Sample records for chlorites

  1. Diagenetic Chlorite

    DEFF Research Database (Denmark)


    This study demonstrates the diagenetic evolution glaucony-rich deep water sandstones from the Rau-1A well in the Siri Canyon, Danish North Sea. The major diagenetic phases in the studied well are microquartz, large syntaxial quartz overgrowth, calcite and chlorite. Chlorite forms an intrareservoir...

  2. 21 CFR 173.325 - Acidified sodium chlorite solutions. (United States)


    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Acidified sodium chlorite solutions. 173.325... HUMAN CONSUMPTION Specific Usage Additives § 173.325 Acidified sodium chlorite solutions. Acidified sodium chlorite solutions may be safely used in accordance with the following prescribed conditions:...

  3. Methane oxidation linked to chlorite dismutation (United States)

    Miller, Laurence G.; Baesman, Shaun M.; Carlström, Charlotte I.; Coates, John D.; Oremland, Ronald S.


    We examined the potential for CH4 oxidation to be coupled with oxygen derived from the dissimilatory reduction of perchlorate, chlorate, or via chlorite (ClO−2) dismutation. Although dissimilatory reduction of ClO−4 and ClO−3 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, ClO−2 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 ClO−2. 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 ClO−2. 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 ClO−2 and CH4 consumption was established in soils and cultures, no upstream connection with either ClO−4 or ClO−3 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.

  4. Deformation of chlorite in naturally deformed low-grade rocks

    NARCIS (Netherlands)

    Bons, A.J.


    The intracrystalline deformation of chlorite in naturally deformed low-grade rocks was investigated with transmission electron microscopy (TEM). As in other phyllosilicates, the deformation of chlorite is dominated by the (001) slip plane. Slip along this plane is very easy through the generation an

  5. Mechanism of reaction of chlorite with mammalian heme peroxidases. (United States)

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


    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 biphasic manner. The first (rapid) phase is shown to correspond to the formation of a MPO-chlorite high-spin complex, whereas during the second (slower) phase degradation of the prosthetic group was observed. Cyanide, chloride and hydrogen peroxide can block or delay heme bleaching. In contrast to HRP, the MPO/chlorite system does not mediate chlorination of target molecules. Irreversible inactivation is shown to include heme degradation, iron release and decrease in thermal stability. Differences between mammalian peroxidases and HRP are discussed with respect to differences in active site architecture and heme modification.

  6. Low-temperature magnetic anisotropy in micas and chlorite

    DEFF Research Database (Denmark)

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


    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 diamagnetic...... of approximately 6.3-8.7 for individual samples of muscovite, phlogopite and chlorite on cooling from RT to 77 K and between 11.2 and 12.4 for biotite. A decrease in temperature enhances the paramagnetic anisotropy in a mineral. Biotite exhibits a relatively stronger enhancement due to the onset of magnetic......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...

  7. Kinetics of chlorite dismutase in a perchlorate degrading reactor sludge. (United States)

    Nadaraja, Anupama Vijaya; Veetil, Prajeesh Gangadharan Puthiya; Vidyadharan, Athira; Bhaskaran, Krishnakumar


    Kinetics of chlorite dismutase (CD), the terminal enzyme involved in the perchlorate (ClO4(-)) reduction pathway, in a ClO4(-)-degrading bioreactor are reported in this study. Enzyme activity was determined from dissolved oxygen released during disproportionation of chlorite (ClO2(-)). CD activity was in the range 29.8-36.4 U/mg dry weight sludge, and kinetic constants Vmax and K(m) of the enzyme were 37.83 U/mg dry weight and 0.28 mM, respectively. Among reactor operational conditions, enzyme activity was observed at pH 4.0-9.0, with an optimum at pH 6.0. Redox potential in the range -50 to +120mV and NaCl up to 3.5 g/L had no significant effect on CD activity. However, co-occurring pollutants such as ammonium at 10 ppm, nitrite at 50 ppm and EDTA at 100 microM reduced CD activity substantially. The present study highlights ideal bioreactor conditions to avoid ClO2(-) toxicity, while indicating the buffering potential of a mixed microbial system against inhibiting factors to maintain stable CD activity in bioreactors.

  8. On the compositional variability of metamorphic chlorites as an effect of the micro-site chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Sassi, Raffaele; Zane, Antonella [Padua, Univ. (Italy). Dipt. di Mineralogia e Petrologia


    Chlorite is a widespread mineral in all metamorphic rock sequence with the exception of the upper part of the amphibolite facies and granulite. Its stability field is well known but the petrologic meaning of its compositional variability is still poorly understood. In this paper, the chemical variability of low grade metamorphic chlorites as an effect of the micro-site chemistry has been tested by means of 2169 microprobe analyses of selected chlorite flakes. The chemistry of studied chlorites turns out to be significantly scattered, as a function of the micro-site chemistry. As a general conclusion, the possible existence in the same thin section, of chlorite flakes having different composition is a serious drawback for geothermobarometry, at least in low grade metamorphic rocks.

  9. 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.


    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.

