar. Accessory minerals are ilmenite, rutila, apatite, zircon and chlorite. Metarhyolites are peraulminous rocks (PI=1.-4.1 having dominantly potassium character (K2O/Na2O=1,3-13,8. Incompatible elements are enriched relative to the normalizing chondrite composition, pointing to the crustal origin of metarhyolite magma. Although phengites typically occur in high pressure rocks, it seems that phengites of metarhyolites of Vranica mountain belong to the seldom group of phengites occurring in the low to medium pressure rocks (the paper is published in Croatian.

  16. Neutron scattering - a method for the investigation of structure and dynamics of minerals

    International Nuclear Information System (INIS)

    Neutron scattering is complementary to X-ray techniques for structural studies. Inelastic scattering offers additional possibilities to investigate lattice dynamics and diffusion of molecules. Applications on the cation distribution in gamets and the Si/Al relation in feldspars are reported. Examples on hydrogen bonds are citd for bayerite(β-Al(OH)3), the chlorite mineral penninite and for the zeolite scolecite. The diffusion of water molecules in natural zeolites is studied by inelastic incoherent neutron scattering. An example is given for natrolite. Preliminary charge and magnetization densities for fayalite (Fe2SiO4) are reported. The experimental phonon dispersion curves for anhydrite (CaSO4) are compared with results from theoretical model calculations. (orig.)

  17. Evaluation methods for ceramic suitability of raw clays

    Directory of Open Access Journals (Sweden)

    Hajjaji M.

    2013-09-01

    Full Text Available Ceramic suitability of kaolinitic-illitic and chloritic-illitic raw clays was assessed by methods involving microstructure investigation and ceramic properties measurements, some reported diagrams and response surface methodology (RSM. Results of the former method showed that all clays are suitable for red stoneware tiles. The stoneware manufacturing is facilitated by the marked reduction of porosity due to the flow of melt, mainly originated from the breakdowns of illite. This result was partially supported by the use of a diagram involving the chemical composition of clays as well as by the RSM results. According to the later method, bricks may be manufactured under restricted firing conditions and stoneware tiles could be prepared at temperatures as low as 950°C.

  18. Mineral characterization of soil type ranker formed on serpentines occurring in southern Belgrade environs Bubanj Potok

    Directory of Open Access Journals (Sweden)

    Cekić Božidar Đ.

    2012-01-01

    Full Text Available The paper addresses the issue of health risk associated with the presence of chrysotile in the soil type ranker formed on massive serpentines occurring in the area of Bubanj Potok, a settlement located in the southern Belgrade environs, Serbia. Characterization of the ranker soil was conducted by scanning electron microscopy, X-ray diffraction, micro-Raman spectroscopy and transmission 57Fe Mössbauer spectroscopy. Scanning electron microscopy figures showed regular shaped smectite (montmorillonite particles, aggregates of chlorite, and elongated sheets of serpentines minerals antigorite. X-ray diffraction analysis confirmed the presence of detrital mineral quartz polymorph as well as minor amounts of other mineral species. Micro-Raman spectroscopy identified the presence of dominant minerals, such as montmorillonite, kaolinite, muscovite, gypsum, calcite, albite, amphiboles (hornblende/kaersutite and orthoclase. Important polymorph silica modifications of quartz, olivine (forsterite, pyroxene (enstatite/ferrosilite, diopside/hedenbergite, and serpentine (antigorite/lizardite/chrysotile were identified.

  19. Distribution of trace elements between clays and zeolites and aqueous solutions similar to sea water

    International Nuclear Information System (INIS)

    The mechanisms of solid-solution partitioning during mineral crystallization in sea water have been investigated for Rb, Cs, Co, Sr, U, Th and lanthanides as trace elements, and Fe, Mg-chlorite/smectites and Na-zeolites as solid phases. These minerals have been synthesized by alteration at 40oC in saline solutions of silicate glasses of appropriate compositions. The variation of the distribution coefficients (D) with the concentration of the elements as well as competition mechanisms between elements of analogous crystallochemical properties have been studied. The ''trapping'' of trace elements is shown to be governed by two mechanisms, according to D values or to water-rock ratios. At low values of D the incorporation of elements is controlled only by D, whereas at high values it is controlled by the number of available crystallochemical sites. (Author)

  20. A special kind of sandstone type uranium deposit in Northeastern Ordos Basin, China

    International Nuclear Information System (INIS)

    The large Dongsheng sandstone type uranium deposit was discovered recently in northeastern Ordos Basin, China. It is a unique kind of deposit, different from other known sandstone type deposits because of its distinctive signatures. It is generally controlled by a transitional zone between greenish and greyish sandstones, both indicating presently reduced geochemical environments. The greenish colour of the paleo-oxidized sandstones is mainly due to chloritization and epidotization related to oil and gas secondary reduction processes. The deposit, which is of more complex origin, has undergone not only paleo-oxidization mineralization process, but also oil-gas fluid and hydrothermal reworking processes and therefore is genetically different from other known sandstone uranium deposits,. The metallogenic model for this uranium deposit is put forward, and exploration outcomes summarized in this paper. (author)

  1. Electric plasma discharge combustion synthesis of chlorine dioxide

    International Nuclear Information System (INIS)

    A process for the production of chlorine dioxide comprises feeding an inert gas to a reaction zone and applying an electrical discharge to the inert gas to produce a high temperature plasma. Chlorine gas and oxygen gas are supplied simultaneously to the reaction zone and reacted in the plasma to produce a gaseous mixture comprised of chlorine dioxide, chlorine, oxygen and inert gas, the molar ratio of oxygen to chlorine in the reaction zone being at least about 2.5;1. The gaseous mixture is recovered from the reaction zone. Chlorine dioxide, which may be recovered as a gas or reacted to produce an alkali metal chlorite, is employed as a bleaching agent and a water treatment agent

  2. Late-Neoproterozoic hydrothermal fluid activity in the Tandilia belt, Argentina

    Directory of Open Access Journals (Sweden)

    Juan C Martínez

    2013-09-01

    Full Text Available In the Barker - Villa Cacique area, Tandilia belt, alteration mineral assemblages were studied by petrography, XRD and EMPA at three different stratigraphic levels: (1 a phyllic alteration at the unconformity palaeoproterozoic basement-neoproterozoic sedimentary succession (TLPU; (2 an advanced argillic alteration in the Las Águilas Formation (middle level; and (3 a phyllic alteration on pyroclastic rocks of the Olavarría Formation (upper level. Special emphasize was placed on the chemical characterization of K-white micas and chlorites. Secondary K-white micas of altered migmatites, from the Las Aguilas and Olavarría Formations have a low paragonite content (Na* 9.5 km for the entire sedimentary pile. Hot fluids would rise from deep-seated realms, metamorphic and/or hidden igneous sources. A correlation with a Brasiliano thermo-tectonic event is hypothesized.

  3. Mineralogical determination, distribution ration, speciation and radionuclides mobility in soil samples from objects 41 and 44/10 NPP Jaslovske Bohunice

    International Nuclear Information System (INIS)

    Mineralogical characterization of a soil from the Nuclear Power Plant Jaslovske Bohunice object 41 and 44/10 was performed by x-ray diffraction method and surface measuring. It was find that the main component was smectite but other minerals like quartz, illite, chlorite and K-feldspar, were observed. Sorption and speciation of 137Cs, 85Sr, 241Am and 60Co in the mix soil was done with continuous leaching and Tessier scheme. It was found that distribution ration for Co and Cs is the highest. Strontium was in ionic form, Cs was leached with nitric acid, americium was fixed on carbonate fraction and cobalt was predominantly leached with reduction solutions as can be observed from the Tessier sequence method. Sorption of iodine on the soil used in the experiment was negligible (authors)

  4. Ion exchange properties of carboxylate bagasse

    International Nuclear Information System (INIS)

    Bagasse fibers were chemically modified using three different reactions: esterification using monochloro acetic acid, esterification using succinic anhydride, and oxidation using sodium periodate and sodium chlorite to prepare cation exchanger bearing carboxylic groups. Bagasse was crosslinked using epichlorohydrin before chemical modification to avoid loss of its constituents during the chemical modification. The structure of the prepared derivatives was proved using Fourier transform infrared (FTIR) and chemical methods. The ability of the prepared bagasse cation exchangers to adsorb heavy metal ions (Cu+2, Ni+2, Cr+3, Fe+3), on a separate basis or in a mixture of them, at different metal ion concentration was tested. Thermal stability of the different bagasse derivative was studied using thermogravimetric analysis (TGA)

  5. Geology and age of mafic magmatism on Jeannette Island (De Long archipelago)—Implications for paleotectonic reconstructions for the Arctic

    Science.gov (United States)

    Matushkin, N. Yu.; Metelkin, D. V.; Vernikovsky, V. A.; Travin, A. V.; Zhdanova, A. I.

    2016-03-01

    The paper presents the first data on the geology of a series of mafic dikes emplaced in the volcanogenic sedimentary sequence composing the structure of Jeannette Island. We show that the island hosts two generations of dikes consisting of fine-grained dolerites. Both magmatic stages were followed by fold deformations. The youngest and weakly deformed dikes are none the less chloritized and serpentinized. However, we were able to obtain the first ever precise geochronological 40Ar/39Ar data for them. According to this analysis, the emplacement age of the intrusive complex of Jeannette Island is close to the Ediacaran (553.6 ± 10.3 Ma). The ages of several superimposed tectonothermal events were determined: Middle Ordovician (463.3 ± 11.7 Ma), Late Silurian (425.3 ± 8.7 Ma), Late Devonian (360.7 ± 8.3 Ma) and Early Carboniferous (341.3 ± 6.8 Ma).

  6. Clay mineral distributions in the southern Yellow Sea and their significance

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    To better understand the characteristics of the clay minerals in the southern Yellow Sea, the X-ray quantitative determinations have been carried out for the surface samples obtained from the Yellow Sea. With newly compiled clay mineral synoptic maps, the depositional processes were described for four main clay minerals (illite, chlorite, kaolinite and smectite). The analysis shows that most clay minerals are of terrigenous source with the Huanghe River acting as the major sediment supplier. Besides, the source of muddy sediments in the Yellow Sea was also discussed. As for the central Yellow Sea mud (CYSM), the sediments in its northern part mainly come from the Huanghe River, and those in the rest are of multi-origin. Very similarly, a large amount of sediments in the northern part of the southeastern Yellow Sea Mud (SEYSM) derive from the Keum River and Yeongsan River, while those in the southern part are of multi-origin.

  7. Apports des phyllosilicates dans la différenciation entre altération hypogène et altération supergène dans le basalte triasique du Moyen Atlas (Maroc)Contribution of phyllosilicates to distinguish between hypogene alteration and weathering in Triassic basalt from Middle Atlas (Morocco)

    Science.gov (United States)

    Dekayir, Abdelilah; Danot, Michel; Allali, Nabil

    2002-09-01

    Triassic basalt of the Middle Atlas has been subject to metamorphic transformation then weathering. Occurrence in both metabasalt and saprolite of ubiquitous clay minerals, such as smectite and mixed layers chlorite-smectite, makes it difficult to distinguish between the two alteration facies and explains the interest of complementary sources of information. In the Bhallil weathering profile, petrographical and mineralogical analyses of primary igneous minerals and their alteration products coupled with Fe oxidation state determination in clay fractions allow to identify three alteration facies: ( i) metamorphic basalt, where iron occurs mainly as the ferrous form; ( ii) the lower part of saprolite, where iron is partially oxidized to its ferric form; ( iii) the upper part of saprolite, where iron is completely oxidized. To cite this article: A. Dekayir et al., C. R. Geoscience 334 (2002) 877-884.

  8. Caractérisation des paragenèses et des paléocirculations fluides dans l'indice d'or de Bleïda (Anti-Atlas, Maroc)Characterization of the paragenesis and the fluid palaeo-circulations in the gold showings of Bleida (Anti-Atlas, Morocco)

    Science.gov (United States)

    Barakat, Ahmed; Marignac, Christian; Boiron, Marie-Christine; Bouabdelli, Mohamed

    2002-01-01

    The gold showings at Bleida are hosted in Late Pan-African N50-80 °E quartz-hematite-chlorite 1 tension lenses that are related to the activity of major sinistral sub-east-west thrusts. Ores result from three superimposed stages of fluid migration. Gold occurs in microcracks offsetting the earlier minerals. Fluids evolved from COHN compositions with a saline component to boiling aqueous fluids. Pressure and temperature decreased from 50 MPa and 300 °C to less than 4 MPa and 150 °C. Thus, the gold showings at Bleida were formed in a typical geothermal (epithermal) setting, likely controlled by the Late Pan-African magmatism. To cite this article: A. Barakat et al., C. R. Geoscience 334 (2002) 35-41

  9. Le volcanisme cambrien du Maroc central : implications géodynamiquesThe Central Morocco Cambrian volcanism: geodynamic implications

    Science.gov (United States)

    Ouali, Houssa; Briand, Bernard; Bouchardon, Jean-Luc; Capiez, Paul

    2003-05-01

    In southeastern Central Morocco, the Bou-Acila volcanic complex is considered of Cambrian age. In spite of low-grade metamorphic effect, initial volcanic texture and mineralogy can be recognized and volcanic rocks are dominated by dolerites and porphyric dolerites. The initial mineralogy is composed of plagioclases, pyroxenes and dark minerals. A secondary mineral assemblage is composed of albite, epidote, chlorite and calcite. According to their immobile elements compositions, the southeastern central Morocco metavolcanites are of within-plate continental tholeiites. This volcanism and those recognized in many other areas in Morocco confirm a Cambrian extensive episode within the Gondwana supercontinent. To cite this article: H. Ouali et al., C. R. Geoscience 335 (2003).To cite this article: H. Ouali et al., C. R. Geoscience 335 (2003).

  10. Quantitative mineralogy and preliminary pore-water chemistry of candidate buffer and backfill materials for a nuclear fuel waste disposal vault

    International Nuclear Information System (INIS)

    The quantitative mineralogy of seven candidate buffer and backfill materials for a nuclear fuel waste disposal vault is presented. Two of the materials were coarse grained: one a blended very pure silica sand, and the other a crushed plagioclase-rich granite or granodiorite. Five materials were fine-grained soils containing abundant clay minerals. Of these, three were fairly pure, Cretaceous, ash-derived bentonites that contained up to 3 percent of soluble sulphates; one was a freshwater glacial clay containing 59 percent interlayered smectite-illite; and one was a crushed Paleozoic shale containing abundant illite and chlorite. The adsorbed cation regimes and the pore-water chemistry of the clays are discussed

  11. Correlation of Cadmium Distribution Coefficients to Soil Characteristics

    DEFF Research Database (Denmark)

    Holm, Peter Engelund; Rootzen, Helle; Borggaard, Ole K.; Maberg, Jens Peter; Christensen, Thomas Højlund

    2003-01-01

    whole soil samples have shown that pH is the main parameter controlling the distribution. To identify further the components that are important for Cd binding in soil we measured Cd distribution coefficients (K-d) at two fixed pH values and at low Cd loadings for 49 soils sampled in Denmark. The Kd...... values for Cd ranged from 5 to 3000 L kg(-1). The soils were described pedologically and characterized in detail (22 parameters) including determination of contents of the various minerals in the clay fraction. Correlating parameters were grouped and step-wise regression analysis revealed that the...... interlayered clay minerals [HIM], chlorite, quartz, microcline, plagioclase) were significant in explaining the Cd distribution coefficient....

  12. Europa's petrological thermal history

    Science.gov (United States)

    Ransford, G. A.; Finnerty, A. A.; Collerson, K. D.

    1981-01-01

    A path of geophysical development which takes into account the petrological sequence is presented to describe the thermal evolution of Europa. On the basis of considerations of the likely temperature-pressure conditions in the Europa zone of the circumjovian nebula during the condensation of the satellite on the one hand and of the early thermal evolution on the other, it is argued that most of the water of Europa can be in the form of hydrated silicates in a thick convective boundary layer or throughout the body of the satellite. Such silicates would include the minerals chlorite and/or serpentine, and brucite, and could be maintained in hydrated states by solid state convection within the body. The model predicts that the ice layer on the surface of Europa is considerably thinner than the 150 km that had been estimated before the Voyager mission.

  13. Sodium hypochlorite-induced acute kidney injury

    Directory of Open Access Journals (Sweden)

    Brandon W Peck

    2014-01-01

    Full Text Available Sodium hypochlorite (bleach is commonly used as an irrigant during dental proce-dures as well as a topical antiseptic agent. Although it is generally safe when applied topically, reports of accidental injection of sodium hypochlorite into tissue have been reported. Local necrosis, pain and nerve damage have been described as a result of exposure, but sodium hypo-chlorite has never been implicated as a cause of an acute kidney injury (AKI. In this report, we describe the first case of accidental sodium hypochlorite injection into the infraorbital tissue during a dental procedure that precipitated the AKI. We speculate that oxidative species induced by sodium hypochlorite caused AKI secondary to the renal tubular injury, causing mild acute tubular necrosis.

  14. ON THE BLACK LIQUOR AND RECYCLE COOKING OF AS-AQ STRAW PULP

    Institute of Scientific and Technical Information of China (English)

    Haiqiang Shi; Beihai He; Bingyue Liu

    2004-01-01

    Thick black liquor, thin black liquor and solid state sodium hydroxide are added to the liquor treated by sulfur dioxide, then the blended liquor is used to recycle cooking of straw pulp. The black liquor,separated liquor and pulp of every cycles are analyzed respectively. Result shows that the content of lignin and organism in recycle black liquor and separated liquor increases faster in the first three cycles and then continues to increase slowly till four or five times, after that it trends to a stable state. The main organism separated from waste liquor of AS-AQ treated by sulfur dioxide is alkali-lignin,above 50% of total lignin in black liquor. The yield of pulp made from recycle cooking is steady, the hardness of pulp has a great improvement with recycle cooking. The brightness of pulp reduces correspondingly before bleaching, and after bleaching the brightness of pulp is relatively high and steady at the same sodium hypo chlorite dosage.

  15. An oxygen isotope and geochemical study of meteoric-hydrothermal systems at Pilot Mountain and selected other localities, Carolina slate belt

    Science.gov (United States)

    Klein, T.L.; Criss, R.E.

    1988-01-01

    Several epigenetic mineral deposits in the Carolina slate belt are intimately related to meteoric-hydrothermal systems of late Precambrian and early Paleozoic age. At Pilot Mountain, low 18O rocks correlate well with zones of strong silicic alteration and alkali leaching accompanied by high alumina minerals (sericite, pyrophyllite, andalusite ?? topaz) and anomalous concentrations of Cu, Mo, Sn, B, and Au. A magmatic source for much of the sulfur and metal is likely, and a subordinate magmatic water component in the fluid of the central zone is possible. This central zone is surrounded by a >30 km2 peripheral zone of low 18O sericite schists, chlorite-sericite schists, and andesitic volcanic rocks. Reconnaissance studies of other alteration zones in the Carolina slate belt have so far disclosed the involvement of meteoric-hydrothermal fluids at the Snow Camp pyrophyllite deposit, at the Hoover Hill and Sawyer Au mines, and probably at the Haile and Brewer Au mines. -from Authors

  16. Secondary mineral-fluid equilibria in the Krafla and Namafjall geothermal systems, Iceland

    International Nuclear Information System (INIS)

    Aquifer fluid compositions and aqueous species distribution have been calculated for 22 samples collected from producing wells in the Krafla and Namafjall geothermal areas, Iceland. Overall mineral-solution equilibrium is rather closely approached in the aquifer beyond the depressurization zone around wells for all major components entering hydrothermal minerals. The minerals involved are in alphabetical order: albite, calcite, chlorite, epidote, K-feldspar (adularia), prehnite, pyrite, pyrrhotite, quartz and wairakite. Calculated saturation indices for OH-bearing Al-silicates show more scatter than for minerals of simpler composition. A large scatter is also observed for pyrite and pyrrhotite. The main uncertainty involved in calculating mineral saturation indices, particularly in the case of 'excess' enthalpy well discharges, lies in the model adopted to calculate the aquifer water composition and its aqueous species distribution and not in the quality of the thermodynamic data on the aqueous species and the minerals with the possible exception of epidote and Fe2+

  17. Core-logs of borehole VI down to 505 m

    International Nuclear Information System (INIS)

    In the hydrogeological program of the Stripa project the vertical borehole V1 has been drilled 505.5 m. The drillcore has been logged with regard to rock characteristic, fracture frequency, dipping and filling. The results presented as cumulative fracture diagram have formed the base for subdivision of the borehole according to fracture frequency. The variation in the fracture dipping was also taken into account. Chlorite is the most common of the infilling material in the fractures. For the borehole 0-466 m the average fracture frequency is 1.46 fractures/m. Below 466 m the core is highly fractured and crushed indicating that the borehole has entered a crushed zone. Because of this the drilling is temporarily stopped. (Auth.)

  18. Surface Microtextures of Slipping Zone Soil of Some Landslides in the Three Gorges Reservoir District and Their Significance

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The mineral assemblage and content and surface microtextures of slipping zone soil of several landslides in the Three Gorges Reservoir District have been analyzed using the scanning electron microscope (SEM) and X-ray diffractometer (XRD). All the mineral assemblages are similar in these landslides. The main minerals are montmorillonite, illite, kaolinite, chlorite, quartz and feldspar. There are two kinds of surface microtexture in the slipping zone soil, i.e., linear scratches and arcuate scratches. Based on analyses of the changes of the microtextures, one can obtain information about the number, directions and stages of landslide movements. The authors have also studied the mechanism of landslide formation, evaluated the stability of landslides and revival possibility of ancient landslides and forecasted the activity of similar landslides in different districts. The surface microtexture features of stable landslides and mobile landslides are summarized and it is concluded that the existence of filamentous bacteria may result in or increase movements of landslides.

  19. The hydrothermal alteration and contact metamorphism on the tonalite and volcanics of the Komahashi-Daini Seamount, northern Kyushu-Palau Ridge

    Science.gov (United States)

    Haraguchi, S.; Ishii, T.; Li, Y.; Kato, Y.

    2011-12-01

    At the Komahashi-Daini Seamount (KDS) in the northern Kyushu-Palau Ridge (KPR), acidic plutonic rocks (tonalite) were recovered by research cruises of Japanese Geodynamics Project (GDP) during 1970's and R/V Tansei-Maru, Ocean Research institute, during 1990's. Haraguchi et al. (2003) considered that this tonalite was produced by fractional crystallization of the basaltic magma during the arc volcanism before spreading of the Shikoku backarc basin. This study was selected flesh samples. However, many altered plutonic rocks and volcanics were recovered by these cruises. These volcanics show highly alteration. In this study, we research these highly altered plutonics and volcanics by petrographical, geochemical and mineralogical processes using chemical analysis by electron microprobe analyses (EPMA) and identification by X-ray diffraction (XRD). And we consider alteration processes during intrusion of acidic plutonic body. Alteration of tonalites is prominent in colored minerals. Many colored minerals are replaced into chlorite identified by EPMA and XRD analyses. Fresh tonalites not altered of colored mineral are about 1/10 amount of all recovered plutonic rocks. Plagioclase resist from alteration compared to colored mineral, however, albitization is observed in some high-altered tonalites. K-feldspar is rare in altered tonalites. Many volcanics show completely replacement into secondary phases and some rocks display relic igneous textures. Plagioclase phenocrysts exhibit albitization, and albite and chlorite are identified by XRF and EPMA, similar to plutonic rocks. Quartz is also identified. Altered colored minerals are identified into epidote by XRD and EPMA analyses. Fine secondary phases are difficult to identify by microscope observation, and minor secondary phase are difficult to identify by XRD. We considered that the analyses of mineral composition by EPMA are the effective tools of identification of fine mineral phases. The mineral assemblage of chlorite

  20. Identification of secondary minerals crystallized by low and high temperature alteration in the Northern Kyushu-Palau Ridge volcanic rocks

    Science.gov (United States)

    Haraguchi, S.

    2008-12-01

    characteristics of bulk composition of the Nichinan Seamount rocks are assumed similarity to primary signature. On the other hand, the Komahashi-Daini Seamount samples show completely re-crystallization, and igneous textures are observed to pseudomorph. These are identified by XRD to be quartz, clinochlore (one of chlorite), and albite. Secondary mineral assemblage is homogeneous in these rocks. The temperature of replacement by chlorite accompanied by enrichment in MgO is estimated to be more than 150°C on the basis of experimental studies (e.g. Mottle 1983). And interpreted two types of albitization, low temperature ( 100°C), are identified on the basis of study of ODP Leg 123 Site 765 igneous rocks (Gillis et al. 1992). Therefore, it is considered that volcanic rocks from the Komahashi-Daini Seamount were under effect of hydrothermal alteration more than 150°C. Many elements show significant movement under high temperature hydrothermal alteration (e.g. Laverne et al. 1996). That is, re-crystallization of chlorite under high temperature hydrothermal alteration accompanied addition of magnesium from seawater and remarkable bulk MgO enrichment (e.g. Nakamura, 2001). Therefore, it is considered that the Komahashi-Daini Seamount rocks show significant MgO-enrichment because of secondary mineralization of chlorite, and assumed to significant movement of other elements. These observations suggest that geochemical investigation of highly altered rocks must be made with caution.

  1. Studies of radionuclide sorption by clays in the Culebra dolomite at the WIPP site, southeastern New Mexico

    International Nuclear Information System (INIS)

    The ability of radionuclide-rock interactions to retard the migration of plutonium and uranium within clay-lined fractures in the Culebra Dolomite Member of the Rustler Formation is being estimated in support of the performance assessment of the Waste Isolation Pilot Plant. This paper describes progress in three coordinated studies: (1) characterization of the properties of the groundwater and minerals in the Culebra that will control radionuclide retardation; (2) development of a thermodynamic model for the adsorption of uranium onto corrensite, the mixed chlorite-smectite clay mineral found in Culebra fractures; and (3) development of a database of equilibrium constants and interaction parameters for calculations of the aqueous speciation of uranium and plutonium in Na-Cl-Ca-SO4-CO3 solutions which contain organic ligands such as EDTA and range in ionic strength from approximately 0.8 - 6.0 molal. 22 refs., 6 figs., 1 tab

  2. Study of removal effect on Mesocyclops leukarti with oxidants

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Cyclops of zooplankton propagates prolifically in eutrophic waterbody and it cannot be exterminated by conventional disinfection process. The mutagenicity of Mesocyclops leukarti and its extermination with oxidants in a drinking waterworks in China were studied. Among five oxidants for use in bench-scale, chlorine dioxide is the most effective and the potassium permanganate is the weakest against Mesocyclops leukarti under the same conditions. Full-scale results showed that Mesocyclops leukarti could be effectively removed from water by 1.0 mg/L chlorine dioxide preoxidation combined with conventional removal physical process. After filtration, chlorite, a by-product of prechlorine dioxide, is stable at 0.45 mg/L, which is lower than the critical value of the USEPA. GC-MS examination and Ames test further showed that the quantity of organic substance and the mutagenicity in water treated by chlorine dioxide preoxidation are obviously less than those of prechlorination.

  3. Bench and Full Scale Study of Removal Effect and Mutagenicity on Mesocyclops Leukarti with Chlorine Dioxide

    Institute of Scientific and Technical Information of China (English)

    ZUO Jin-long; YANG Wei; LIU Yan-an; LIN Tao

    2006-01-01

    Mesocyclops Leukarti of zooplankton propagates excessively in eutrophic water body and it can not be effectively inactivated by the conventional process in drinking waterworks for its special surface structure. In this paper, a study of removal efficiency on Mesocyclops Leukarti with chlorine dioxide in a drinking waterworks was performed.Bench scale results showed that chlorine dioxide is more effective against Mesocyclops Leukarti. And Mesocyclops Leukarti could be effectively removed from water by 1.0 mg/L chlorine dioxide preoxidation cooperated with the conventional process during the full scale study. The chlorite, by-preduct of prechlorine dioxide, was constant at 0.45 mg/L after filtration, which was lower than the critical value of the USEPA. GC-MS examination and Ames test showed that the quantity of organics and the mutagenicity in the water treated by chlorine dioxide is obviously less than that of prechlorination.

  4. Phase Equilibria and Thermobarometry of Lawsonite and Pumpellyite-Bearing Metabasalts From Crete

    Science.gov (United States)

    Manon, M. R.; Essene, E. J.

    2007-12-01

    High-pressure, blueschist facies rocks associated with the subduction and subsequent exhumation of sedimentary rocks along the Hellenic subduction zone now outcrop over a large portion of the Greek island of Crete. They host the rare pelitic index mineral, carpholite, and has one of the few occurrences of metamorphic aragonite in marbles. Though largely composed of pelites, many small pods of metabasalts contain index minerals such as lawsonite and glaucophane. The assemblage lawsonite + pumpellyite has been found, providing an excellent opportunity to unravel the pressures and temperatures to which these rocks were subjected during subduction. Blueschists from the central part of Crete are typically glaucophane-bearing, with plentiful epidote, sphene and chlorite. Millimeter scale domains within some of the rocks contain the assemblage, quartz + lawsonite + albite + chlorite + epidote ± pumpellyite ± glaucophane. The presence of lawsonite and epidote roughly locates the rocks between the lawsonite and epidote blueschist facies as defined by Evans (1990). Chemically the lawsonite is fairly pure, with only small amounts of Fe (less than 0.4 wt %). Although some pumpellyite has almost no iron, when in equilibrium with the lawsonite it typically contains subequal amounts of Fe and Mg, (Fe/(Fe+Mg) is on average ~0.45). Chlorite is also roughly halfway between clinochlore and chamosite. The glaucophane is crossitic in composition. Clinozoisite has around 4 weight percent Fe2O3 (0.25 atoms Fe per formula unit). The albite and quartz are pure. The reaction albite + pumpellyite + lawsonite = glaucophane + clinozoisite + quartz + fluid has a somewhat steep slope (74 bar/°C) and can be used to constrain temperatures. Another reaction between lawsonite and pumpellyite is glaucophane + lawsonite = pumpellyite + chlorite + albite + quartz + fluid. The slope of this reaction is (24 bar/°C) and so the intersection of the two provides a reasonable estimate of the P

  5. Pressure, temperature, and timing of mineralization of the sedimentary rock-hosted orogenic gold deposit at Klipwal, southeastern Kaapvaal Craton, South Africa

    Science.gov (United States)

    Chinnasamy, Sakthi Saravanan; Uken, Ron; Reinhardt, Jürgen; Selby, David; Johnson, Spencer

    2015-08-01

    Gold mineralization in the Klipwal Shear Zone (KSZ) at the Klipwal Gold Mine is confined to laminated quartz-carbonate lodes, stringers, and associated alteration in sandstone and siltstone of the Delfkom Formation in the upper Mozaan Group of the Mesoarchaean Pongola Supergroup. The moderately dipping brittle-ductile KSZ strikes N-S with an oblique-reverse, sinistral sense of shear. The deformational events that are recognized include an early compressional phase that produced anastomosing shears defined by shear fabrics with numerous shear-parallel laminated quartz-carbonate fault-fill veins and, in places, extensional quartz vein stockworks, and a late brittle reactivation phase that produced fault breccias, displacing earlier extensional veins. Three closely spaced economic reefs (lodes) are developed: the main R-reef constitutes the KSZ, while the J- and H-reefs represent footwall splays. Alteration comprises chlorite, muscovite, epidote, feldspar, and carbonates along with pyrite, arsenopyrite, and chalcopyrite ± pyrrhotite. An inner alteration zone is dominated by laminated quartz-carbonate veins with alternating quartz-carbonate-rich and muscovite-chlorite-rich laminae, whereas the proximal zone is characterized by alteration halos of K-feldspar, albite, epidote, chlorite, and muscovite along with carbonates and associated quartz veins. Chlorite thermometry from the inner and proximal zones yielded temperatures of 267 to 312 °C. Arsenopyrite compositions provide temperatures in the same range, 255 to 318 °C. Fluid inclusion microthermometry and Raman spectrometry of quartz veins in the mineralized reefs reveal the presence of metamorphogenic aqueous-gaseous fluid with an average salinity of 6.5 wt% NaCl equiv. Fluid compositions and estimated pressure-temperature (P-T) range (1.1 to 2.5 kbar at 255 to 318 °C) are typical of orogenic gold deposits. Devolatilization during the regional facies metamorphism of the Pongola Supergroup is considered the likely

  6. Collective sulphide flotation of the polymetallic molybdenic ore

    International Nuclear Information System (INIS)

    Results of investigations on polymetallic molybdenic ore are presented. The useful minerals of this ore are as follows: molybdenite, sphalerite, galena and chalcopyrite whereas quartz, feldspars, chlorite and sericite are barren rocks. The flotation process parameters are established i.e. the consumption of flotation reagents, the flotation time and the most advantageous grain composition of the ore submitted to flotation. Taking into consideration the established parameters, a collective sulphide flotation of ore and a control flotation of wastes were carried out. The obtained concentrate was submitted to a single cleaning flotation whereby a concentrate was obtained containing: 4,65% Mo, 2,51% Cu, 0,9% Zn, 0,69% Pb, and 1,4% Bi. (author)

  7. Deep reservoirs of the Pendencia Formation, Pescada Field; Potiguar Basin: porosity potential and controlling factors

    International Nuclear Information System (INIS)

    The arkoses and sub arkoses of the Pendencia Formation form oil and gas reservoirs at depths greater than 3,400 m in the Pescada Field, Potiguar Basin. Depositional environment, framework composition, and burial history were the major controls on diagenesis and reservoir quality. Chlorite, calcite, and quartz and feldspar over growths are the main cements. Depositional environment played an important role in the course of eodiagenesis. Fluvial channel, delta-front, and lacustrine rhythmite facies were submitted to different geochemical conditions during eodiagenesis. In fluvial channels, under saturated fresh waters prompted early dissolution, while diagenesis in the delta-front and turbidity sandstones can be explained as a result of the flow of lacustrine connate water saturated in Mg, Fe, and Ca in a strongly reducing environment. (author)

  8. Determination of the surface energy of kaolinite and serpentine using PACHA formalism-comparison with immersion experiments.

    Science.gov (United States)

    Salles, Fabrice; Henry, Marc; Douillard, Jean-Marc

    2006-11-15

    Clays play an important role in a wide variety of industrial processes. Indeed, they present interesting surface properties. For these reasons, we study the surface energy of models of clays by solid state calculations using electronegativities equalization. In this article, we focus on kaolinite and serpentine, two clays characterized by a simple structure of the TO type. We describe the clays and their structures and we develop a simple model from solid state calculations used to determine the surface energy. The results are in agreement with a recent interpretation of the immersion of kaolinite in water. This article must be related to some others focusing on solid surface energy, especially some treating talc and chlorites, and montmorillonites saturated by alkaline cations, to be published. PMID:16978637

  9. Competitive Oxidation and Hydration During Aqueous Alteration of Asteroids

    Science.gov (United States)

    Zolotov, M. Y.; Mironenko, M. V.; Shock, E. L.

    2005-01-01

    Introduction: Studies of chondrites show that incorporation of H2O ice during formation of asteroids followed by radioactive heating caused partial oxidation and hydration of primary reduced and anhydrous rocks. Oxidation of kamacite, phosphides, troilite and organic polymers occurred through consumption of water s oxygen and release of H2. Hydration caused formation of serpentine, saponite, chlorite, talc and hydrated salts. Since H2O was the major reactant in oxidation and hydration, these processes could have been competitive. Redox reactions in asteroids should have been closely connected to hydration (dehydration) during aqueous alteration and thermal metamorphism. For example, dehydration and reduction release H2O that can be consumed in oxidation and hydration, respectively. We model asteroidal processes in order to quantify the fate of H2O and water s oxygen in major redox and hydration/dehydration reactions. Model: Equilibrium compositions in the gas-solid-liquid

  10. Rayleigh-type parametric chemical oscillation

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Shyamolina; Ray, Deb Shankar, E-mail: pcdsr@iacs.res.in [Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India)

    2015-09-28

    We consider a nonlinear chemical dynamical system of two phase space variables in a stable steady state. When the system is driven by a time-dependent sinusoidal forcing of a suitable scaling parameter at a frequency twice the output frequency and the strength of perturbation exceeds a threshold, the system undergoes sustained Rayleigh-type periodic oscillation, wellknown for parametric oscillation in pipe organs and distinct from the usual forced quasiperiodic oscillation of a damped nonlinear system where the system is oscillatory even in absence of any external forcing. Our theoretical analysis of the parametric chemical oscillation is corroborated by full numerical simulation of two well known models of chemical dynamics, chlorite-iodine-malonic acid and iodine-clock reactions.

  11. Proteomic detection of proteins involved in perchlorate and chlorate metabolism.

    Science.gov (United States)

    Bansal, Reema; Deobald, Lee A; Crawford, Ronald L; Paszczynski, Andrzej J

    2009-09-01

    Mass spectrometry and a time-course cell lysis method were used to study proteins involved in perchlorate and chlorate metabolism in pure bacterial cultures and environmental samples. The bacterial cultures used included Dechlorosoma sp. KJ, Dechloromonas hortensis, Pseudomonas chloritidismutans ASK-1, and Pseudomonas stutzeri. The environmental samples included an anaerobic sludge enrichment culture from a sewage treatment plant, a sample of a biomass-covered activated carbon matrix from a bioreactor used for treating perchlorate-contaminated drinking water, and a waste water effluent sample from a paper mill. The approach focused on detection of perchlorate (and chlorate) reductase and chlorite dismutase proteins, which are the two central enzymes in the perchlorate (or chlorate) reduction pathways. In addition, acetate-metabolizing enzymes in pure bacterial samples and housekeeping proteins from perchlorate (or chlorate)-reducing microorganisms in environmental samples were also identified. PMID:19199051

  12. Spinifex-textured komatiites in the south border of the Carajas ridge, Selva Greenstone belt, Carajás Province, Brazil

    Science.gov (United States)

    Siepierski, Lincoln; Ferreira Filho, Cesar Fonseca

    2016-03-01

    Spinifex-textured komatiites in the Selva greenstone belt are the first unequivocal examples of komatiites in the Transition Subdomain of the Carajás Mineral Province. Outcrops of spinifex-textured komatiites, located ∼1.5 km to the south of the Carajás ridge, were discovered during regional exploration for Ni-Cu-(PGE) sulfide deposits by VALE. They are associated with a 3.8 km long unit consisting of variable types of ultramafic rocks (talc schist, serpentinite and spinifex-textured komatiite). This ultramafic unit follows the steep dipping NW-SE trending Selva greenstone belt composed mainly by quartz-chlorite schists (interpreted as metasediments) and chlorite-actinolite schists (interpreted as metabasalts). Greenschist facies metamorphic parageneses characterize all rock types in the Selva greenstone belt. The komatiitic rocks in the Selva belt comprise a sequence of flows consisting of an upper spinifex-textured layer and a lower olivine cumulate layer. Although the spinifex and cumulus textures are well preserved in the field, the primary mineralogy of the komatiites has been completely replaced by greenschist facies metamorphic minerals. Platy olivine spinifex texture, consisting of an array of roughly parallel olivine plates, and random spinifex texture, consisting of randomly oriented olivine plates, are the most common primary volcanic textures in komatiites in the Selva greenstone belt. Platy and random spinifex texture is defined by former plates of olivine replaced by serpentine with minor actinolite, chlorite and magnetite, alternating with former matrix replaced by abundant actinolite and minor chlorite, talc, serpentine, and magnetite. The domains between olivine plates in both platy and random spinifex-textured rocks contain irregular arrays of fine-grained parallel crystals, representing primary fine-grained "quench" clinopyroxene crystals replaced by actinolite. Spinifex-textured komatiites have MgO contents bracket between 22.8 and 26.9 wt

  13. Influence of microwaves on the leaching kinetics of uraninite from a low grade ore in dilute sulfuric acid.

    Science.gov (United States)

    Madakkaruppan, V; Pius, Anitha; T, Sreenivas; Giri, Nitai; Sarbajna, Chanchal

    2016-08-01

    This paper describes a study on microwave assisted leaching of uranium from a low-grade ore of Indian origin. The host rock for uranium mineralization is chlorite-biotite-muscovite-quartzo-feldspathic schist. The dominant presence of siliceous minerals determined leaching of uranium values in sulfuric acid medium under oxidizing conditions. Process parametric studies like the effect of sulfuric acid concentration (0.12-0.50M), redox potential (400-500mV), particle size (600-300μm) and temperature (35°-95°C) indicated that microwave assisted leaching is more efficient in terms of overall uranium dissolution, kinetics and provide relatively less impurities (Si, Al, Mg and Fe) in the leach liquor compared to conventional conductive leaching. The kinetics of leaching followed shrinking core model with product layer diffusion as controlling mechanism. PMID:27045621

  14. Uranium deposit research, 1983

    International Nuclear Information System (INIS)

    Research on uranium deposits in Canada, conducted as a prerequisite for assessment of the Estimated Additional Resources of uranium, revealed that (a) the uranium-gold association in rudites of the Huronian Supergroup preferably occurs in the carbon layers; (b) chloritized ore at the Panel mine, Elliot Lake, Ontario, occurs locally in tectonically disturbed areas in the vicinity of diabase dykes; (c) mineralization in the Black Sturgeon Lake area, Ontario, formed from solutions in structural and lithological traps; (d) the Cigar Lake deposit, Saskatchewan, has two phases of mineralization: monomineralic and polymetallic; (e) mineralization of the JEB (Canoxy Ltd.) deposit is similar to that at McClean Lake; (f) the uranium-carbon assemblage was identified in the Claude deposit, Carswell Structure; and (g) the Otish Mountains area, Quebec, should be considered as a significant uranium-polymetallic metallogenic province

  15. Evidence of heterogeneous crustal origin for the Pan-African Mbengwi granitoids and the associated mafic intrusions (northwestern Cameroon, central Africa)

    Science.gov (United States)

    Mbassa, Benoît Joseph; Kamgang, Pierre; Grégoire, Michel; Njonfang, Emmanuel; Benoit, Mathieu; Itiga, Zénon; Duchene, Stéphanie; Bessong, Moïse; Nguet, Pauline Wonkwenmendam; Nfomou, Ntepe

    2016-02-01

    The Mbengwi plutonics consist of intermediate to felsic granitoids forming a continuous magmatic series from monzonite to granite and mafic intrusions. Their mineralogical composition consists of quartz, plagioclases, K-feldspars, biotite, muscovite, and amphibole. The accessory phase includes opaque minerals + titanite ± apatite ± zircon, while secondary minerals are pyrite, phengite, chlorite, epidote, and rarely calcite. These plutonics are assigned high-K calc-alkaline to shoshonitic series, metaluminous to weakly peraluminous and mostly belong to an I-type suite (A/CNK = 0.63-1.2). They are typically post-collisional, with a subduction signature probably being inherited from their protoliths emplaced during the subduction phase. The Sr and Nd isotopic data evidence that these plutonics result from melting of the lower continental crust with variable contribution of the oceanic crust. Their geochemical features are similar to those of western Cameroon granitoids related to the Pan-African D1 event in Cameroon.

  16. Mineralogic and petrologic investigation of pre-test core samples from the spent fuel test-climax

    Energy Technology Data Exchange (ETDEWEB)

    Ryerson, F.J.; Qualheim, B.J.

    1983-12-01

    Pre-test samples obtained from just inside the perimeter of the canister emplacement holes of the Spent Fuel Test-Climax have been characterized by petrographic and microanalytical techniques. The primary quartz monzonite has undergone various degrees of hydrothermal alteration as a result of natural processes. Alteration is most apparent on primary plagioclase and biotite. The most common secondary phases on plagioclase are muscovite and calcite, while the most common secondary phases on biotite are epidote and chlorite. The major alteration zones encountered are localized along filled fractures, i.e. veins. The thickness and mineralogy of the alteration zones can be correlated with the vein mineralogy, becoming wider and more complex mineralogically when the veins contain calcite. 7 references, 10 figures, 4 tables.

  17. Mineralogic and petrologic investigation of pre-test core samples from the spent fuel test-climax

    International Nuclear Information System (INIS)

    Pre-test samples obtained from just inside the perimeter of the canister emplacement holes of the Spent Fuel Test-Climax have been characterized by petrographic and microanalytical techniques. The primary quartz monzonite has undergone various degrees of hydrothermal alteration as a result of natural processes. Alteration is most apparent on primary plagioclase and biotite. The most common secondary phases on plagioclase are muscovite and calcite, while the most common secondary phases on biotite are epidote and chlorite. The major alteration zones encountered are localized along filled fractures, i.e. veins. The thickness and mineralogy of the alteration zones can be correlated with the vein mineralogy, becoming wider and more complex mineralogically when the veins contain calcite. 7 references, 10 figures, 4 tables

  18. Pedogenetic processes on Mars

    Science.gov (United States)

    Chiara Tangari, Anna; Marinangeli, Lucia; Piluso, Eugenio; Pompilio, Loredana; Scarciglia, Fabio

    2014-05-01

    Clay minerals, such as Fe/Mg smectite and Al-rich phyllosilicates (i.e., montmorillonite and kaolinite) were detected in the last years on Mars by numerous missions[1,2]. These minerals can be formed by fluid/rock interaction. Therefore, their study may provide important information on the climatic conditions and consequent habitability of the Martian surface. In this work we compare the mineralogy observed with CRISM data in the eastern part of Valles Marineris (Coprates-Ganges-Capri-Eos Chasmata), Margaritifer Terra and Margaritifer Chaos regions, with soils sampled on the Etna volcano (Sicily) and Cerviero Mount (Calabria, Southern Italy). We use an integrated approach of remote sensing coupled with pedological, petrographical and mineralogical investigations. Our purpose, here, is to find possible analogies between some Andosols developed on the basaltic substrates of Etna and Cerviero Mount, and the Martian soils, based on their spectral response and formation processes. CRISM data show poor abundance of clay minerals, such as illite, smectite and montmorillonite, in the eastern part of Valles Marineris. On the contrary, these phases are widely exposed in the Margaritifer Terra and Margaritifer Chaos, where we detected allophone (poorly crystalline clay), vermiculite, chlorite and other phyllosilicates belonging to the smectite group, such as saponite and nontronite. The surrounding area shows dominant signatures of basaltic composition.Our preliminary analysis on terrestrial soil profiles, using X-ray diffraction analysis, shows similar characteristics to Mars in terms of bedrock composition and clay mineralogy. Etnean soils, formed from lavas and pyroclastics of various ages (from 12 ka to 122 BC) [3] show the presence of clay minerals, such as kaolinite and small amounts of illite. The Cerviero Mount soils, developed on pillow basalts of Maastrichtian-Paleocene ages [4] are composed of vermiculite, illite, chlorite and interstratified clays such as

  19. Selective extraction procedure and its importance in a natural analogue study. Case study at the Koongarra uranium deposit

    International Nuclear Information System (INIS)

    A sequential extraction procedure was used to study the distribution of uranium in mineral phases of rocks at the Koongarra uranium deposit as a natural analogue study. The mineral phases studied were adsorbed materials, amorphous iron minerals, crystalline iron minerals, chlorite, and remaining residual mineral phases. The majority of uranium in samples from the weathered zone coexist within crystalline iron minerals, and uranium in the primary ore body mainly occurred as uranium minerals. Downgradient in the unweathered zone, the concentration of uranium in rock was relatively low. From the 234U/238U activity ratios in extracted phases, 234U enrichment was observed in residual mineral phases coated in a microscale by iron minerals, possibly by alpha recoil effect. (author)

  20. Evolution of models for conversion of smectite to non-expandable minerals

    International Nuclear Information System (INIS)

    Hydrothermal alteration of smectite has long been regarded as conversion to illite and chlorite as concluded from investigations of Gulf sediments. As manifested by statements given earlier at various international scientific meetings and in the literature, smectite-to-illite conversion (S→I) has been assumed to be a solid-state reaction with layer-by-layer alteration via mixed layer I/S to illite. In the last 10 years this opinion has successively changed and in recent years the concept of dissolution of smectite and accessory minerals and precipitation of illite and possibly I/S has been favored by many investigators. The present report reports laboratory and field investigations on bentonite and also calculations based on geochemical codes, which all support the dissolution/precipitation process. Applying Pytte's model for calculating the rate of conversion to illite, one finds good agreement with a number of experiments and field data, and this model is therefore recommended for practical use

  1. Effects of natural heating on a clay formation

    International Nuclear Information System (INIS)

    As a contribution to the characterization of clay deposits as possible sites for nuclear waste disposal, the metamorphic effects induced on Pliocene argillaceous sediments by the small subvolcanic body of Orciatico (Tuscany, Italy) were investigated. In areas close to marginal facies of the magmatic body, where temperatures were presumably ranging from 100 to 5000C, the thermo-metamorphic aureole thickness doesn't exceed 2 meters. In this zone the clay fraction (45-69% of the bulk rock) changes from an illite+illite/smectite interstratified+vermiculite+chloritic intergrades assemblage to a paragenesis characterized only by illite+smectite, the later being the most stable phase among the clay minerals. Within such zone alkalis (Na,K, and Rb) and alkaline-earths (Ca and Sr) result to be the most highly mobilized elements

  2. MECHANISM OF CHLORATE FORMATION IN CHLORINE DIOIXDE DELIGNIFICATION

    Institute of Scientific and Technical Information of China (English)

    Byung-HoYoon; Li-JunWangI; Se-JongKim

    2004-01-01

    The effect of pH on chlorate formation duringchlorine dioxide delignification of oxygen delignifiedkraft pulp was studied. Chlorate formation was foundto increase slightly when pH was increased from 1.8to 2.5, further increase of pH decreased chlorateformation.The above phenomenon is explained by thecombination of two mechanisms, one by the reactionbetween hypochlorous acid and chlorite, another bythe effect of chlorine on the regeneration of chlorinedioxide. The first mechanism suggests that chlorateformation is highly dependent on HC10concentration which decreases with increasing pHand causes chlorate formation to behave in the sametrend. The second mechanism suggests that chlorinefavors the regeneration of chlorine dioxide whileHCIO favors chlorate formation, thus lowering thepH from about 4 to the acidic end should decreaseschlorate formation. Thethe maximum formation2.5.two opposite effects lead toof chlorate at around pH

  3. Rayleigh-type parametric chemical oscillation.

    Science.gov (United States)

    Ghosh, Shyamolina; Ray, Deb Shankar

    2015-09-28

    We consider a nonlinear chemical dynamical system of two phase space variables in a stable steady state. When the system is driven by a time-dependent sinusoidal forcing of a suitable scaling parameter at a frequency twice the output frequency and the strength of perturbation exceeds a threshold, the system undergoes sustained Rayleigh-type periodic oscillation, wellknown for parametric oscillation in pipe organs and distinct from the usual forced quasiperiodic oscillation of a damped nonlinear system where the system is oscillatory even in absence of any external forcing. Our theoretical analysis of the parametric chemical oscillation is corroborated by full numerical simulation of two well known models of chemical dynamics, chlorite-iodine-malonic acid and iodine-clock reactions. PMID:26429035

  4. Parametric spatiotemporal oscillation in reaction-diffusion systems.

    Science.gov (United States)

    Ghosh, Shyamolina; Ray, Deb Shankar

    2016-03-01

    We consider a reaction-diffusion system in a homogeneous stable steady state. On perturbation by a time-dependent sinusoidal forcing of a suitable scaling parameter the system exhibits parametric spatiotemporal instability beyond a critical threshold frequency. We have formulated a general scheme to calculate the threshold condition for oscillation and the range of unstable spatial modes lying within a V-shaped region reminiscent of Arnold's tongue. Full numerical simulations show that depending on the specificity of nonlinearity of the models, the instability may result in time-periodic stationary patterns in the form of standing clusters or spatially localized breathing patterns with characteristic wavelengths. Our theoretical analysis of the parametric oscillation in reaction-diffusion system is corroborated by full numerical simulation of two well-known chemical dynamical models: chlorite-iodine-malonic acid and Briggs-Rauscher reactions. PMID:27078346

  5. Petrographic and EMP study of metamorphic rocks from the Variscan basement of Dinarides (Vranica Mountains, Bosnia and Herzegovina)

    International Nuclear Information System (INIS)

    The Vranica Mountains are located in the middle part of Bosnia and Herzegovina or in the southeastern part of the Mid - Bosnian schist Mountains (MBSM). The Mid - Bosnian schist Mountains represent one of the largest allochtonous Paleozoic terranes in the Dinarides. This region is characterized by a multistage geodynamic evolution. The presented results concern Variscan metamorphism of the Silur-Devonian protolith formations that occurred mainly during the Early Carboniferous in LT/MP greenschist facies. Petrographical description of metamorphic rocks is completed by EMPA of muscovite, chlorite and chloritoid. The Early Alpine metamorphic overprint is related to the closure of a Tethyan Basin and Early Cretaceous collision of the Adria microplate with the Tissia-Moesia continental Blocks. The Neo-Alpine metamorphic overprint occurred due to the collision of the African and Euroasian Plates. (authors)

  6. Geochemistry of clay minerals for uranium exploration in the Grants mineral belt, New Mexico

    Science.gov (United States)

    Brookins, D. G.

    1982-03-01

    Clay mineralogy studies of ore rocks versus barren rocks in the Grants mineral belt, New Mexico, show that some combination of chlorite (rosette form), illite, mixed-layer illite-montmorillonite, (±Mg-montmorillonite) are penecontemporaneous with uranium minerals in trend ore; these same clay minerals plus kaolinite are related to the roll-type ore near the main redox front of the Grants mineral belt. Clay minerals from barren rocks are characterized by a greater abundance of Na-montmorillonite, kaolinite, and face-to-edge form chlorite. Chlorites from ore zones contain much more vanadium than do chlorites from barren rocks. Trend orr probably formed from southeasterly flowing waters following paleochannels in the Late Jurassic. These deposits are found almost entirely in reduced rocks, and organic carbon may have been an important reductant to remove U-V-U-V-Se-Mo from solution as carbonate from ore zones contains some organic carbon based on stable isotope studies. Uplift, remobilization, and reprecipitation of some of the trend ore resulted in the formation of redistributed ore, some of which possesses a roll-type geometry. Mineralization for the roll-type ore was apparently controlled by sulfide-sulfate equilibria at or near the main redox front in the Grants mineral belt. Trend and roll-type ore possess different assemblages of clay minerals and different trace element abundances. Laramide-age faults cut both trend ore and some roll-type ores. Stack ore is found in Laramide-age fault zones. Limited oxygen isotopic data from clay minerals collected from two mines at Ambrosia Lake in reduced rocks indicate probable preservation of ancient, formational waters and show no evidence of infiltration by young meteoric waters. This information, plus the pre-Laramide-age faults, suggest, but do not unequivocally prove, that the main redox front has been relatively stable since its formation, probably some time in the Cretaceous. Younger encroachment of the redox front

  7. Mapping Hydrothermal Alterations in the Muteh Gold Mining Area in Iran by using ASTER satellite Imagery data

    Science.gov (United States)

    Asadi Haroni, Hooshang; Hassan Tabatabaei, Seyed

    2016-04-01

    Muteh gold mining area is located in 160 km NW of Isfahan town. Gold mineralization is meso-thermal type and associated with silisic, seresitic and carbonate alterations as well as with hematite and goethite. Image processing and interpretation were applied on the ASTER satellite imagery data of about 400 km2 at the Muteh gold mining area to identify hydrothermal alterations and iron oxides associated with gold mineralization. After applying preprocessing methods such as radiometric and geometric corrections, image processing methods of Principal Components Analysis (PCA), Least Square Fit (Ls-Fit) and Spectral Angle Mapper (SAM) were applied on the ASTER data to identify hydrothermal alterations and iron oxides. In this research reference spectra of minerals such as chlorite, hematite, clay minerals and phengite identified from laboratory spectral analysis of collected samples were used to map the hydrothermal alterations. Finally, identified hydrothermal alteration and iron oxides were validated by visiting and sampling some of the mapped hydrothermal alterations.

  8. Persistent blooms of surf diatoms along the pacific coast U. S. A. I. physical characteristics of the coastal region in relation to the distribution and abundance of the species

    Energy Technology Data Exchange (ETDEWEB)

    Garver, J.L.; Lewin, J.

    1981-01-01

    The surf diatom populations at thirteen beaches along the Oregon and Washington coast were studied from June 1977 through August 1978. Chaetoceros armatum T. West and Asterionella socialis Lewin and Norris, the two species responsible for the blooms, were present in the surf along beaches between Point Grenville, Washington, and Cape Blanco, Oregon. On the basis of the cell densities of these two species, the beaches were arranged into four distinct groups. Discriminant analysis showed that the four groups could also be completely separated by three discriminant functions composed of four physical variables: offshore bottomslope, per cent chlorite, per cent montmorillonite and beach length. The absence of surf diatoms at two beaches south of Cape Blanco can probably be explained by the unsuitable physical conditions along the coast south of the Cape.

  9. Ion chromatography in the manufacture of multilayer circuit boards

    Science.gov (United States)

    Smith, Robert E.

    1990-09-01

    Ion chromatography (IC) has proven useful in analyzing chemical solutions used in the manufacture of multilayer circuit boards. The manufacturing process is described briefly and previously published IC methods are reviewed. Then, methods are described for determining chlorate and chlorite in a brown oxide solution; salicylic acid in an epoxy cure agent; formate, sulfate, and tartrate in an electroless copper bath; anionic detergents in a tin-lead brightener and in a cleaning solution; and aqueous photoresist and nonionic brightener in a tin-lead bath. Anion exchange, reverse phase HPLC on a poly(styrene/divinylbenzene), PS/DVB, column and 2-D liquid chromatography also are described. Chemically suppressed conductivity and photometric detection are used.

  10. Mid amphibolite facies metamorphism of harzburgites in the Neoproterozoic Cerro Mantiqueiras Ophiolite, southernmost Brazil

    Directory of Open Access Journals (Sweden)

    HARTMANN LÉO A.

    2003-01-01

    Full Text Available Valuable information is retrieved from the integrated investigation of the field relationships, microstructure and mineral compositions of harzburgites from the Neoproterozoic Cerro Mantiqueiras Ophiolite. This important tectonic marker of the geological evolution of southernmost Brazilian Shield was thoroughly serpentinized during progressive metamorphism, because the oldest mineral assemblage is: olivine + orthopyroxene + tremolite + chlorite + chromite. This M1 was stabilized in mid amphibolite facies - 550-600ºC as calculated from mineral equilibria. No microstructural (e.g. ductile deformation of olivine or chromite or compositional (e.g. mantle spinel remnant of mantle history was identified. A metamorphic event M2 occurred in the low amphibolite facies along 100 m-wide shear zones, followed by intense serpentinization (M3 and narrow 1-3 m-wide shear zones (M4 containing asbestos.

  11. Amphiboles of basic schists in the Sanbagawa metamorphic terrain of the Kodama-Nagatoro area, Kanto mountains. Kanto sanchi Kodamater dot Nagatoro chiiki no Sanbagawa enkisei hengan no kakusenseki

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, M.; Funakoshi, R. (Hitachi Ltd., Tokyo (Japan))

    1991-10-01

    On the basis of mineral parageneses and the graphitizing degrees of pelitic and psammitic schists, the Sambagawa metamorphic terrain of the Kodama-Nagatoro area in Kanto mountains is divided into three zones, i.e. Zone l (chlorite zone), Zone 2 (garnet zone) and Zone 3 (biotite zone) in the order of lower temperature. Amphibole of basic schists is actinolite in Zone 1. The range of composition variance widens gradually with the increase in the temperature, ranging from actinolite to hornblend in Zone 2, and from actinolite to barroisite through actinolitic hornblend in Zone 3. The amount of Al in amphiboles increases gradually with the increase in temperature. The lowest value becomes higher with the widening of the range of variation towards higher side. The metamorphosis in this area is assumed to have taken place principally under increasing temperature with slight increase in pressure. 21 refs., 8 figs.

  12. Paragenesis of sodic pyroxene-bearing quartz schists: implications for the P-T history of the Sanbagawa belt

    Science.gov (United States)

    Enami, Masaki; Wallis, Simon R.; Banno, Yasuyuki

    1994-03-01

    Sodic pyroxene (jadeite content X jd=0.1 0.3) occurs locally as small inclusions within, albite porphyroblasts and in the matrix of hematite-bearing quartz schists in the Sanbagawa (Sambagawa) metamorphic belt, central Shikoku, Japan. The sodic, pyroxene-bearing samples are characteristically free from chlorite and their typical mineral assemblage is sodic pyroxene+subcalcic (or sodic) amphibole+phengitic mica+albite+quartz+hematite+titanite±epidote. Spessartine-rich garnet occurs in Mn-rich samples. Sodic pyroxene in epidote-bearing samples tends to be poorer in acmite content (average X Acm=0.26 0.50) than that in the epidote-free samples ( X Acm=0.45 0.47). X Jd shows no systematic relationship to metamorphic grade, and is different among the three sampling regions [Saruta-gawa, Asemi-gawa and Bessi (Besshi)]. The average X Jd of the Saruta-gawa samples (0.21 0.29) is higher than that of the Asemi-gawa (0.13 0.17) and Bessi (0.14 0.23). The P-T conditions of the Asemi-gawa and Bessi regions are estimated at 5.5 6.5 kbar, >360°C in the chlorite zone, 7 8.5 kbar, 440±15°C in the garnet zone and 8 9.5 kbar, 520±25°C in the albite-biotite zone. Metamorphic pressure of the Saruta-gawa region is systematically 1 1.5 kbar higher than that of the Asemi-gawa and Bessi regions, and materials of the Saruta-gawa region have been subducted to a level 3 5 km deeper than materials that underwent metamorphism at equivalent temperatures and are now exposed in the Asemi-gawa and Bessi regions. Pressure slightly increases toward the north (structurally high levels) through the Sanbagawa belt of central shikoku. Two types of zonal structure were observed in relatively coarse-grained sodic pyroxenes in the matrix. One type is characterized by increasing X Jd from core to rim, the other type by decreasing X Jd from core to rim. Both types of zoned pyroxenes show an increase in X Fe 2+[=Fe2+/(Fe2++Mg)] from core to rim. The first type of zoning was observed in a sample from the

  13. Co-evolution of monsoonal precipitation in East Asia and the tropical Pacific ENSO system since 2.36 Ma: New insights from high-resolution clay mineral records in the West Philippine Sea

    Science.gov (United States)

    Yu, Zhaojie; Wan, Shiming; Colin, Christophe; Yan, Hong; Bonneau, Lucile; Liu, Zhifei; Song, Lina; Sun, Hanjie; Xu, Zhaokai; Jiang, Xuejun; Li, Anchun; Li, Tiegang

    2016-07-01

    Clay mineralogical analysis and scanning electron microscope (SEM) analysis were performed on deep-sea sediments cored on the Benham Rise (core MD06-3050) in order to reconstruct long-term evolution of East Asian Summer Monsoon (EASM) rainfall in the period since 2.36 Ma. Clay mineralogical variations are due to changes in the ratios of smectite, which derive from weathering of volcanic rocks in Luzon Island during intervals of intensive monsoon rainfall, and illite- and chlorite-rich dusts, which are transported from East Asia by winds associated with the East Asian Winter Monsoon (EAWM). Since Luzon is the main source of smectite to the Benham Rise, long-term consistent variations in the smectite/(illite + chlorite) ratio in core MD06-3050 as well as ODP site 1146 in the Northern South China Sea suggest that minor contributions of eolian dust played a role in the variability of this mineralogical ratio and indicate strengthening EASM precipitation in SE Asia during time intervals from 2360 to 1900 kyr, 1200 to 600 kyr, and after 200 kyr. The EASM rainfall record displays a 30 kyr periodicity suggesting the influence of El Niño-Southern Oscillation (ENSO). These intervals of rainfall intensification on Luzon Island are coeval with a reduction in precipitation over central China and an increase in zonal SST gradient in the equatorial Pacific Ocean, implying a reinforcement of La Niña-like conditions. In contrast, periods of reduced rainfall on Luzon Island are associated with higher precipitation in central China and a weakening zonal SST gradient in the equatorial Pacific Ocean, thereby suggesting the development of dominant El Niño-like conditions. Our study, therefore, highlights for the first time a long-term temporal and spatial co-evolution of monsoonal precipitation in East Asia and of the tropical Pacific ENSO system over the past 2.36 Ma.

  14. Clay minerals in surface sediments of the Pearl River drainage basin and their contribution to the South China Sea

    Institute of Scientific and Technical Information of China (English)

    LIU ZhiFei; Christophe COLIN; HUANG Wei; CHEN Zhong; Alain TRENTESAUX; CHEN JianFang

    2007-01-01

    Clay minerals have played a significant role in the study of the East Asian monsoon evolution in the South China Sea by being able to track oceanic current variations and to reveal contemporaneous paleoclimatic changes prevailing in continental source areas. As one of the most important rivers inputting terrigenous matters to the northern South China Sea, the Pearl River was not previously paid attention to from the viewpoint of clay mineralogy. This paper presents a detailed study on clay minerals in surface sediments collected from the Pearl River drainage basin (including all three main channels,various branches, and the Lingdingyang in the estuary) by using the X-ray diffraction (XRD) method.The results indicate that the clay mineral assemblage consists dominantly of kaolinite (35%-65%),lesser abundance of chlorite (20%-35%) and illite (12%-42%), and very scare smectite occurrences (generally <5%). Their respective distribution does not present any obvious difference throughout the Pearl River drainage basin. However, downstream the Pearl River to the northern South China Sea, the clay mineral assemblage varies significantly: kaolinite decreases gradually, smectite and illite increase gradually. Additionally, illite chemistry index steps down and illite crystallinity steps up. These variations indicate the contribution of major kaolinite, lesser illite and chlorite, and very scarce smectite to the northern South China Sea from the Pearl River drainage basin. The maximum contribution of clay minerals from the Pearl River is 72% to the northern margin and only 15% to the northern slope of the South China Sea. In both glacials and interglacials, kaolinite indicates that the ability of mechanical erosion occurred in the Pearl River drainage basin.

  15. Mineralogy, geochemistry and petrophysics of red coloured granite adjacent to fractures

    International Nuclear Information System (INIS)

    Mineralogical, geochemical and petrophysical investigations were conducted of red-coloured alteration rims and of the neighbouring unaltered equivalents along fractures within granite from Aespoe. An investigation was made also of a weak to rather strong, red-coloured granite from the Stripa mine, as well as a weak brownish-red colouration, definitely no hydrothermal in origin, of weathered rinds at a glacial polished rock surface in the Bohus granite. When approaching the fracture planes in the Aespoe granite, the most diagnostic alteration features are * the saussuritisation and Fe-oxyhydroxide staining of plagioclase, * the crystallisation chlorite pseudomorphs after biotite and * the hematisation of magnetite. The porosity within the alteration zones increases generally 2 to 3 times compared with the protolith rock, whereas the densities decrease by some 5 to 10%. The oxidation of magnetite gives as much as a tenfold lowering of the magnetic susceptibility. The red colouration of the Stripa granite is caused by hematite ± Fe-oxyhydroxide formation along microfractures, grain boundaries and, subordinately, the main minerals. Oxidation and re-precipitation of iron liberated during a retrograde muscovitisation of principally chlorite is interpreted to be the cause of the formation of the ferric oxides. The rather homogeneous density and porosity values of the grey and of the red-coloured granites reflect the minor change in the mineralogy when going from fresh into altered granite. Weathering and whitening of plagioclase in the bleached, outer zone and precipitation of small quantities of Fe-oxyhydroxides/hydroxides in the brownish-red zone cause the macroscopic colouration of the weathering rind below the glacial polished rock surface of Bohus granite. There is a marked increase in porosity from the interior fresh (c. 0.4-0.5%) towards the exterior bleached zone (c.1.5-2%) of the subaerialy, weathered Bohus granite surface. The incipient decomposition of

  16. Petrography and geochemical study of Nezam-Abad area, Southwest of Shazand, Arak

    Directory of Open Access Journals (Sweden)

    Robabeh Jafari

    2010-05-01

    Full Text Available Nezam-Abad area is located in southwest of Shazand (Arak which is a part of Sanandaj-Sirjan zone. Major intrusive rocks of Nezam-Abad are quartz diorite and minor amount of granodiorite. Leucogranitic, pegmatite dykes and quartz-tourmaline veins were intruded the quartz diorite. Quartz diorites are mainly composed of plagioclase, hornblende, biotite, quartz and pyroxene as major minerals. Major minerals of leucogranite are microcline, orthoclase, albite, quartz, biotite and muscovite. Accessory minerals consist of apatite, zircon, sphene, epidote, allanite, tourmaline and opaque. The presence of hydrous minerals like hornblende and biotite in these rocks indicate that the corresponding magma initially contained >3 wt% H2O (wet magma. The occurrences of garnet and andalusite minerals suggest assimilation process. Primary textures in these rocks are granular, granophyre, and poikilitic. Secondary textures are perthite, myrmekite, sericitization, chloritization and kaolinitization. Later hydrothermal activities and tectonic strains are factors for presence of perthite texture in leucogranite. K amount for sericitization of feldspars come from the K-feldspars and chloritization of biotite. Transformation of biotite to muscovite indicates the act of K rich fluid in later stages. On the basis of chemical analysis on the intrusive rocks, it is shown that the magma was calc-alkaline, metaluminous-peraluminous and medium-K to high-K. Study of major elements in Harker diagrams indicates Al2O3, FeO, Fe2O3 and CaO decrease with increasing of SiO2 and K2O and Na2O increase indicating that fractional crystallization may have played an important role in the formation of granitoid rocks from Nezam-Abad.

  17. Environmental effect and genetic influence: a regional cancer predisposition survey in the Zonguldak region of Northwest Turkey

    Science.gov (United States)

    Kadir, Selahattin; Önen-Hall, A. Piril; Aydin, S. Nihal; Yakicier, Cengiz; Akarsu, Nurten; Tuncer, Murat

    2008-03-01

    The Cretaceous-Eocene volcano-sedimentary units of the Zonguldak region of the western Black Sea consist of subalkaline andesite and tuff, and sandstone dominated by smectite, kaolinite, accessory chlorite, illite, mordenite, and analcime associated with feldspar, quartz, opal-CT, amphibole, and calcite. Kaolinization, chloritization, sericitization, albitization, Fe-Ti-oxidation, and the presence of zeolite, epidote, and illite in andesitic rocks and tuffaceous materials developed as a result of the degradation of a glass shards matrix, enclosed feldspar, and clinopyroxene-type phenocrysts, due to alteration processes. The association of feldspar and glass with smectite and kaolinite, and the suborientation of feldspar-edged, subparallel kaolinite plates to fracture axes may exhibit an authigenic smectite or kaolinite. Increased alteration degree upward in which Al, Fe, and Ti are gained, and Si, Na, K, and Ca are depleted, is due to the alteration following possible diagenesis and hydrothermal activities. Micromorphologically, fibrous mordenite in the altered units and the presence of needle-type chrysotile in the residential buildings in which cancer cases lived were detected. In addition, the segregation pattern of cancer susceptibility in the region strongly suggested an environmental effect and a genetic influence on the increased cancer incidence in the region. The most likely diagnosis was Li-Fraumeni syndrome, which is one of the hereditary cancer predisposition syndromes; however, no mutations were observed in the p53 gene, which is the major cause of Li-Fraumeni syndrome. The micromorphology observed in the altered units in which cancer cases were detected may have a role in the expression of an unidentified gene, but does not explain alone the occurrence of cancer as a primary cause in the region.

  18. Discovery of the Jabiluka uranium deposits, East Alligator River Region, Northern Territory of Australia

    International Nuclear Information System (INIS)

    The Jabiluka One and Two uranium deposits occur in Lower Proterozoic metasediments of the Cahill Formation. The observed part of the Cahill Formation exhibits four horizons which are favourable hosts for uranium mineralization. The host rocks are mainly chlorite and/or graphite schists and their brecciated equivalents which have undergone initial regional prograde metamorphism to amphibolite facies, then retrograde metamorphism to greenschist facies. Mineralization consists of uraninite, mainly filling open spaces and to a lesser extent in disseminated form. Chlorite alteration is intimately associated with the uranium mineralization. A portion of the Jabiluka Two deposit contains economic concentrations of gold. Although the deposits are generally stratabound, structural preparation appears to be the most significant ore control on a local scale. The Jabiluka case history illustrates an effective philosophy which was successful in exploration for stratabound uranium deposits in the East Alligator River Region. This philosophy encompassed the following points: (a) The value of regional appraisals in selection of a property; (b) The recognition of the detection limits of airborne radiometric surveys; (c) The importance of ground prospecting for low-order point-source radiometric anomalies which cannot be detected by airborne survey; (d) The importance of evaluating all anomalies and the flexibility to change priorities as further exploration results are obtained; (e) The necessity of establishing the controls on the mineralization before proceeding with further exploration; (f) The necessity of exploring extensions of favourable lithologies to test for periodicity of mineralization even where cover precludes surface expression; and (g) The desirability for modification of exploration techniques on different types of anomalies

  19. Time of flight secondary ion mass spectrometry and high-resolution transmission electron microscopy/energy dispersive spectroscopy: A preliminary study of the distribution of Cu{sup 2+} and Cu{sup 2+}/Pb{sup 2+} on a Bt horizon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Cerqueira, B.; Vega, F.A. [Department of Plant Biology and Soil Science, Faculty of Biology, University of Vigo, Lagoas, Marcosende, 36310 Vigo, Pontevedra (Spain); Serra, C. [CACTI, University of Vigo, Campus Lagoas-Marcosende, 36310 Vigo (Spain); Silva, L.F.O. [Environmental Science and Nanotechnology Department, Catarinense Institute of Environmental Research and Human Development - IPADHC, Capivari de Baixo, Santa Catarina (Brazil); Andrade, M.L., E-mail: mandrade@uvigo.es [Department of Plant Biology and Soil Science, Faculty of Biology, University of Vigo, Lagoas, Marcosende, 36310 Vigo, Pontevedra (Spain)

    2011-11-15

    Highlights: {yields} TOF-SIMS and HR-TEM/EDS allow checking which soil components retain heavy metals. {yields} Pb{sup 2+} favorably competes for the soil sorption sites. Mainly in oxides and clay. {yields} Cu{sup 2+} and Pb{sup 2+} are associated with hematite, gibbsite, vermiculite and chlorite. {yields} This study serves as a basis for further research on soil sorption of heavy metals. - Abstract: Relatively new techniques can help in determining the occurrence of mineral species and the distribution of contaminants on soil surfaces such as natural minerals and organic matter. The Bt horizon from an Endoleptic Luvisol was chosen because of its well-known sorption capability. The samples were contaminated with Cu{sup 2+} and/or Pb{sup 2+} and both sorption and desorption experiments were performed. The preferential distribution of the contaminant species ({sup 63}Cu and {sup 208}Pb) to the main soil components and their associations were studied together with the effectiveness of the surface sorption and desorption processes. The results obtained were compared with non-contaminated samples as well as with previous results obtained by different analytical techniques and advanced statistical analysis. Pb{sup 2+} competes favorably for the sorption sites in this soil, mainly in oxides and the clay fraction. Cu{sup 2+} and Pb{sup 2+} were mainly associated with hematite, gibbsite, vermiculite and chlorite. This study will serve as a basis for further scientific research on the soil retention of heavy metals. New techniques such as spectroscopic imaging and transmission electron microscopy make it possible to check which soil components retain heavy metals, thereby contributing to propose effective measures for the remediation of contaminated soil.