  10. Investigation of U(VI) adsorption in quartz-chlorite mineral mixtures. (United States)

    Wang, Zheming; Zachara, John M; Shang, Jianying; Jeon, Choong; Liu, Juan; Liu, Chongxuan


    A batch and cryogenic laser-induced time-resolved luminescence spectroscopy investigation of U(VI) adsorbed on quartz-chlorite mixtures with variable mass ratios have been performed under field-relevant uranium concentrations (5×10(-7) M and 5×10(-6) M) in pH 8.1 synthetic groundwater. The U(VI) adsorption Kd values steadily increased as the mass fraction of chlorite increased, indicating preferential sorption to chlorite. For all mineral mixtures, U(VI) adsorption Kd values were lower than that calculated from the assumption of component additivity possibly caused by surface modifications stemming from chlorite dissolution; The largest deviation occurred when the mass fractions of the two minerals were equal. U(VI) adsorbed on quartz and chlorite displayed characteristic individual luminescence spectra that were not affected by mineral mixing. The spectra of U(VI) adsorbed within the mixtures could be simulated by one surface U(VI) species on quartz and two on chlorite. The luminescence intensity decreased in a nonlinear manner as the adsorbed U(VI) concentration increased with increasing chlorite mass fraction-likely due to ill-defined luminescence quenching by both structural Fe/Cr in chlorite, and trace amounts of solubilized and reprecipitated Fe/Cr in the aqueous phase. However, the fractional spectral intensities of U(VI) adsorbed on quartz and chlorite followed the same trend of fractional adsorbed U(VI) concentration in each mineral phase with approximate linear correlations, offering a method to estimate of U(VI) concentration distribution between the mineral components with luminescence spectroscopy.

  11. Determination of Chlorine Dioxide and Chlorite in Water Supply Systems by Verified Methods (United States)

    Tkáčová, Jana; Božíková, Jarmila


    This work is dedicated to the development and optimization of appropriate analytical methods for the determination of chlorine dioxide and chlorite in drinking water in order to obtain accurate and correct results in the quality control of drinking water. The work deals with the development and optimization of a method for the determination of chlorine dioxide using chlorophenol red. Furthermore, a new spectrophotometric method for the determination of chlorite via bromometry using methyl orange was developed, optimized and validated. An electrochemical method for the determination of chlorite by flow coulometry was also developed, optimized and validated.

  12. The smectite to chlorite transition in the Chipilapa geothermal system, El Salvador

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, D. [Univ. of Bristol (United Kingdom). Dept. of Earth Sciences; Santana de Zamora, A. [Comision Ejecutiva Hidroelectrica del Rio Lempa (El Salvador)


    Clay mineralogical, X-ray diffraction and electron microprobe studies have been carried out on separated <2 {micro}m fractions from cutting and core material from three wells in the Chipilapa geothermal system in El Salvador. The data indicate that the smectite to chlorite transition is prevalent, but a secondary smectite to illite transition is also present. At depths approximately <750 m, smectite with very minor chlorite mixed-layers (approximately <15%) is dominant, and has a composition midway between a di- and tri-smectite. At {approximately}750 m there is a very clear distinction and sharp transition into discrete chlorite with very minor smectite mixed-layers (approximately <10%). Corrensite is recorded only as a rare and minor phase. Smectite occurs in abundance at temperatures up to {approximately}200 C, and the transition from a smectite-dominant to chlorite-dominant assemblage takes place over a narrow temperature range ({approximately}150 to 200 C). The stability range of smectite is very similar to that recorded in other geothermal systems, whereas the smectite to chlorite transition differs greatly from that recorded in other systems. The transition does not involve continuous chlorite/smectite mixed-layering but a marked step: It is the sharpest and most discontinuous stepped sequence of this mineralogical transition recorded.

  13. 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.


    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)

  14. Kinetics and mechanism of styrene epoxidation by chlorite: role of chlorine dioxide. (United States)

    Leigh, Jessica K; Rajput, Jonathan; Richardson, David E


    An investigation of the kinetics and mechanism for epoxidation of styrene and para-substituted styrenes by chlorite at 25 °C in the pH range of 5-6 is described. The proposed mechanism in water and water/acetonitrile includes seven oxidation states of chlorine (-I, 0, I, II, III, IV, and V) to account for the observed kinetics and product distributions. The model provides an unusually detailed quantitative mechanism for the complex reactions that occur in mixtures of chlorine species and organic substrates, particularly when the strong oxidant chlorite is employed. Kinetic control of the reaction is achieved by the addition of chlorine dioxide to the reaction mixture, thereby eliminating a substantial induction period observed when chlorite is used alone. The epoxidation agent is identified as chlorine dioxide, which is continually formed by the reaction of chlorite with hypochlorous acid that results from ClO produced by the epoxidation reaction. The overall stoichiometry is the result of two competing chain reactions in which the reactive intermediate ClO reacts with either chlorine dioxide or chlorite ion to produce hypochlorous acid and chlorate or chloride, respectively. At high chlorite ion concentrations, HOCl is rapidly eliminated by reaction with chlorite, minimizing side reactions between HOCl and Cl2 with the starting material. Epoxide selectivity (>90% under optimal conditions) is accurately predicted by the kinetic model. The model rate constant for direct reaction of styrene with ClO2(aq) to produce epoxide is (1.16 ± 0.07) × 10(-2) M(-1) s(-1) for 60:40 water/acetonitrile with 0.20 M acetate buffer. Rate constants for para substituted styrenes (R = -SO3(-), -OMe, -Me, -Cl, -H, and -NO2) with ClO2 were determined. The results support the radical addition/elimination mechanism originally proposed by Kolar and Lindgren to account for the formation of styrene oxide in the reaction of styrene with chlorine dioxide.