  20. Geology of Wadi Wassif Area, Central Eastern Desert, Egypt, With Emphasis on Mineralogy of Stream Sediments

    International Nuclear Information System (INIS)

    This study deals with the geology and mineralogy of stream sediments at Wadi Wassif, C.E.D., Egypt. The area is built up of igneous and metamorphic rocks of Late Precambrian age in addition to Quaternary alluviam deposits. Geologically, the area consists of metavolcanics, older granitoids, Hammamat sediments, younger granites, and Quaternary sediments filling the streams of the studied area. Microscopically, metavolcanics comprise meta andesite, metadacite and crystal tuffs. They are weakly metamorphosed to the green schist facies (chlorite zone). Hammamat sediments comprise conglomerate, sandstone, siltstone and mud stone. They are weakly metamorphosed to the chlorite zone of the green schist facies. Gravity and magnetic separation techniques in addition to microscopic examination for the studied stream sediment samples were applied to evaluate the heavy minerals concentration of these sediments. The average heavy mineral concentration of the stream sediments of Wadi Wassif is 5.56%, ranging from 1.58% and 10.91%. These heavy minerals increase from upstream to downstream of Wadi Wassif. The average contents of the concerned heavy minerals in Wadi Wassif are 0.347% for zircon, 0.058% for thorite, 0.074% for monazite, 0.097 for titanite, 0.038% for rutile. The other heavy minerals include epidot, garnet in addition to opaque minerals; magnetite, ilmenite and hematite. The radiometric study of the stream sediments of Wadi Wassif indicates that the average concentrations of U and Th are 2.9ppm and 17ppm respectively, ranging from 1 to 4ppm for U and 8 to 28ppm for Th, which reveals a significant fractionation during weathering of these sediments.

  1. Mineralogical variations across Mariano Lake roll-type uranium deposits, McKinley County

    International Nuclear Information System (INIS)

    Mineralogy of core samples from the Mariano orebody was determined. The data obtained were used to develop exploration tools for roll-type uranium deposits. Preliminary interpretations of the physical and chemical conditions of ore deposition were made on the basis of paragenetic relationships. The host sandstones occur between the bentonitic rock units and contain scattered intercalations of detrital montmorillonitic material in the form of clay galls, stringers, and lenses derived from these bentonites. Authigenic clay minerals identified in the host rocks include cellular montmorillonite, platy chlorite, and pseudohexagonal books of kaolinite. The cellular montmorillonite is concentrated in the oxidized zone and appears to have formed prior to ore deposition. Authigenic chlorite is most abundant in the ore zone and has formed at the expense of cellular montmorillonite; its formation is interpreted as being related to the ore-forming processes. Kaolinite in sandstones is the last clay mineral to form and is enriched in the reduced zone. Calcite, considered typical of such deposits, is not found in this orebody. Iron-titanium oxides and their alteration products are the most abundant heavy-mineral species in the host rocks. In addition to anatase and rutile, the alteration products include hematite in the oxidized zone and pyrite in the ore and reduced zones. Carbonaceous material introudced later into the potential ore zone appears to have been responsible for the decomposition of Fe-Ti oxides and the formation of pyrite. The paragenetic relationship indicates oxidation of pyrite by mineralizing solutions, resulting in reduction and subsequent deposition of uranium. The positive correlation between organic carbon and uranium suggests that carbonaceous material also acted as a reductant for uranium

  2. Uranium deposits of Turamdih- Nandup area, Singhbhum district, Bihar and their spatial relationship

    International Nuclear Information System (INIS)

    The Turamdih-Nandup cluster of uranium deposits covering an area of 3.5 km2 in the western part of the Singhbhum shear zone includes low grade deposits of Turamdih (east, south, and west), Keruadungri west, central Keruadungri, and Nandup, holding a substantial part of the estimated uranium reserves of India. Chlorite-quartz schist with magnetite and apatite is the most common host for mineralization, besides chlorite-sericite-quartz schist and to a lesser extent feldspathic schist, all belonging to the Dhalbhum formation of lower proterozoic - late Archaean age. Surface structures indicate that the superimposition of at least three deformational episodes have resulted in transposing the ore body at different levels and shapes in the different sectors of the deposits. The overall structure deciphered in the area is a major asymmetrical synform, trending NW-SE. The uranium lodes are essentially parallel or subparallel to the schistosity. Sericite schists mark the lower part of the mineralized horizon in the subsurface. Evaluation and synthesis of surface and sub-surface data on lithological controls, geometry of the ore horizons, and nature of mineralisation from over 500 boreholes have revealed that the mineralisation in different blocks is in fact the manifestation of single ore body. Uranium mineralisation is of low grade (0.03-0.04 % U3O8), but is compensated by large thickness of ore horizons, some measuring up to 120 m. Further, ore horizons at places, occur very near to the surface making them easily amenable for open cast mining. (author). 18 refs., 7 figs., 2 tabs

  3. Systematic evaluation of satellite remote sensing for identifying uranium mines and mills

    International Nuclear Information System (INIS)

    In this report, we systematically evaluate the ability of current-generation, satellite-based spectroscopic sensors to distinguish uranium mines and mills from other mineral mining and milling operations. We perform this systematic evaluation by (1) outlining the remote, spectroscopic signal generation process, (2) documenting the capabilities of current commercial satellite systems, (3) systematically comparing the uranium mining and milling process to other mineral mining and milling operations, and (4) identifying the most promising observables associated with uranium mining and milling that can be identified using satellite remote sensing. The Ranger uranium mine and mill in Australia serves as a case study where we apply and test the techniques developed in this systematic analysis. Based on literature research of mineral mining and milling practices, we develop a decision tree which utilizes the information contained in one or more observables to determine whether uranium is possibly being mined and/or milled at a given site. Promising observables associated with uranium mining and milling at the Ranger site included in the decision tree are uranium ore, sulfur, the uranium pregnant leach liquor, ammonia, and uranyl compounds and sulfate ion disposed of in the tailings pond. Based on the size, concentration, and spectral characteristics of these promising observables, we then determine whether these observables can be identified using current commercial satellite systems, namely Hyperion, ASTER, and Quickbird. We conclude that the only promising observables at Ranger that can be uniquely identified using a current commercial satellite system (notably Hyperion) are magnesium chlorite in the open pit mine and the sulfur stockpile. Based on the identified magnesium chlorite and sulfur observables, the decision tree narrows the possible mineral candidates at Ranger to uranium, copper, zinc, manganese, vanadium, the rare earths, and phosphorus, all of which are

  4. Magnitude and symmetry of seismic anisotropy in mica- and amphibole-bearing metamorphic rocks and implications for tectonic interpretation of seismic data from the southeast Tibetan Plateau

    Science.gov (United States)

    Ji, Shaocheng; Shao, Tongbin; Michibayashi, Katsuyoshi; Oya, Shoma; Satsukawa, Takako; Wang, Qian; Zhao, Weihua; Salisbury, Matthew H.

    2015-09-01

    We calibrated the magnitude and symmetry of seismic anisotropy for 132 mica- or amphibole-bearing metamorphic rocks to constrain their departures from transverse isotropy (TI) which is usually assumed in the interpretation of seismic data. The average bulk Vp anisotropy at 600 MPa for the chlorite schists, mica schists, phyllites, sillimanite-mica schists, and amphibole schists examined is 12.0%, 12.8%, 12.8%, 17.0%, and 12.9%, respectively. Most of the schists show Vp anisotropy in the foliation plane which averages 2.4% for phyllites, 3.3% for mica schists, 4.1% for chlorite schists, 6.8% for sillimanite-mica schists, and 5.2% for amphibole schists. This departure from TI is due to the presence of amphibole, sillimanite, and quartz. Amphibole and sillimanite develop strong crystallographic preferred orientations with the fast c axes parallel to the lineation, forming orthorhombic anisotropy with Vp(X) > Vp(Y) > Vp(Z). Effects of quartz are complicated, depending on its volume fraction and prevailing slip system. Most of the mica- or amphibole-bearing schists and mylonites are approximately transversely isotropic in terms of S wave velocities and splitting although their P wave properties may display orthorhombic symmetry. The results provide insight for the interpretation of seismic data from the southeast Tibetan Plateau. The N-S to NW-SE polarized crustal anisotropy in the Sibumasu and Indochina blocks is caused by subvertically foliated mica- and amphibole-bearing rocks deformed by predominantly compressional folding and subordinate strike-slip shear. These blocks have been rotated clockwise 70-90° around the east Himalayan Syntaxis, without finite eastward or southeastward extrusion, in responding to progressive indentation of India into Asia.

  5. Petrology and radiogeology of the Stripa pluton

    International Nuclear Information System (INIS)

    Both the quartz monzonite and the metavolcanic leptite which it intruded are strongly fractured. Two stages of fracture filling are evident; an earlier stage encompassing quartz, sericite, feldspar, epidote, and chlorite, and a later stage dominated by carbonate minerals. The Stripa quartz monozite is chemically and mineralogically distinct from other plutons in the region. Muscovite is the predominant mica in the quartz monzonite; biotite has been altered to chlorite, hornblende is absent, and accessory minerals are scarce. In contrast, in other plutons in the Stripa region, biotite and hornblende are prominent mafic minerals and accessory minerals are abundant. The Stripa quartz monzonite is also considerably more radioactive than the the leptite and other plutons in the region. Uranium and thorium abundances are both approx. 30 ppM, considerably higher than in normal granitic rocks where the thorium-to-uranium ratio generally exceeds 2. Potassium-argon dating of muscovite from the Stripa quartz monzonite indicates that this rock may be older, at 1691 million years than granitic rock of the neighboring Gusselby and Kloten massifs, whose ages, based on K-Ar dating of biotite, are respectively 1604 and 1640 m.y. Heat flow and heat productivity considerations show that although Stripa quartz monzonite contains high abundances of radioelements, the pluton has little efect on the regional heat flow. If it occurs in a layered plutonic setting, it is not more than 1.5 km thick; otherwise it may comprise a stock, dike, or border phase that is relatively small compared with the large granitic plutons exposed in the region

  6. Validation of intervention strategies to control Escherichia coli O157:H7 and Salmonella typhimurium DT 104 in mechanically tenderized and brine-enhanced beef.

    Science.gov (United States)

    Echeverry, Alejandro; Brooks, J Chance; Miller, Markus F; Collins, Jesse A; Loneragan, Guy H; Brashears, Mindy M

    2009-08-01

    After three different outbreaks were linked to the consumption of nonintact meat products contaminated with Escherichia coli O157:H7, the U.S. Department of Agriculture, Food Safety and Inspection Service published notice requiring establishments producing mechanically tenderized and moisture-enhanced beef products to reassess their respective hazard analysis and critical control point system, due to potential risk to the consumers. The purpose of this study was to determine the effectiveness of different intervention strategies (lactic acid, lactic acid bacteria, and acidified sodium chlorite) to control E. coli O157:H7 and Salmonella enterica serotype Typhimurium definitive phage type 104 in mechanically tenderized and brine-enhanced beef strip loins when applied to the steaks prior to packaging and shipment for processing. After the mechanical process, translocation of E. coli O157:H7 and Salmonella Typhimurium DT 104 from the surface into the internal muscles occurred at levels between 2.0 and 4.0 log CFU/g (from an initial inoculation level of 5.0 log) after mechanical tenderization, and at levels of 1.0 to 3.0 log CFU/g after injection, with all the interventions consistently presenting lower microbial counts (P 2.2 log cycles, while the acidified sodium chlorite and lactic acid reduced them between 0.8 and 3.0 log, respectively. Salmonella Typhimurium DT 104 was also reduced internally after application of all interventions between 0.9 and 2.2 log. The application of antimicrobials to the steaks prior to packaging and shipment on day 0 was effective in reducing internalization of both pathogens in nonintact beef products stored for both 14 and 21 days. PMID:19722392

  7. Mineralogy of the pollutant products formed in the Masca exploration area (Lower Iara Valley Basin, Cluj County, Romania

    Directory of Open Access Journals (Sweden)

    Lucret̡ia Ghergari

    2004-04-01

    Full Text Available In the present study the mineralogy of a tailing dam situated in the Maşca mining area is discussed. Our aim was to point out the physicochemical processes, which occur under the action of the exogenous factors. The studied samples were collected from different levels of the dam wall, from the Maşca mine and Iara river waters. The applied analytical methods are: transmission polarized microscopy, transmission electron microscopy, X-ray diffractometry, and atomic absorption spectrometry. The physicochemical parameters have been measured in situ and in the laboratory. The minerals present in the tailings are represented by: garnets (andradite-grossular and almandine series, diopside, hedenbergite, actinolite, tremolite, epidote, zoisite, biotite, phlogopite, serpentine minerals, chlorite, tourmaline, quartz, feldspar, anatase, apatite and opaque minerals (pyrrhotite, pyrite, magnetite and hematite. The carbonate minerals belonging to the mining waste are represented mostly by dolomite and subordinately by calcite. The identified neoformation minerals formed as a result of the action of the exogenous factors are the following: illite, illite/smectite, nontronite, palygorskite, chlorite-vermiculite, gypsum, epsomite, hexahydrite, wattevillite, ferrohexahydrite, hallotrichite, bilinite(?, goethite and amorphous iron hydroxide. The chemical analyses undertaken on the water samples show high values of the soluble salts (Na+, K+, Ca2+, Mg2+, and SO42- and heavy metals (Cu2+, Pb+, Fe2+, Fe3+, and Zn2+ contents, exceeding international and national guidelines. Although the pH of the streams originating from the mine area vary between neutral to slightly alkaline, pollution occurs and significantly impacts the mineralized area as well as the neighboring areas.

  8. Mineral Sequestration of Carbon Dixoide in a Sandstone-Shale System

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tianfu; Apps, John A.; Pruess, Karsten

    2004-07-09

    A conceptual model of CO2 injection in bedded sandstone-shale sequences has been developed using hydrogeologic properties and mineral compositions commonly encountered in Gulf Coast sediments. Numerical simulations were performed with the reactive fluid flow and geochemical transport code TOUGHREACT to analyze mass transfer between sandstone and shale layers and CO2 immobilization through carbonate precipitation. Results indicate that most CO2 sequestration occurs in the sandstone. The major CO2 trapping minerals are dawsonite and ankerite. The CO2 mineral-trapping capacity after 100,000 years reaches about 90 kg per cubic meter of the medium. The CO2 trapping capacity depends on primary mineral composition. Precipitation of siderite and ankerite requires Fe+2 supplied mainly by chlorite and some by hematite dissolution and reduction. Precipitation of dawsonite requires Na+ provided by oligoclase dissolution. The initial abundance of chlorite and oligoclase therefore affects the CO2 mineral trapping capacity. The sequestration time required depends on the kinetic rate of mineral dissolution and precipitation. Dawsonite reaction kinetics is not well understood, and sensitivity regarding the precipitation rate was examined. The addition of CO2 as secondary carbonates results in decreased porosity. The leaching of chemical constituents from the interior of the shale causes slightly increased porosity. The limited information currently available for the mineralogy of natural high-pressure CO2 gas reservoirs is also generally consistent with our simulation. The ''numerical experiments'' give a detailed understanding of the dynamic evolution of a sandstone-shale geochemical system.

  9. Influences of petrographic parameters on technological properties of greywackes used for crushed stone production

    Science.gov (United States)

    Prikryl, Richard; Cermak, Martin; Krutilova, Katerina

    2014-05-01

    This study focuses on the influence of petrographic parameters on technological properties of greywackes. These sedimentary rocks make about 27 % of crushed stone market in the Czech Republic. Mainly in Moravia (eastern part of the Czech Republic), greywackes represent almost exclusive high quality aggregate. The behaviour of greywackes varies, however, from quarry to quarry. In this study, we have selected the most important deposits that cover major lithological variation of local greywackes. Studied greywackes were analysed for their petrographic parameters quantitatively (using image analysis of thin sections). The pore space characteristics were determined by using fluorescent dye - epoxy resin impregnated specimens. The studied rocks are composed of subangular and angular quartz grains, lithoclasts (stable rocks: quartzites, and unstable rocks: phylites, metaphylites, siltstones, slates, greywackes, and less frequently acid eruptive rocks), feldspars (orthoclas, microcline, plagioclase), and detrital micas. Detrital and authigenic chlorite has been found as well. The matrix which represents the largest volume of rock-forming components contains a mixture of sericite, chlorite, clay minerals, cements, and clasts in aleuropelitic size. Based on the microscopic examination, all studied rock types were classified as greywacke with fine- to medium-grained massive rock fabric. Only specimen from Bělkovice has shown partly layered structure. Alteration of feldspars and unstable rock fragments represents common feature. Diagenetic features included pressure dissolution of quartz clasts and formation of siliceous and/or calcite cements. Based on the experimental study of technological performance of studied greywackes and its correlation to petrographic features, the average size of clasts and volume of matrix make the driving factors affecting the LA values. The LA values decrease with the increasing of volume of matrix (R = 0.61) and with decreasing average grain

  10. The compositions of minerals within high pressure tectonic blocks from Horse Mountain, Northern California

    Energy Technology Data Exchange (ETDEWEB)

    Gilliam, C.E. (Mount Holyoke College, South Hadley, MA (United States). Geology Dept.)

    1993-03-01

    High pressure metamorphic blocks occur within serpentinite between the South Fork Mountain Schist and the Coast Range Fault, Humboldt Co., Northern California. Samples from three of these blocks were studied by petrographic techniques and quantitatively analyzed using the energy dispersive spectrometer on out scanning electron microscope. The mineral assemblages for three samples are as follows: WC86-7-3 contains omphacite (jd53, di36, hd11), pumpellyite, and relic igneous clinopyroxene. WC86-9-3 contains titanite, epidote chlorite, pumpellyite, and relic clinopyroxene. WC86-18-3 contains garnet, lawsonite, glaucophane, albite, chlorite, pumpellyite, minor quartz, and relic clinopyroxene. All samples contain relic clinopyroxene that, in the case of SC86-7-3, acts as a nucleus for omphacite growth. When present in cross cutting veins, omphacite has both radiating fibrous and blocky textures. Some epidote, titanite, clinopyroxene and pumpellyite were too fine to identify optically as well, but occur in the ground mass. Large grains of euhedral glaucophane, (Na[sub 2.0] Ca[sub .2])(Mg[sub 1.3] Fe[sub 2.0] Al[sub 1.7])Si[sub 8.0] O[sub 22] (OH)[sub 2], and garnet, (alm 33, pyO, sp30, gr37), containing relic ( ) clinopyroxene, glaucophane, and albite inclusions, were present in WC86-18-3. The high SiO[sub 2] and low TiO[sub 2] relative to Al[sub 2]O[sub 3] in relic clinopyroxene indicates a non-alkaline tholeiitic protolith. Omphacite compositions correspond to the type IV blueschist typical of the Franciscan Complex and constrain the pressures of metamorphism to be approximately 9 kb while lawsonite in WC86-18-3 implies a temperature below 450C. These observations indicate that the blocks are derived from subducted material that underwent metamorphism in a low temperature, high pressure setting. The process of their exhumation remains a mystery.

  11. Rock magnetic expression of fluid infiltration in the Yingxiu-Beichuan fault (Longmen Shan thrust belt, China)

    Science.gov (United States)

    Yang, Tao; Yang, Xiaosong; Duan, Qingbao; Chen, Jianye; Dekkers, Mark J.

    2016-03-01

    Fluid infiltration within fault zones is an important process in earthquake rupture. Magnetic properties of fault rocks convey essential clues pertaining to physicochemical processes in fault zones. In 2011, two shallow holes (134 and 54 m depth, respectively) were drilled into the Yingxiu-Beichuan fault (Longmen Shan thrust belt, China), which accommodated most of the displacement of the 2008 Mw 7.9 Wenchuan earthquake. Fifty-eight drill core samples, including granitic host rock and various fault rocks, were analyzed rock-magnetically, mineralogically, and geochemically. The magnetic behavior of fault rocks appears to be dominated by paramagnetic clay minerals. Magnetite in trace amounts is identified as the predominant ferrimagnetic fraction in all samples, decreasing from the host rock, via fault breccia to (proto-)cataclasite. Significant mass-losses (10.7-45.6%) are determined for the latter two with the "isocon" method. Volatile contents and alteration products (i.e., chlorite) are enriched toward the fault core relative to the host rocks. These observations suggest that magnetite depletion occurred in these fault rocks—exhumed from the shallow crust—plumbed by fluid-assisted processes. Chlorite, interpreted to result from hydrothermal activity, occurs throughout almost the entire fault core and shows high coefficients of determination (R2 > 0.6) with both low and high-field magnetic susceptibility. Close relationships, with R2 > 0.70, are also observed between both low and high-field magnetic susceptibility and the immobile elements (e.g., TiO2, P2O5, MnO), H2O+, and the calculated mass-losses of fault rocks. Hence, magnetic properties of fault rocks can serve as proxy indicators of fluid infiltration within shallow fault zones.

  12. Hydrophilic characteristics of soft rock in deep mines

    Institute of Scientific and Technical Information of China (English)

    Guo Hongyun; Li Bing; Zhang Yumei; Wang Xinbo; Zhang Feng

    2015-01-01

    A series of water absorption tests on dried soft rock have been conducted by the intelligent testing system for water absorption tests in deep soft rock, including tests of water absorption with and without pres-sure. The results show that the water absorbing capacity of rock with a certain pressure is larger than that of rock without pressure; however, the relationship between the water absorbing percentage and the time can be expressed by w(t)=a(1-e-bt). In bi-logarithmic coordinates, the hydrophilic relationship with time in tests with pressure could be characterized by linearity, while they present concave or convex in tests without pressure. Based on the hypothesis that each influential factor is irrelevant and they have a linear correlation with the water absorbing capacity, we calculated the weight coefficient of each factor according to experimental results under different conditions. The calculations demonstrate that the effec-tive porosity, content of smectite and kaolinite are all positively correlated with the water absorption capacity of rock;meanwhile, the fractal dimension of the effective pores presents a negative correlation with the water absorption capacity of rock. The water absorption capacity with pressure increases with increasing illite, chlorite and chlorite/smectite formation and a decrease in illite/smectite formation and the fractal dimension of the effective pores, while it is opposite in tests without pressure. The weight coefficient of smectite is smallest among positive factors, and the fractal dimension of the effective pores is the smallest amongst the negative factors.

  13. Peptide biomarkers as evidence of perchlorate biodegradation.

    Science.gov (United States)

    Bansal, Reema; Crawford, Ronald L; Paszczynski, Andrzej J

    2011-02-01

    Perchlorate is a known health hazard for humans, fish, and other species. Therefore, it is important to assess the response of an ecosystem exposed to perchlorate contamination. The data reported here show that a liquid chromatography-mass spectrometry-based proteomics approach for the detection of perchlorate-reducing enzymes can be used to measure the ability of microorganisms to degrade perchlorate, including determining the current perchlorate degradation status. Signature peptides derived from chlorite dismutase (CD) and perchlorate reductase can be used as biomarkers of perchlorate presence and biodegradation. Four peptides each derived from CD and perchlorate reductase subunit A (PcrA) and seven peptides derived from perchlorate reductase subunit B (PcrB) were identified as signature biomarkers for perchlorate degradation, as these sequences are conserved in the majority of the pure and mixed perchlorate-degrading microbial cultures examined. However, chlorite dismutase signature biomarker peptides from Dechloromonas agitata CKB were found to be different from those in other cultures used and should also be included with selected CD biomarkers. The combination of these peptides derived from the two enzymes represents a promising perchlorate presence/biodegradation biomarker system. The biomarker peptides were detected at perchlorate concentrations as low as 0.1 mM and at different time points both in pure cultures and within perchlorate-reducing environmental enrichment consortia. The peptide biomarkers were also detected in the simultaneous presence of perchlorate and an alternate electron acceptor, nitrate. We believe that this technique can be useful for monitoring bioremediation processes for other anthropogenic environmental contaminants with known metabolic pathways. PMID:21115710

  14. Petrology and radiogeology of the Stripa pluton

    Energy Technology Data Exchange (ETDEWEB)

    Wollenberg, H.; Flexser, S.; Andersson, L.

    1980-12-01

    Both the quartz monzonite and the metavolcanic leptite which it intruded are strongly fractured. Two stages of fracture filling are evident; an earlier stage encompassing quartz, sericite, feldspar, epidote, and chlorite, and a later stage dominated by carbonate minerals. The Stripa quartz monozite is chemically and mineralogically distinct from other plutons in the region. Muscovite is the predominant mica in the quartz monzonite; biotite has been altered to chlorite, hornblende is absent, and accessory minerals are scarce. In contrast, in other plutons in the Stripa region, biotite and hornblende are prominent mafic minerals and accessory minerals are abundant. The Stripa quartz monzonite is also considerably more radioactive than the the leptite and other plutons in the region. Uranium and thorium abundances are both approx. 30 ppM, considerably higher than in normal granitic rocks where the thorium-to-uranium ratio generally exceeds 2. Potassium-argon dating of muscovite from the Stripa quartz monzonite indicates that this rock may be older, at 1691 million years than granitic rock of the neighboring Gusselby and Kloten massifs, whose ages, based on K-Ar dating of biotite, are respectively 1604 and 1640 m.y. Heat flow and heat productivity considerations show that although Stripa quartz monzonite contains high abundances of radioelements, the pluton has little efect on the regional heat flow. If it occurs in a layered plutonic setting, it is not more than 1.5 km thick; otherwise it may comprise a stock, dike, or border phase that is relatively small compared with the large granitic plutons exposed in the region.

  15. Systematic evaluation of satellite remote sensing for identifying uranium mines and mills.

    Energy Technology Data Exchange (ETDEWEB)

    Blair, Dianna Sue; Stork, Christopher Lyle; Smartt, Heidi Anne; Smith, Jody Lynn

    2006-01-01

    In this report, we systematically evaluate the ability of current-generation, satellite-based spectroscopic sensors to distinguish uranium mines and mills from other mineral mining and milling operations. We perform this systematic evaluation by (1) outlining the remote, spectroscopic signal generation process, (2) documenting the capabilities of current commercial satellite systems, (3) systematically comparing the uranium mining and milling process to other mineral mining and milling operations, and (4) identifying the most promising observables associated with uranium mining and milling that can be identified using satellite remote sensing. The Ranger uranium mine and mill in Australia serves as a case study where we apply and test the techniques developed in this systematic analysis. Based on literature research of mineral mining and milling practices, we develop a decision tree which utilizes the information contained in one or more observables to determine whether uranium is possibly being mined and/or milled at a given site. Promising observables associated with uranium mining and milling at the Ranger site included in the decision tree are uranium ore, sulfur, the uranium pregnant leach liquor, ammonia, and uranyl compounds and sulfate ion disposed of in the tailings pond. Based on the size, concentration, and spectral characteristics of these promising observables, we then determine whether these observables can be identified using current commercial satellite systems, namely Hyperion, ASTER, and Quickbird. We conclude that the only promising observables at Ranger that can be uniquely identified using a current commercial satellite system (notably Hyperion) are magnesium chlorite in the open pit mine and the sulfur stockpile. Based on the identified magnesium chlorite and sulfur observables, the decision tree narrows the possible mineral candidates at Ranger to uranium, copper, zinc, manganese, vanadium, the rare earths, and phosphorus, all of which are

  16. Uruguay geology contributions no. 3

    International Nuclear Information System (INIS)

    The recognised metals are regularly represented by Pb and Zn occurrences with the exception of Mina la Oriental (Cu) and Cerro Estela (Cu-Mo). All of them have as field rocks the volcano-sedimentary sequence of the Lavalleja Group. Three types of mineralizations are recognized: sulphurated amas linked to volcanism, limestones associated mineralizations, and structural controls. Moreover hidrothermalism explains many mineralizations, and is frequently linked to structural factors. Stratigraphy the mineralizations are located at different positions in the series. Apolonia and Chape at the base, Euritina, Reus and La Oriental are intermediate, Valencia Mines, Cu-Mo mineralization and the Mn occurrence at the topo At Apolonia the field rocks are basic metavulcanites. Three types of mineralizations are defined: dissemined Cu in the stockwerk made by chlorite and quartz, galene micro-amas in a epidotized metavulcanite and alteration of sulphurated chloritic levels. It can be classified as proximal sulphurated amas. At Chape the mineralization is fundamentally blende-galene-pyrite in a basic vulcanoclastites. Reus is found in black phyllites in a calcopelitic unit, being the mineralization formed by galene-pyrite. At Euritina the mineralization is made by malachite in a basic metavulcanite. Chape/Reus/Euritina are controled by structural factors associated to hidrothermalism of primary mineralizations. At Mine La Oriental the field rocks is a set of calcareous-chloritite-metamarges-jasper rocks. Mineralization is by Cu and belong to distal sulphurated amas. Valencia Mine is in dolomites with evidences 01emerging volcanic centers wich leed a dolomitic sedimentation. lt is mineralized with blende-galene. The mineralization Cu-Mo belongs to two types: the Mo is the result of periplutonic hidrothermalism and the Cu is associated to de volcano-sedimentary sequence. The Mn occurrences are associated to jasper levels and are constituted by pyrolusite and psilomelane.

  17. Hydrogeothermal characteristics of groundwater from Ribarska Banja spa, central Serbia

    Directory of Open Access Journals (Sweden)

    Dragišić Veselin S.

    2015-01-01

    Full Text Available Ribarska Banja spa is one of the most popular balneotherapy and recreation centers in Serbia. It features several thermal groundwater sources whose temperatures range from 26 to 54°C. The mineral content of these waters is low and their composition is of the SO4-Na or HCO3-Na type. Thermal water exploration has been conducted in the general area for many years, to assess the hydrogeothermal potential in order to extract larger amounts of thermal water for multiple uses. The hydrogeothermal system of Ribarska Banja spa was defined based on a synthesis of the results of comprehensive structural geology, geophysical, hydrogeological, hydrochemical and geothermal research. The primary groundwater reservoir of the hydrogeothermal system is comprised of tectonic zones (systems of faults and fractures within Cretaceous-Paleogene metamorphosed and non-metamorphosed rocks. The overlying hydrogeological and temperature barrier is made up of a series of low metamorphosed rocks (chlorite, chlorite-sericite schists, gabbros, etc., highly metamorphosed rocks (gneisses and Neogene clay and sand sediments. The system is recharged by infiltration of atmospheric precipitation and surface water at the highest elevations of Mt. Jastrebac. Investigations have also shown that the system’s heat source is younger granitoide intrusion spreading northwest of Ribarska Banja spa. Based on the quartz geothermometers, expected reservoir temperatures are in the range of 85-97°C that can be expected at a depth of 1.87 km. Total energy usage at Ribarska Banja spa is 31 TJ/y with thermal capacity of 1.65 MWt and utilization factor of 0.58. Geothermal gradient is 0,051°C/m, while heat flow density is 163.5 mW/m2. [Projekat Ministarstva nauke Republike Srbije, br. 43004

  18. Contribution of Clay mineralogy of Bengal Fan deposits at 8°N for understanding of Himalayan provenance and environmental conditions

    Science.gov (United States)

    Huyghe, Pascale; France-Lanord, Christian; IODP Expedition 354 Scientists

    2016-04-01

    The IODP 354 expedition (February-March 2015) focused on the middle part of the Bengal Fan (8°N). Seven sites were drilled along a 320 km- long transect and provided good recovery and excellent data to study both provenance of the material from the Himalayan orogeny and palaeoceanography linked to the Asian monsoon. Neogene sediments consist of an alternation of rapidly deposited, silty to muddy turbidites (10-100 cm/kyr) forming levees of channels intercalated with minor slowly deposited hemipelagic clays (1-2 cm/kyr), which may be found over the whole investigated area. Thick interlevee sand sheet units also occur between channel levees. The turbiditic sand, silt and clay have mineralogical signatures very similar to those of the modern Ganges and Brahmaputra rivers and are therefore relevant for reconstructing time series of erosion, weathering, and changes in Himalayan sources regions. Hemipelagic calcareous clays may provide additional information on environmental conditions throughout the Himalayan basin. Preliminar shipboard XRD analysis revealed that the clayey assemblages of sediments are relatively constant through the Neogene. Turbidite clay assemblages are dominated by detrital illite and chlorite as observed in the modern Himalayan rivers, suggesting that erosion conditions were relatively steady over the last 25 Ma. Hemipelagic clay assemblages vary from 1) identical to the illite-chlorite rich clays of turbidites, characteristic for Himalayan rivers, to 2) smectite rich assemblages enriched in iron and depleted in potassium, representing either more extreme sorting of the same material or input from another source. Further detailed investigation using decomposition of X-Ray diffraction (XRD) patterns reveals much more complex clay assemblages, especially great quantities of mixed-layers, the quantity and mineralogy of which varies and differs in the three depositional units as determined by turbidites levees, hemipelagic clayey beds and interlevees

  19. Quartz-sericite and argillic alterations at the Peschanka Cu-Mo-Au deposit, Chukchi Peninsula, Russia

    Science.gov (United States)

    Marushchenko, L. I.; Baksheev, I. A.; Nagornaya, E. V.; Chitalin, A. F.; Nikolaev, Yu. N.; Kal'ko, I. A.; Prokofiev, V. Yu.

    2015-05-01

    The porphyry Peschanka copper-molybdenum-gold deposit and the Nakhodka ore field located in the Baimka ore trend on the western Chukchi Peninsula are spatially related to monzonitic rocks of the Early Cretaceous Egdykgych Complex. Two types of quartz-sericite metasomatic rocks (QSR) have been identified at both the deposits and the ore field: (I) chlorite-quartz-muscovite rock with bornite and chalcopyrite (porphyry type) and (II) tourmaline-quartz-carbonate-muscovite ± phengite rock accompanied by veins with base-metal mineralization (subepithermal or transitional type), as well as carbonate-quartz-illite rock (argillic alteration) accompanied by veins with precious metal mineralization (epithermal type). The QSR I chlorite evolves from chamosite to clinochlore, which is caused by increasing H2S activity in mineralizing fluid and precipitation of sulfide minerals. The QSR I clinochlore is significantly depleted in silica as compared with that from the rocks affected by argillic alteration. The chemical composition of muscovite from both quartz-sericite alterations is similar. The QSR II carbonates evolve from calcite through dolomite to siderite, which results from the increasing activity of CO2 followed by the decreasing activity of H2S in mineralizing fluid. The Mn content in dolomite is similar to that in beresite (quartz-muscovite-carbonate-pyrite metasomatic rock) of the intrusion-related gold deposits. Illite from argillic alteration is depleted in Al as compared with that of postvolcanic epithermal Au-Ag deposits. However, carbonates from the discussed argillic alteration rhodochrosite and Mn-rich dolomite are similar to those from quartz-illite rock at postvolcanic epithermal Au-Ag deposits.

  20. Actinide and rare earth element characteristics of deep fracture zones in the Lac du Bonnet granitic batholith, Manitoba, Canada

    International Nuclear Information System (INIS)

    The history of major, trace, and actinide element mobility and fluid infiltration has been studied in two deep fractures (>1 km) in the Lac du Bonnet batholith as part of the Canadian Nuclear Fuel Waste Management Program. Core samples collected from two fracture zones, FR1 and FR2 (∼1,175 m deep), containing saline groundwater (TDS = 50 g/L) were investigated mineralogically, chemically, and isotopically (238U-series, O and H). Several sequentially overprinting alteration states were identified from early high-temperature to later low-temperature hydrothermal alteration. K-feldspar, illite, chlorite, and later kaolinite formed during these stages. Subsequent infiltration of oxidizing fluids produced alteration of the chlorite to hydrous iron oxides. Fracture zone FR1 contains predominantly hematite coating; fracture zone FR2 is characterized by the formation of a breccia and by an intense alteration of the granite in contact with this breccia to illitic clay. Alteration occurred during infiltration either of formation brines or of isotopically evolved meteoric water where δ18O = 8 to 12 per-thousand and δD = -65 to -20 per-thousand, at calculated temperatures between ∼250 and ≤25 degrees C. Pronounced disequilibria of 234U/238U (230Th/234U (∼0.7), and 226Ra/230Th (∼0.9) exist in the illitic clay, indicating loss of 234U, 230Th, and 226Ra to the groundwater within the last 1.5 Ma. In contrast, an excess of 234U, 230Th, and 226Ra was measured in the brecciated samples. The disequilibria are consistent with a model involving loss of 234U, 230Th, and 226Ra to groundwater by α-recoil from U deposited on the illitic clay surfaces. These radionuclides were deposited subsequently in the nearby brecciated zone. 51 refs., 11 figs., 8 tabs

  1. Cement/bentonite interaction. Results from 16 month laboratory tests

    International Nuclear Information System (INIS)

    The work concerns possible bentonite clay mineral alteration in constructions with bentonite in close contact with cement, and the effect of such changes on bentonite buffer properties. The investigation comprises a 16 months laboratory test series with hydrothermal cell tests, percolation tests and diffusion tests. MX-80 Wyoming bentonite was used in all tests. Two types of artificial cement pore water solutions were used in the percolation and diffusion tests. The swelling pressure and the hydraulic conductivity were measured continuously in the percolation tests. After termination, the clay was analyzed with respect to changes in element distribution, mineralogy and shear strength. The water solutions were analyzed with respect to pH, cations and major anions. The results concerning chemical and mineralogical changes are in summary: Ion exchange in the montmorillonite until equilibrium with cement pore-water ions was reached; Increase in cation exchange capacity; Dissolution of original cristobalite; Increase in quartz content; Minor increase in illite content; Minor formation of chlorite; Formation of CSH(I); Wash away of CSH-gel into surrounding water. A large decrease in swelling pressure and a moderate increase in hydraulic conductivity were recorded in the samples percolated by SULFACEM pore-water solution. The mineralogical alterations only concerned a minor part of the total bentonite mass and the changes in physical properties were therefore most likely due to the replacement of the original charge balancing cation by cement pore-water cations. Comparisons between the current test result and results from 4 month tests indicate that the rates of illite and chlorite formation were reduced during the tests. The presence of zeolites in the clay could not be ensured. However, the discovery of CSH material is important since CSH is expected to precede the formation of zeolites

  2. Alteration and petrology of Intrusive Rocks associated with Gold Mineralization at Kuh-E-Zar Gold Deposit, Torbat-e-Heydaryeh

    Directory of Open Access Journals (Sweden)

    Alireza Mazloumi Bajestani

    2009-09-01

    Full Text Available Kuh- e -Zar gold deposit located 35 km west of Torbat-e-Heydaryeh, (Khorassan e- Razavi province, East of Iran. This deposit is a specularite-rich Iron oxide type (IOCG. This mine is situated within Khaf-Bardascan volcanic plutonic belt. Based on recent exploration along this belt, several IOCG type system plus Kuh-e-Zar deposit are discovered. In the study area, several type of tuff and lava having acid to intermediate composition are identified (upper Eocene. Oligo-Miocene granite, granodiorite, synogranite and monzonite intruded upper Eocene andesite-dacite-rhyolite. Intrusive rocks are meta-aluminous, medium to high-K series I-type. Based on spider diagram, intrusive rocks show enrichment in LILE = K, Th, Rb and depletion in HFSE = Nb, Sr, Ti. Based geochemistry of igneous rock, they formed in continental margin subduction zone. Propylitic (chlorite alteration is dominated and covers large area. Silicification is restricted only to mineralized zones. Argillic and albitization is found in certain location and cover small areas. The style of mineralization was controlled by the type and geometry of fault zones. Mineralization is found as vein, stockwork and breccias. Hypogene mineral Paragenesis include: specularite-quartz-gold-chlorite ± chalcopyrite ± pyrite ± galena ± barite. Secondary minerals formed due to oxidation are: goethite, limonite, lepidocrucite, Malachite, Azurite, Covelite, Cerucite, hydrocerucite, Pyrolusite and Smitsonite. In a few localities, chalcopyrite and minor pyrite and galena are found. Based on SEM analysis gold is present as electrum. Mineralization appeared in different type such as vein, stockwork and Hydrothermal breccia in strike sleep fault zone which are hidden inside volcano plutonic rocks. The average gold grade is between 3.02 ppm and ore reserve is estimated more than 3 million tons (cut off grade = 0.7 ppm.

  3. [Mineral Spectrum Change Analysis under the Conditions of Different Particle Size].

    Science.gov (United States)

    Wang, Yan-xia; Wu, Jian; Zhou, Liang-guang; Hou, Lan-gong; Wang, Dong; Cao, Min

    2015-03-01

    Mineral particle size is an important factor affecting mineral spectrum characteristics, so to explore the changes of the mineral spectrum curves under different particle sizes and the spectrum difference of different minerals under the same particle size are the keys of hyperspectral remote sensing information mineral identification and the theoretical basis of research on spectral differences of different particle -sizes. Six kinds of collected minerals were observed by spectrometer to get the reflectivity spectrum curve and first order differential spectral curve under different particle sizes, and the spectral characteristics of various kinds of minerals under different particle sizes were analyzed. At the same time, spectrum difference of different mineral under the same particle size was compared to explore possible wavelengths of hyperspectral remote sensing mineral identify. Results show that the spectrum curves of various minerals have a larger difference with the change of the particle size, but change law is not the same. The whole spectrum curve of hypersthene will be decreased with the increase of particle size, and the spectrum curve at a specific wavelength range of antigorite, hematite, kaolinite and chlorite will be decreased with the increase of particle size, and there is no direct correlation between the spectrum of olivine and the particle size. Under the same size, different mineral spectral reflectance change a lot in most band range and it provides the possibility for high precision identification of mineral. Antigorite, kaolinite and chlorite all have more absorption peaks of narrow width and smaller intensity than the other minerals. Spectrum curves of hematite, olivine and hypersthene are relatively smooth, and the number of the absorption and reflection peaks is relatively small. This study aims at providing basic data and theoretical support for mineral spectral library construction and mineral hyperspectral identification technology

  4. Hydrated silicate minerals on Mars observed by the Mars Reconnaissance Orbiter CRISM instrument.

    Science.gov (United States)

    Mustard, John F; Murchie, S L; Pelkey, S M; Ehlmann, B L; Milliken, R E; Grant, J A; Bibring, J-P; Poulet, F; Bishop, J; Dobrea, E Noe; Roach, L; Seelos, F; Arvidson, R E; Wiseman, S; Green, R; Hash, C; Humm, D; Malaret, E; McGovern, J A; Seelos, K; Clancy, T; Clark, R; Marais, D D; Izenberg, N; Knudson, A; Langevin, Y; Martin, T; McGuire, P; Morris, R; Robinson, M; Roush, T; Smith, M; Swayze, G; Taylor, H; Titus, T; Wolff, M

    2008-07-17

    Phyllosilicates, a class of hydrous mineral first definitively identified on Mars by the OMEGA (Observatoire pour la Mineralogie, L'Eau, les Glaces et l'Activitié) instrument, preserve a record of the interaction of water with rocks on Mars. Global mapping showed that phyllosilicates are widespread but are apparently restricted to ancient terrains and a relatively narrow range of mineralogy (Fe/Mg and Al smectite clays). This was interpreted to indicate that phyllosilicate formation occurred during the Noachian (the earliest geological era of Mars), and that the conditions necessary for phyllosilicate formation (moderate to high pH and high water activity) were specific to surface environments during the earliest era of Mars's history. Here we report results from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) of phyllosilicate-rich regions. We expand the diversity of phyllosilicate mineralogy with the identification of kaolinite, chlorite and illite or muscovite, and a new class of hydrated silicate (hydrated silica). We observe diverse Fe/Mg-OH phyllosilicates and find that smectites such as nontronite and saponite are the most common, but chlorites are also present in some locations. Stratigraphic relationships in the Nili Fossae region show olivine-rich materials overlying phyllosilicate-bearing units, indicating the cessation of aqueous alteration before emplacement of the olivine-bearing unit. Hundreds of detections of Fe/Mg phyllosilicate in rims, ejecta and central peaks of craters in the southern highland Noachian cratered terrain indicate excavation of altered crust from depth. We also find phyllosilicate in sedimentary deposits clearly laid by water. These results point to a rich diversity of Noachian environments conducive to habitability. PMID:18633411

  5. A possible source of water in seismogenic subduction zones

    Science.gov (United States)

    Kameda, J.; Yamaguchi, A.; Kimura, G.; Iodp Exp. 322 Scientists

    2010-12-01

    Recent works on the subduction megathrusts have emphasized the mechanical function of fluids contributing dynamic slip-weakening. Basalt-hosting fault zones in on-land accretionary complexes present several textures of seismic slip under fluid-assisted condition such as implosion breccia with carbonate matrix and decrepitation of fluid inclusion. In order to clarify initiation and evolution processes of such fault zones as well as possible source of fluid in the seismogenic subduction zone, we examined a mineralogical/geochemical feature of basaltic basement recovered by IODP Exp. 322 at C0012, that is a reference site for subduction input in the Nankai Trough. A total of 10 samples (about 4 m depth interval from the basement top) were analyzed in this study. XRD analyses indicate that all of the samples contain considerable amount of smectite. The smectite does not appear as a form of interstratified phase with illite or chlorite. Preliminary chemical analyses by EDS in TEM suggest that the smectite is trioctahedral saponite with Ca as a dominant interlayer cation. To determine the saponite content quantitatively, cation exchange capacity (CEC) of bulk samples was measured. The samples show almost similar CEC of around 30 meq/100g, implying that bulk rock contains about 30 wt% of saponite, considering a general CEC of 100 meq/100g for monomineralic saponite. Such abundance of saponite might be a result from intense alteration of oceanic crust due to sea water circulation at low temperature. Previous experimental work suggests that saponite might be highly hydrated (two to three water layer hydration form) at the seismogenic P-T condition. Hence, altered upper oceanic crust is a possible water sink in the seismogenic zone. The water stored in the smectite interlayer region will be expelled via smectite to chlorite transition reaction, that might contribute to the dynamic weakening of the seimogenic plate boundary between the basement basalt and overlying

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

    Science.gov (United States)

    Kaur, Gurmeet; Mitchell, Roger H.

    2016-04-01

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

  7. Mount Taylor uranium deposit, San Mateo, New Mexico

    International Nuclear Information System (INIS)

    The Mount Taylor uranium deposit is located at the extreme eastern end of the Ambrosia Lake District in the Grants Mineral Belt of New Mexico. This deposit is a sandstone-type uranium deposit which was formed by lateral secretion. This study has demonstrated the existence of a clay mineral alteration pattern around the Mount Taylor deposit. Montmorillonite is the dominant clay downdip of the deposit. As the deposit is approached from the downdip side, montmorillonite gives way to chlorite in edge-to-face arrangement. In the ore body, chlorite as rosettes is the dominant clay mineral. Updip of the ore zone the dominant clay mineral is kaolinite. A positive correlation has been demonstrated between uranium and organic materials as determined by LOI in the ore zones of the deposit. Organic geochemical leaching studies have also shown organic acids to be effective uranium leaching agents; and traces of them have been found in SEM photomicrographs. This suggests that organic acids or short-chain functional groups may have been transporting agents for the uranium. Adsorption of these polar molecules to clays to form the ore body would explain the lack of uranium-bearing minerals. Several of the trace elements studied may be useful pathfinders: Manganese, ytterbium, and cerium show positive downdip anomalies; sodium and samarium show negative updip anomalies; and zinc and uranium show positive updip anomalies. Additional work is needed to verify theusefulness of each of these. The presence of a redox interface in a deposit which is 3000 to 5000 feet deep suggests that the oxidation phenomena responsible for ore remobilization may be a relic Morrison feature

  8. Investigation on type and origin of iron mineralization at Mesgar occurrence, south of Zanjan, using petrological, mineralogical and geochemical data

    Directory of Open Access Journals (Sweden)

    Mohammad Ebrahimi

    2015-04-01

    150 m in length and average 1.5 m in width, reaching a maximum of 3 m. Two stages of mineralization identified at Mesgar. Stage-1 mineralization formed before the hydrothermal brecciation events. This stage is characterized by disseminated fine-grained hematite in the andesitic basalt lavas. Clasts of stage-1 mineralization have been recognized in the hydrothermal breccias of stage-2. Stage-2 is represented by quartz, hematite and chlorite veins and breccias cement. This stage contains abundant hematite, together with minor magnetite and chalcopyrite. The hydrothermal alteration assemblages at Mesgar grade from proximal quartz and chlorite to distal sericite and chlorite-calcite. The quartz and chlorite alteration types are spatially and temporally closely associated with iron mineralization. The sericite and chlorite-calcite alterations mark the outer limit of the hydrothermal system. Supergene alteration (kaolinite is commonly focused along joints and fractures. The ore minerals at Mesgar formed as vein and hydrothermal breccia cements, and show vein-veinlet, massive, brecciated, clastic and disseminated textures. Hematite is the main ore which is accompanied by minor magnetite and chalcopyrite. Goethite is a supergene mineral. Quartz and chlorite are present in the gangue minerals that represent vein-veinlet, vug infill, colloform, cockade and crustiform textures. The Mesgar volcanic host rocks are characterized by LILE and LREE enrichment coupled with HFSE depletion. They have positive U, Th and Pb and negative Ba, Nb, P and Ti anomalies. Our geochemical data indicate a calc-alkaline affinity for the volcanic rocks (Kuster and Harms, 1998; Ulmer, 2001, and suggest that they originated from mantle melts contaminated by the crustal materials (Chappell and White, 1974; Miyashiro, 1977; Harris et al., 1986. The ore zones show lower concentrations of REE, except Ce, relative to fresh volcanic host rocks. LREE are more depleted than HREE. These signatures indicate high

  9. Statistical analysis of results from the quantitative mapping of fracture minerals in Forsmark. Site descriptive modelling - complementary studies

    Energy Technology Data Exchange (ETDEWEB)

    Loefgren, Martin (Niressa AB, Norsborg (Sweden)); Sidborn, Magnus (Kemakta Konsult AB, Stockholm (Sweden))

    2010-12-15

    Within the Forsmark site investigation campaign, quantitative mapping of different fracture minerals has been performed. This has been done by studying fracture surfaces of drill core sections from many different boreholes at the Forsmark site /Eklund and Mattsson 2009/. The drill core mapping was focused on the rock in the vicinity of flow anomalies detected by the Posiva Flow Log (PFL). The quantitative mapping was performed only on open fractures. The fracture minerals that were mapped are calcite, chlorite, clay minerals (as a group), hematite, and pyrite. In this present report, data from the quantitative mineral mapping campaign are refined, sorted into different data subsets, and analysed by parametric and non-parametric statistical methods. The data subsets are associated with 21 different rock volumes, representing different elevations, rock domains, fracture domains, and groups of deformation zones. In total 2,071 fractures were mapped at the site, and the most frequent mineral was calcite. Its amount could be quantitatively estimated in 32% of the mapped fractures. Of the other minerals, chlorite was quantitatively estimated in 24%, clay minerals in 11%, pyrite in 10%, and hematite in 0.4% of the mapped fractures. For fractures where the averaged fracture mineral thickness, d{sub mean} [mm], and visible coverage, C{sub vis} [%], could be quantitatively estimated, the following arithmetic means were found: calcite = 0.11 mm and 18%, chlorite = 0.22 mm and 38%, clay minerals = 0.14 mm and 40%, pyrite = 2.3 mum and 0.5%, hematite = 19 mum and 14%. These quantities are based on visual inspection of fracture surfaces and do not include the contribution from non-consolidated fracture fillings. It is shown that there is significant spatial variability of d{sub mean} and C{sub vis} within the examined rock volumes. Furthermore, the non-parametric analyses indicate that there are differences in d{sub mean} and C{sub vis} between the different rock volumes. Even

  10. Statistical analysis of results from the quantitative mapping of fracture minerals in Laxemar. Site descriptive modelling - complementary studies

    Energy Technology Data Exchange (ETDEWEB)

    Loefgren, Martin (Niressa AB, Norsborg (Sweden)); Sidborn, Magnus (Kemakta Konsult AB, Stockholm (Sweden))

    2010-12-15

    Within the Laxemar site investigation campaign, quantitative mapping of different fracture minerals has been performed. This has been done by studying fracture surfaces of drill core sections from many different boreholes at the Laxemar site /Eklund and Mattsson 2008/. The drill core mapping was focused on the rock in the vicinity of flow anomalies detected by the Posiva Flow Log (PFL). The quantitative mapping was performed only on open fractures. The fracture minerals that were mapped are calcite, chlorite, clay minerals (as a group), hematite, and pyrite. In this present report, data from the quantitative mineral mapping campaign are refined, sorted into different data subsets, and analysed by parametric and non-parametric statistical methods. The data subsets are associated with 17 different rock volumes, representing different elevations, rock domains, fracture domains, and groups of deformation zones. In total 1,852 fractures were mapped at the site, and the most frequent mineral was calcite. Its amount could be quantitatively estimated in 51% of the mapped fractures. Of the other minerals, chlorite was quantitatively estimated in 46%, pyrite in 19%, clay minerals in 16%, and hematite in 0.05% of the mapped fractures. For fractures where the averaged fracture mineral thickness, d{sub mean} [mm], and visible coverage, C{sub vis} [%], could be quantitatively estimated, the following arithmetic means were found: calcite = 0.25 mm and 22%, chlorite = 0.29 mm and 41%, pyrite =1.3 mum and 0.2%, and clay minerals = 0.15 mm and 35%. These quantities are based on visual inspection of fracture surfaces and do not include the contribution from non-consolidated fracture fillings. It is shown that there is significant spatial variability of d{sub mean} and C{sub vis} within the examined rock volumes. Furthermore, the non-parametric analyses indicate that there are differences in d{sub mean} and C{sub vis} between the different rock volumes. Even so, the differences are

  11. Geomorphological stability of Permo-Triassic albitized profiles - case study of the Montseny-Guilleries High (NE Iberia)

    Science.gov (United States)

    Parcerisa, D.; Casas, L.; Franke, C.; Gomez-Gras, D.; Lacasa, G.; Nunez, J. A.; Thiry, M.

    2010-05-01

    Massif paleoalteration profiles (≥ 200 m) occur in the upper parts of the Montseny-Guilleries High (NE Catalan Coastal Ranges). The profiles consist of hard albitized-chloritized-hematized facies in the lower part and softer kaolinized-hematized facies in the upper part of the section. Preliminary paleomagnetic data show Triassic ages for both, the albitized and the kaolinized parts, and point to a surficial formation altered under oxidising conditions. Similar paleoalteration profiles have already been described and dated to Triassic ages elsewhere in Europe [Schmitt, 1992; Ricordel et al., 2007; Parcerisa et al., 2009]. These Permian-Triassic alterations are following a succession of different mineral transformations from the top to the base of the profile: 1) Red facies are defined by an increase in the amount and size of haematite crystals leading to the red colour of the rocks. The increase on haematite content is pervasively affecting the whole rock and is accompanied by the kaolinitization of the feldspars. 2) Pink facies: here, the granite shows an uniform pink colouration, which is mainly due to the albitization of the primary Ca-bearing plagioclases, accompanied by a precipitation of minute haematite, sericite, and calcite crystals inside the albite. Additionally primary biotite is fully chloritized. The pink granites are much more resistant to the present-day weathering than the "unaltered" facies at the base of the profile. 3) Spotted facies is characterized by a partial alteration of the rock, which caused a pink-screened aspect to the rock. The alteration developed along the fractures and is less well developed or absent in the non-fractured zones. In the pink-screened facies, the plagioclases are partially albitized and contain numerous hematite inclusions. Biotites are usually almost entirely chloritized. 4) Unaltered facies: These granites are coloured white to greyish, containing plagioclase and K-feldspar that do not show any trace of

  12. The "green stones" of Valtellina and Valchiavenna (central Alps, northern Italy)

    Science.gov (United States)

    Cavallo, Alessandro

    2015-04-01

    Valtellina and Val Chiavenna (Sondrio, Central Alps, northern Italy) are traditionally areas of production of building and ornamental stones (e.g. Serizzo Ghiandone, Serizzo Valmasino, San Fedelino Granite), and among these the "green stones" have a leading position. These stones had an extensive use in Lombardy, as well as abroad (e.g Switzerland). The "green stones" are related to the two mafic-ultramafic bodies of Valmalenco and Chiavenna, where the two largest quarrying districts of the Province of Sondrio are located. Until the early decades of the XX century, serpentinites (and other lithologies from Valtellina) were also extracted from the erratic boulders of Brianza (north of Milan), but at present time the law protects the few remaining boulders. The extracted and processed materials are various: serpentinites, ophicalcites, soapstones. Even the "Stone of Tresivio", used in the past in important monuments of Valtellina, could be classified among the "green stones" in a broad sense: it is a green chloritic schist with scarce and thin ferriferous calcitic veins, pertaining to the sedimentary "Servino" Formation. In recent times, the ancient quarries of this stone were rediscovered near the homonymous village, a few kilometers from Sondrio. There are also historic reports about other "green stones", used in ancient times, such as the "Stone of Grosio", a chloritic schist, and the "Bormio Prasinite". Currently the extraction and processing of "green stones" occurs mostly in Valmalenco, with 22 active serpentinite quarries and a gross volume of 70000 m3 extracted per year, with a yield of about 50%. The Malenco serpentinite (interpreted as sub-continental mantle rocks) forms a 1-2 km thick tabular body, outcropping over an area of about 170 km2, almost entirely confined within the boundaries of the valley. The antigoritic serpentinites (with variable amounts of olivine, clinopyroxene, chlorite and magnetite) are moderately up to strongly foliated, sometimes

  13. The Marianas-San Marcos vein system: characteristics of a shallow low sulfidation epithermal Au-Ag deposit in the Cerro Negro district, Deseado Massif, Patagonia, Argentina

    Science.gov (United States)

    Vidal, Conrado Permuy; Guido, Diego M.; Jovic, Sebastián M.; Bodnar, Robert J.; Moncada, Daniel; Melgarejo, Joan Carles; Hames, Willis

    2016-01-01

    The Cerro Negro district, within the Argentinian Deseado Massif province, has become one of the most significant recent epithermal discoveries, with estimated reserves plus resources of ˜6.7 Moz Au equivalent. The Marianas-San Marcos vein system contains about 70 % of the Au-Ag resources in the district. Mineralization consists of Upper Jurassic (155 Ma) epithermal Au- and Ag-rich veins of low to intermediate sulfidation style, hosted in and genetically related to Jurassic intermediate composition volcanic rocks (159-156 Ma). Veins have a complex infill history, represented by ten stages with clear crosscutting relationships that can be summarized in four main episodes: a low volume, metal-rich initial episode (E1), an extended banded quartz episode with minor mineralization (E2), a barren waning stage episode (E3), and a silver-rich late tectonic-hydrothermal episode (E4). The first three episodes are interpreted to have formed at the same time and probably from fluids of similar composition: a 290-230 °C fluid dominated by meteoric and volcanic waters (-3‰ to -0‰ δ18Owater), with <3 % NaCl equivalent salinity and with a magmatic source of sulfur (-1 to -2 ‰ δ34Swater). Metal was mainly precipitated at the beginning of vein formation (episode 1) due to a combination of boiling at ˜600 to 800 m below the paleowater table, and associated mixing/cooling processes, as evidenced by sulfide-rich bands showing crustiform-colloform quartz, adularia, and chlorite-smectite banding. During episodes 2 and 3, metal contents progressively decrease during continuing boiling conditions, and veins were filled by quartz and calcite during waning stages of the hydrothermal system, and the influx of bicarbonate waters (-6 to -8.5 ‰ δ18Owater). Hydrothermal alteration is characterized by proximal illite, adularia, and silica zone with chlorite and minor epidote, intermediate interlayered illite-smectite and a distal chlorite halo. This assemblage is in agreement with

  14. Mineralogical investigations of the interaction between iron corrosion products and bentonite from the NF-PRO Experiments (Phase 1)

    Energy Technology Data Exchange (ETDEWEB)

    Milodowski, A.E.; Cave, M.R.; Kemp, S.J.; Taylor, B.H.; Vickers, B.P.; Green, K.A.; Williams, C.L.; Shaw, R.A. (British Geological Survey (United Kingdom))

    2009-01-15

    observations, potentially indicating the early stages of conversion of montmorillonite towards an iron-rich clay mineral as a result of interaction with Fe released by the corrosion of iron or steel. The cation exchange capacity (CEC) and exchangeable cation chemistry of the bentonite was also seen to be subtly affected by interaction with Fe. Bentonite from within the zones where corroded steel wires were present displayed a slightly reduced CEC, and depletion in exchangeable Ca and Na, and an increase in exchangeable Fe. This is consistent with at least partial displacement of the interlayer cations in montmorillonite by Fe. The loss in CEC might also correlate with a partial conversion of the montmorillonite to chlorite, which is tentatively suggested from the XRD analyses. Fe released from the corroding steel was also observed to displace Ca2+ from the interlayer cation sites in the montmorillonite component. This was manifested by the marked concentration of Ca at the interface with the corroding metal and along the leading edges of 'fronts' of Fe diffusing into the bentonite matrix. The displaced Ca was seen to have re-precipitated as aragonite. The petrographical observations show that the bentonite within the alteration zone, that has reacted with and is enriched by Fe, has a tendency to show significantly reduced shrinkage on sample drying in comparison to the background unaltered bentonite. Conversely, this would suggest that the reacted and altered clay will also have less ability to swell on hydration with water. This behaviour might be consistent with the partial conversion of the montmorillonite to an iron rich dioctahedral smectite such as nontronite, or to non-swelling clay mineral such as chlorite (or chlorite-smectite mixed-layer clay). If this is the case, then this may have important implications for the long-term behaviour of bentonite seals around radioactive waste canisters made of iron or steel

  15. Fluid-related modifications of Cr-spinel and olivine from ophiolitic peridotites by contact metamorphism of granitic intrusions in the Ablah area, Saudi Arabia

    Science.gov (United States)

    Ahmed, Ahmed Hassan; Surour, Adel Abdullah

    2016-05-01

    The Ablah serpentinized peridotites and overlying layered metagabbros represent an allochthonous piece of a dismembered ophiolite in the southern Hijaz terrane that belongs to the Neoproterozoic Arabian Shield in Saudi Arabia. On both sides, the ophiolite is bounded by wider domains of granitic intrusions and volcano-sedimentary successions, all together follow a N-S trend. The protolith of the Ablah serpentinized peridotites is mainly harzburgite which is partly or totally serpentinized. Carbonate veins of variable sizes invade and hydrate the serpentinized peridotites. Away from the contact with the granitic intrusions, fresh primary (igneous) olivine and Cr-spinel are preserved in the partly serpentinized peridotites. These relict primary minerals are used to infer their tectonic setting of formation as a nascent spreading center rock association of mid-ocean ridge or back-arc basin setting. Based on the re-distribution of elements related to different thermal effects, three patterns of Cr-spinel modification can be defined. The first pattern can be followed in the partly serpentinized peridotites where Cr-spinel displays simple zoning that is characterized by sharp contact between primary Al-rich cores and secondary Fe3+-rich rims. These cores and rims are homogeneous and show progressive decrease in Mg, Al and Cr, but with remarkable increase in Fe3+ and Fe2+ toward the rims. Mineral assemblage in equilibrium with this type of Cr-spinel is primary olivine + antigorite + chlorite ± talc ± chrysotile. The second pattern of Cr-spinel modification is represented by homogeneous weakly zoned Cr-rich spinel with no distinct sharp contacts between Cr-rich cores and magnetite rims. Cr-spinel cores of this type are rich in Cr and Fe2+, and poor in Mg, Al and Fe3+. The mineral assemblage in equilibrium with this Cr-spinel type is Fe-rich olivine + antigorite + enstatite + chlorite + tremolite + anthophyllite ± talc. The third pattern is defined by pervasive

  16. Systematics of hydrothermal alteration at the volcanic-hosted Falun Zn-Pb-Cu-(Au-Ag) deposit - implications for ore genesis, structure and exploration in a 1.9 Ga ore district, Fennoscandian Shield, Sweden

    Science.gov (United States)

    Kampmann, Tobias C.; Jansson, Nils J.; Stephens, Michael B.; Majka, Jarosław

    2016-04-01

    The Palaeoproterozoic, volcanic-hosted Falun Zn-Pb-Cu-(Au-Ag) sulphide deposit was mined for base and precious metals during several centuries, until its closure in 1992. The deposit is located in a 1.9 Ga ore district in the Bergslagen lithotectonic unit, Fennoscandian Shield, south-central Sweden. Both the ores and their host rock underwent polyphase ductile deformation, and metamorphism under amphibolite facies and later retrograde conditions at 1.9-1.8 Ga (Svecokarelian orogenic system). This study has the following aims: (i) Classify styles and intensities of alteration in the hydrothermally altered zone at Falun; (ii) identify precursor rocks to hydrothermally altered rocks and their spatial distribution at the deposit; (iii) evaluate the chemical changes resulting from hydrothermal alteration using mass change calculations; and (iv) assess the pre-metamorphic alteration assemblages accounting for the observed metamorphic mineral associations in the altered rocks at Falun. Results will have implications for both the ore-genetic and structural understanding of the deposit, as well as for local and regional exploration. Metamorphic mineral associations in the altered rocks include biotite-quartz-cordierite-(anthophyllite) and, more proximally, quartz-anthophyllite-(biotite-cordierite/almandine), biotite-cordierite-(anthophyllite) and biotite-almandine-(anthophyllite). The proximal hydrothermally altered zone corresponds to intense chlorite-style alteration. Subordinate dolomite or calcite marble, as well as calc-silicate (tremolite, diopside) rocks are also present at the deposit. Metavolcanic rocks around the deposit are unaltered, weakly sericitized or sodic-altered. Immobile-element (e.g. Zr, TiO2, Al2O3, REE) systematics of the silicate-rich samples at and around the deposit suggest that the precursors to the hydrothermally altered rocks at Falun were predominantly rhyolitic in composition, dacitic rocks being subordinate and mafic-intermediate rocks

  17. The Freyenstein Shear Zone - Implications for exhumation of the South Bohemian Batholith (Moldanubian Superunit, Strudengau, Austria)

    Science.gov (United States)

    Griesmeier, Gerit; Iglseder, Christoph; Konstantin, Petrakakis

    2016-04-01

    The Moldanubian superunit is part of the internal zone of the Variscan Orogen in Europe and borders on the Saxothuringian and Sudetes zones in the north. In the south, it is blanketed by the Alpine foreland molasse. Tectonically it is subdivided into the Moldanubian Nappes (MN), the South Bohemian Batholith (SBB) and the Bavarian Nappes. This work describes the ~ 500 m thick Freyenstein shear zone, which is located at the southern border of the Bohemian Massif north and south of the Danube near Freyenstein (Strudengau, Lower Austria). The area is built up by granites of Weinsberg-type, which are interlayered by numerous dikes and paragneisses of the Ostrong nappe system. These dikes include medium grained granites and finegrained granites (Mauthausen-type granites), which form huge intrusions. In addition, smaller intrusions of dark, finegrained diorites und aplitic dikes are observed. These rocks are affected by the Freyenstein shear zone und ductily deformed. Highly deformed pegmatoides containing white mica crystals up to one cm cut through the deformed rocks and form the last dike generation. The Freyenstein shear zone is a NE-SW striking shear zone at the eastern edge of the SBB. The mylonitic foliation is dipping to the SE with angles around 60°. Shear-sense criteria like clast geometries, SĆ structures as well as microstructures show normal faulting top to S/SW with steep (ca. 50°) angles. The Freyenstein shear zone records a polyphase history of deformation and crystallization: In a first phase, mylonitized mineral assemblages in deformed granitoides can be observed, which consist of pre- to syntectonic muscovite-porphyroclasts and biotite as well as dynamically recrystallized potassium feldspar, plagioclase and quartz. The muscovite porphyroclasts often form mica fishes and show top to S/SW directed shear-sense. The lack of syntectonic chlorite crystals points to metamorphic conditions of lower amphibolite-facies > than 450° C. In a later stage fluid

  18. Gemmological and mineralogical investigations and genesis of the kammererite from the Keşiş (Erzincan) and Kop (Erzurum) mountains

    Science.gov (United States)

    Hatipoğlu, Murat; Oğuzer, Melis Buşra; Baki Buzlu, H.

    2013-08-01

    Even though there are many chromitite deposits in Turkey, the most productive chromitite deposits including chromian clinochlore and chromian are present in the eastern Anatolia region. Kammererite (chromian clinochlore), in essence, is one of the rarest clinochlore minerals as a sub-variety of large family of the chlorite minerals. Even though it is the monoclinic IIb-2 polytype, with symmetry C2/m, which is one of the most abundant regular-stacking one-layer chlorites occurring in nature, the crystallization of chromian clinochlore is less abundance. Hence, gem-quality magenta colored kammererite which may be formulized as [Mg5(Al, Cr, Fe)2Si3O10(OH)8] with reference to the abundance of the main oxides in the XRF bulk analyses, is only found in Turkey worldwide. Therefore, they are called Turkish kammererite. Beside of the mineral kammererite, the minerals uvarovite, magnesite, chromian spinel, chlorite and some garnets are also present in the paragenesis. Geological field observations and data in the region reveal that the kammererite specimens are crystallized as remobilized-origin on a chromitite matrix, deposited in the podiform-type chromitite ore deposits, and surrounded by the peridotitic and harzburgitic ultrabasic rocks. Thus, it can be stated that this rare mineral formation is derived from the secondary components of the hydrothermal alteration of the principle amphibole, pyroxene and biotite minerals in the surrounding peridotitic and harzburgitic (partially serpentinitic) rocks where they are embedded throughout the Northeastern Ophiolitic Belt comprising the Keşiş and Kop Mountains in the Eastern Anatolia region of Turkey. In this study, unique loose Turkish kammererite crystals were the first time investigated as both mineralogically and gemmologically. Accordingly, the well-known some further spectroscopic analytical methods were used to characterize and identify in detail for provenance and genesis. Firstly, as a structural characterization, in

  19. 鄂尔多斯盆地陇东地区长4+5油层组致密砂岩储层成岩作用及成岩相%Diagenesis and diagenetic facies of the Chang 4+5 tight sandstone reservoirs in Longdong area,Ordos Basin

    Institute of Scientific and Technical Information of China (English)

    王峰; 陈蓉; 田景春; 李明瑞; 章辉若; 刘鑫

    2014-01-01

    Based on thin sections,SEM,X-ray diffraction,mercury injection,this paper analyzed the diagenesis and its im-pact on Chang4+5(the 4th and 5th Member of the Yanchang Fm)oil layers in Longdong area,Ordos Basin.Based on the analysis results ,we studied the characteristics of diagenetic facies and the distribution of favorable facies .The Chang4+5 oil layers is at the mid-diagenetic A-B stage ,and the early compaction and carbonate cementation resulted in loss of great numbers of primary pores ,resulting in poor reservoir quality .However,the early chlorite thin film was favorable for the protection of primary pores and dissolution improved reservoir quality .According to the impact of the diagenesis on reser-voir quality,five types of diagenetic facies were identified ,namely chlorite thin film-residual intergranular pore facies , kaolinite cementation-feldspar dissolution facies , illite cementation-feldspar dissolution facies , carbonate cementation facies and siliceous-illite cementation facies .High quality reservoirs are closely related to the diagenetic facies , and the chlorite thin film-residual intergranular pore diagenetic facies is the best in reservoir physical property and petroliferous property ,thus is the most favorable diagenetic facies for oil enrichment in this area .%运用铸体薄片鉴定、扫描电镜、X-衍射及高压压汞等测试方法,系统分析了鄂尔多斯盆地陇东地区长4+5油层组砂岩储层的成岩作用特征及其对储层物性的影响,进而对储层成岩相特征及有利成岩相的分布进行了研究。结果表明:研究区长4+5储层成岩阶段总体处于中成岩阶段A-B期,压实作用与碳酸盐胶结作用造成原始孔隙的大量损失,使储集层物性变差;早期绿泥石薄膜的发育有利于原生孔隙的保存;溶蚀作用使物性得到明显改善。根据成岩作用对物性的影响,划分出绿泥石薄膜-粒间孔相、高岭石胶结-长石溶蚀相、伊

  20. Tectonic evolution of the western boundary of the Attico-Cycladic complex (Lavrio, Greece)

    Science.gov (United States)

    Scheffer, Christophe; Vanderhaeghe, Olivier; Tarantola, Alexandre; Lanari, Pierre; Ponthus, Leandre; France, Lyderic; Photiades, Adonis

    2015-04-01

    The Lavrio peninsula, South East of Athens, is located along the western boundary of the Attic-Cycladic Metamorphic Complex in the internal zone of the Hellenic orogenic belt, at the intersection between thrusts and detachments. It is thus a perfect target to decipher the tectonic evolution of an orogenic wedge from tectonic accretion to gravitational collapse. The nappe stack is overlain by a non-metamorphic limestone and is made, from top to bottom by (i) an ophiolitic melange, (ii) the Lavrio tectonic unit dominated by schists and displaying mineral paragenesis typical of blueschist facies, (iii) the Kamariza tectonic unit dominated by marbles and affected by pervasive greenschist facies metamorphism. The Lavrio and Kamariza tectonic units are juxtaposed by a low-angle mylonitic to cataclastic detachement. A more detailed investigation of the relationships between mineral paragenesis and microstructures indicates that the transition from the Lavrio to the Kamariza tectonic units, across the low-angle detachment, is marked by progressive transposition of the blueschist facies fabric coeval with retrogression under greenschist facies conditions. Indeed, the Kamariza unit is characterized by a relatively steep foliation associated with isoclinal folds of weakly organized axial orientation that is partially to totally transposed into a shallow dipping foliation bearing a N-S trending lineation. The degree of transposition increases from top to bottom and is particularly marked at the transition from the Lavrio to the Kamariza unit across the low-angle detachement. The blueschist facies foliation of the Lavrio schists is underlined by glaucophane and HP phengite intergrown with chlorite crystals. The Kamariza tectonic unit is dominated by LP phengite intergrown with chlorite but contains relics of the blueschist mineral paragenesis. Detailed microprobe mapping of the composition of the phengite and chlorite crystals reveal distinct variations of the PT conditions

  1. Accretionary wedge harzburgite serpentinization and rodingitization constrained by perovskite U/Pb SIMS age, trace elements and Sm/Nd isotopes: Case study from the Western Carpathians, Slovakia

    Science.gov (United States)

    Li, Xian-Hua; Putiš, Marián; Yang, Yue-Heng; Koppa, Matúš; Dyda, Marian

    2014-09-01

    Perovskite-bearing harzburgites occur in a “mélange” type blueschist-bearing accretionary wedge complex of the Inner Western Carpathians Meliata Unit in Slovakia. Although dark rounded, slightly hydrated relic “cores” of harzburgite boulders are perovskite-free, perovskite (Prv) occurrence in the surrounding serpentinites and rodingites enabled dating of hydration, resulting in two metamorphic-metasomatic Prv generations. Perovskite (1) grows parallel to relic clinopyroxene exsolution lamellae or forms randomly oriented grain clusters in serpentinized orthopyroxene (Opx1) porphyroclasts, often accompanied by tiny andradite lamellae clusters, or it is partly replaced by Ti-andradite. Perovskite crystallization indicates evolving rodingitization fluids pervading the boundary between the harzburgite “cores” and Prv-free serpentinite. This strictly limited occurrence of Prv (1) within a 1 to 20-cm across-zone implies slightly postponed Prv crystallization to serpentinization by LREE(Ce,La), Ca2+, Ti/Fe3+-enriched aqueous fluids. A grain scale metasomatic mechanism partitioned Ca and Ti from the host orthopyroxene porphyroclasts, spinel (Ti) and grain-boundary pervasive fluids to Prv. In contrast, Prv (2) occurs in a 1 to 3 cm across chlorite-rich blackwall zone between hosting serpentinite and rodingite veins, thus indicating channelled rodingitization fluid flow and accompanying hydraulic fracturing. Here, Prv (2) is ingrown by chlorite and apatite. Part of this Prv (2) formed in a rodingite vein mineral assemblage composed of diopside, andradite, vesuvianite, epidote/zoisite, apatite and chlorite. Both perovskite 1 and 2 are replaced by pyrophanite along the grain rims and interiors; most likely via fluid-aided coupled dissolution-reprecipitation at increased Si-Fe-Mn-Al element solubility in rodingitization fluids pervading serpentinized harzburgite. Both Prv generations, especially Prv (2), can be partly to almost totally replaced by (Ti-) Adr

  2. Mineralogical Description of the Skarn from Mraconia Valley, Almaj Mountains, Romania

    Science.gov (United States)

    Anason, Maria Angela; Stefan, Marincea; Delia Georgeta, Dumitras

    2014-05-01

    The purpose of this paper is to update knowledge of the investegated area. The research are overlaps of the hidrographic basin of the Mraconia Valley, at north is bounded by the alignment Poiana Mraconia and Lugojistea; at east by the Satului Valley; souther limit is constitutes by the Ponicova Valley and the western limit is Cracul Radului-Cracul Urzicea. The skarn was described for the first time in the 1934 by the A. Streckeisan with the name Catramat Series; this series was a kata-mezonal character, which is the debris of an old canvas with Upper Carbonifer age. The crystalline schist of the Poiana Mraconia Series, are studied by Al. Codarcea, I. Bercia, E. Bercia (1934) and suffered a progressive metamorphism in the amphibolites with alamandine facies and the disten-alamandine-muscovite subfacies, together revealed the metapelithe paragenesis including disten, green hornblende, andezine and alamandine.The primar metamorphism were followed to the regressive metamorphism by the Assyntic orogene and Varisc cycles (I. Bercia, E. Bercia, 1975). Petrografically exceed the amphibolites paragnaice and the micacee paragnaice, with biotite and garnet, associated with the quartz-feldspar gneiss and feldspar quartzite, affected by the arthritic migmatization. Fine grain, sharp sistuozity, the muscovite are frequent and the pegmatite absence leading to the Poiana Mraconia crystalline differentiation by the Ielova crystalline, bud both are included in the Almaj complex. Mineralogical and petrographic study of the Mraconia skarns serves in predicting the relations between the magmatite form the upper basin of the valley (with the mineralization of the W and Mo), and the adjacent formations. This paper wants to emphasize the next petrographic types following: 1. the micacee paragnais are characterized by the existing of the quartz, plagioclase, microcline, muscovite, biotite, chlorite and epidote; 2. The micacee paragnais with garnet are definite by the paragenisis: quartz

  3. Initiating intermediate-depth earthquakes: Insights from a HP-LT ophiolite from Corsica

    Science.gov (United States)

    Deseta, N.; Ashwal, L. D.; Andersen, T. B.