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

    Directory of Open Access Journals (Sweden)

    Y. Hashimoto


    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.

  16. Chloritization and associated alteration at the Jabiluka unconformity-type uranium deposit, Northern Territory, Australia (United States)

    Nutt, Constance J.


    Jabiluka is the largest of four known uncomformity-type uranium deposits that are hosted by brecciated and altered metasedimentary rocks in the Pine Creek geosyncline, Northern Territory, Australia. The alteration zone at Jabiluka is dominated by chlorite, but also contains white mica, tourmaline and apatite; hematite is present, but only in minor amounts. Added quartz is mainly restricted to fractures and breccias. Chlorite, which formed during episodic fluid movement, partly to totally replaced all pre-existing minerals. Chloritized rocks are enriched in Mg, and depleted in K, Ca, Na and Si. Five types of chlorite are optically and chemically distinguishable in the rocks at Jabiluka. Chloritization is proposed as a mechanism that lowered the pH of the circulating fluid, and also caused significant loss of silica from the altered rocks. The proposed constraints on alteration, and presumably on at least part of the uranium mineralization, neither require nor preclude the existence of the unconformity as necessary for the formation of ore.

  17. Dehydration of chlorite explains anomalously high electrical conductivity in the mantle wedges. (United States)

    Manthilake, Geeth; Bolfan-Casanova, Nathalie; Novella, Davide; Mookherjee, Mainak; Andrault, Denis


    Mantle wedge regions in subduction zone settings show anomalously high electrical conductivity (~1 S/m) that has often been attributed to the presence of aqueous fluids released by slab dehydration. Laboratory-based measurements of the electrical conductivity of hydrous phases and aqueous fluids are significantly lower and cannot readily explain the geophysically observed anomalously high electrical conductivity. The released aqueous fluid also rehydrates the mantle wedge and stabilizes a suite of hydrous phases, including serpentine and chlorite. In this present study, we have measured the electrical conductivity of a natural chlorite at pressures and temperatures relevant for the subduction zone setting. In our experiment, we observe two distinct conductivity enhancements when chlorite is heated to temperatures beyond its thermodynamic stability field. The initial increase in electrical conductivity to ~3 × 10(-3) S/m can be attributed to chlorite dehydration and the release of aqueous fluids. This is followed by a unique, subsequent enhancement of electrical conductivity of up to 7 × 10(-1) S/m. This is related to the growth of an interconnected network of a highly conductive and chemically impure magnetite mineral phase. Thus, the dehydration of chlorite and associated processes are likely to be crucial in explaining the anomalously high electrical conductivity observed in mantle wedges. Chlorite dehydration in the mantle wedge provides an additional source of aqueous fluid above the slab and could also be responsible for the fixed depth (120 ± 40 km) of melting at the top of the subducting slab beneath the subduction-related volcanic arc front.

  18. Influence of drinking water treatments on chlorine dioxide consumption and chlorite/chlorate formation. (United States)

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


    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%.

  19. Elucidation of the mechanism of enzymatic browning inhibition by sodium chlorite (United States)

    Sodium chlorite (SC) is a well known anti-microbial agent and its strong inhibitory effect on enzymatic browning of fresh-cut produce has recently been identified. We investigated the mechanisms of browning inhibition by SC using chlorogenic acid (CA) and PPO extracted from mushroom to emulate the b...

  20. Chlorite dismutases - a heme enzyme family for use in bioremediation and generation of molecular oxygen. (United States)

    Hofbauer, Stefan; Schaffner, Irene; Furtmüller, Paul G; Obinger, Christian


    Chlorite is a serious environmental concern, as rising concentrations of this harmful anthropogenic compound have been detected in groundwater, drinking water, and soil. Chlorite dismutases (Clds) are therefore important molecules in bioremediation as Clds catalyze the degradation of chlorite to chloride and molecular oxygen. Clds are heme b-containing oxidoreductases present in numerous bacterial and archaeal phyla. This review presents the phylogeny of functional Clds and Cld-like proteins, and demonstrates the close relationship of this novel enzyme family to the recently discovered dye-decolorizing peroxidases. The available X-ray structures, biophysical and enzymatic properties, as well as a proposed reaction mechanism, are presented and critically discussed. Open questions about structure-function relationships are addressed, including the nature of the catalytically relevant redox and reaction intermediates and the mechanism of inactivation of Clds during turnover. Based on analysis of currently available data, chlorite dismutase from "Candidatus Nitrospira defluvii" is suggested as a model Cld for future application in biotechnology and bioremediation. Additionally, Clds can be used in various applications as local generators of molecular oxygen, a reactivity already exploited by microbes that must perform aerobic metabolic pathways in the absence of molecular oxygen. For biotechnologists in the field of chemical engineering and bioremediation, this review provides the biochemical and biophysical background of the Cld enzyme family as well as critically assesses Cld's technological potential.