    2014-10-01

    The hypocentres of intermediate-depth earthquakes have been shown to overlap with the regions in subducting slabs that contain high abundances of hydrous minerals. This relationship was initially revealed using geophysical and numerical modelling and until recently has lacked corroboration from direct field-based research. We evaluated the relationship of the coincidence of intermediate-depth earthquakes with hydrous minerals in the slab by undertaking detailed geochemical analyses of blueschist to lawsonite to eclogite facies pseudotachylytes and their hostrocks located within an exhumed ophiolite, the Eocene Schistes Lustres Complex in Corsica. These units comprise incompletely metamorphosed metagabbro and peridotite. The wallrocks of the pseudotachylytes contain variable amounts of hydrous minerals: tremolite, Mg-hornblende, glaucophane in the metagabbro, and serpentine, tremolite and chlorite in the peridotite. Back-scatter-electron images show that the hydrous minerals entrained in the melt undergo fusion rather than dehydration. Vesicular and H2O-rich melt veins are observed cross-cutting partially molten pseudotachylyte fault veins and show evidence of H2O exsolution during melt solidification. The crystallisation products of these melts indicate formation under high temperature, high pressure conditions (1400-1700 °C; 1.5 GPa). The peridotite-hosted pseudotachylytes crystallised olivine, orthopyroxene and diopside, which are surrounded by interstitial Al- and H2O-rich glass. The metagabbro pseudotachylyte is dominated by Al-rich omphacite, ilmenite and high-Fe anorthite. XRF bulk analyses of the wallrock of the pseudotachylyte and electron microprobe analyses of the pseudotachylyte matrix, entrained survivor clasts and the crystallisation products show that near-total disequilibrium melting took place. The peridotite-hosted pseudotachylyte composition is skewed strongly towards chlorite; however, the preservation of delicate dendritic diopside and olivine

  4. Change of the Surface Soil in the Ohno River Drainage and its Impact on the Detrital Composition of the Sediments in the Beppu Bay, the Southwestern Japan, during the Holocene

    Science.gov (United States)

    Irino, T.; Yamamoto, M.; Ikehara, K.; Kuwae, M.; Takemura, K.

    2012-12-01

    Detrtal fraction contained in marine sediments can be generally used as climate proxies because variations in provenance and mineralogy could be affected by the precipitation distribution and weathering intensity. Change in the surface soil composition could be observed if a well-preserved depositional soil sequence was found. In order to detect the change in provenances and interpret the terrestrial environment using detrital proxies in the marine sediments, it is necessary to know the variability or range of the mineral composition of a particular provenance during the targeted time periods. The Ohno River is located in the northeast Kyushu Island, the southwestern Japan, which has the head water region at the Mt. Kuju and Mt. Aso, flows eastward combining some tributaries from the south, and then flows northward to the Beppu Bay. Surface geology of the drainage area is roughly divided into two as andosol in the northeast and brown forest soil in the south. Such contrasting detrital provenances could provide a variety of grain composition to the marine sediments deposited in the Beppu Bay. The No. 5 boring core was drilled at a landfill site on the mouth of the Ono River. The core continuously recovers 97 m length and consists of Holocene marine sediments which could be a good record of the terrestrial environment of hinterland (the Ohno River Basin). We also found a soil sequence on the foot of the Mt. Kuju at 850 m altitude, which covers the similar time interval as the No.5. The soil sequence consists of brown loam overlain by the alternation of tephra and andosol. We tried to compare the variations in mineral compositions both for this soil sequence and the No.5 core since about 8,000 yrs age. The No. 5 core mainly consists of smectite, illite, chlorite (or kaolinite), amphiboles, quartz, feldspars, and amorphous materials with minor calcite. Amorphous material is supposed to mainly consists biogenic opal. Amorphous material is higher during 7000 to 3500 yrs

  5. Mineralogy and microstructure of roofing slate: thermo-optical behaviour and fissility

    Directory of Open Access Journals (Sweden)

    García-Guinea, J.

    1998-09-01

    Full Text Available The mineralogy and microstructure, which affect the slaty cleavage, are linked with the strong preferred orientation of phyllosilicates and this enables the rock to be split into large, thin, flat sheets. Roofing slate samples with different commercial fissilities have been analyzed by radioluminescence (RL, thermoluminescence (3DTL, by X-ray diffraction (XRD, by scanning electron microscopy (SEM using the back-scattered mode (BSEI and by electron microprobe (EMP. They are made up of white micas, chlorite, quartz, detrital feldspars, ilmenite, pyrite, rutile apatite and tourmaline. Texturally, all consist of silt-sized clasts of detrital quartz, feldspars, chlorite-mica stacks, muscovite and ilmenite in a recrystalline, lepidoblastic matrix of white micas and chlorite with quartz lenses, all showing a very strong preferred orientation. The luminescence emission centers are a low broad blue band around the 400 nm spectra positions linked with alkali losses and formation of [AlO4]º defects; a peak at 473 nm interpreted as a the first thermal step (150-300ºC of a non-isothermal dehydroxylation of the slate phyllosilicates; and a 568 nm peak which agrees with Mn2+ point defects in aluminosilicate lattices. The studies on the slaty cleavage could be significant because Spain is the largest producer of roofing slate tiles in the world (87% of world production.

    La exfoliación de las pizarras depende fundamentalmente de su mineralogía y microestructura, especialmente de la fuerte orientación de los filosilicatos. Esta propiedad permite hendir o abrir las pizarras de techar en láminas muy grandes, delgadas y planas. Se han analizado varias pizarras de techar con diferentes calidades comerciales, correspondientes a diferentes grados de físibilidad, por radioluminiscencia (RL, termoluminiscencia espectral (TL3D, difracción de rayos X (DRX, microscopía electrónica de barrido (MEB utilizando el modo backscattered (BSEI

  6. Origin of solutes in surface waters from high Alpine catchments, Zermatt area (Swiss Alps)

    Science.gov (United States)

    Zhou, Wei; Bucher, Kurt

    2010-05-01

    summarized as: 1) Meteoric water + CO2 + O2 + pyrite + epidote + chlorite + albite + phengite + "halite" = "quartz" + goethite + kaolinite + Ca-HCO3 water and 2) Meteoric water + CO2 + O2 + calcite + pyrite + albite + phengite + chlorite ± "halite" = ±"quartz" + goethite + kaolinite + Ca-HCO3 water. Magnesium-rich Mg-HCO3 water is produced from reaction of precipitation with serpentinite: 3) Meteoric water + CO2 + O2 + antigorite + diopside + phengite + pyrite = magnesite + talc + goethite + Mg-HCO3 water. Sulphate-rich Ca-SO4 water occur mainly in gneiss and granite catchments, where the precipitation interacted with pyrite-baring rocks according to the reaction: 4) Initial water ± CO2 + O2 + pyrite + plagioclase + K-feldspar + chlorite ± halite = goethite + kaolinite + albite ± quartz + Ca-SO4 water.

  7. Mineralogical investigations of the interaction between iron corrosion products and bentonite from the NF-PRO Experiments (Phase 1)

    International Nuclear Information System (INIS)

    observations, potentially indicating the early stages of conversion of montmorillonite towards an iron-rich clay mineral as a result of interaction with Fe released by the corrosion of iron or steel. The cation exchange capacity (CEC) and exchangeable cation chemistry of the bentonite was also seen to be subtly affected by interaction with Fe. Bentonite from within the zones where corroded steel wires were present displayed a slightly reduced CEC, and depletion in exchangeable Ca and Na, and an increase in exchangeable Fe. This is consistent with at least partial displacement of the interlayer cations in montmorillonite by Fe. The loss in CEC might also correlate with a partial conversion of the montmorillonite to chlorite, which is tentatively suggested from the XRD analyses. Fe released from the corroding steel was also observed to displace Ca2+ from the interlayer cation sites in the montmorillonite component. This was manifested by the marked concentration of Ca at the interface with the corroding metal and along the leading edges of 'fronts' of Fe diffusing into the bentonite matrix. The displaced Ca was seen to have re-precipitated as aragonite. The petrographical observations show that the bentonite within the alteration zone, that has reacted with and is enriched by Fe, has a tendency to show significantly reduced shrinkage on sample drying in comparison to the background unaltered bentonite. Conversely, this would suggest that the reacted and altered clay will also have less ability to swell on hydration with water. This behaviour might be consistent with the partial conversion of the montmorillonite to an iron rich dioctahedral smectite such as nontronite, or to non-swelling clay mineral such as chlorite (or chlorite-smectite mixed-layer clay). If this is the case, then this may have important implications for the long-term behaviour of bentonite seals around radioactive waste canisters made of iron or steel

  8. Mineralogía y génesis de las arcillas de la Unidad de Almarchal (series flysch del Campo de Gibraltar. S de España

    Directory of Open Access Journals (Sweden)

    Carrasco, F.

    1990-08-01

    Full Text Available A study of the fine fraction of the Almarchal unit (Campo de Gibraltar flysch series revealed several very characteristic mineralogical associations, closely associated with the types of the rocks in this area. 1. Kaolinite-(illite-swelling minerals, characteristically associated with the lutitic leves, clearly preponderate in this unit.2. Illite-chlorite, a well-developed association found only in calcareous rocks. 3. Chlorite and/or berthierine, a characteristic association of silicified levels. Thus, it is possible to determine a group of levels, typically turbiditic and another group of lutitic levels, probably hemipelagic deposits, in which the content of organic material is noteworthy. The control of the mineralogic evolution by lithology is a result of different permeabilities in alternating levels. In calcareous beds the mineralogy of the fine fraction could result from the diagenetic degradation of aluminosilicates. Diagenetic Fe-rich chlorites, preferably developed in siliceous rocks resulting from the evolution of detrital kaolinites. In lutitic beds, two types of mineral constituents are mixed: Typically detrital mineral species (like kaolinite and diagenetic materials (swelling minerals. The abundance of organic matter in these levels can be related with oceanic anoxic events in Cretaceous time in North Atlantic basins.El estudio de la fracción fina de la Unidad de Almarchal (series flysch del Campo de Gibraltar ha permitido poner de manifiesto varias asociaciones mineralógicas relacionadas estrechamente con los tipos litológicos presentes: 1. Caolinita-(ilita-minerales hinchables, asociación propia de los niveles lutíticos, claramente dominantes en esta Unidad.2. Bita-clorita, asociación bien desarrollada en las rocas calcáreas.3. Clorita y/o bertierina, minerales que caracterizan a los niveles silicificados.En la mayor parte de las secuencias es posible, por lo tanto, determinar una serie de niveles típicamente turbid

  9. The influence of natural trace element distribution on the mobility of radionuclides. The exemple of nickel in a clay-rock

    International Nuclear Information System (INIS)

    Highlights: • Ni distribution in the Callovian–Oxfordian formation (Bure, France) was investigated. • Ni is mainly borne by pyrite (Py), chlorite and organic matter (OM). • 63Ni sorption on clays is hindered by competition with trace metals (e.g. Zn, Co). • Additional sorption mechanisms are necessary to explain 63Ni long-term retention. • These may be isotopic exchange and structural incorporation (into calcite, OM or Py). - Abstract: The natural distribution of nickel (Ni) in the Callovian–Oxfordian clay-rich rock of Bure (France) was investigated, together with that of cobalt (Co), zinc (Zn) and lead (Pb). The most Ni-enriched phases are pyrite (∼400 × 10−6 g g−1 Ni), sphalerite (∼300 × 10−6 g g−1), chlorite (∼285 × 10−6 g g−1), organic matter (∼300 × 10−6 g g−1), muscovite (100–200 × 10−6 g g−1) and possibly carbonate minerals (mainly calcite and minor dolomite, ∼10 × 10−6 g g−1). Despite their high abundance (up to ∼80% in the upper part of the formation), carbonate minerals are quantitatively a minor Ni reservoir; most of the Ni is borne by chlorite and pyrite, which are minor mineral phases. Co and Ni have a similar distribution, whereas Pb and Zn have partly different reservoirs (e.g. sphalerite – ZnS). In parallel, the equilibrium between rock and pore water was investigated, and importance of pyrite (or reduced sulfur minerals) as Ni reservoir in the formation was confirmed from an in situ experiment perturbed by oxidation processes. Under unperturbed conditions (laboratory kinetics experiments and in situ pore water sampling), Ni solubility ranges from ∼0.2 to 1 × 10−6 mol L−1. The rock sorption capacities with regards to radioactive Ni (in the range of ∼1.5 × 10−10 mol L−1 to ∼1.5 × 10−9 mol L−1 of spiked 63Ni) were also tested using batch experiments. Sorption kinetics of 63Ni on the Callovian–Oxfordian clay-rich rock was explained by two mechanisms: fast and reversible

  10. Geochemical, microtextural and petrological studies of the Samba prospect in the Zambian Copperbelt basement: a metamorphosed Palaeoproterozoic porphyry Cu deposit.

    Science.gov (United States)

    Master, Sharad; Mirrander Ndhlovu, N.

    2015-04-01

    , including potassic (biotite+sericite+ quartz), propylitic (clinozoisite+chlorite+saussuritized plagioclase), phyllic (sericite+quartz+ pyrite+hydromuscovite/illite) and argillic (kaolinite+chlorite+dolomite) alteration. The clays were identified with XRD. All the rocks show penetrative deformational textures and fabrics. Our textural studies show that phyllic zone pyrite crystals have quartz-rich pressure shadows, and they predate all phases of deformation. Similarly, in the potassic zone, fracture-controlled biotite stringers in particular orientations are deformed, and partly replaced by chlorite, again showing their pre-deformational, pre-metamorphic origin. Copper sulfide-bearing quartz veinlets are deformed. Many of the alteration assemblages containing biotite or sericite have been deformed into crenulated schists, showing that they were formed early in the deformation history. Coupled with the dating of a Samba metavolcanic rock at 1964±12 Ma (Rainaud et al., 2005, JAES, 42, 1-31), we regard the Samba deposit as a metamorphosed Palaeoproterozoic porphyry-type Cu deposit, which has undergone deformation, and retrograde metamorphism of its alteration assemblages, during the Neoproterozoic Lufilian Orogeny, followed by post-tectonic cooling, which occurred throughout the Copperbelt at about 480±20 Ma. Samba, together with the Mkushi deposits, is part of a long-lived (>100 Ma) Palaeoproterozoic porphyry-Cu province in the Zambian Copperbelt basement, and ore genetic theories for the Copperbelt mineralization must now seriously take this into account.

  11. A-type and I-type granitoids and mylonitic granites of Hassan Salaran area of SE Saqqez, Kurdistan, Iran

    Science.gov (United States)

    Abdullah, Fakhraddin Mohammad; Saeed Ahmad, Sheler

    2014-05-01

    event. The mylonitic granites are elongated masses with a NE-SW trend and their contacts with the A-type and I-type granitoids are fault contact. Hand specimens have a layered appearance with green bands made from chlorite and epidote and grey to white bands with quartz and feldspar. These rocks contain plagioclase, quartz and orthoclase under the microscope. Also fine-grained minerals such as quartz, sericite, epidote, chlorite and opaque minerals make the groundmass wrapping the porphyroclasts. Pressure shadows around porphyroclasts of plagioclase and quartz and crystallization of fine-grained quartz and sericite in these places along with intense alteration of plagioclase to epidote and sericite, existence of quartz with different sizes, andaluse extinction in quartz crystals, and elongation of chlorites, resulted from dynamic recrystallisation of biotites all indicate effect of stresses on the rocks. Considering the similar mineralogical composition of the mylonitic rocks with I-type granitoid, it could be concluded that the granodioritic magma, after intrusion and solidification, is changed to mylonite in a shear zone due to tectonical forces.

  12. Syn- to post-orogenic exhumation of metamorphic nappes: Structure and thermobarometry of the western Attic-Cycladic metamorphic complex (Lavrion, Greece)

    Science.gov (United States)

    Scheffer, Christophe; Vanderhaeghe, Olivier; Lanari, Pierre; Tarantola, Alexandre; Ponthus, Léandre; Photiades, Adonis; France, Lydéric

    2016-05-01

    The Lavrion peninsula is located along the western boundary of the Attic-Cycladic metamorphic complex in the internal zone of the Hellenic orogenic belt. The nappe stack is well exposed and made, from top to bottom, of (i) a non-metamorphic upper unit composed of an ophiolitic melange, (ii) a middle unit mainly composed of the Lavrion schists in blueschist facies, (iii) and a basal unit mainly composed of the Kamariza schists affected by pervasive retrogression of the blueschist facies metamorphism in greenschist facies. The middle unit is characterized by a relatively steep-dipping foliation associated with isoclinal folds of weakly organized axial orientation. This foliation is transposed into a shallow-dipping foliation bearing a N-S trending lineation. The degree of transposition increases with structural depth and is particularly marked at the transition from the middle to the basal unit across a low-angle mylonitic to cataclastic detachment. The blueschist facies foliation of the Lavrion schists (middle unit) is underlined by high pressure phengite intergrown with chlorite. The Kamariza schists (basal unit) contains relics of the blueschist mineral paragenesis but is dominated by intermediate pressure phengite also intergrown with chlorite and locally with biotite. Electron probe micro-analyzer chemical mapping combined with inverse thermodynamic modeling (local multi-equilibrium) reveals distinct pressure-temperature conditions of crystallization of phengite and chlorite assemblages as a function of their structural, microstructural and microtextural positions. The middle unit is characterized by two metamorphic conditions grading from high pressure (M1, 9-13 kbar) to lower pressure (M2, 6-9 kbar) at a constant temperature of ca. 315 °C. The basal unit has preserved a first set of HP/LT conditions (M1-2, 8-11 kbar, 300 °C) partially to totally transposed-retrogressed into a lower pressure mineral assemblage (M3, 5-8.5 kbar) associated with a slight but

  13. Mineralogy and Colosation of Oil-Green Jadeite Jade%“油青种”翡翠的矿物学特征及颜色成因

    Institute of Scientific and Technical Information of China (English)

    殷科; 田键; 马遇伯; 吴钰; 汪洋

    2014-01-01

    采用X射线衍射、红外吸收光谱及扫描电镜等现代测试方法,对“油青种”翡翠的矿物学特征及颜色成因进行了深入研究。X射线衍射分析结果显示,“油青种”翡翠“肉”的矿物组成为较纯的硬玉,而“皮”由硬玉、绿泥石及纤蛇纹石等三种矿物组成。红外吸收光谱分析所揭示的矿物组成与X射线衍射较为一致,同时发现“油青种”翡翠“肉”及“皮”具有~2956,~2919和~2850 cm -1等三个典型有机质的特征吸收峰。“油青种”翡翠“肉”中硬玉呈现明显的柱状,结晶程度明显好于“皮”中的硬玉,但“皮”中硬玉比“肉”中硬玉明显富含Mg ,说明“皮”中硬玉发生过强烈的水/岩反应。纤蛇纹石仅在“油青种”翡翠的“皮”中出现,晶面呈现明显的弯曲状。在“油青种”翡翠“肉”的裂隙处及“皮”中均发现片状绿泥石的存在,可能为“油青种”翡翠致色的主要原因。形成于还原性水/岩反应的绿泥石,会吸附或者包裹一定量的有机质,导致“油青种”翡翠出现有机质的特征吸收峰。%Mineralogy and coloration of oil-green jadeite jade were investigated using X-Ray diffraction (XRD) ,Fourier trans-form infrared absorption spectroscopy (FTIR) and scanning electron microscopy (SEM ) .XRD results show that “flesh” of oil-green jadeite jade is mainly composed of relatively pure jadeite ,whereas the“skin”of which is dominated by jadeite ,chlorite and chrysotile .The mineral constituents revealed by FTIR are fairly consistent with XRD . Three typical adsorption peaks of~2 956 ,~2 919 and ~2 850 cm -1 related to organic matters occurred in both “flesh”and“skin”of oil-green jadeite jade .Jade-ite in“flesh”exhibits an obvious columnar growth and has a better crystallinity than that of “skin” .However ,jadeite in“skin”is richer in magnesium than that of

  14. Mineralogy, chemistry of magnetite and genesis of Korkora-1 iron deposit, east of Takab, NW Iran

    Directory of Open Access Journals (Sweden)

    Mohammad Maanijou

    2014-10-01

    Full Text Available Introduction There is an iron mining complex called Shahrak 60 km east of Takab town, NW Iran. The exploration in the Shahrak deposit (general name for all iron deposits of the area started in 1992 by Foolad Saba Noor Co. and continued in several periods until 2008. The Shahrak deposit comprising 10 ore deposits including Korkora-1, Korkora-2, Shahrak-1, Shahrak-2, Shahrak-3, Cheshmeh, Golezar, Sarab-1, Sarab-2, and Sarab-3 deposits Sheikhi, 1995 with total 60 million tons of proved ore reserves. The Fe grade ranges from 45 to 65% (average 50%. The ore reserves of these deposits vary and the largest one is Korkora-1 with 15 million tons of 55% Fe and 0.64% S. The Korkora-1 ore deposit is located in western Azarbaijan and Urumieh-Dokhtar volcanic zone, at the latitude of 36°21.8´, and longitude of 47°32´. Materials and methods Six thin-polished sections were made on magnetite, garnet, and amphibole for EPMA (Electron Probe Micro Analysis. EPMA was performed using a JEOL JXA-733 electron microprobe at the University of New Brunswick, Canada, with wavelength-dispersive spectrometers. Results and discussion Outcropped units of the area are calc-alkaline volcanics of rhyolite, andesite and dacite and carbonate rocks of Qom Formation in which intrusion of diorite to granodiorite and quartzdoirite caused contact metamorphism, alteration plus skarnization and formation of actinolite, talc, chlorite, phlogopite, quartz, calcite, epidote and marblization in the vicinity of the ore deposit. Iron mineralization formed at the contacts of andesite and dacite with carbonates in Oligo-Miocene. The study area consists of skarn, metamorphic rocks, and iron ore zones. The shape of the deposit is lentoid to horizontal with some alteration halos. The ore occurred as replacement, massive, disseminated, open-space filling and breccia. The ore minerals of the deposit include low Ti-magnetite (0.04 to 0.2 wt % Ti, minor apatite, and sulfide minerals such as pyrite

  15. An experimental evaluation of the reaction of granite with streamwater, seawater and NaCl solutions at 200°C

    Science.gov (United States)

    Savage, David; Bateman, Keith; Milodowski, Antoni E.; Hughes, Colin R.

    1993-10-01

    Experiments reacting granite with streamwater, seawater, and NaCl solutions have been conducted at 200°C, 50 MPa under batch conditions using direct-sampling autoclaves for durations up to 80 days. Granite-streamwater experiments at 10:1 and 2:1 water/rock ratios produced fluids of low TDS (precipitated was directly related to the amount of Mg present in the initial system. The reaction of granite with seawater produced a fluid of low pH (≈ 3.5), and principal changes in the fluid chemistry as follows: a gain of SiO 2; and losses of sulphate, magnesium, and calcium. Appreciable mobilisation of heavy metals into the fluid phase such as Fe (up to 15 mg/l) and Mn (up to 2 mg/l) were noted. Solid precipitates consisted of anhydrite, caminite (magnesium hydroxide sulphate hydrate) and a mixed-layer smectite-chlorite clay. The low pH of the evolved fluid is attributed to the precipitation of the hydroxyl-consuming mineral phases, caminite and the smectite-chlorite clay. The reaction of granite with NaCl solutions (0.008 and 0.028 M) produced fluids which were similar to those of the streamwater experiments. However, pH was lower in the NaCl experiments (=7.4-7.8), so that the steady-state concentrations of a number of the cationic constituents of the fluids were slightly greater in these experiments compared with the streamwater experiments. The dominant constituent of the product fluids (excepting NaCl) was SiO 2, the concentration of which was buffered by quartz solubility. The sole secondary solid product identified was a sparsely-developed illitic clay. The injection of a Li-Rb-Cs-Na-Cl fluid into the experiments after 1000 hours demonstrated that the concentrations of the rare alkalis in the fluids were controlled by non-equilibrium processes. Other chemical components perturbed by dilution returned to the steady states developed prior to the injection process, demonstrating buffering by metastable reactions with the rock. The steady-state composition of the

  16. Grain size distribution, clay mineralogy and chemistry of bottom sediments from the outer Thermaikos Gulf, Aegean Sea, Greece

    Directory of Open Access Journals (Sweden)

    K.G. PEHLIVANOGLOU

    2012-12-01

    Full Text Available The Thermaikos Gulf constitutes the NW part of the North Aegean Sea and is limited eastward from the Chalkidiki Peninsula and westward from the Pieria Prefecture. Its plateau covers an area of 3,500 km2. The mechanisms responsible for the grain size distribution into the Gulf, the clay mineralogy and the chemistry of some bottom sediments from the outer Thermaikos Gulf, are examined. Source mixing during transportation, flocculation, differential settling processes and organic matter appear to be the main mechanisms for the distribution of clay minerals in shallow waters. All grain size fractions studied present a wide range of values confirming the extreme variations of the discharged load and the variability in marine processes. Plagioclases predominate over K-feldspars, while quartz is the most abundant mineral present. In addition, micas, chlorites, amphiboles and pyroxenes exist as primary and/or accessory minerals in all samples. Among clay minerals, illite predominates over smectite and smectite over chlorite (+ kaolinite. The ordered interstratified phase of I/S, with 30-35% S layers, is present in the 2-0.25µm fraction. The randomly interstratified phase of I/S, with 50% S layers, is present in the <0.25& micro; m fraction. On average the clay mineral content of the studied samples is: 48% I, 23% S, 17% Ch (+K and 12% others for the 2-0.25µm fraction and 50% I, 30% S and 20% Ch (+K for the <0.25 µm fraction. All these minerals are the weathering products of the rocks from the drainage basins of the rivers flowing into the Gulf, as well as of the Neogene and Quaternary unconsolidated sediments of the surrounding coasts. The terrigenous input, the water mass circulation and, to a lesser extent, the quality of the discharged material and the differential settling of grains, control the grain size distribution within the outer Thermaikos Gulf. The chemical composition of the analysed samples is generally in agreement with their mineral

  17. Paleoenvironmental Implications of Clay Minerals at Yellowknife Bay, Gale Crater, Mars

    Science.gov (United States)

    Bristow, Thomas F.; Blake, David F.

    2014-01-01

    The Mars Science Laboratory (MSL) Rover, Curiosity spent approx 150 sols at Yellowknife Bay (YKB) studying a section of fluvio-lacustrine sedimentary rocks (with potential indications of volcanic influence), informally known as the Yellowknife Bay formation. YKB lies in a distal region of the Peace Vallis alluvial fan, which extends from the northern rim of Gale Crater toward the dune field at the base of Mt Sharp. Sedimentological and stratigraphic observations are consistent with the Yellowknife Bay formation being part of a distal fan deposit, which could be as young as middle Hesperian to even early Amazonian in age (approx. 3.5 to 2.5 Ga). The Yellowknife Bay formation hosts a unit of mudstone called the Sheepbed member. Curiosity obtained powdered rock samples from two drill holes in the Sheepbed Member, named John Klein and Cumberland, and delivered them to instruments in Curiosity. Data from CheMin, a combined X-ray diffraction (XRD)/X-ray fluorescence instrument (XRF), has allowed detailed mineralogical analysis of mudstone powders revealing a clay mineral component of approx. 20 wt.% in each sample. The clay minerals are important indicators of paleoenvironmental conditions and sensitive recorders of post-depositional alteration processes. The XRD pattern of John Klein reveals a 02l band consistent with a trioctahedral phyllosilicate. A broad peak at approx. 10A with a slight inflexion at approx. 12A indicates the presence of 2:1 type clay minerals in the John Klein sample. The trioctahedral nature of the clay minerals, breadth of the basal reflection, and presence of a minor component with larger basal spacing suggests that John Klein contains a trioctahedral smectite (probably saponite), whose interlayer is largely collapsed because of the low-humidity conditions. The XRD patterns show no evidence of corrensite (mixed-layer chlorite/smectite) or chlorite, which are typical diagenetic products of trioctahedral smectites when subjected to burial and

  18. Grain-rimming kaolinite in Permian Rotliegend reservoir rocks

    Science.gov (United States)

    Waldmann, Svenja; Gaupp, Reinhard

    2016-04-01

    Upper Rotliegend sediments of Permian age from the northeast Netherlands show moderate to good reservoir qualities. The predominant control is by the presence of authigenic grain-rimming kaolinite, which has a negative, but in some parts also a positive, effect on reservoir quality. To better understand the formation and distribution of grain-rimming kaolinite, reservoir rocks were studied in terms of composition and diagenetic processes. Petrographic evidence, summarized as a paragenetic sequence, is integrated with geochemical modeling results to identify early mesodiagenetic water-rock interactions under the participation of gases, i.e., CO2 and H2S, released from underlying Carboniferous source rocks. The sediments investigated were deposited at varying distance from the southern flank of the Southern Permian Basin. Sediments near the basin margin are mainly attributed to a fluvial environment and comprise medium to coarse-grained sandstones and conglomerates. There, vermicular kaolinite occurs with a lath-like structure. Distal to the basin margin, mainly in sandstones intercalated with fine-grained playa sediments, comparatively high amounts of grain-rimming kaolinite occur. There, the presence of this mineral has a significant influence on the rock properties and the reservoir quality. Geochemical modeling suggests that the formation of such kaolinites cannot be explained exclusively by in situ feldspar dissolution. The modeling results support evidence that kaolinite can be formed from precursor clay minerals under the presence of CO2-rich formation waters. Such clay minerals could be corrensite, smectite-chlorite mixed-layer minerals, or chlorite that is potentially present in Rotliegend sediments during early diagenesis. Furthermore, the geochemical modeling can reflect several mineral reactions that were identified from petrographic analysis such as the formation of illite and kaolinite at the expense of feldspar dissolution and consequent silica

  19. Clay minerals and geochemistry of the bottom sediments in the northwestern East China Sea

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Clay minerals of 34 sediments collected from the northwestern continental shelf of the East China Sea have been determined by X-ray diffraction analysis. The clay mineral distribution is mainly controlled by the sediment source and the dominant circulation pattern. The predominant clay mineral in our study area is illite comprising more than 67% of the whole clay fraction. The highest concentration of illite (>68%) is found in the southeastern offshore parts beyond the reach of terrigenous input from the Jeju Island. It means that these illites are largely transported by the Kuroshio Current from the South China Sea (SCS). Smectite is highly concentrated in the northwest middle part and in the outer-shelf mud patch. It seems to be due to the high supply of smectite transported from China where fine-grained sediments are discharged from modern and ancient Huanghe (Yellow) River. The relatively high abundant kaolinite is likely derived from the Changjiang (Yangtze) River via the Taiwan Warm Current. In contrast,large amounts of chlorite and high chlorite/kaolinite ratios occur in the northwestern area, reflecting the transportation by the Yellow Sea Coastal Current from the southern Yellow Sea. The discrimination diagrams clearly show that the sediments in the northwestern East China Sea are ultimately sourced from Chinese rivers, especially from the Huanghe River, whereas the sediment in the northeast part might come from the Jeju Island. The muddy sediments of the Changjiang River's submerged delta have much lower 87Sr/86Sr ratios (0.7162-0.7180) than those of the Shandong Peninsular mud wedge (0.7216-0.7249),which are supposed to be originated from the Huanghe River, suggesting the distribution pattern of 87Sr/86Sr ratios as a new tracer to discriminate the provenance of shelf sediments in the study area. The 87Sr/86Sr ratios of the outer-shelf muddy sediments ranged from 0.7169 to 0.7216 in a wide range and was between those of the Huanghe River and Changjiang

  20. The First X-ray Diffraction Patterns of Clay Minerals from Gale Crater

    Science.gov (United States)

    Bristow, Thomas; Blake, David; Bish, David L.; Vaniman, David; Ming, Douglas W.; Morris, Richard V.; Chipera, Steve; Rampe, Elizabeth B.; Farmer, Jack, D.; Treiman, Allan H; Downs, Robert; Morrison, Shaunna; Achilles, Cherie; DesMarais, David J.; Crisp, Joy A.; Sarrazin, Philippe; Morookian, John Michael; Grotzinger. John P.

    2013-01-01

    The Mars Science Laboratory (MSL) Rover, Curiosity spent approx 150 sols at Yellowknife Bay (YKB) studying a section of fluvio-lacustrine sedimentary rocks (with potential indications of volcanic influence), informally known as the Yellowknife Bay formation. YKB lies in a distal region of the Peace Vallis alluvial fan, which extends from the northern rim of Gale Crater toward the dune field at the base of Mt Sharp. Sedimentological and stratigraphic observations are consistent with the Yellowknife Bay formation being part of a distal fan deposit, which could be as young as middle Hesperian to even early Amazonian in age (approx 3.5 to 2.5 Ga). The Yellowknife Bay formation hosts a unit of mudstone called the Sheepbed member. Curiosity obtained powdered rock samples from two drill holes in the Sheepbed Member, named John Klein and Cumberland, and delivered them to instruments in Curiosity. Data from CheMin, a combined X-ray diffraction (XRD)/X-ray fluorescence instrument (XRF), has allowed detailed mineralogical analysis of mudstone powders revealing a clay mineral component of approx 20 wt.% in each sample. The clay minerals are important indicators of paleoenvironmental conditions and sensitive recorders of post-depositional alteration processes. The XRD pattern of John Klein reveals a 021 band consistent with a trioctahedral phyllosilicate. A broad peak at approx 10A with a slight inflexion at approx 12A indicates the presence of 2:1 type clay minerals in the John Klein sample. The trioctahedral nature of the clay minerals, breadth of the basal reflection, and presence of a minor component with larger basal spacing suggests that John Klein contains a trioctahedral smectite (probably saponite), whose interlayer is largely collapsed because of the low-humidity conditions. The XRD patterns show no evidence of corrensite (mixed-layer chlorite/smectite) or chlorite, which are typical diagenetic products of trioctahedral smectites when subjected to burial and heating

  1. Identification of mineral composition and weathering product of tuff using reflectance spectroscopy

    Science.gov (United States)

    Hyun, C.; Park, H.

    2009-12-01

    Tuff is intricately composed of various types of rock blocks and ash matrixes during volcanic formation processes. Qualitative identification and quantitative assessment of mineral composition of tuff usually have been done using manual inspection with naked-eyes and various chemical analyses. Those conventional methods are destructive to objects, time consuming and sometimes carry out biased results from subjective decision making. To overcome limits from conventional methods, assessment technique using reflectance spectroscopy was applied to tuff specimens. Reflectance spectroscopy measures electromagnetic reflectance on rock surface and can extract diagnostic absorption features originated from chemical composition and crystal structure of constituents in the reflectance curve so mineral species can be discriminated qualitatively. The intrinsic absorption feature from particular mineral can be converted to absorption depth representing relative coverage of the mineral in the measurement area by removing delineated convex hull from raw reflectance curve. The spectral measurements were performed with field spectrometer FieldSpec®3 of ASD Inc. and the wavelength range of measurement was form 350nm to 2500nm. Three types of tuff blocks, ash tuff, green lapilli tuff and red lapilli tuff, were sampled from Hwasun County in Korea and the types of tuffs. The differences between green tuff and red tuff are from the color of their matrixes. Ash tuff consists of feldspars and quartz and small amount of chalcedony, calcite, dolomite, epidote and basalt fragments. Green lapilli tuff consists of feldspar, quartz and muscovite and small amount of calcite, chalcedony, sericite, chlorite, quartzite and basalt fragments. Red lapilli tuff consists of feldspar, quartz and muscovite and small amount of calcite, chalcedony, limonite, zircon, chlorite, quartzite and basalt fragments. The tuff rocks were coarsely crushed and blocks and matrixes were separated to measure standard

  2. The First X-ray Diffraction Patterns of Clay Minerals from Gale Crater

    Science.gov (United States)

    Bristow, T.; Blake, D.; Bish, D. L.; Vaniman, D.; Ming, D. W.; Morris, R. V.; Chipera, S.; Rampe, E. B.; Farmer, J. D.; Treiman, A. H.; Downs, R.; Morrison, S.; Achilles, C.; Des Marais, D. J.; Crisp, J. A.; Sarrazin, P.; Morookian, J.; Grotzinger, J. P.; Team, M.

    2013-12-01

    The Mars Science Laboratory (MSL) Rover, Curiosity spent ~150 sols at Yellowknife Bay (YKB) studying a section of fluvio-lacustrine sedimentary rocks (with potential indications of volcanic influence), informally known as the Yellowknife Bay formation. YKB lies in a distal region of the Peace Vallis alluvial fan, which extends from the northern rim of Gale Crater toward the dune field at the base of Mt Sharp. Sedimentological and stratigraphic observations are consistent with the Yellowknife Bay formation being part of a distal fan deposit, which could be as young as middle Hesperian to even early Amazonian in age (~3.5 to 2.5 Ga). The Yellowknife Bay formation hosts a unit of mudstone called the Sheepbed member. Curiosity obtained powdered rock samples from two drill holes in the Sheepbed Member, named John Klein and Cumberland, and delivered them to instruments in Curiosity. Data from CheMin, a combined X-ray diffraction (XRD)/X-ray fluorescence instrument (XRF), has allowed detailed mineralogical analysis of mudstone powders revealing a clay mineral component of ~20 wt.% in each sample. The clay minerals are important indicators of paleoenvironmental conditions and sensitive recorders of post-depositional alteration processes. The XRD pattern of John Klein reveals a 02l band consistent with a trioctahedral phyllosilicate. A broad peak at ~10A with a slight inflexion at ~12A indicates the presence of 2:1 type clay minerals in the John Klein sample. The trioctahedral nature of the clay minerals, breadth of the basal reflection, and presence of a minor component with larger basal spacing suggests that John Klein contains a trioctahedral smectite (probably saponite), whose interlayer is largely collapsed because of the low-humidity conditions. The XRD patterns show no evidence of corrensite (mixed-layer chlorite/smectite) or chlorite, which are typical diagenetic products of trioctahedral smectites when subjected to burial and heating >60°C in the presence of water

  3. Environmentálne aspekty transformácie nízko-sulfidického postflotačného kalu na antropogénnu pôdu (Smolník, Slovensko

    Directory of Open Access Journals (Sweden)

    Mangová Kristína

    2015-12-01

    Full Text Available An anthropogenic soil developed on the mine tailing impoundment in Smolník was studied to document a transformation of post flotation mud (tailings to the soil. The tailing can be characterised as fine sand to silt grain size milled wall rock mineral matter composed by quartz, mica, chlorite, and siderite with low pyrite content. Surface of the tailing impoundment have been covered by a 10–15 cm thick layer of wood-waste material and forested by pine-plants. Two soil horizons A-topsoil (humus and B-subsoil horizons have been recognised above the post flotation mud (tailings. Oxidation of pyrite and “acid” generation, leach and dissolution of the minerals and precipitation of iron oxy-hydroxides have been main processes beginning the tailings alteration. The processes were indicated by yellowish colours and raised homogeneity of the subsoil tailings. Variegated and relative high content of organic matter (TOC ≈ 3–15 wt. %, neutral to low acid pH (6.01–7.25, decreased amount of carbonates but a saturation with the bases (CEC: 20–80 mmol.100 g-1, especially with Ca2+ characterised A horizon. Contents of 0.5 M HCl extractable fractions of Cu, Pb, Zn and As were locally higher as in the sub-soils, respective as in the tailings/substrate. There were favourable conditions to Fe oxide precipitation as indicated contents of oxalate extractable Fe oxide (FeOX in range 1.3–6.1 wt. % in the soil profile. Besides the iron oxide precipitation the remobilization of metals has been limited by other factors, mainly by organic matter accumulation and by humus formation which actively “aggregated” mineral particles in A horizon. Indicated mixed-layered vermiculite-chlorite or vermiculite-illite minerals formation also suggested a role of organic matter in the soil-pH decrease and primary phyllosilicates transformation. Soil-forming process was positively “accelerated” by fine-milled character and primary mineralogy (pyrite < 5 wt. % of the

  4. Recent advances in the study of H environments and behavior in minerals using neutron powder diffraction

    Science.gov (United States)

    Welch, M. D.

    2002-12-01

    It is now possible to probe the structural environments and behavior of H atoms directly in complex minerals such as amphiboles, micas, chlorites and humites using neutron powder diffraction, in some cases as a function of pressure and/or temperature. A combination of high neutron flux and increased detector sensitivity and size offers the chance to see details of H behaviour. In the last year or so the advent of new gasket designs for the Paris-Edinburgh pressure cell allow the use of ethanol/methanol (EtOD/MeOD) as a pressure medium, removing peak broadening arising from deviatoric stress that occurs above 3 GPa for the standard fluorinert pressure medium. Essentially hydrostatic conditions obtain with EtOD/MeOD to 8 GPa at 298 K. A further recent development has been the design of a high P-T module for use with the Paris-Edinburgh cell. These technological improvements in pressure-cell design now allow us to make meaningful correlations between OH vibrational spectra collected at high P and/or T and detailed structural information on H behaviour obtained from neutron diffraction under similar conditions. In this talk I shall discuss recent neutron diffraction experiments on the effect of pressure upon hydrogen bonding in deuterated chlorite to 5 GPa (298 K), and a high P-T study of hydrogen bonding in deuterated brucite to 7 GPa, 1100 K. These two studies illustrate how far high-pressure neutron diffraction has come in the last 5 years. Finally, I shall describe a neutron powder diffraction study (ambient conditions) of leucophoenicite, Mn7Si3O12(OH)2, a close structural analogue of Phase-B and Superhydrous-B: the structure of leucophoenicite is topologically identical to the hydrous sheet of Phase-B and similar to that of Superhydrous-B. For various reasons it was not possible to deuterate the sample. Nonetheless, the two distinct H atoms were approximately located in difference-Fourier maps and then refined isotropically. The H positions in Phase-B were only

  5. Mineralogy and Geochemistry of Clay Rich Volcano-Sedimentary Units from South of Elazıǧ Basin (Eastern Turkey)

    Science.gov (United States)

    Akkoca, Dicle Bal; Bakır, Zülfü

    2016-04-01

    The investigated area covers Upper Cretaeous Elazıǧ Magmatics and Middle Eocene Maden Group in the southern of Elazıǧ. X-ray powder diffraction (XRD), ICP-AES, ICP-MS were performed on three sections samples belonging to Elazıǧ Magmatics (Yemişlik and Kavallı sections) and Maden Group (Alıncık section), to investigate the depositional environment of volcano-sediments. The Elazıǧ magmatic rocks are composed of diorites, monzodiorites, quartz-diorites, and tonalites, basaltic pillow-lavas, andesitic lavas, and andesitic pyroclastic rocks. The Maden Group has a complex lithology consisting of limestones, red-green clayey limestones, sandstone, agglomerate, tuffs, reddish mudstone and basaltic-andesitic pillow lavas. Yemişlik section is composed mainly of altered grey tuffites, Kavallı section is represented by brown altered sediments, intercalated with basaltic, andesitic lava flows. Reddish mudstones constiture the Alıncık section. All samples consist of clay minerals (chlorite, illite), quartz, and feldspar. Yemişlik and Kavallı sections also contain calcite. Chlorite is the dominant clay in three sections. SiO2, Al2O3, Fe2O3, K2O contents show that Kavallı, Yemişlik and Alıncık samples are convenient with Fe shales and shales. The ratios of TiO2, Zr, Th/Sc, Zr/Sc, Y/Ni-Cr/V, Al/(Al+Fe+Mn) show dominance of neutral-basic volcanism in the area. REE concentrations of samples are normalized to chondrite values. It is determined that low light rare earth elements (LREEs) are enriched in comparison to high rare earth elements (HREEs), and the absence of Eu anomalies shows that our samples are generally mafic in composition. Rare earth elements (REE) of samples were compared with North American shale composite (NASC), European shale (ES) and Post-Archean Australian shale (PAAS). Elements are not in concurrence with these compositions. Th-Hf/3-Nb/16 tectono-magmatic discrimination diagram for samples in the study area indicate that all samples were

  6. W-Au skarns in the Neo-Proterozoic Seridó Mobile Belt, Borborema Province in northeastern Brazil: an overview with emphasis on the Bonfim deposit

    Science.gov (United States)

    Souza Neto, João Adauto; Legrand, Jean Michel; Volfinger, Marcel; Pascal, Marie-Lola; Sonnet, Philippe

    2008-02-01

    The Seridó Mobile Belt (SMB) is located in the Borborema Province in northeastern Brazil and consists of a gneiss basement (Archean to Paleo-Proterozoic), a metasedimentary sequence (marble, quartzites, and schists), and the Brasiliano igneous suite (both of Neo-Proterozoic age). In this region, skarns occur within marble and at the marble-schist contact in the metasedimentary sequence. Most of the skarn deposits have been discovered in the early 1940s, and since then, they have been exploited for tungsten and locally gold. Recently, the discovery of gold in the Bonfim tungsten skarn has resulted in a better understanding of the skarn mineralization in this region. The main characteristics of the SMB skarns are that they are dominantly oxidized tungsten skarns, with the exception of the Itajubatiba and Bonfim gold-bearing skarns, which are reduced based on pyrrhotite as the dominant sulfide, garnet with high almandine and spessartine component, and elevated gold contents. In the Bonfim deposit, pressure estimates indicate that the skarns formed at 10- to 15-km depth. The mineralized skarns present the prograde stage with almandine, diopside, anorthite, and actinolite-magnesio-hornblende, and titanite, apatite, allanite, zircon, and monazite as accessory minerals. The retrograde stage is characterized by alkali feldspar, clinozoisite-zoisite-sericite, calcite, and quartz. Scheelite occurs in four ore-shoots distributed within the marble and at the marble-schist contact. The main ore body is 5-120 cm wide and contains an average of 4.8-wt.% WO3, which occurs in the basal marble-schist contact. Fold hinges appear to control the location of high-grade scheelite. The late-stage gold mineralization contains bismite (Bi2O3), fluorine-bearing bismite, native bismuth, bismuthinite (Bi2S3), and joseite [Bi4(Te,S)3], and also chlorite, epidote, prehnite, chalcopyrite, and sphalerite. This gold-bismuth-tellurium mineralization exhibits a typical late character and occurs as a

  7. Desilicification and iron activation-reprecipitation in the high-grade magnetite ores in BIFs of the Anshan-Benxi area, China: Evidence from geology, geochemistry and stable isotopic characteristics

    Science.gov (United States)

    Li, Hou-Min; Yang, Xiu-Qing; Li, Li-Xing; Zhang, Zhao-Chong; Liu, Ming-Jun; Yao, Tong; Chen, Jing

    2015-12-01

    The high-grade magnetite ores related to banded iron formations (BIFs) in the Anshan-Benxi area, Liaoning Province in China, have been widely interpreted as the product of replacement of protore by epigenetic hydrothermal fluids. The high-grade iron ore reserves in the mining area II (164 million tons) in the Gongchangling (G2) and Qidashan-Wangjiabuzi (QW) iron deposits (11.45 million tons) are the largest deposits in the Anshan-Benxi area. We present a detailed comparison of the geology, geochemical and stable isotopic compositions of the iron ores in the G2 with those in the QW to constrain the role of desilicification and iron activation-reprecipitation in converting the BIFs to high-grade magnetite ores. These two deposits show marked difference in wall-rock alteration, geochemical features, and oxygen and sulfur isotopic compositions. Wall-rock alteration in the G2 is characterized by garnetization, actinolitization, and chloritization, whereas the QW shows chloritization, biotitization and sericitization. The geochemistry of altered rocks in the G2 is characterized by slight REE fractionation, positive Eu and no significant Ce anomalies, whereas the QW is characterized by high ΣREE contents, strong REE fractionation, and the absence of significant Eu and Ce anomalies. High-grade iron ores in the G2 show similar δ18OV-SMOW values for magnetite, lower δ18OV-SMOW values for quartz and higher δ34SV-CDT values for pyrite when compared to the BIFs, whereas the QW shows lower δ18OV-SMOW values for magnetite, similar δ18OV-SMOW values for quartz and similar δ34SV-CDT values for pyrite. These features indicate that desilicification process by hypogene alkaline-rich hydrothermal fluids were possibly responsible for the formation of high-grade iron ores in the G2 whereas iron activation-reprecipitation process by migmatitic-hydrothermal fluids generated the high-grade iron orebodies in QW.

  8. Structures, microfabrics and textures of the Cordilleran-type Rechnitz metamorphic core complex, Eastern Alps☆

    Science.gov (United States)

    Cao, Shuyun; Neubauer, Franz; Bernroider, Manfred; Liu, Junlai; Genser, Johann

    2013-01-01

    Rechnitz window group represents a Cordilleran-style metamorphic core complex, which is almost entirely located within nearly contemporaneous Neogene sediments at the transition zone between the Eastern Alps and the Neogene Pannonian basin. Two tectonic units are distinguished within the Rechnitz metamorphic core complex (RMCC): (1) a lower unit mainly composed of Mesozoic metasediments, and (2) an upper unit mainly composed of ophiolite remnants. Both units are metamorphosed within greenschist facies conditions during earliest Miocene followed by exhumation and cooling. The internal structure of the RMCC is characterized by the following succession of structure-forming events: (1) blueschist relics of Paleocene/Eocene age formed as a result of subduction (D1), (2) ductile nappe stacking (D2) of an ophiolite nappe over a distant passive margin succession (ca. E–W to WNW–ESE oriented stretching lineation), (3) greenschist facies-grade metamorphism annealing dominant in the lower unit, and (4) ductile low-angle normal faulting (D3) (with mainly NE–SW oriented stretching lineation), and (5) ca. E to NE-vergent folding (D4). The microfabrics are related to mostly ductile nappe stacking to ductile low-angle normal faulting. Paleopiezometry in conjunction with P–T estimates yield high strain rates of 10− 11 to 10− 13 s− 1, depending on the temperature (400–350 °C) and choice of piezometer and flow law calibration. Progressive microstructures and texture analysis indicate an overprint of the high-temperature fabrics (D2) by the low-temperature deformation (D3). Phengitic mica from the Paleocene/Eocene high-pressure metamorphism remained stable during D2 ductile deformation as well as preserved within late stages of final sub-greenschist facies shearing. Chlorite geothermometry yields two temperature groups, 376–328 °C, and 306–132 °C. Chlorite is seemingly accessible to late-stage resetting. The RMCC underwent an earlier large-scale coaxial

  9. Mineralogía y génesis de las arcillas de las unidades del Campo de Gibraltar. V. Unidad de Bolonia

    Directory of Open Access Journals (Sweden)

    Ruiz Cruz, M. D.

    1990-04-01

    Full Text Available The mineralogical results of the Bolonia Unit are analysed in the work. The Cabrito-l section is characterized by the mineralogical association kaolinite-illite-interestratified I-S, and is similar to the section of Punta Tarifa series of the Algeciras Unit. The Pulido section, characterized by the mineralogical association (kaolinite-illite-chlorite, may be considered as the most distal zone of the «areniscoso-micaceo» flysch of the Algeciras Unit. The most significant difference between the fine fractions of these Units is the remarkable development, in the Bolonia Unit, of authigenic chlorites, whose composition shows a diagenetic environment rich in Fe and Mg. On the other hand, the mineralogical composition of the fine fraction has made possible the identification in the Bolonia Unit, not only the «areniscas del Aljibe» levels, but also clay levels of Aljibe Unit, which has not been noticed until now. These mineralogical and lithological aspects lead to consider the Bolonia Unit as an intermediate Unit between the Algeciras and the Aljibe ones.En este trabajo se recogen los resultados obtenidos a partir del estudio mineralógico de la Unidad de Bolonia. De los perfiles estudiados, el del Cabrito, caracterizado por la asociación mineralógica caolinita-ilita, interestratificados I-E, es similar en gran medida a la serie tipo punta Tarifa de la Unidad de Algeciras. El perfil del Pulido, caracterizado por la asociación (caolinita-ilita-clorita puede interpretarse como la parte más distal del flysch areniscoso-micáceo de la Unidad de Algeciras. La diferencia más notable en la mineralogía de la fracción fina entre ambas Unidades se refiere al desarrollo notable, en Bolonia, de cloritas autigénicas, cuya composición indica un medio diagenético rico en Fe y Mg. Por otra parte, la mineralogía de la fracción fina ha permitido identificar en la Unidad de Bolonia no sólo los niveles de areniscas del Aljibe sino tambi

  10. Prediction of Diagenetic Facies using Well Logs: Evidences from Upper Triassic Yanchang Formation Chang 8 Sandstones in Jiyuan Region, Ordos Basin, China

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    Lai Jin

    2016-05-01

    Full Text Available The eighth member of Upper Triassic Yanchang Formation (Chang 8 is the major oil reservoir unit in Jiyuan oil field, though with the high potential for oil exploration. The Chang 8 sandstones are characterized with low porosity, low permeability and strong microscopic heterogeneities due to the complex deep-burial diagenetic history. Detailed petrological studies by thin section, X-ray diffraction, scanning electron microscopy, core analysis have been used to investigate the lithogology characteristics, diagenesis, diagenetic minerals and their coupling impacts on reservoir property. The results show that Chang 8 sandstones comprise fine to mediumgrained subarkoses, feldspathic litharenites. The pore systems are dominated by remaining primary intergranular pores, secondary dissolution porosity and micropores. Then, five diagenetic facies were divided in Chang 8 sandstones based on the type and degree of diagenesis, diagenetic minerals assemblages and their coupling effects on the reservoir quality. They consist of grain-coating chlorite weak dissolution facies, unstable component dissolution facies, tight compaction facies, clay minerals filling facies and carbonate cementation facies. The well logging response characteristics of various diagenetic facies are summarized on Gamma Ray (GR, Density Logging (DEN, Acoustic (AC, Compensated Neutron Logging (CNL, and True Formation Resistivity (RT by translating diagenetic facies to well log responses, the diagenetic facies were defined by a set of log responses, and porosity, permeability ranges for each diagenetic facies were determined from core analyses. Well log data of Luo 13 and Chi 212 are processed to evaluate the accuracy of the predictive model. The diagenetic facies are predicted on the vertical profile based on the generated model. Predicted distribution of diagenetic facies precisely coincide with the microscopic observations, and diagenetic facies in Chang 8 sandstones are generally

  11. Metamorphic and Ar/Ar geochronology constraints on the Alakeci shear zone: Implications for the extensional exhumation history of the northern Kazdag Massif, NW Turkey

    Energy Technology Data Exchange (ETDEWEB)

    Bonev, N [Sofia University ' St. Kliment Ohridski' , Department of Geology and Paleontology, Sofia 1504 (Bulgaria); Beccaletto, L [BRGM Geological Survey/Geology of Sedimentary Basins, 45060 Orleans, Cedex 2 (France); Robyr, M [Geological Sciences Department, University of Texas, Austin, TX 787 12-0254 (United States); Monie, P [Geosciences, University of Montpellier 2, UMR 5243, 34095 Montpellier Cedex 5 (France)], E-mail: niki@gea.uni-sofia.bg

    2008-07-01

    The Kazdag Massif exposes a metamorphic dome in the Biga Peninsula of northwest Turkey. An extensional origin has been proposed for the dome, limited on both flanks by detachments and/or shear zones. The northern flank is bounded by the extensional Alakeci Shear Zone (ASZ), whose P-T-t path is still poorly known. We therefore focus on its metamorphic conditions and related temporal history to precise its tectono-metamorphic evolution. The local tectonostratigraphy in structurally ascending order comprises: (i) the high-grade metamorphic core rocks of the Kazdag Massif (gneisses and micaschists intercalated with amphibolites and marbles); (ii) the two kilometer-thick ASZ; (iii) the overlaying unmetamorphosed pre-Cenomanian accretionary Cetmi melange; and (iv) Neogene sedimentary and volcanic cover rocks. ASZ mylonites were derived from both the core rocks and the melange lithologies. From the north to the south the mylonitic fabrics in the ASZ depict a top-to-the N-NNE shearing, parallel to the NNE-plunging stretching lineation and NNW-dipping mylonitic foliation. This geometry implies normal sense movement i.e. north-side down-dip extensional displacement along this flank of the Kazdag Massif. The northward transition from ductile to brittle-ductile regime through the ASZ shows that the deformation occurred at decreasing temperatures and degree of metamorphism. The paragenesis in equilibrium within the mylonitic gneisses and schists contains Qtz + Fs + Ms + Bt + Grt {+-} St {+-} Sill, with late retrogressive chlorite after biotite and garnet. Four samples of ASZ rocks yielded pressures between 6.9-5.7 kbar and temperatures between 706-587 deg. C. Three samples from the mylonitic rocks supplied in situ isochron {sup 36}Ar/{sup 40}Ar mica ages between 31.2-24.2 Ma, which we interpret to date the cooling of the mylonites following the P-T decrease across the ASZ. The metamorphic and structural results support the extensional character of the ASZ, and sketch transition

  12. Coupled mass transfer through a fluid phase and volume preservation during the hydration of granulite: An example from the Bergen Arcs, Norway

    Science.gov (United States)

    Centrella, Stephen; Austrheim, Håkon; Putnis, Andrew

    2015-11-01

    The Precambrian granulite facies rocks of Lindås Nappe, Bergen Arcs, Caledonides of W. Norway are partially hydrated at amphibolite and eclogite facies conditions. The Lindås Nappe outcrops over an area of ca. 1000 km2 where relict granulite facies lenses make up only ca. 10%. At Hillandsvatnet, garnetite displays sharp hydration fronts across which the granulite facies assemblage composed of garnet (55%) and clinopyroxene (45%) is replaced by an amphibolite facies mineralogy defined by chlorite, epidote and amphibole. The major element bulk composition does not change significantly across the hydration front, apart from the volatile components (loss on ignition, LOI) that increases from 0.17 wt.% in the granulite to 2.43 wt.% in the amphibolite. However the replacements of garnet and of clinopyroxene are pseudomorphic so that the grain shapes of the garnet and clinopyroxene are preserved even when they are completely replaced. The textural evolution during the replacement of garnet by pargasite, epidote and chlorite and of pyroxene by hornblende and quartz in our rock sample conforms to that expected by a coupled dissolution-precipitation mechanism. SEM and electron microprobe analysis coupled with the software XMapTools V 1.06.1 were used to quantify the local mass transfer required during the replacement processes. The element losses and gains in replacing the garnet are approximately balanced by the opposite gains and losses associated with the replacement of clinopyroxene. The coupling between dissolution and precipitation on both the grain and whole rock spatial scale preserves the volume of the rock throughout the hydration process. However, the hydration involves reduction of rock density and mass balance calculations, together with volume preservation (isovolumetric reaction) require a significant loss of the mass of the rock to the fluid phase. This suggests a mechanism for coupling between the local stress generated by hydration reactions and mass

  13. Alteration hydrothermale et deformation ductile des roches volcaniques acides associees au gisement sulfure de draa sfar (Jebilet Centrales, Maroc

    Directory of Open Access Journals (Sweden)

    Zinbi, Y.

    2005-12-01

    Full Text Available The volcanics and volcanoclastic rocks of Draa Sfar (Central Jebilet, Moroccan hercynian belt are affected by ductile stress and hydrothermal alteration accompanied by a weak degree of metamorphism (greenschist facies. Some N-S oriented shearing zones, affect locally these formations while being the site of an important hydrothermal activity. The consequences of these transformations from a non to slightly- deformed rhyodacite, show that through these ductile shearing zones: (1 the mineralogical assemblage of hydrothermal alteration is essentially formed by chlorite, sericite, quartz and magnetite; (2 the gradual increase of the alteration indexes is accompanied by the destruction of the phenocrists and the recrystallization of the matrix by phyllosilicates and quartz; (3 the progressive transfer of material is more intense in the more deformed zones where the values of Ti, Al and Zr remain constant. These shearing zones played a very important role in the circulation of fluids and the transformation of the rhyodacite of Draa Sfar.Les roches volcaniques et volcanoclastiques de Draa Sfar (Jebilet centrales, Maroc hercynien sont affectées par une déformation ductile accompagnée d’un métamorphisme de faible degré (faciès schistes verts et d’une altération hydrothermale. Des zones de cisaillement de direction N-S, ont affecté localement ces formations tout en étant vecteurs d’une importante activité hydrothermale. Le suivi de ces transformations à partir de la rhyodacite non ou peu déformée, montre qu’à travers ces zones de cisaillements ductiles : (1 l’assemblage minéralogique d’altération hydrothermale est formé essentiellement de chlorite, de séricite, de quartz et de magnétite ; (2 l’augmentation graduelle des indices d’altération s’exprime par la destruction des phénocristaux au profit d’une matrice recristallisée en phyllosilicates et quartz ; (3 le transfert progressif de la matière est plus intense

  14. Carbon, hydrogen, and oxygen isotope studies of the regional metamorphic complex at Naxos, Greece

    Science.gov (United States)

    Rye, R.O.; Schuiling, R.D.; Rye, D.M.; Jansen, J.B.H.

    1976-01-01

    At Naxos, Greece, a migmatite dome is surrounded by schists and marbles of decreasing metamorphic grade. Sillimanite, kyanite, biotite, chlorite, and glaucophane zones are recognized at successively greater distances from the migmatite dome. Quartz-muscovite and quartz-biotite oxygen isotope and mineralogie temperatures range from 350 to 700??C. The metamorphic complex can be divided into multiple schist-rich (including migmatites) and marblerich zones. The ??18O values of silicate minerals in migmatite and schist units and quartz segregations in the schist-rich zones decrease with increase in metamorphic grades. The calculated ??18OH2O values of the metamorphic fluids in the schist-rich zones decrease from about 15??? in the lower grades to an average of about 8.5??? in the migmatite. The ??D values of OH-minerals (muscovite, biotite, chlorite, and glaucophane) in the schist-rich zones also decrease with increase in grade. The calculated ??DH2O values for the metamorphic fluid decrease from -5??? in the glaucophane zone to an average of about -70??? in the migmatite. The ??D values of water in fluid inclusions in quartz segregations in the higher grade rocks are consistent with this trend. The??18O values of silicate minerals and quartz segregations in marble-rich zones are usually very large and were controlled by exchange with the adjacent marbles. The ??D values of the OH minerals in some marble-rich zones may reflect the value of water contained in the rocks prior to metamorphism. Detailed data on 20 marble units show systematic variations of ??18O values which depend upon metamorphic grade. Below the 540??C isograd very steep ??18O gradients at the margins and large ??18O values in the interior of the marbles indicate that oxygen isotope exchange with the adjacent schist units was usually limited to the margins of the marbles with more exchange occurring in the stratigraphic bottom than in the top margins. Above the 540??C isograd lower ??18O values occur in

  15. Reduction and immobilization of hexavalent chromium by microbially reduced Fe-bearing clay minerals

    Science.gov (United States)

    Bishop, Michael E.; Glasser, Paul; Dong, Hailiang; Arey, Bruce; Kovarik, Libor

    2014-05-01

    Hexavalent chromium (Cr6+) is a major contaminant in the environment. As a redox-sensitive element, the fate and toxicity of chromium is controlled by reduction-oxidation (redox) reactions. Previous research has shown the ability of structural Fe(II) in naturally present and chemically reduced clay minerals to reduce Cr6+ to Cr(III) as a way of immobilization and detoxification. However, it is still poorly known whether or not structural Fe(II) in biologically reduced clay minerals exhibits a similar reactivity and if so, what the kinetics and mechanisms of Cr6+ reduction are. The objective of this study was to determine the kinetics and possible mechanisms of Cr6+ reduction by structural Fe(II) in microbially reduced clay minerals and the nature of reduced Cr(III). Structural Fe(III) in nontronite (NAu-2), montmorillonite (SWy-2), chlorite (CCa-2), and clay-rich sediments from the Ringold Formation of the Hanford site of Washington State, USA was first bioreduced to Fe(II) by an iron-reducing bacterium Geobacter sulfurreducens with acetate as the sole electron donor and anthraquinone-2,6-disulfonate (AQDS) as electron shuttle in synthetic groundwater (pH 7). Biogenic Fe(II) was then used to reduce aqueous Cr6+ at three different temperatures, 10, 20, and 30 °C, in order to determine the temperature dependence of the redox reaction between Cr6+ and clay-Fe(II). The results showed that nontronite and montmorillonite were most effective in reducing aqueous Cr6+ at all three temperatures. In contrast, most Fe(II) in chlorite was not reactive towards Cr6+ reduction at 10 °C, though at 30 °C there was some reduction. For all the clay minerals, the ratio of total Fe(II) oxidized to Cr6+ reduced was close to the expected stoichiometric value of 3. Characterization of the Cr-clay reaction product with scanning electron microscopy with focused ion beam and transmission electron microscopy with electron energy loss spectroscopy revealed that reduced chromium was possibly

  16. Reduction And Immobilization Of Hexavalent Chromium By Microbially Reduced Fe-bearing Clay Minerals

    Energy Technology Data Exchange (ETDEWEB)

    Bishop, Michael E.; Glasser, Paul; Dong, Hailiang; Arey, Bruce W.; Kovarik, Libor

    2014-05-15

    Hexavalent chromium (Cr6+) is a major contaminant in the environment. As a redox-sensitive element, the fate and toxicity of chromium is controlled by reduction-oxidation (redox) reactions. Previous research has shown the ability of structural Fe(II) in naturally present and chemically reduced clay minerals to reduce Cr6+ to Cr(III) as a way of immobilization and detoxification. However, it is still poorly known whether or not structural Fe(II) in biologically reduced clay minerals exhibits a similar reactivity and if so, what the kinetics and mechanisms of Cr6+ reduction are. The objective of this study was to determine the kinetics and possible mechanisms of Cr6+ reduction by structural Fe(II) in microbially reduced clay minerals and the nature of reduced Cr(III). Structural Fe(III) in nontronite (NAu-2), montmorillonite (SWy-2), chlorite (CCa-2), and clay-rich sediments from the Ringold Formation of the Hanford site of Washington State, USA was first bioreduced to Fe(II) by an iron-reducing bacterium Geobacter sulfurreducens with acetate as the sole electron donor and anthraquinone-2,6-disulfate (AQDS) as electron shuttle in synthetic groundwater (pH 7). Biogenic Fe(II) was then used to reduce aqueous Cr6+ at three different temperatures, 10°, 20°, and 30°C, in order to determine the temperature dependence of the redox reaction between Cr6+ and clay-Fe(II). The results showed that nontronite and montmorillonite were most effective in reducing aqueous Cr6+ at all three temperatures. In contrast, most Fe(II) in chlorite was not reactive towards Cr6+ reduction at 10°C, though at 30°C there was some reduction. For all the clay minerals, the ratio of total Fe(II) oxidized to Cr6+ reduced was close to the expected stoichiometric value of 3. Characterization of the Cr-clay reaction product with scanning electron microscopy with focused ion beam and transmission electron microscopy with electron energy loss spectroscopy revealed that reduced chromium was possibly

  17. What Are the Time Scales for Carbonate Mineral Sequestration in the Subsurface?

    Science.gov (United States)

    Steefel, C. I.; Landrot, G.; Bolton, E. W.; Pride, S. R.

    2013-12-01

    Mineral trapping of CO2 in the subsurface is acknowledged to be the most secure form of sequestration, but some studies have suggested that the process is extremely slow, perhaps on the order of 10,000 years or more. But what are the arguments for these long time scales based on? Certainly part of it has to do with the slow dissolution rates of silicates needed to provide a source of cations (Ca2+, Mg2+, and Fe2+) and alkalinity for carbonate precipitation. Rates of dissolution for many silicates are very slow (e.g., albitic plagioclase and chlorite), while other silicate minerals (anorthitic feldspar, olivine) dissolve appreciably faster. Determining which mineral is rate-limiting in the case of the faster dissolving silicates (is it the dissolving silicate or precipitating carbonate?), however, is not always straightforward without a careful analysis of dissolution and precipitation as a coupled process. We use micro-continuum modeling to address the issue of time scales for carbonate mineral trapping of CO2. Two sets of simulations have been carried out: 1) largely generic simulations at the centimeter scale that include heterogeneous distributions of both residually trapped scCO2 and reactive mineral phases (Ca-bearing plagioclase and chlorite), and 2) flow plus diffusion and pure diffusion simulations of the reactivity of a reservoir sandstone from a scCO2 pilot injection site at Cranfield, Mississippi. The first set of simulations are designed specifically to examine the assumption that the reservoir within which carbonate mineral precipitation might occur is well-mixed and therefore characterized everywhere by the low pH values typical of brine in equilibrium with supercritical CO2. Our analysis of physically and chemically heterogeneous subsurface materials, especially during the residual trapping stage, suggest that local chemical microenvironments can develop in which pH, alkalinity, and cation concentrations rise sufficiently high that substantial

  18. Metamorphic evolution of the high-pressure metamorphic rocks from the Kemer area (Biga Peninsula, NW Turkey): Implications for the accretionary continental growth and closure of the Intra-Pontide Ocean

    Science.gov (United States)

    Aygül, M.; Topuz, G.; Satır, M.