  1. Contribution of long-term hydrothermal experiments for understanding the smectite-to-chlorite conversion in geological environments (United States)

    Mosser-Ruck, Régine; Pignatelli, Isabella; Bourdelle, Franck; Abdelmoula, Mustapha; Barres, Odile; Guillaume, Damien; Charpentier, Delphine; Rousset, Davy; Cathelineau, Michel; Michau, Nicolas


    The smectite-to-chlorite conversion is investigated through long-duration experiments (up to 9 years) conducted at 300 °C. The starting products were the Wyoming bentonite MX80 (79 % smectite), metallic iron and magnetite in contact with a Na-Ca chloride solution. The predominant minerals in the run products were an iron-rich chlorite (chamosite like) and interstratified clays interpreted to be chlorite/smectite and/or corrensite/smectite, accompanied by euhedral crystals of quartz, albite and zeolite. The formation of pure corrensite was not observed in the long-duration experiments. The conversion of smectite into chlorite over time appears to take place in several steps and through several successive mechanisms: a solid-state transformation, significant dissolution of the smectite and direct precipitation from the solution, which is over-saturated with respect to chlorite, allowing the formation of a chamosite-like mineral. The reaction mechanisms are confirmed by X-ray patterns and data obtained on the experimental solutions (pH, contents of Si, Mg, Na and Ca). Because of the availability of some nutrients in the solution, total dissolution of the starting smectite does not lead to 100 % crystallization of chlorite but to a mixture of two dominant clays: chamosite and interstratified chlorite/smectite and/or corrensite/smectite poor in smectite. The role of Fe/(Fe + Mg) in the experimental medium is highlighted by chemical data obtained on newly formed clay particles alongside previously published data. The newly formed iron-rich chlorite has the same composition as that predicted by the geothermometer for diagenetic to low-grade metamorphic conditions, and the quartz + Fe-chlorite + albite experimental assemblage in the 9-year experiment is close to that fixed by water-rock equilibrium.

  2. “Development of an Automated On-line Electrochemical Chlorite Ion Sensor” (United States)

    Myers, John N.; Steinecker, William H.; Sandlin, Zechariah D.; Cox, James A.; Gordon, Gilbert; Pacey, Gilbert E.


    A sensor system for the automatic, in-line, determination of chlorite ion is reported. Electroanalytical measurements were performed in electrolyte-free liquids by using an electrochemical probe (EC), which enables in-line detection in high-resistance media such as disinfected water. Cyclic voltammetry scan rate studies suggest that the current arising from the oxidation of chlorite ion at an EC probe is mass-transfer limited. By coupling FIA with an EC probe amperometric cell, automated analysis was achieved. This sensor is intended to fulfill the daily monitoring requirements of the EPA DBP regulations for chlorite ion. Detection limits of 0.02-0.13 mg/L were attained, which is about one order of magnitude below the MRDL. The sensor showed no faradaic signal for perchlorate, chlorate, or nitrate. The lifetime and stability of the sensor were investigated by measuring calibration curves over time under constant-flow conditions. Detection limits of <0.1 mg/L were repeatedly achieved over a period of three weeks. PMID:22608440

  3. Development of an automated on-line electrochemical chlorite ion sensor. (United States)

    Myers, John N; Steinecker, William H; Sandlin, Zechariah D; Cox, James A; Gordon, Gilbert; Pacey, Gilbert E


    A sensor system for the automatic, in-line, determination of chlorite ion is reported. Electroanalytical measurements were performed in electrolyte-free liquids by using an electrochemical probe (EC), which enables in-line detection in high-resistance media such as disinfected water. Cyclic voltammetry scan rate studies suggest that the current arising from the oxidation of chlorite ion at an EC probe is mass-transfer limited. By coupling FIA with an EC probe amperometric cell, automated analysis was achieved. This sensor is intended to fulfill the daily monitoring requirements of the EPA DBP regulations for chlorite ion. Detection limits of 0.02-0.13 mg/L were attained, which is about one order of magnitude below the MRDL. The sensor showed no faradaic signal for perchlorate, chlorate, or nitrate. The lifetime and stability of the sensor were investigated by measuring calibration curves over time under constant-flow conditions. Detection limits of <0.1 mg/L were repeatedly achieved over a period of three weeks.