    2009-04-01

    The northwestern part of the Biga Peninsula, NW Turkey, corresponds to the so-called Intra-Pontide suture, separating the Rhodope-Strandja zone to the north and Sakarya zone to the south. This suture zone is marked by the exposures of high-pressure metamorphics, oceanic accretionary complexes and ophiolites, which are widely covered by Eocene to Miocene volcanics and volcano-clastics, and crosscut by Eocene to Miocene granites. The Kemer area is one of the key-areas where high-pressure metamorphics and an ophiolitic mélange were widely exposed. This contribution deals with the metamorphic evolution of the Kemer high-pressure rocks, and their implications for the geodynamic evolution. The Kemer high-pressure rocks comprise predominantly micaschist, calcschist, marble and minor metabasite and serpentinite. The micaschists contain mineral assemblages involving garnet, phengite (3,30-3,44 c.p.f.u.), paragonite, epidote, chlorite, albite and titanite, and the metabasites consists of garnet, barrosite, albite, chlorite, epidote, albite and titanite. The equilibrium conditions are poorly constrained as 550 ± 50 °C temperature and >8-10 kbar pressure by Fe-Mg partitioning between garnet and phengite, and phengite-barometry, respectively. Timing of the high-pressure metamorphism is constrained as 84-64 Ma by Rb-Sr phengite-whole rock dating on four samples. Although the obtained age values display a wide scatter, they are consistent with geochronological data from the neighboring high-pressure areas: 86 ± 2 Ma from the Şarköy blueschists (Topuz et al. 2008) and 65-69 Ma from the Çamlıca garnet-micaschists (Okay and Satır, 2000). These data in conjunction with those from the literature suggest that Late Cretaceous represent a time of substantional accretionary continental growth related to the northward subduction of the Intra-Pontide Ocean. The closure of the Intra-Pontide Ocean is constrained between Late Cretaceous and Eocene, because Eocene volcanics and volcano

  19. Integrated Numerical Simulation of Thermo-Hydro-Chemical Phenomena Associated with Geologic Disposal of High-Level Radioactive Waste

    Science.gov (United States)

    Park, Sang-Uk; Kim, Jun-Mo; Kihm, Jung-Hwi

    2014-05-01

    A series of numerical simulations was performed using a multiphase thermo-hydro-chemical numerical model to predict integratedly and evaluate quantitatively thermo-hydro-chemical phenomena due to heat generation associated with geologic disposal of high-level radioactive waste. The average mineralogical composition of the fifteen unweathered igneous rock bodies, which were classified as granite, in Republic of Korea was adopted as an initial (primary) mineralogical composition of the host rock of the repository of high-level radioactive waste in the numerical simulations. The numerical simulation results show that temperature rises and thus convective groundwater flow occurs near the repository due to heat generation associated with geologic disposal of high-level radioactive waste. Under these circumstances, a series of water-rock interactions take place. As a result, among the primary minerals, quartz, plagioclase (albite), biotite (annite), and muscovite are dissolved. However, orthoclase is initially precipitated and is then dissolved, whereas microcline is initially dissolved and is then precipitated. On the other hand, the secondary minerals such as kaolinite, Na-smectite, chlorite, and hematite are precipitated and are then partly dissolved. In addition, such dissolution and precipitation of the primary and secondary minerals change groundwater chemistry (quality) and induce reactive chemical transport. As a result, in groundwater, Na+, Fe2+, and HCO3- concentrations initially decrease, whereas K+, AlO2-, and aqueous SiO2 concentrations initially increase. On the other hand, H+ concentration initially increases and thus pH initially decreases due to dissociation of groundwater in order to provide OH-, which is essential in precipitation of Na-smectite and chlorite. Thus, the above-mentioned numerical simulation results suggest that thermo-hydro-chemical numerical simulation can provide a better understanding of heat transport, groundwater flow, and reactive

  20. Shear-hosted base metal mineralisation at the Dana Peaks, Murchison Mountains, Fiordland, New Zealand

    International Nuclear Information System (INIS)

    Darran Suite dioritic, tonalitic and granodioritic plutonic rocks and schistose Loch Burn Formation volcaniclastic rocks in the central Murchison Mountains at the Dana Peaks have been affected by widespread biotite-sericite-chlorite-albite-quartz-pyrite ± carbonate ± epidote/clinozoisite ± titanite/rutile ± actinolite alteration. More intense, paler coloured sericite-albite-quartz-pyrite ± carbonate alteration is concentrated along orange weathered shear zones. Alteration assemblages are transitional between those commonly referred to as propylitic, potassic and phyllic. Altered rocks contain anomalous concentrations of copper, lead, zinc and silver over an area of c. 2.56 km. Metal concentrations 2-5 times those typical of Darran Suite plutonic rocks and the Loch Burn Formation are commonly associated with more extensive weak to moderate intensity alteration. Higher metal grades up to c. 0.5% copper, 1% zinc, 1.3% lead and 30 ppm silver are concentrated in or adjacent to the 1-5 m wide, more intensely altered shear zones which contain entrained lenses of pyritised country rock, breccias and quartz ± K-feldspar ± chlorite ± carbonate ± hematite ± tourmaline veins. Some mineralised rocks also contain traces of tungsten (2-7 ppm), arsenic (<5-35 ppm) and tellurium (0.2-5.4 ppm). Most samples lack detectable molybdenum (<3 ppm), gold (<0.004 ppm) or bismuth (<0.2 ppm), with atypical higher values (40, 0.03 and 50 ppm, respectively) generally restricted to the most intensely altered and/or deformed rocks. The mineralised rocks show a close spatial and temporal relationship with several narrow ductile shear zones that probably developed in the Early Cretaceous between c. 128 and 110 Ma. Mineralised shear zones form minor splays off larger shear zones that are part of a major intra-arc fault system, active along or near the boundary between inboard and outboard parts of the Median Batholith at this time. Traces of similar lead mineralisation are present at the

  1. Reconstruction of seawater chemistry from deeply subducted oceanic crust; hydrogen and oxygen isotope of lawsonite eclogites preserving pillow structure

    Science.gov (United States)

    Hamabata, D., VI; Masuyama, Y.; Tomiyasu, F.; Ueno, Y.; Yui, T. F.; Okamoto, K.

    2014-12-01

    In order to understand evolution of life, change of seawater chemistry from Hadean, Archean to present is significant. Pillow structure is well-preserved in the Archean greenstone belt (e.g. Komiya et al., 1999). Oxygen and hydrogen isotope of rims in the pillow is useful conventional tool to decipher chemistry of Paleao-seawater from Archean to Present. However, Archean greenstone belt suffered regional metamorphism from greenschist to Amphibolite facies conditions. Therefore, it is necessary to testify the validity of pillow chemistry from recent (Phanerozoic) metamorphosed greenstone. We have systematically collected pillowed greenstone from blueschist and eclogites. Two eclogite exhibiting pillow structures were chosen for oxygen and hydrogen isotope analysis. One is from Corsica (lawsonite eclogite collected with Dr. Alberto Vidale Barbarone) and another is from Cazadero, Franciscan belt (collected by Dr. Tatsuki Tsujimori). The both are ascribed as MORB from major and trace bulk chemistry and Ca is rich in the core and Na is poor in the rims. The former exhibits garnet, omphacite, lawsonite, and glacophane. Phengite is in core of the pillow and chlorite is in the rims. In the latter, besides garnet, omphacite, epdiote and glaucophane, chlorite is recognized with phengite in the core. Glaucophane is richer in the rims from the both samples, therefore istope analysis of glaucophane was done. Mineral separation was carefully done using micro-mill, heavy liquid and isodynamic separator. 20 mg specimens were used for oxygen isotope analysis and 2mg were for hydrogen analysis. δ18O of the all analysis (7.7 to 8.3) is within the range of unaltered igneous oceanic crust and high temperature hydrothermal alteration although rims (8.3 for Franciscan and 8.0 for Corsica) are higher than cores (7.7 for Franciscan and Corsica). δD data is also consistent with hydrothermal alteration. It is relative higher in core from the Corsica and Franciscan (-45 and -56) than of the

  2. Petrology of HP/LT metapelitic rocks of an accretionary wedge, the Central Pontides, Turkey: evidence for tectonic stacking and syn-subduction exhumation

    Science.gov (United States)

    Aygül, Mesut; Okay, Aral; Oberhänsli, Roland

    2015-04-01

    Cretaceous HP/LT chloritoid-bearing metapelitic rocks crop out widely in the central part of the Pontides, northern Turkey. They are associated with eclogite to blueschist-facies metabasites and represent deep levels of an underplated subduction-accretion complex, which is tectonically overlain by low-grade HP phyllite/metasandstone intercalation along an extensional shear zone. Close to the shear zone, the footwall micaschists consist of quartz, phengite, paragonite, chlorite, rutile with syn-kinematic albite porphyroblast formed by pervasive shearing during exhumation. This type of micaschists is tourmaline-bearing and their retrograde nature suggests high-fluid flux along shear zones. Peak metamorphic assemblages are partly preserved in the chloritoid-micaschist farther away from the shear zone. Three peak metamorphic assemblages are identified and their PT conditions are constrained by pseudosections produced by Theriak-Domino and by Raman spectra of carbonaceous material: 1) garnet-chloritoid-glaucophane with lawsonite pseudomorphs (P: 17.5 ± 1 Kbar, T: 390-450 °C) 2) chloritoid with glaucophane pseudomorphs (P: 16-18 Kbar, T: 475 ± 40 °C) and 3) relatively high-Mg chloritoid (17%) with jadeite pseudomorphs (22-25 Kbar; T: 440 ± 30 °C) in addition to phengite, paragonite, quartz, chlorite, rutile. The last mineral assemblage is interpreted as transformation of the chloritoid + glaucophane assemblage to chloritoid + jadeite paragenesis with increasing pressure. Absence of tourmaline suggests that the chloritoid-micaschist did not interact with B-rich fluids during zero strain exhumation. Peak metamorphic assemblages and PT estimates suggest tectonic stacking within wedge with different depths of burial. 40Ar/39Ar phengite age of a pervasively sheared footwall micaschist is constrained to 100.6 ± 1.3 Ma and that of a chloritoid-micaschist is constrained to 91.8 ± 1.8 Ma suggesting exhumation during on-going subduction. Coupling and exhumation of the

  3. Site investigation SFR. Boremap mapping of core drilled borehole KFR106

    Energy Technology Data Exchange (ETDEWEB)

    Winell, Sofia (Geosigma AB (Sweden))

    2010-06-15

    This report presents the result from the Boremap mapping of the core drilled borehole KFR106, drilled from an islet ca 220 m southeast of the pier above SFR. The borehole has a length of 300.13 m, and a bearing and inclination of 195.1 deg and -69.9 deg, respectively. The purpose of the location and orientation of the borehole is to investigate the possible occurrence of gently dipping, water-bearing structures in the area. The geological mapping is based on simultaneous study of drill core and borehole image (BIPS). The two lowermost meters of the drill core was mapped in Boremap without access to complementary BIPS-image. The dominating rock type, which occupies 72% of KFR106, is fine- to medium-grained, metagranite granodiorite (rock code 101057), which is foliated with a medium to strong intensity. Pegmatite to pegmatitic granite (rock code 101061) is the second most common rock type and it occupies 16% of the mapped interval. It is also frequent as smaller rock occurrences (< 1 m) in other rock types throughout the borehole. Subordinate rock types are fine- to medium-grained granite (rock code 111058), felsic to intermediate meta volcanic rock (rock code 103076), fine- to medium-grained metagranitoid (rock code 101051) and amphibolite (rock code 102017). Totally 49% of the rock in KFR106 has been mapped as altered, where muscovitization and oxidation is the two most common. Additional shorter intervals of alterations are in decreasing order of abundance quartz dissolution, epidotization, argillization, albitization, chloritization, laumontization and carbonatization. A total number of 2801 fractures are registered in KFR106. Of these are 1059 open, 1742 sealed and 84 partly open. This result in the following fracture frequencies: 6.0 sealed fractures/m, 3.7 open fractures/m and 0.3 partly open fractures/m. In addition there are 5 narrow brecciated zones, and 20 sealed networks with a total length of 18 m. The most frequent fracture fillings in KFR106 are

  4. Evaluation of ultramafic deposits in the Eastern United States and Puerto Rico as sources of magnesium for carbon dioxide sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Fraser Goff; George Guthrie; Bruce Lipin; Melissa Fite; Steve Chipera; Dale Counce; Emily Kluk; Hans Ziock

    2000-04-01

    In this report, the authors evaluate the resource potential of extractable magnesium from ultramafic bodies located in Vermont, the Pennsylvania-Maryland-District-of-Columbia (PA-MD-DC) region, western North Carolina, and southwestern Puerto Rico. The first three regions occur in the Appalachian Mountains and contain the most attractive deposits in the eastern United States. They were formed during prograde metamorphism of serpentinized peridotite fragments originating from an ophiolite protolith. The ultramafic rocks consist of variably serpentinized dunite, harzburgite, and minor iherzolite generally containing antigorite and/or lizardite as the major serpentine minor phases. Chrysotile contents vary from minor to major, depending on occurrence. Most bodies contain an outer sheath of chlorite-talc-tremolite rock. Larger deposits in Vermont and most deposits in North Carolina contain a core of dunite. Magnesite and other carbonates are common accessories. In these deposits, MgO ranges from 36 to 48 wt % with relatively pure dunite having the highest MgO and lowest H{sub 2}O contents. Ultramafic deposits in southwestern Puerto Rico consist of serpentinized dunite and harzburgite thought to be emplaced as large diapirs or as fragments in tectonic melanges. They consist of nearly pure, low-grade serpentinite in which lizardite and chrysotile are the primary serpentine minerals. Chlorite is ubiquitous in trace amounts. Magnesite is a common accessory. Contents of MgO and H{sub 2}O are rather uniform at roughly 36 and 13 wt %. Dissolution experiments show that all serpentinites and dunite-rich rocks are soluble in 1:1 mixtures of 35% HCl and water by volume. The experiments suggest that low-grade serpentinites from Puerto Rico are slightly more reactive than the higher grade, antigorite-bearing serpentinites of the Appalachian Mountains. The experiments also show that the low-grade serpentinites and relatively pure dunites contain the least amounts of undesirable

  5. Modes of deformation in ultramafic rocks exhumed in the footwall of detachment faults at the Mid-Atlantic Ridge

    Science.gov (United States)

    Picazo, S. M.; Cannat, M.; Delacour, A.; Silantiev, S.; Fouquet, Y.

    2010-12-01

    Mantle exhumation by detachment faulting is common at slow spreading mid-ocean ridges. We present deformation structures related to exhumation in ultramafic and associated mafic rocks which were dredged and sampled by ROV during the SERPENTINE cruise (2007) in the footwall of detachments along the Mid-Atlantic Ridge: next to the Ashadze vent field at 13°N, and to the Logatchev vent field at 14°45'N. At these two locations, the main fault zones have been eroded by rockslides. However, we infer that our samples come from peridotites with (25 to 49%) and without (2 to 74%) gabbroic injections. We focused our study on these last two types and identified 4 types of deformation. For each type of deformation, we use the weight % of affected samples as an indicator of the distributed character of this deformation in the detachment footwall. Only 0,2% of the ultramafic rocks is affected to some degree by lithospheric ductile deformation with recrystallization of primary minerals (olivine, pyroxenes). 17% presents brittle-ductile shear zones. Most of these shear zones contains mineral assemblages typical of greenschist facies hydrous alteration of gabbroic material (tremolite after hornblende, chlorite after plagioclase, and occasional zircon). These minerals, with serpentine and less common talc are recrystallized, or kinked and fractured. A small number of shear zones are comprised of strongly oriented tremolite fibbers with post-kinematic replacement by talc and carbonates. These are interpreted as sheared hydrothermal veins. Matrix-supported cataclasites are observed in samples collected near the Logatchev vent field, where they represent 13% of the ultramafics. These cataclasites contain serpentinized and gabbroic clasts in a matrix of sheared and/or fractured chlorite, serpentine, tremolite and less common talc. Finally, 47% of the ultramafics, most of which is devoid of gabbroic material, are affected by a moderate cataclastic event. Serpentine in these samples

  6. Geochemical and tectonic implications on plate-interface evolution achieved from high-pressure ultramafic rocks in mélange settings

    Science.gov (United States)

    Cannaò, E.; Agostini, S.; Scambelluri, M.; Tonarini, S.

    2014-12-01

    Geochemical studies of fluid-mobile elements (FME) joined with B, Sr and Pb isotopic analyses of high-pressure mélanges terranes help constraining tectonic processes and mass transfer during accretion of slab and suprasubduction mantle in plate-interface domains. Here we focus on ultramafic rocks from two plate interface settings: (I) metasediment-dominated mélange (Cima di Gagnone, CdG, Adula Unit), where eclogite-facies de-serpentinized garnet peridotite and chlorite harzburgite lenses are embedded in paraschist; (II) dominated by high-pressure serpentinite (Erro-Tobbio, ET, and Voltri Units, VU, Ligurian Alps). CdG metaperidotite shows low [B], negative δ 11B and high Sr and Pb isotopic ratios. As, Sb loss from metasediment and gain by garnet and chlorite metaperidotite points to exchange between the two systems. Presence of As and Sb in eclogite-facies peridotite minerals and preferential low-T mobility of such elements suggest that exchange was during early subduction burial and prior to eclogitization. Based on high [B], positive δ11B, oxygen and hydrogen isotope, the ET serpentinties were recently interpreted as supra-subduction mantle flushed by slab fluids (Scambelluri & Tonarini, 2012, Geology, 40, 907-910). Their 206Pb/204Pb and 87Sr/86Sr isotope ratios range between 18.300-18.514 and 0.7048-0.7060, respectively. Compared with ET rocks, VU serpentinites have higher As, Sb (up to 1.3 and 0.39 ppm, respectively) and are enriched in radiogenic Sr (up to 0.7105 87Sr/86Sr). This signature reflects interaction with fluids that exchanged with sedimentary rocks, either in outer rise environments or during accretion atop the slab. In the above cases, the serpentinized mantle rocks fingerprint interaction with fluids from different sources, indicating a timing of accretion to plate interface domains. We provide evidence that serpentinized mantle slices of different size and provenance (slab or wedge) accreted to plate interface domains since early subduction

  7. Petrology and radiogeology of the Stripa pluton

    Energy Technology Data Exchange (ETDEWEB)

    Wollenberg, Harold; Flexser, Steve; Andersson, Lennart

    1980-12-01

    To better define the character of the rock encompassing the thermomechanical and hydrological experiments at the Stripa mine in central Sweden, and to help determine the size of the Stripa pluton, detailed studies were conducted of the petrology and radiogeology of the quartz monzonite and adjacent rocks. Petrologic studies emphasized optical petrography, with supplementary X-ray diffraction, X-ray fluorescence and microprobe analyses. Radiogeologic investigations were based primarily on surface and underground gamma-ray spectrometric measurements of uranium, thorium and potassium, supplemented by laboratory gamma spectrometric analyses and fission-track radiographic determinations of the locations and abundance of uranium in the rock matrix. Both the quartz monzonite and the metavolcanic leptite which it intruded are strongly fractured. Two stages of fracture filling are evident; an earlier stage encompassing quartz, sericite, feldspar, epidote, and chlorite, and a later stage dominated by carbonate minerals. The Stripa quartz monzonite is chemically and mineralogically distinct from other plutons in the region. Muscovite is the predominant mica in the quartz monzonite; biotite has been altered to chlorite, hornblende is absent, and accessory minerals are scarce. In contrast, in other plutons in the Stripa region biotite and hornblende are prominent mafic minerals and accessory minerals are abundant. The Stripa quartz monzonite is also considerably more radioactive than the leptite and other plutons in the region. Uranium and thorium abundances are both- 30 ppm, considerably higher than in "normal" granitic rocks where the thorium-to-uranium ratio generally exceeds 2. Potassium-argon dating of muscovite from the Stripa quartz monzonite indicates that this rock may be older, at 1691 million years than granitic rock of the neighboring Gusselby and Kloten massifs, whose ages, based on K-Ar dating of biotite, are respectively 1604 and 1640 m.y. Heat flow and heat

  8. From chemical mapping to pressure temperature deformation micro-cartography: mineralogical evolution and mass transport in thermo-mechanic disequilibrium systems: application to meta-pelites and confinement nuclear waste materials

    International Nuclear Information System (INIS)

    The mineralogical composition of metamorphic rocks or industrial materials evolves when they are submitted to thermomechanical disequilibria, i.e. a spatial or temporal pressure and temperature evolution, or chemical disequilibria as variations in redox conditions, pH... For example, during low temperature metamorphic processes, rocks re-equilibrate only partially, and thus record locally thermodynamic equilibria increasing so the spatial chemical heterogeneities. Understanding the P-T evolution of such systems and deciphering modalities of their mineralogical transformation imply to recognize and characterize the size of these local 'paleo-equilibria', and so to have a spatial chemical information at least in 2 dimensions. In order to get this information, microprobe X-ray fluorescence maps have been used. Computer codes have been developed with Matlab to quantify these maps in view of thermo-barometric estimations. In this way, P-T maps of mineral crystallisation were produced using the multi-equilibria thermodynamic technique. Applications on two meta-pelites from the Sambagawa blue-schist belt (Japan) and from the Caledonian eclogitic zone in Spitsbergen, show that quantitative chemical maps are a powerful tool to retrieve the metamorphic history of rocks. From these chemical maps have been derived maps of P-T-time-redox-deformation that allow to characterize P-T conditions of minerals formation, and so, the P-T path of the sample, the oxidation state of iron in the chlorite phase. As a result, we underline the relation between deformation and crystallisation, and propose a relative chronology of minerals crystallisation and deformations. The Fe3+ content map in chlorite calculated by thermodynamic has also been validated by a μ-XANES mapping at the iron K-edge measured at the ESRF (ID24) using an innovative method. Another application relates to an experimental study of clay materials, main components of an analogical model of a nuclear waste storage site

  9. Metamorphism of mineral matter in coal from the Bukit Asam deposit, south Sumatra, Indonesia

    Energy Technology Data Exchange (ETDEWEB)

    Susilawati, Rita; Ward, Colin R.

    2006-10-02

    The coal of the Miocene Bukit Asam deposit in south Sumatra is mostly sub-bituminous in rank, consistent with regional trends due to burial processes. However, effects associated with Plio-Pleistocene igneous intrusions have produced coal with vitrinite reflectance up to at least 4.17% (anthracite) in different parts of the deposit. The un-metamorphosed to slightly metamorphosed coals, with Rv{sub max} values of 0.45-0.65%, contain a mineral assemblage made up almost entirely of well-ordered kaolinite and quartz. The more strongly heat-affected coals, with Rv{sub max} values of more than 1.0%, are dominated by irregularly and regularly interstratified illite/smectite, poorly crystallized kaolinite and paragonite (Na mica), with chlorite in some of the anthracite materials. Kaolinite is abundant in the partings of the lower-rank coals, but is absent from the partings in the higher-rank areas, even at similar horizons in the same coal seam. Regularly interstratified illite/smectite, which is totally absent from the partings in the lower-rank coals, dominates the mineralogy in the partings associated with the higher-rank coal beds. A number of reactions involving the alteration of silicate minerals appear to have occurred in both the coal and the associated non-coal lithologies during the thermal metamorphism generated by the intrusions. The most prominent involve the disappearance of kaolinite, the appearance of irregularly interstratified illite/smectite, and the formation of regular I/S, paragonite and chlorite. Although regular I/S is identified in all of the non-coal partings associated with the higher-rank coals, illite/smectite with an ordered structure is only recognised in the coal samples collected from near the bases of the seams. The I/S in the coal samples adjacent to the floor of the highest rank seam also appears to have a greater proportion of illitic components. The availability of sodium and other non-mineral inorganic elements in the original coal

  10. From chemical mapping to pressure temperature deformation micro-cartography: mineralogical evolution and mass transport in thermo-mechanic disequilibrium systems: application to meta-pelites and confinement nuclear waste materials; De l'imagerie chimique a la micro-cartographie Pression-Temperature-Deformation: evolution mineralogique et transport de matiere dans des systemes en desequilibre thermomecanique. Applications aux metapelites et aux materiaux de stockage de dechets radioactifs

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, V. de

    2006-03-15

    The mineralogical composition of metamorphic rocks or industrial materials evolves when they are submitted to thermomechanical disequilibria, i.e. a spatial or temporal pressure and temperature evolution, or chemical disequilibria as variations in redox conditions, pH... For example, during low temperature metamorphic processes, rocks re-equilibrate only partially, and thus record locally thermodynamic equilibria increasing so the spatial chemical heterogeneities. Understanding the P-T evolution of such systems and deciphering modalities of their mineralogical transformation imply to recognize and characterize the size of these local 'paleo-equilibria', and so to have a spatial chemical information at least in 2 dimensions. In order to get this information, microprobe X-ray fluorescence maps have been used. Computer codes have been developed with Matlab to quantify these maps in view of thermo-barometric estimations. In this way, P-T maps of mineral crystallisation were produced using the multi-equilibria thermodynamic technique. Applications on two meta-pelites from the Sambagawa blue-schist belt (Japan) and from the Caledonian eclogitic zone in Spitsbergen, show that quantitative chemical maps are a powerful tool to retrieve the metamorphic history of rocks. From these chemical maps have been derived maps of P-T-time-redox-deformation that allow to characterize P-T conditions of minerals formation, and so, the P-T path of the sample, the oxidation state of iron in the chlorite phase. As a result, we underline the relation between deformation and crystallisation, and propose a relative chronology of minerals crystallisation and deformations. The Fe{sup 3+} content map in chlorite calculated by thermodynamic has also been validated by a {mu}-XANES mapping at the iron K-edge measured at the ESRF (ID24) using an innovative method. Another application relates to an experimental study of clay materials, main components of an analogical model of a nuclear

  11. Implications of spinel compositions for the petrotectonic history of abyssal peridotite from Southwest Indian Ridge (SWIR)

    Science.gov (United States)

    Chen, T.; Jin, Z.; Wang, Y.; Tao, C.

    2012-12-01

    Abyssal peridotites generate at mid-ocean ridges. Lherzolite and harzburgite are the main rock types of peridotites in the uppermost mantle. The lherzolite subtype, less depleted and less common in ophiolites, characterizes mantle diapirs and slow-spreading ridges. Along the Earth's mid-ocean ridges, abyssal peridotites undergo hydration reactions to become serpentinite minerals, especially in slow to ultraslow spreading mid-ocean ridges. Spinel is common in small quantities in peridotites, and its compositions have often been used as petrogenetic indicators [1]. The Southwest Indian Ridge (SWIR) is one of the two ultraslow spreading ridges in the world. The studied serpentinized peridotite sample was collected by the 21st Voyage of the Chinese oceanic research ship Dayang Yihao (aka Ocean No. 1) from a hydrothermal field (63.5°E, 28.0°S, and 3660 m deep) in SWIR. The studied spinels in serpentinized lherzolite have four zones with different compositions: relic, unaltered core is magmatic Al-spinels; micro- to nano- sized ferrichromite zoned particles; narrow and discontinuous magnetite rim; and chlorite aureoles. The values Cr# of the primary Al-spinels indicate the range of melting for abyssal peridotites from SWIR extends from ~4% to ~7% [2]. The alteration rims of ferrichromite have a chemical composition characterized by Fe enrichment and Cr# increase indicating chromite altered under greenschist-amphibolite facies. Magnetites formed in syn- and post- serpentinization. Chlorite (clinochlore) formed at the boundary and crack of spinel indicating it had undergone with low-temperature MgO- and SiO2-rich hydrothermal fluids [3]. It suggests that serpentinized lherzolite from SWIR had undergone poly-stage hydration reactions with a wide range of temperature. Acknowledgments: EMPA experiment was carried out by Xihao Zhu and Shu Zheng in The Second Institute of Oceanography and China University of Geosciences, respectively. The work was supported by NSFC

  12. How does a brittle-ductile fault nucleate and grow in dolostone? A lesson learnt from a structural, geochemical and K-Ar chronological study of a reactivated Paleozoic thrust fault

    Science.gov (United States)

    Viola, G.; Torgersen, E.; Zwingmann, H.; Harris, C.

    2014-12-01

    Carbonate-hosted faults in the upper crust are mechanically strong, yet, under certain environmental conditions, carbonates may decompose into mechanically weak minerals, with major consequences for faults´ rheological behavior. We combine structural analysis, geochemistry, stable isotopes and K-Ar dating of synkinematic illite/muscovite to investigate the processes that control localization and weakening of initially strong, seismogenic brittle faults. We aim at better understanding how the constantly evolving architecture and composition of brittle-ductile faults affect their seismogenic properties. The Kvenklubben fault in northern Norway is part of a Caledonian compressional imbricate stack. It juxtaposes greenschist facies metabasalts in the hanging wall against meta-dolostones and has a 2.5 m thick fault core consisting of talc-bearing calc-phyllonites and chlorite phyllonites. Petrographic and geochemical results indicate that the phyllonites formed mainly through fluid-rock interaction and progressive decomposition of the adjacent wall rocks. K-Ar dating and chlorite geothermometry documents that the fault damage zone developed from the base upwards with fault initiation at 530 Ma around 200°C and the main development during reactivation around 440 Ma at c. 285°C. Early strain increments were accommodated in the dolostone by pressure-solution, formation of optimally oriented tensional fractures and cataclasis along geometrical irregularities of the growing fault plane. Fluids caused sequential decarbonation of the dolostones and carbonation of the metabasalts, resulting in the formation of phyllosilicate-decorated planar fabrics. The newly formed phyllosilicate levels weakened the fault under overall viscous creep conditions. The strongly anisotropic fluid-flow within the phyllonites, together with vein sealing following localized and transient high pore pressure-driven embrittlement, caused strain hardening. Together, the interaction between strain

  13. Metasomatic modification of oceanic crust during early stages of subduction recorded in Mariana blueschist

    Science.gov (United States)

    Zack, Thomas; Savov, Ivan P.; Pabst, Sonja; Schmitt, Axel K.

    2013-04-01

    Serpentine mud volcanoes from the Mariana forearc bear unique witness of metasomatic processes in an active subduction zone in the form of centimeter-size blueschist-facies xenoliths. Charcateristic metamorphic assemblages point to conditions of ca 400°C and a formation depth of 27 km. Bulk rock compositions of amphibole-talc schists and chlorite-rich schists lie on a mixing line, extending from typical MORB towards SiO2-enriched mantle. Such mixing trends are remarkably similar to findings from the amphibolite-facies assemblages of the Catalina schist, although they equilibrated at much lower temperatures (Pabst et al. 2012). These observations demonstrate that the material experienced severe metasomatic changes at the slab-mantle interface in the shallow forearc. Further supporting evidence derives from δ11B measurements: phengite, amphibole and chlorite within the clasts have boron isotope values of -6±4‰, significantly lighter than oceanic crust, requiring isotopic fractionation by fluids carrying an isotopically heavy B component (Pabst et al. 2012). Although most current models assume that the Mariana blueschists record conditions of the ongoing subduction process, our recent findings indicate otherwise. Large (>100 µm) rutiles with high U (ca 20 ppm) found in one blueschist clast were dated by HR-SIMS at UCLA employing recently established U/Pb dating techniques (Schmitt & Zack 2012). Rutile concordia ages were tightly constrained at 48.1±2.9 Ma and are reproduced by concordia ages of low Th/U zircons at 47.5±1.5 Ma in the same sample. As those ages are interpreted to be formation ages of metasomatically modified blueschists and are only a few million years older than subduction initiation (at ca 50-52 Ma), we draw the following conclusions: (1) fast cooling of the downgoing oceanic crust must occur right after subduction initiation; (2) effective metasomatic and mechanical mixing processes (subduction channels?) must be established early in

  14. Mass transfer and trace element redistribution during hydration of granulites in the Bergen Arcs, Norway.

    Science.gov (United States)

    Centrella, Stephen; Austrheim, Håkon; Putnis, Andrew

    2016-04-01

    The Bergen Arcs located on the Western coast of Norway are characterized by Precambrian granulite facies rocks partially hydrated at amphibolite and eclogite facies conditions. Over an area of ca. 1000 km², relict of granulite facies lenses make up only ca. 10% of the observed outcrops. At Hilland Radöy, granulite displays sharp hydration fronts across which the granulite facies assemblage composed of garnet (55%) and clinopyroxene (45%) is replaced by an amphibolite facies mineralogy defined by chlorite, epidote and amphibole. The major element bulk composition does not change significantly across the hydration front, apart from the volatile components (loss on ignition, LOI) that increases from 0.17 wt.% in the granulite to 2.43 wt.% in the amphibolite (Centrella et al., 2015). The replacements of garnet and clinopyroxene are pseudomorphic indicating a perfect preservation of the parent crystal shape. The textural evolution during the replacement is consistent with the coupled dissolution-precipitation mechanism where garnet is replaced by chlorite, epidote and pargasite and clinopyroxene by hornblende and quartz. Based on the observations of an isovolumetric replacement, the mass loss during hydration was estimated at 13%. This study is based on the trace element redistribution during the hydration using the same samples as Centrella et al. (2015). The local mass transfer during the replacement process determined from the major element is also confirmed by the trace element redistribution. The LILE, HFSE and REE losses and gains in replacing the garnet are approximately balanced by the opposite gains and losses associated with the replacement of clinopyroxene. Because the hydration involves reduction of rock density, the volume preservation (isovolumetric reaction), together with the mass balance calculations, requires a significant loss of the mass of the rock to the fluid phase: 13% based on the major element redistribution and around 20% based on the REE

  15. Provenance and composition of unusually chrome and nickel-rich bucket-shaped pottery from Rogaland (southwestern Norway)

    Science.gov (United States)

    Zimmermann, Udo; Kristoffersen, Elna Siv; Fredriksen, Per Ditlef; Bertolino, Silvana A. R.; Andò, Sergio; Bersani, Danilo

    2016-05-01

    We report results from FE-SEM-EDS, geochemical, mineralogical analyses and Raman spectroscopy of pottery of bucket-shaped ceramic from Rogaland (southwestern Norway) dated between the 5th and 6th Century. The study reveals a very rare pottery composition including asbestos-group minerals and an unusual enrichment in compatible elements like Cr (8-27 × Post Archean average shale (PAS), McLennan et al., 2006), Ni (2-8 × normal shale) and Co (2-3 × PAS). X-Rray diffraction and Raman spectroscopy could pinpoint that Ni is introduced by specific Ni-rich talc mineral and chlorite minerals and Cr occurs in a rare Cr-rich talc, and possibly in a Cr-chlorite, these minerals are the most abundant in the pottery, which is supported by strong enrichment in Mg (10-20 × PAS). The addition of Mg, Cr, Ni and Co and other compatible trace elements is to our current knowledge not caused by anthropogenic activity but related to the used materials, which are alteration products of mafic and ultramafic rocks or genetically related to mafic and ultramafic rocks. Rocks of this type are exposed in vicinity of the sampling areas in a region called Karmøy, hosting a world famous ophiolite complex, which is identified as the major source for the mafic and ultramafic component, as the next succession of a similar composition is far further north located in Norway and a number of rock types on Karmøy matches the chemical composition of the pottery. The here reported composition is spectacular and extremely rare - if ever found - in pottery. Our study shows that unusual material sources have been used in pottery production, and this opens for discussion whether the materials were deliberately selected by the manufacturers, thereby expressing a specific social function, in a time period where more functional clay types and additives, and certainly functional and sufficient for use in pottery, where abundant in areas of Rogaland closer to where the pots were found.

  16. Geology of the epithermal Ag-Au Huevos Verdes vein system and San José district, Deseado massif, Patagonia, Argentina

    Science.gov (United States)

    Dietrich, Andreas; Gutierrez, Ronald; Nelson, Eric P.; Layer, Paul W.