  4. Mineralogy and geochemistry of laterites developed on chlorite schists in Tchollire region, North Cameroon (United States)

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


    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

  5. Reactions of aquacobalamin and cob(II)alamin with chlorite and chlorine dioxide. (United States)

    Dereven'kov, Ilia A; Shpagilev, Nikita I; Valkai, László; Salnikov, Denis S; Horváth, Attila K; Makarov, Sergei V


    Reactions of aquacobalamin (H2O-Cbl(III)) and its one-electron reduced form (cob(II)alamin, Cbl(II)) with chlorite (ClO2(-)) and chlorine dioxide (ClO 2(•) ) were studied by conventional and stopped-flow UV-Vis spectroscopies and matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS). ClO2(-) does not react with H2O-Cbl(III), but oxidizes Cbl(II) to H2O-Cbl(III) as a major product and corrin-modified species as minor products. The proposed mechanism of chlorite reduction involves formation of OCl(-) that modifies the corrin ring during the course of reaction with Cbl(II). H2O-Cbl(III) undergoes relatively slow destruction by ClO 2(•) via transient formation of oxygenated species, whereas reaction between Cbl(II) and ClO 2(•) proceeds extremely rapidly and leads to the oxidation of the Co(II)-center.

  6. Determination of chlorate and chlorite and mutagenicity of seafood treated with aqueous chlorine dioxide. (United States)

    Kim, J; Marshall, M R; Du, W X; Otwell, W S; Wei, C I


    The use of chlorine dioxide (ClO(2)) as a potential substitute for aqueous chlorine to improve the quality of seafood products has not been approved by regulatory agencies due to health concerns related to the production of chlorite (ClO(2)(-)) and chlorate (ClO(3)(-)) as well as possible mutagenic/carcinogenic reaction products. Cubes of Atlantic salmon (Salmo salar) and red grouper (Epinephelus morio) were treated with 20 or 200 ppm aqueous chlorine or ClO(2) solutions for 5 min, and extracts of the treated fish cubes and test solutions were checked for mutagenicity using the Ames Salmonella/microsome assay. No mutagenic activity was detected in the treated fish samples or test solutions with ClO(2). Only the sample treated with 200 ppm chlorine showed weak mutagenic activity toward S. typhimurium TA 100. No chlorite residue was detected in sea scallops, mahi-mahi, or shrimp treated with ClO(2) at 3.9-34.9 ppm. However, low levels of chlorate residues were detected in some of the treated samples. In most cases, the increase in chlorate in treated seafood was time- and dose-related.

  7. Dissimilatory perchlorate reduction linked to aerobic methane oxidation via chlorite dismutase (United States)

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


    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

  8. 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


    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.

  9. Fe-SAPONITE and Chlorite Growth on Stainless Steel in Hydrothermal Engineered Barrier Experiments (United States)

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


    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

  10. Identification of spectrally similar materials using the USGS Tetracorder algorithm: The calcite-epidote-chlorite problem (United States)

    Dalton, J.B.; Bove, D.J.; Mladinich, C.S.; Rockwell, B.W.


    A scheme to discriminate and identify materials having overlapping spectral absorption features has been developed and tested based on the U.S. Geological Survey (USGS) Tetracorder system. The scheme has been applied to remotely sensed imaging spectroscopy data acquired by the Airborne Visible and Infrared Imaging Spectrometer (AVIRIS) instrument. This approach was used to identify the minerals calcite, epidote, and chlorite in the upper Animas River watershed, Colorado. The study was motivated by the need to characterize the distribution of calcite in the watershed and assess its acid-neutralizing potential with regard to acidic mine drainage. Identification of these three minerals is difficult because their diagnostic spectral features are all centered at 2.3 ??m, and have similar shapes and widths. Previous studies overestimated calcite abundance as a result of these spectral overlaps. The use of a reference library containing synthetic mixtures of the three minerals in varying proportions was found to simplify the task of identifying these minerals when used in conjunction with a rule-based expert system. Some inaccuracies in the mineral distribution maps remain, however, due to the influence of a fourth spectral component, sericite, which exhibits spectral absorption features at 2.2 and 2.4 ??m that overlap the 2.3-??m absorption features of the other three minerals. Whereas the endmember minerals calcite, epidote, chlorite, and sericite can be identified by the method presented here, discrepancies occur in areas where all four occur together as intimate mixtures. It is expected that future work will be able to reduce these discrepancies by including reference mixtures containing sericite. ?? 2004 Elsevier Inc. All rights reserved.

  11. Scales of equilibrium and disequilibrium during cleavage formation in chlorite and biotite-grade phyllites, SE Vermont (United States)

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


    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

  12. Elucidation of the mechanism of enzymatic browning inhibition by sodium chlorite. (United States)

    He, Qiang; Luo, Yaguang; Chen, Pei


    Sodium chlorite (SC) is a well known anti-microbial agent and its strong inhibitory effect on enzymatic browning of fresh-cut produce has recently been identified. We investigated the effect of SC on polyphenol oxidase (PPO) and its substrate, chlorogenic acid (CA), as it relates to the mechanisms of browning inhibition by SC. Results indicate that the browning reaction of CA (1.0mM) catalyzed by PPO (33U/mL) was significantly inhibited by 1.0mM SC at pH 4.6. Two PPO isoforms were identified by native polyacrylamide gel electrophoresis, and both were inactivated by SC (3.0mM). This suggests that SC serves as a PPO inhibitor to prevent enzymatic browning. Furthermore, the effect of SC on the stability of CA in both acidic (pH 4.5) and basic conditions (pH 8.3) was studied by UV-Vis scan and LC-MS analysis. The results showed that at the presence of SC (3.0mM), CA (0.1mM) degraded to quinic acid and caffeic acid as well as other intermediates. Hence, the anti-browning property of SC can be attributed to the two modes of action: the inactivation of polyphenol oxidase directly and the oxidative degradation of phenolic substrates.

  13. Removal of Hg~0 with sodium chlorite solution and mass transfer reaction kinetics

    Institute of Scientific and Technical Information of China (English)


    The absorption behavior of Hg0 was studied experimentally by using sodium chlorite solution(NaClO2) as the absorbent in a bubble reactor.Primary influencing factors on removal efficiency of Hg0 such as NaClO2 concentration,pH,reaction temperature and the concentration of Hg0 were investigated.The results indicated that 72.91% of Hg0 removal efficiency could be achieved in acidic NaClO2 solution.The removal mechanism of Hg0 was proposed by analyzing of Hg2+ concentration in ab-sorption solution after reaction and comparing the electrode potentials between NaClO2 species and Hg2+/Hg0.The experimental results of mass transfer-reaction kinetics on oxidation of Hg0 by NaClO2 solution showed that with the increase of NaClO2 concentration and the decrease of pH value,the enhancement factor(E) and ratio of KG(Hg0)/kG(Hg0) increased and the liquid phase mass transfer resistance decreased,which is benefit to the mass transfer adsorption reaction.Although the increase of reaction temperature could improve the enhancement factor(E),but the ratio of KG(Hg0)/kG(Hg0) decreased;as a result,the liquid phase mass transfer resistance increased,therefore,the reaction rate for removal of Hg0 decreased.

  14. Ordinary Toxicity of Chlorine Dioxide and By-products Chlorite and Chlorate in Water

    Institute of Scientific and Technical Information of China (English)

    王丽; 常爱敏; 黄君礼


    Acute toxicity and accumulated toxicity of chlorine dioxide (C1O2) and by-products chlorite ( C1O-2 ) and chlorate (C1O-3) in water acted on mice are studied by the method of Horn and accumulation coefficient.Subchronic toxicity of the mixture of C1O2 and C1O-2 and ClO-3 in water acted on rat is studied though feeding test for 90 days, including statistical analysis of variance on weight gaining, food utilization efficiency, index of blood and serum, liver (or kidney)to body weight ratio, and histopathological examination on liver and kidney. The results show that aqueous solution of C1O2, NaC1O2 and NaC1O3 (with the concentration of 276. 5 mg/L, 200 mg/L and 200 mg/L respectively) and the mixed aqueous solution of C1O2 with the concentration of 553 mg/L are actually non poisonous, and non-cumulative aqueous solution as well.

  15. Temperature micro-mapping and redox conditions of a chlorite zoning pattern in green-schist facies fault zone (United States)

    Trincal, Vincent; Lanari, Pierre; Lacroix, Brice; Buatier, Martine D.; Charpentier, Delphine; Labaume, Pierre; Muñoz, Manuel


    Faults are major discontinuities driving fluid flows and playing a major role in precipitation of ore deposits. Mineral paragenesis and crystal chemistry depend on Temperature (T) condition, fluid composition but also on the redox environment of precipitation. The studied samples come from the Pic de Port Vieux thrust sheet, a minor thrust sheet associated to Gavarnie thrust fault zone (Central Pyrenees). The Pic de Port Vieux Thrust sheet comprises a 1-20 meter thick layer of Triassic red beds and mylonitized Cretaceous limestone. The thrust sheet is affected by faults and cleavage; the other important deformation product is a set of veins filled by quartz and chlorite. Microstructural and mineralogical investigations were performed based on the previous work of Grant (1992). The crystallization of chlorite is syn-tectonic and strongly controlled by the fluid circulation during the Gavarnie thrust sheet emplacement. Chlorite precipitated in extension veins, crack-seal shear veins or in open cavities. The chlorite filling the open cavities occurs as pseudo-uniaxial plates arranged in rosette-shaped aggregates. These aggregates appear to have developed as a result of radial growth of the chlorite platelets. According to point and microprobe X-ray images, these chlorites display oscillatory chemical zoning patterns with alternating iron rich and magnesium rich bands. The chlorite composition ranges from Fe rich pole (Si2.62Al1.38O10(Al1.47Fe1.87Mg2.61)6(OH)8) to Mg rich pole (Si2.68Al1.31O10(Al1.45Fe1.41Mg3.06)6(OH)8). In metamorphic rocks, zoning pattern or rimmed minerals results for varying P or T conditions and can be used to unravel the P-T history of the sample. In the present study, temperature maps are derived from standardized microprobe X-ray images using the program XMapTools (Lanari et al 2014). The (Fe3+/Fetot) value in chlorite was directly measured using μXANES spot analyses collected at the Fe-K edge. The results indicate a homogeneous temperature of

  16. Acidified sodium chlorite as an alternative to chlorine for elimination of salmonella on alfalfa seeds. (United States)