    2012-03-01

    The San José district is located in the northwest part of the Deseado massif and hosts a number of epithermal Ag-Au quartz veins of intermediate sulfidation style, including the Huevos Verdes vein system. Veins are hosted by andesitic rocks of the Bajo Pobre Formation and locally by rhyodacitic pyroclastic rocks of the Chon Aike Formation. New 40Ar/39Ar constraints on the age of host rocks and mineralization define Late Jurassic ages of 151.3 ± 0.7 Ma to 144.7 ± 0.1 Ma for volcanic rocks of the Bajo Pobre Formation and of 147.6 ± 1.1 Ma for the Chon Aike Formation. Illite ages of the Huevos Verdes vein system of 140.8 ± 0.2 and 140.5 ± 0.3 Ma are 4 m.y. younger than the volcanic host rock unit. These age dates are among the youngest reported for Jurassic volcanism in the Deseado massif and correlate well with the regional context of magmatic and hydrothermal activity. The Huevos Verdes vein system has a strike length of 2,000 m, with several ore shoots along strike. The vein consists of a pre-ore stage and three main ore stages. Early barren quartz and chalcedony are followed by a mottled quartz stage of coarse saccharoidal quartz with irregular streaks and discontinuous bands of sulfide-rich material. The banded quartz-sulfide stage consists of sulfide-rich bands alternating with bands of quartz and bands of chlorite ± illite. Late-stage sulfide-rich veinlets are associated with kaolinite gangue. Ore minerals are argentite and electrum, together with pyrite, sphalerite, galena, chalcopyrite, minor bornite, covellite, and ruby silver. Wall rock alteration is characterized by narrow (Gangue minerals are dominantly massive quartz intergrown with minor to accessory adularia. Epidote, illite, illite/smectite, and, preferentially at deeper levels, Fe-chlorite gangue indicate near-neutral pH hydrothermal fluids at temperatures of >220°C. Kaolinite occurring with the late sulfide-rich veinlet stage indicates pH 315°, whereas strike directions of <315° are

  17. Mineralization stages of the unique shear zone-hosted "Felsit-type" Sn-polymetallic mineralization in the eastern Erzgebirge, Germany

    Science.gov (United States)

    Járóka, Tom; Seifert, Thomas

    2014-05-01

    The polymetallic cassiterite-bearing mineralization of the "Felsit-type" is located in the NW of the Freiberg mining district within the Großschirma area. The mineralization is hosted by metamorphic rocks of the Preßnitzer Group unit that form the most northeastern part of the Erzgebirge metamorphic core complex. This geological unit is in the Großschirma area predominantly composed of two-mica gneisses and mica schists, whereas intercalations of muscovite-gneiss ("red gneiss"), amphibolites and metacarbonates occur less commonly. These metamorphic rocks were deformed by several NE-SW striking fault zones. The hydrothermal Sn-bearing fluids migrated within shear zones that developed primarily at the contact between different lithotypes. The shear zones are characterized by strong pervasive metasomatic alterations which were triggered by small chlorite-cassiterite-quartz-sulfide-veins. The rock-forming minerals are strongly corroded and displaced by the ore and gangue minerals within the shear zones. The bulk geochemistry of selected drill core samples feature grades up to 0.28 wt. % Sn, 0.15 wt. % Cu, 300 ppm Pb, 140 ppm Zn, 1.1 wt. % F, 250 ppm Li, 820 ppm Rb, 90 ppm Cs, and 130 ppm W. Microscopic and geochemical studies of the samples show that the Sn-polymetallic mineralization of the "Felsit-type" can be distinguished into three different mineralization stages. The first one is dominated by chlorite and quartz. Cassiterite probably appears in two generations with different grain shapes: acicular (< 1 - 100 µm) and isometric cassiterite (< 10 - 650 µm). Smaller amounts of fluorite, rutile, apatite, and scheelite are also associated with the first stage. The second mineralization stage is dominated by pyrite which is the most abundant ore mineral of this paragenesis, while marcasite, chalcopyrite, pyrrhotite, galena, sphalerite, arsenopyrite, bismuthinite, and magnetite appear only subordinately. The third stage is dominated by carbonates that are often

  18. Diagenetic characteristics and reservoir quality of the Lower Cretaceous Biyadh sandstones at Kharir oilfield in the western central Masila Basin, Yemen

    Science.gov (United States)

    Hakimi, Mohammed Hail; Shalaby, Mohamed Ragab; Abdullah, Wan Hasiah

    2012-06-01

    The Lower Cretaceous Biyadh Formation in the Masila Basin is an important hydrocarbon reservoir. However, in spite of its importance as a reservoir, published studies on the Biyadh Formation more specifically on the diagenesis and relate with reservoir quality, are limited. Based on core samples from one well in the Kharir oilfield, western central Masila Basin, this study reports the lithologic and diagenetic characteristics of this reservoir. The Biyadh sandstones are very fine to very coarse-grained, moderate to well sorted quartzarenite and quartzwacke. The diagenetic processes recognized include mechanical compaction, cementation (carbonate, clay minerals, quartz overgrowths, and a minor amount of pyrite), and dissolution of the calcite cement and feldspar grains. The widespread occurrences of early calcite cement suggest that the Biyadh sandstones lost a significant amount of primary porosity at a very early stage of its diagenetic history. Based on the framework grain-cement relationships, precipitation of the early calcite cement was either accompanied or followed by the development of part of the pore-lining and pore-filling clay cements. Secondary porosity development occurred due to partial to complete dissolution of early calcite cement and feldspar grains. In addition to calcite, several different clay minerals including kaolinite and chlorite occur as pore-filling and pore-lining cements. Kaolinite largely occurs as vermiform and accelerated the minor porosity loss due to pore-occlusion. Chlorite coating grains helps to retain primary porosity a by retarding the envelopment of quartz overgrowths. Porosity and permeability data exhibit good inverse correlation with cement. Thus, reservoir quality is controlled by pore occluding cement. Diagenetic history of the Biyadh sandstones as established here is expected to help better understanding and exploitation of this reservoir. The relation between diagenesis and reservoir quality is as follows: the

  19. Dynamics of mineral crystallization at inclusion-garnet interface from precipitated slab-derived fluid phase: first in-situ synchrotron x-ray measurements

    Science.gov (United States)

    Malaspina, Nadia; Alvaro, Matteo; Campione, Marcello; Nestola, Fabrizio

    2015-04-01

    Remnants of the fluid phase at ultrahigh pressure (UHP) in subduction environments may be preserved as primary multiphase inclusions in UHP minerals. These inclusions are frequently hosted by minerals stable at mantle depths, such as garnet, and show the same textural features as fluid inclusions. The mineral infillings of the solid multiphase inclusions are generally assumed to have crystallized by precipitation from the solute load of dense supercritical fluids equilibrating with the host rock. Notwithstanding the validity of this assumption, the mode of crystallization of daughter minerals during precipitation within the inclusion and/or the mechanism of interaction between the fluid at supercritical conditions and the host mineral are still poorly understood from a crystallographic point of view. A case study is represented by garnet orthopyroxenites from the Maowu Ultramafic Complex (China) deriving from harzburgite precursors metasomatised at ~ 4 GPa, 750 °C by a silica- and incompatible trace element-rich fluid phase. This metasomatism produced poikilitic orthopyroxene and inclusion-rich garnet porphyroblasts. Solid multiphase primary inclusions in garnet display a size within a few tens of micrometers and negative crystal shapes. Infilling minerals (spinel: 10-20 vol.%; amphibole, chlorite, talc, mica: 80- 90 vol.%) occur with constant volume ratios and derive from trapped solute-rich aqueous fluids. To constrain the possible mode of precipitation of daughter minerals, we performed for the first time a single-crystal X-ray diffraction experiment by means of Synchrotron Radiation at DLS-Diamond Light Source. In combination with electron probe microanalyses, this measurement allowed the unique identification of each mineral phase and their reciprocal orientations. We demonstrated the epitaxial relationship between spinel and garnet and between some hydrous minerals. Epitaxy drives a first-stage nucleation of spinel under near-to-equilibrium conditions

  20. Mineralogía y génesis de la fracción fina de la serie de El Rinconcillo (formaciones Flysch del Campo de Gibraltar. SW de España

    Directory of Open Access Journals (Sweden)

    Carrasco, F.

    1987-04-01

    Full Text Available The stratigraphic sequence of El Rinconcillo belong to the Algeciras Unit. Illite, kaolinite, chlorite and interstratified illite-smectite are common minerals for materials of this Unit, but a high proportion of Fe-Al smectites and sporadic presence of palygorskite is characteristic of the series of El Rinconcillo in relation to the others studied in Northern Africa and Southwestern Spain. Illite, kaolinite and chlorite are considered to be inherited minerals. Smectides and interestratified illite-smectite are also inherited in the turbidites but they were formed in the source area by transformation from illite under different weathering degree. Finally, the formation of palygorskite in the Middle Eocene carbonatic turbidites accompanied by many smectide, and no kaolinite, is difficult to explain in relation with turbiditic materials. It is more feasible to suppose a removal process that implicates the existence of a previous clay sediment in which such association -palygorskite + smectite- took place by transformation and/or by neoformation.La serie de El Rinconcillo, atribuida a la Unidad de Algeciras, presenta variaciones mineralógicas notables respecto a las series "tipo" definidas en esta Unidad tanto en el norte de Africa como en el suroeste de España. Aunque en gran parte la mineralogía es común con otras series de esta Unidad (ilita, caolinita, clorita, interestratificados I-E, se diferencia no obstante, por la elevada proporción de esmectita Fe-Al y la presencia esporádica de paligorskita. Ilita, caolinta y clorita, se consideran minerales heredados. La esmectita y los interestratificados I-E son también heredados en las turbiditas, procedentes de la transformación de la ilita en el área fuente bajo diferente grado de meteorización. Finalmente, la formación de paligorskita en las turbidítas calcáreas del Eoceno medio acompañada por esmectita y la ausencia de caolinita en este tramo, es difícil de explicar en relación con

  1. An integrated multidisciplinary re-evaluation of the geothermal system at Valles Caldera, New Mexico, using an immersive three-dimensional (3D) visualization environment

    Science.gov (United States)

    Fowler, A.; Bennett, S. E.; Wildgoose, M.; Cantwell, C.; Elliott, A. J.

    2012-12-01

    We describe an approach to explore the spatial relationships of a geothermal resource by examining diverse geological, geophysical, and geochemical data sets using the immersive 3-dimensional (3D) visualization capabilities of the UC Davis Keck Center for Active Visualization in the Earth Sciences (KeckCAVES). The KeckCAVES is a facility where stereoscopic images are projected onto four, surfaces (three walls and a floor), which the user perceives as a seamless 3D image of the data. The user can manipulate and interact with the data, allowing a more intuitive interpretation of data set relationships than is possible with traditional 2-dimensional techniques. We incorporate multiple data sets of the geothermal system at Valles Caldera, New Mexico: topography, lithology, faults, temperature, alteration mineralogy, and magnetotellurics. With the ability to rapidly and intuitively observe data relationships, we are able to efficiently and rapidly draw conclusions about the subsurface architecture of the Valles Caldera geothermal system. We identify two high-temperature anomalies, one that corresponds with normal faults along the western caldera ring fracture, and one that with the resurgent dome. A cold-temperature anomaly identified adjacent to the resurgent dome high-temperature anomaly appears to relate to a fault controlled graben valley that acts as a recharge zone, likely funneling cold meteoric water into the subsurface along normal faults observed on published maps and cross sections. These high-temperature anomalies broadly correspond to subsurface regions where previous magnetotelluric studies have identified low apparent resistivity. Existing hot springs in the Sulfur Springs area correspond to the only location where our modeled 100°C isotherm intersects the ground surface. Correlation between the first occurrence of key alteration minerals (pyrite, chlorite, epidote) in previously drilled boreholes and our temperature model vary, with chlorite showing a

  2. Deglacial Record in the Illinois River Valley Explains Asynchronous Phases of Meltwater Pulses and Clay Mineral Excursions in the Gulf of Mexico

    Science.gov (United States)

    Wang, H.

    2014-12-01

    One prominent event of the Bølling/Allerød (B/A) interstadial was the large meltwater release to global oceans. The Laurentide Ice Sheet (LIS) is usually considered the main source. But, the large LIS meltwater discharge conflicts with the marine record showing an active North Atlantic meridional overturning circulation (AMOC) during the B/A interval. Continuous dune-lacustrine successions in the Illinois River Valley (IRV) have shown complete records of the last deglacial chronozones. Their grain-size distributions and accurate B/A age 14C dates of plant fossils from 15 m deep lacustrine sediment in the IRV suggest that most of the IRV and parts of the adjacent upland were inundated by water. The inundation was caused by a sediment dam interpreted to have been constructed and followed by a breach at the confluence of the Mississippi and Illinois Rivers during the B/A interval due to sediment mobilization by the large meltwater release. The grain size distributions correlate with meltwater pulses and mineralogical excursions in sediments from the Gulf of Mexico (GOM) very well. The blockage and release of illite and chlorite rich fine-grained sediments from the Lake Michigan basin changed the relative abundance of clay minerals and thus the ratio of smectite/(illite + chlorite) in the sediment of the GOM. This finding explains why the meltwater episodes from the LIS and the associated detrital discharges are not synchronous in the sediments in the GOM. The finding also ties meltwater pulses and associated detrital discharges in the GOM closely to the LIS discharges via the Mississippi River Valley on chronozonal scales. Three arguments can be made from this result: 1) unaffected AMOC during B/A interval resulted potentially from the hyperpycnal inflow into the GOM floor; 2) limited volume of the meltwater discharge did not significantly influence the AMOC; and 3) the freshwater input into the GOM from the LIS at this particular location did not significantly

  3. Remote Sensing, Geology and Geochemistry on the GVIII Uranium Mineralization, Gabal Gattar, North Eastern Desert, Egypt

    International Nuclear Information System (INIS)

    GVIII- uranium occurrence of Gabal Gattar is located at the intersection of Lat. 27° 05' 56and Long. 33° 16' 33to the south of GH-uranium occurrence. This occurrence is hosted in the alkali feldspar granite of Gabal Gattar. It is dissected by NNE-SSW, ENE-WSW and NW-SE faults and fractures. The granite is strongly altered in the zones of these faults and fractures. This granite is composed of K-feldspars, quartz, plagioclase and biotite as essential minerals and zircon, apatite, fluorite as accessories. The secondary minerals are chlorite, sericite, muscovite and iron oxides. The main alterations along the fault and fracture zones are hematitization, silicification, kaolintiization, chloritization and fluoritization that increase at the zones of intersection.The Advanced Spacebome Thermal Emission and Reflection Radiometer (ASTER) discriminated and mapped the hematitized zones in the studied granitic rocks predicting iron oxides as pathfinder minerals that be helpful in localizing high uranium concentration. The compilated and integrated data as alteration zones, geological and structural features using Geographic Information System (GIS) played an important role in correlating, manipulating, visualizing and extracting the information getting a better result for interpretation and evaluation of this occurrence. The study granite is geochemically, alkali- feldspar granite to syenogranite originated from weakly peraluminous magma of alkaline affinity and of within plate tectonic setting due to crustal relaxation. This granite shows many geochemical characterestics similar to the A-type granite, high contents of SiO2, (Na2O + K2O), Rb, Nb, Y, low contents of MgO, CaO and Sr and apparently F-rich granite.Radiometric measurements of GVIII U-occurrence show that the study granite records uranium values between 15 and 28 ppm, while the anomalies record uranium values range from 400 to more than 30000 ppm. Surfacial yellow secondary uranium mineralization was

  4. Mesozoic metamorphism and its tectonic implication along the Solonker suture zone in central Inner Mongolia, China

    Science.gov (United States)

    Zhang, Jinrui; Wei, Chunjing; Chu, Hang; Chen, Yaping

    2016-09-01

    The Xing'an-Inner Mongolia Orogenic Belt (XIMOB) exposed in the eastern section of the Central Asian Orogenic Belt (CAOB) is generally thought to have resulted from closure of the Paleo-Asian Ocean. However, disputations still exist on the age and detailed tectonic processes involved in its final amalgamation. The Solonker suture zone in the central Inner Mongolia, once recognized as the major paleo-plate boundary recording the terminal collision of the XIMOB, is characterized by extensive regional low-temperature metamorphism of greenschist to epidote-amphibolite facies with local presence of blueschists, which lacks systematic study. Four metabasite and garnet-mica schist samples were studied for determination of metamorphic P-T evolution using pseudosection and conventional thermobarometry. The two metabasite samples from Wulangou and Daqing Pasture contain actinolite, albite, epidote, chlorite and hornblende (in Daqing Pasture) and are estimated to have peak P-T conditions of 5.2-5.9 kbar/415-450 °C in Wulangou and 7.0-7.9 kbar/470-475 °C in Daqing Pasture. Two garnet-mica schist samples from Shuangjing (or Shuangjing schist) contain garnet porphyroblasts, muscovite, quartz, plagioclase, chlorite with or without potassium feldspar, biotite, and calcite, and are modeled to record prograde P-T vectors respectively of 3.0 kbar/482 °C-3.3 kbar/495 °C and 4.2 kbar/478 °C-4.8 kbar/483 °C, followed by near-isothermal decompression. The zircon U-Pb dating analyses suggest that the metamorphism probably occurred soon afterwards in the Early Mesozoic. The peak P-T conditions for the metabasite and garnet-mica schist samples yield thermal gradients respectively of 18-22 °C/km and 26-33 °C/km, being intermediate and low P/T series, and the metamorphic evolution in these rocks characteristic of clockwise P-T paths may correspond to tectonic thickening and thinning processes. The extensive low-temperature metamorphism of intermediate to low P/T types along the

  5. Diagenesis and reservoir quality evolution of palaeocene deep-water, marine sandstones, the Shetland-Faroes Basin, British continental shelf

    Energy Technology Data Exchange (ETDEWEB)

    Mansurbeg, H. [Department of Earth Sciences, Uppsala University, Villavaegen 16, SE 752 36 Uppsala (Sweden); Morad, S. [Department of Earth Sciences, Uppsala University, Villavaegen 16, SE 752 36 Uppsala (Sweden); Department of Petroleum Geosciences, The Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates); Salem, A. [Faculty of Education at Kafr El-Sheikh, Tanta University, Kafr El-Sheikh (Egypt); Marfil, R.; Caja, M.A. [Departmento Petrologia y Geoquimica, Facultad de Geologia, UCM, 28040 Madrid (Spain); El-ghali, M.A.K. (Geology Department, Al-Fateh University, P.O. Box 13696, Libya); Nystuen, J.P. [Department of Geosciences, University of Oslo, P.O. Box 1047 Blindern, NO-0316 Oslo (Norway); Amorosi, A. [Department of Earth Sciences, University of Bologna, Via Zamboni 67, 40127 Bologna (Italy); Garcia, D. [Centre SPIN, Department GENERIC, Ecole Nationale Superieure des Mines de Saint Etienne 158, Cours Fauriel 42023, Saint-Etienne (France); La Iglesia, A. [Instituto de Geologia Economica (CSIC-UCM), Facultad de Geologia, UCM, 28040 Madrid (Spain)

    2008-06-15

    The Palaeocene, deep-water marine sandstones recovered from six wells in the Shetland-Faroes Basin represent lowstand, transgressive and highstand systems tract turbiditic sediments. Mineralogic, petrographic, and geochemical analyses of these siliciclastics are used to decipher and discuss the diagenetic alterations and subsequent reservoir quality evolution. The Middle-Upper Palaeocene sandstones (subarkoses to arkoses) from the Shetland-Faroes Basin, British continental shelf are submarine turbiditic deposits that are cemented predominantly by carbonates, quartz and clay minerals. Carbonate cements (intergranular and grain replacive calcite, siderite, ferroan dolomite and ankerite) are of eogenetic and mesogenetic origins. The eogenetic alterations have been mediated by marine, meteoric and mixed marine/meteoric porewaters and resulted mainly in the precipitation of calcite ({delta}{sup 18}O{sub V-PDB}=-10.9 permille and -3.8 permille), trace amounts of non-ferroan dolomite, siderite ({delta}{sup 18}O{sub V-PDB}=-14.4 permille to -0.6 permille), as well as smectite and kaolinite in the lowstand systems tract (LST) and highstand systems tract (HST) turbiditic sandstone below the sequence boundary. Minor eogenetic siderite has precipitated between expanded and kaolinitized micas, primarily biotite. The mesogenetic alterations are interpreted to have been mediated by evolved marine porewaters and resulted in the precipitation of calcite ({delta}{sup 18}O{sub V-PDB}=-12.9 permille to -7.8 permille) and Fe-dolomite/ankerite ({delta}{sup 18}O{sub V-PDB}=-12.1 permille to -6.3 permille) at temperatures of 50-140 and 60-140 C, respectively. Quartz overgrowths and outgrowth, which post- and pre-date the mesogenetic carbonate cements is more common in the LST and TST of distal turbiditic sandstone. Discrete quartz cement, which is closely associated with illite and chlorite, is the final diagenetic phase. The clay minerals include intergranular and grain replacive

  6. Site investigation SFR. Fracture mineralogy including identification of uranium phases and hydrochemical characterisation of groundwater in borehole KFR106

    International Nuclear Information System (INIS)

    This report presents the fracture mineralogy and hydrochemistry of borehole KFR106. The most abundant fracture minerals in the examined drill core samples are clay minerals, calcite, quartz and adularia; chlorite is also common but is mostly altered and found interlayered with corrensite. The most common clay mineral is a mixed layer clay consisting of illite-smectite. Pyrite, galena, chalcopyrite, barite (-celestine) and hematite are also commonly found in the fractures, but usually in trace amounts. Other minerals identified in the examined fractures are U-phosphate, pitchblende, U(Ca)-silicate, asphaltite, biotite, monazite, fluorite, titanite, sericite, xenotime, rutile and (Ca, REEs)-carbonate. Uranium has been introduced, mobilised and reprecipitated during at least four different episodes: 1) Originally, during emplacement of U-rich pegmatites, probably as uraninite. 2) At a second event, uranium was mobilised under brittle conditions during formation of breccia/cataclasite. Uraninite was altered to pitchblende and partly coffinitised. Mobilised uranium precipitated as pitchblende closely associated with hematite and chlorite in cataclasite and fracture sealings prior to 1,000 Ma. 3) During the Palaeozoic U was remobilised and precipitated as U-phosphate on open fracture surfaces. 4) An amorphous U-silicate has also been found in open fractures; the age of this precipitation is not known but it is inferred to be Palaeozoic or younger. Groundwater was sampled in two sections in borehole KFR106 with pumping sequences of about 6 days for each section. The samples from sections KFR106:1 and KFR106:2 (260-300 m and 143-259 m borehole length, i.e. -261 and -187 m.a.s.l. mid elevation of the section, respectively) were taken in November 2009 and yielded groundwater chemistry data in accordance with SKB chemistry class 3 and 5. In section KFR106:1 and KFR106:2, the chloride contents were 850 and 1,150 mg/L and the drilling water content 6 and 4%, respectively

  7. 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

  8. Geology, alteration, and lithogeochemistry of the Hood volcanogenic massive sulfide (VMS) deposits, Nunavut, Canada

    Science.gov (United States)

    Mills, Hannah K.; Piercey, Stephen J.; Toole, Trish

    2016-04-01

    Finlayson Lake). The similarities of the ABVB to other Slave Craton greenstone belts further highlights the overall potential for greenstone-hosted VMS mineralization in the Slave Craton. Chlorite-sericite (+/- quartz) is the dominant hydrothermal alteration assemblage in the Hood deposits and is typical of VMS-style mineralization. Mass change calculations illustrate that elemental changes are typical of VMS environments with gains in Fe2O3, MgO, and base metals associated with chlorite alteration near mineralized zones; K2O gains associated with sericite alteration; and losses of Na2O in both alteration types.

  9. Experimental Study of Cement - Sandstone/Shale - Brine - CO2 Interactions

    Directory of Open Access Journals (Sweden)

    Carroll Susan A

    2011-11-01

    Full Text Available Abstract Background Reactive-transport simulation is a tool that is being used to estimate long-term trapping of CO2, and wellbore and cap rock integrity for geologic CO2 storage. We reacted end member components of a heterolithic sandstone and shale unit that forms the upper section of the In Salah Gas Project carbon storage reservoir in Krechba, Algeria with supercritical CO2, brine, and with/without cement at reservoir conditions to develop experimentally constrained geochemical models for use in reactive transport simulations. Results We observe marked changes in solution composition when CO2 reacted with cement, sandstone, and shale components at reservoir conditions. The geochemical model for the reaction of sandstone and shale with CO2 and brine is a simple one in which albite, chlorite, illite and carbonate minerals partially dissolve and boehmite, smectite, and amorphous silica precipitate. The geochemical model for the wellbore environment is also fairly simple, in which alkaline cements and rock react with CO2-rich brines to form an Fe containing calcite, amorphous silica, smectite and boehmite or amorphous Al(OH3. Conclusions Our research shows that relatively simple geochemical models can describe the dominant reactions that are likely to occur when CO2 is stored in deep saline aquifers sealed with overlying shale cap rocks, as well as the dominant reactions for cement carbonation at the wellbore interface.

  10. A Petrographic and Mineralogical Study of Volcanic Rocks from the Mayaxueshan Area, North Qilian Fold Belt, NW China

    Institute of Scientific and Technical Information of China (English)

    徐达伟; 萧炎宏

    2002-01-01

    The Ordovician volcanic rocks in the Mayaxueshan area have been pervasively altered or metamorphosedand contain abundant secondary minerals such as albite, chlorite, epidote, prehnite, pumpellyite, actinolite, titanite, quartz,and/or calcite. They were denoted as spilites or spilitic rocks in terms of their petrographic features and mineral assem-blages. The metamorphic grades of the volcanic rocks are equivalent to that of the intercalated metaclastic rocks. Thisindicates that both the spilitic volcanic rocks and metaclastic rocks in the Mayaxueshan area have formed as a result ofCaledonian regional metamorphism. We suggest that the previously denoted spilitic rocks or altered volcanic rocks shouldbe re-denoted as metabasalts or metabasaltic rocks. The metamorphic grade of the volcanic rocks increases with their age:prehnite-pumpellyite facies for the upper part of the Middle Ordovician volcanic rocks, prehnite-pumpellyite to lowergreenschist facies for the lower part of the Middle Ordovician volcanic rocks, and lower greenschist facies for the LowerOrdovician volcanic rocks. The P-T conditions are estimated as T = 240 - 290C and P = 1.5 - 4.5 kbar for the lower partof the Middle Ordovician rocks, and T = ~ 300~C for the Lower Ordovician rocks. The variations of mineral assemblagesoccurring at different domains of the volcanic rocks were controlled by the variations of the effective bulk composition inthose domains during metamorphism. The geochemical characteristics of Mg-Al chromite in the Mayaxueshan volcanicrocks are consistent with an origin of island arc environment.

  11. Water Disinfection Byproducts Induce Antibiotic Resistance-Role of Environmental Pollutants in Resistance Phenomena.

    Science.gov (United States)

    Li, Dan; Zeng, Siyu; He, Miao; Gu, April Z

    2016-03-15

    The spread of antibiotic resistance represents a global threat to public health, and has been traditionally attributed to extensive antibiotic uses in clinical and agricultural applications. As a result, researchers have mostly focused on clinically relevant high-level resistance enriched by antibiotics above the minimal inhibitory concentrations (MICs). Here, we report that two common water disinfection byproducts (chlorite and iodoacetic acid) had antibiotic-like effects that led to the evolution of resistant E. coli strains under both high (near MICs) and low (sub-MIC) exposure concentrations. The subinhibitory concentrations of DBPs selected strains with resistance higher than those evolved under above-MIC exposure concentrations. In addition, whole-genome analysis revealed distinct mutations in small sets of genes known to be involved in multiple drug and drug-specific resistance, as well as in genes not yet identified to play role in antibiotic resistance. The number and identities of genetic mutations were distinct for either the high versus low sub-MIC concentrations exposure scenarios. This study provides evidence and mechanistic insight into the sub-MIC selection of antibiotic resistance by antibiotic-like environmental pollutants such as disinfection byproducts in water, which may be important contributors to the spread of global antibiotic resistance. The results from this study open an intriguing and profound question on the roles of large amount and various environmental contaminants play in selecting and spreading the antibiotics resistance in the environment. PMID:26928861

  12. Mineral Composition of Loess—Paleosol Samples from the Loess Plateau of China and Its Environmental Significance

    Institute of Scientific and Technical Information of China (English)

    郑洪汉; B.K.G.THENG; 等

    1994-01-01

    34samples of loess-paleosol from the Luochuan and Xifeng sections in the Loess Plateau,northern China were eparated into sand,silt and clay fractions and analyzed for their mineral compositions.The results indicate that there is almost no difference between loess and paleosol in mineral composition.Major mineral species are quartz,mica,feldspar and chlorite,accounting for about 88-92% of the total;other minerals are kandite,smectite,vermiculite and a few heavy minerals.The calcite,magnetite and hematite were not taken into consideration because of their removal in the process of sample preparation.The main difference with respect to the mineral composition of samples collected from different sections and different statigraphic levels lies in the amount and grain size of minerals hosted.Comparisons between the Luochuan section and the Xifeng section,between paleosol and loess and between the upper part and the lower part of some paleosol layers show that the formers contain less feldspar but more mica and vermiculite and are finer in grain size,indicating the co-occurrence of both biochemical weathering process responsible for mineral change and physical weathering process leading to grain-size change during the soil-forming processes.This result favours such an explanation of the soil-forming mechanism that loess deposition and paleosol development occurred synchronously,though the rate of soil formation was greater than that of loess deposition,thus leading to soil development.

  13. Mineralogical characteristics of airborne particles collected in Beijing during a severe Asian dust storm period in spring 2002

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Asian dust storm (ADS) samples were collected on March 20,2002 in Beijing,China. High-resolution field emission scanning electron microscopy with energy dispersive X-ray detector (FESEM-EDX) and X-ray diffraction (XRD) were used to study the morphology,chemical compositions,number-size dis-tributions and mineralogical compositions of ADS particles. The mineral particles were major compo-nents in the ADS samples,accounting for 94% by number. The XRD analysis indicated that the dust particles were dominated by clay (40.3%),and quartz (19.5%),followed by plagioclase (8.4%),calcite (7.5%),K-feldspar (1.5%),hematite (0.9%),pyrite (0.9%),hornblende (0.4%) and gypsum (0.3%),with a certain amount of noncrystalline materials (20.3%). Clay minerals were mainly illite/smectite mixed lay-ers (78%),followed by illite (9%),kaolinite (6%),and chlorite (7%). In addition to these main minerals,FESEM-EDX also detected some trace minerals,such as dolomite,pyrite,thenardite,as well as heavy minerals represented by rutile,ilmenite and apatite. The mineralogical compositions of the 2002-03-20 Asian dust storm and the Saharan dust plumes were similar but the clay mineralogy showed a great distinction,with the illite/smectite mixed layers being common in the Asian dust storm but illite being common in the Saharan dust plumes.

  14. Mineral Composition and Weathering of Soils Derived from Xiashu Loess

    Institute of Scientific and Technical Information of China (English)

    DENGYOU-JUN; MAYI-JIE; 等

    1992-01-01

    Mineralogical,physical and chemical analyses of the soils derived from Xiashu loess were carried out.The primary minerals of these soils were found to be mainly composed of light minerals,such as quartz,feldspar and mica,with traces of heavy minerals.Clay minerals,more complicate in composition,were dominated by hydromica,accompanied by smectite,vermiculite,chlorite,kaolinite,2:1/1:1 randomly interstratified minerals and small amounts of quartz,goethite,lepidocrocite and hematite,Clay minerals were characterized by low crystallinity and fine particle size.In light of the quartz/feldspars ratio of the 0.01-0.05mm silt fraction,and the clay mineral composition,the freeness of iron oxide,and the silica/ sesquioxide and silica/ alumina ratios in <0.002mm clay fraction,it is concluded that the weathering intensity of these soils was lower than those of red soil and yellow earth,but higher than that of brown earth,and that the soil allitization,depotassication and hydroxylation of clay minerals increased from west to east and from north to south geographically.However,this general tendence did not coincide exactly with the gradual alteration of the geographic coordinates,and in some places,a reverse tendency also appeared,which could be attributed to the influence of some soil forming factors such as parent material and microtopography.

  15. Zinc-rich clays in supergene non-sulfide zinc deposits

    Science.gov (United States)

    Choulet, F.; Buatier, M.; Barbanson, L.; Guégan, R.; Ennaciri, A.

    2016-04-01

    The nature and the origin of zinc clays are poorly understood. With the example of the Bou Arhous Zn-Pb ore deposit in the Moroccan High Atlas, this study presents new data for the mineralogical and chemical characterization of barren and zinc clays associated with non-sulfide zinc ores. In the field, white to ocher granular clays are associated with willemite (Zn2SiO4), while red clays fill karst-related cavities cutting across the non-sulfide ore bodies. Red clays (kaolinite, chlorite, illite, and smectite) present evidence of stratification that reflects internal sedimentation processes during the karst evolution. White clays contain 7-Å clay mineral/smectite irregular interstratified minerals with less than 20 % of smectite layers. Willemite is partially dissolved and is surrounded by authigenic zinc clay minerals. Together with XRD results, WDS analyses on newly formed clay aggregates suggest that this interstratified mineral is composed of fraipontite and sauconite. CEC measurements support that zinc is only located within the octahedral sheets. These new results support the following process: (i) dissolution of willemite, leading to release of Si and Zn, (ii) interaction between Zn-Si-rich solutions and residual-detrital clays, and (iii) dissolution of kaolinite and formation of interstratified zinc clay minerals that grew over detrital micas.

  16. Uraniferous mineralizations in the Kuusamo Schist Belt, northeastern Finland

    International Nuclear Information System (INIS)

    The Kouveraara Co-Cu-Au mineralization was found in 1982 with the aid of a geophysical ground survey. This survey was connected with research on the Kouvervaara uranium mineralization in the Early Proterozoic Kuusamo Schist Belt, located just south of the Arctic Circle. In further work, using the Kouvervaara sulphide mineralization as a reference, six Co and Au bearing sulphide mineralizations were discovered, with the help of low altitude aerial geophysical techniques. The Co-Au mineralizations, hosted by the Sericite Quartzite Formation, occur within the hydrothermally altered zones. These zones consist of chloritization, carbonatization, sulphidization, sericitization and albitization, the latter being the most extensive. Excluding the Juomasuo mineralization, uranium is only a trace element in these mineralizations. Other characteristic trace elements are molybdenum and tungsten. The Sivakkaharju and Konttiaho Co-Au-U-Mo mineralizations were found by radiometric ground surveys carried out in 1985 and 1986. These hydrothermal mineralizations occur within brecciated quartz-albite-carbonate rocks and are good manifestations of the positive correlation between uranium and gold in the Kuusamo area. Compared with the other sulphide mineralizations, the Au, U, and Mo contents are remarkably high. Genetically, the mineralizations in the Kuusamo area are associated with deep seated fracture and fault zones, controlled by ancient intracontinental hot spot activity and continental rifting. (author). 31 refs, 6 figs, 2 tabs

  17. High-strength nanocellulose-talc hybrid barrier films.

    Science.gov (United States)

    Liimatainen, Henrikki; Ezekiel, Ngesa; Sliz, Rafal; Ohenoja, Katja; Sirviö, Juho Antti; Berglund, Lars; Hormi, Osmo; Niinimäki, Jouko

    2013-12-26

    Hybrid organic-inorganic films mimicking natural nacre-like composite structures were fabricated from cellulose nanofibers obtained from sequential periodate-chlorite oxidation treatment and talc platelets, using a simple vacuum-filtration method. As a pretreatment, commercial talc aggregates were individualized into well-dispersed talc platelets using a wet stirred media mill with high-shear conditions to promote the homogeneity and mechanical characteristics of hybrids. The nanofiber-talc hybrids, which had talc contents from 1 to 50 wt %, were all flexible in bending, and possessed tensile strength and Young's modulus values up to 211 ± 3 MPa and 12 ± 1 GPa, respectively, the values being remarkably higher than those reported previously for nanofibrillated cellulose-talc films. Because of the lamellar and well-organized structure of hybrids in which the talc platelets were evenly embedded, they possessed a small pore size and good oxygen barrier properties, as indicated by the preliminary results. The talc platelets decreased the moisture adsorption of highly talc-loaded hybrids, although they still exhibited hydrophilic surface characteristics in terms of contact angles. PMID:24215630

  18. Strong, self-standing oxygen barrier films from nanocelluloses modified with regioselective oxidative treatments.

    Science.gov (United States)

    Sirviö, Juho Antti; Kolehmainen, Aleksi; Visanko, Miikka; Liimatainen, Henrikki; Niinimäki, Jouko; Hormi, Osmo E O

    2014-08-27

    In this work, three self-standing nanocellulose films were produced from birch pulp using regioselective oxidation and further derivatization treatments. The modified celluloses were synthesized using periodate oxidation, followed by chlorite oxidation, bisulfite addition, or reductive amination with amino acid taurine, which resulted in dicarboxylic acid cellulose (DCC), α-hydroxy sulfonic acid cellulose (HSAC), and taurine-modified cellulose (TC), respectively. The nanocelluloses were fabricated by mechanical disintegration using high-pressure homogenization. Mechanical and barrier properties of the nanocellulose films were characterized. Two (2,2,6,6-tetramethyl-piperidin-1-yl)oxyl (TEMPO) oxidation-based nanocellulose films were also produced, and their properties were compared to the periodate-based nanocellulose films. All of the periodate-based nanocellulose films showed high tensile strength (130-163 MPa) and modulus (19-22 GPa). Oxygen barrier properties of the films were superior to many synthetic and composite materials; in particular, the nanofibrillated DCC films had oxygen permeability as low as 0.12 cm(3) μm/(m(2) d kPa) at 50% relative humidity. Compared to films of TEMPO-oxidized nanocelluloses, all of the periodate-based nanocellulose films had similar or even better mechanical and barrier properties, demonstrating versatility of periodate oxidation to obtain nanocellulose films with adjustable properties. Also, for the first time, amino-acid-based cellulose modification was used in the production of nanocellulose. PMID:25089516

  19. ‘Diffuse faulting’ in the Machu Picchu granitoid pluton, Eastern Cordillera, Peru

    Science.gov (United States)

    Mazzoli, Stefano; Vitale, Stefano; Delmonaco, Giuseppe; Guerriero, Vincenzo; Margottini, Claudio; Spizzichino, Daniele

    2009-11-01

    A series of batholiths, forming part of the 'roots' of a Permo-Liassic rift system, are exposed in the high Eastern Cordillera of central Peru as a result of tectonic inversion. Shortening of the Machu Picchu granitoid pluton was accommodated by widespread shear reactivation of primary joints, by a process termed here 'diffuse faulting'. Fault-like reactivation of precursor joint surfaces, marked by chlorite, epidote and quartz shear fibres, is locally evidenced by few centimetres offsets within apparently undeformed granite. Analysis of fault slip data indicates that shear reactivation of different joint sets was kinematically consistent with ENE oriented shortening. Less frequent mylonitic shear zones appear to have evolved from the common brittle precursors. Apart from rare phyllonitic shear zones, fluid-rock interaction along the brittle precursors was generally limited, and pluton deformation appears to be mainly controlled by the geometry and distribution of primary joints. Three main sets of reactivated joints can be recognized, characterized by oblique-slip kinematics with variable reverse and strike-slip components of motion. Theoretical modelling based on quantitative fracture analysis (scan-line data) and different displacement-length relationships applied to the main reactivated joint sets yield first-order estimates of pluton finite strain. The results suggest that bulk finite strain is oblate and essentially coaxial, and is characterized by horizontal shortening not exceeding 10%. Relatively small finite strains, integrated over the size of the pluton, still result in a few kilometres of crustal shortening.

  20. Geology and fracture system at Stripa. Technical information report No. 21

    International Nuclear Information System (INIS)

    The Stripa test site has been excavated in granitic rock between 338 m and 360 m below the ground surface, and is located under the north limb of an ENE-plunging synclinal structure. The granitic rocks, in the areas mapped, are of Archean age and are dominated by a reddish, medium-grained, massive monzogranite that shows varying degrees of deformation. The granitic rocks have been intruded by diabase (dolerite) and pegmatite dikes. Surface and subsurface mapping shows that the Stripa granite is highly fractured and that there are at least four joint sets in the area of the test excavations. In addition to the joints, the rock mass contains fissures, fracture zones, and small-scale shear zones, representing the complete spectrum of the fracture family. Most of the fractures are lined with chlorite, occasionally with calcite. Many of the small-scale shear fractures are filled or coated with epidote. Offsets of pegmatite dikes formed by these fractures are usually limited to one to two meters. Water seepage is observed only as drops from fractures or moist fracture surfaces. It was found that reconstruction of the local three-dimensional fracture system is the heater-experiment sites was difficult, and in some cases subjective. Such reconstruction is a prerequisite to accurate interpretation of thermal and mechanical data from such sites