    Liao, C-H


    The health and environmental hazard associated with the use of chlorine for food processing has been documented previously. This study was conducted to determine if acidified sodium chlorite (ASC) could be used to replace calcium hypochlorite (Ca[OCl](2)) for disinfection of alfalfa seeds. Contaminated seeds containing approximately 1.5 x 10(7) CFU/g of Salmonella were treated with ASC or Ca(OCl)(2) at different concentrations and for different periods of time. Results showed that the efficacy of ASC and Ca(OCl)(2) for elimination of Salmonella on contaminated seeds could be improved greatly by extending the treatment time from the traditional 15 to 45 min. Treatment of seeds with 800 ppm of ASC for 45 min reduced the number of Salmonella by 3.9 log units, approximately 1.2 log units higher than that treated with 20000 ppm of Ca(OCl)(2). Treatment of seeds with a lower concentration (100 to 400 ppm) of ASC for 45 min reduced the number of Salmonella by 1.3 to 2.2 log units. Soaking alfalfa seeds in 800 ppm of ASC for 45 min did not affect seed germination. However, soaking seeds in 20000 ppm of Ca(OCl)(2) for 45 min reduced seed germination by 20%. Unlike Ca(OCl)(2), antimicrobial efficiency of ASC was not affected by pre-exposure to alfalfa seeds. Data presented also showed that Salmonella on newly inoculated seeds that had been stored at 4 degrees C for less than 7 d were more sensitive to sanitizer treatment than those on seeds that had been stored for 4 wk or longer.

  17. Formation of chlorite during thrust fault reactivation. Record of fluid origin and P-T conditions in the Monte Perdido thrust fault (southern Pyrenees) (United States)

    Lacroix, B.; Charpentier, D.; Buatier, M.; Vennemann, T.; Labaume, P.; Adatte, T.; Travé, A.; Dubois, M.


    The chemical and isotopic compositions of clay minerals such as illite and chlorite are commonly used to quantify diagenetic and low-grade metamorphic conditions, an approach that is also used in the present study of the Monte Perdido thrust fault from the South Pyrenean fold-and-thrust belt. The Monte Perdido thrust fault is a shallow thrust juxtaposing upper Cretaceous-Paleocene platform carbonates and Lower Eocene marls and turbidites from the Jaca basin. The core zone of the fault, about 6 m thick, consists of intensely deformed clay-bearing rocks bounded by major shear surfaces. Illite and chlorite are the main hydrous minerals in the fault zone. Illite is oriented along cleavage planes while chlorite formed along shear veins (<50 μm in thickness). Authigenic chlorite provides essential information about the origin of fluids and their temperature. δ18O and δD values of newly formed chlorite support equilibration with sedimentary interstitial water, directly derived from the local hanging wall and footwall during deformation. Given the absence of large-scale fluid flow, the mineralization observed in the thrust faults records the P-T conditions of thrust activity. Temperatures of chlorite formation of about 240°C are obtained via two independent methods: chlorite compositional thermometers and oxygen isotope fractionation between cogenetic chlorite and quartz. Burial depth conditions of 7 km are determined for the Monte Perdido thrust reactivation, coupling calculated temperature and fluid inclusion isochores. The present study demonstrates that both isotopic and thermodynamic methods applied to clay minerals formed in thrust fault are useful to help constrain diagenetic and low-grade metamorphic conditions.

  18. Formation mechanisms and sequence response of authigenic grain-coating chlorite: evidence from the Upper Triassic Xujiahe Formation in the southern Sichuan Basin, China

    Directory of Open Access Journals (Sweden)

    Yu Yu


    Full Text Available Abstract Authigenic grain-coating chlorite is widely distributed in the clastic rocks of many sedimentary basins around the world. These iron minerals were mainly derived from flocculent precipitates formed when rivers flow into the ocean, especially in deltaic environments with high hydrodynamic conditions. At the same time, sandstone sequences with grain-coating chlorites also tend to have relatively high glauconite and pyrite content. EPMA composition analysis shows that glauconites with “high Al and low Fe” content indicate slightly to semi-saline marine environments with weak alkaline and weakly reducing conditions. By analyzing the chlorite-containing sandstone bodies of the southern Sichuan Xujiahe Formation, this study found that chlorite was mainly distributed in sedimentary microfacies, including underwater distributary channels, distributary channels, shallow lake sandstone dams, and mouth bars. Chlorite had a tendency to form in the upper parts of sandstone bodies with signs of increased base level, representing the influence of marine (lacustrine transgression. This is believed to be influenced by megamonsoons in the Middle and Upper Yangtze Region during the Late Triassic Epoch. During periods of abundant precipitation, river discharges increased and more Fe particulates flowed into the ocean (lake. In the meantime, increases or decreases in lake level were only affected by precipitation for short periods of time. The sedimentary environment shifted from weakly oxidizing to weak alkaline, weakly reducing conditions as sea level increased, and Fe-rich minerals as authigenic chlorite and glauconite began to form and deposit.

  19. 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


    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.

  20. The origin of copiapite from chlorite pyritic schist (Wiesciszowice, Lower Silesia, Poland) in the light of Moessbauer analysis

    Energy Technology Data Exchange (ETDEWEB)

    Adamczyk, Z., E-mail: [Silesian University of Technology, Institute of Applied Geology (Poland); Komraus, J. L., E-mail: [University of Silesia, Institute of Physics (Poland)


    This work presents the results of the analysis of copiapite, formed from weathering and oxidation of pyrite in pyritic schist from Wiesciszowice, Lower Silesia (Poland). The pure phase of copiapite was found in secondary minerals after pyrite and identified by optical microscopy, XRD and Moessbauer spectroscopy. In the analyzed copiapite major cations appear to be Fe{sup 2+} and Fe{sup 3+}. Some Fe{sup 3+} is substituted by other cations, mainly Al{sup 3+}. Al{sup 3+} probably comes from leaching of chlorite from which hydrated sulphates of iron, mainly szomolnokite, form followed by hydrated sulphates fibroferrite, which is replaced by copiapite.

  1. Chlorite, Biotite, Illite, Muscovite, and Feldspar Dissolution Kinetics at Variable pH and Temperatures up to 280 C

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Smith, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Lammers, K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)


    Summary Sheet silicates and clays are ubiquitous in geothermal environments. Their dissolution is of interest because this process contributes to scaling reactions along fluid pathways and alteration of fracture surfaces, which could affect reservoir permeability. In order to better predict the geochemical impacts on long-term performance of engineered geothermal systems, we have measured chlorite, biotite, illite, and muscovite dissolution and developed generalized kinetic rate laws that are applicable over an expanded range of solution pH and temperature for each mineral. This report summarizes the rate equations for layered silicates where data were lacking for geothermal systems.

  2. Succession of Permian and Mesozoic metasomatic events in the eastern Pyrenees with emphasis on the Trimouns talc-chlorite deposit (United States)

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


    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.

  3. Impact of Acidified Sodium Chlorite and Enzyme Treatment on the Microbial Load and Energy Bioavailability of Feedstuffs

    Directory of Open Access Journals (Sweden)

    Thakur R


    Full Text Available The presence of microbial load and high fiber content in various non conventional feedstuffs limit their utilization in poultry feed. In the present study, the feedstuffs were treated with acidified sodium chlorite (ASC and its impact on  the microbial load and metabolizable energy availability was assessed in  the chickens. The effect of supplementation of feed grade enzyme was also evaluated either alone or in combination with ASC treatment.  ASC was prepared by adding citric acid to an aqueous solution of sodium chlorite (625 g/liter. The sanitizing effect of ASC was assessed at  0,  100,  250 and  500 ppm levels in  the meat cum bone meal (MBM and sunflower meal (SFM, while its impact on  the energy bioavailability from SFM and de-oiled rice bran (DORB was assessed  at  0, 100 and  250 ppm levels with (0.3  g/kg and without exogenous enzyme supplementation.  The results revealed that  ASC treatment was effective in reducing  the  microbial load in MBM and SFM. Regarding  the metabolizable energy availability, ASC treatment produced appreciable improvement both in SFM and DORB, while enzyme supplementation was effective only with SFM. It may be concluded that ASC treatment has a sanitizing effect and improves the energy bioavailability from feed ingredients like SFM and DORB in the chicken.

  4. Effectiveness of acidified sodium chlorite and other sanitizers to control Escherichia coli O157:H7 on tomato surfaces. (United States)

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


    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.

  5. Multiple hydrothermal and metamorphic events in the Kidd Creek volcanogenic massive sulphide deposit, Timmins, Ontario: evidence from tourmalines and chlorites (United States)

    Slack, J.F.; Coad, P.R.


    The tourmalines and chlorites record a series of multiple hydrothermal and metamorphic events. Paragenetic studies suggest that tourmaline was deposited during several discrete stages of mineralization, as evidence by brecciation and cross-cutting relationships. Most of the tourmalines have two concentric growth zones defined by different colours (green, brown, blue, yellow). Some tourmalines also display pale discordant rims that cross-cut and embay the inner growth zones and polycrystalline, multiple-extinction domains. Late sulphide veinlets (chalcopyrite, pyrrhotite) transect the inner growth zones and pale discordant rims of many crystals. The concentric growth zones are interpreted as primary features developed by the main ore-forming hydrothermal system, whereas the discordant rims, polycrystalline domains, and cross-cutting sulphide veinlets reflect post-ore metamorphic processes. Variations in mineral proportions and mineral chemistry within the deposit mainly depend on fluctuations in temperature, pH, water/rock ratios, and amounts of entrained seawater. -from Authors

  6. Comparison of the effects of chlorite-oxidized oxyamylose and polyacrylic acid on the multiplication of phytopathogenic viruses. (United States)

    Kluge, S


    Polyacrylic acid (PAA) and chlorite-oxidized oxyamylose (COAM) inhibit the multiplication of tobacco mosaic virus (TMV) in leaf disks by up to 50%. The reduction in TMV content is time-dependent and decreases with longer time intervals between the virus infection and the application of substances. The multiplication of potato virus X (PVX) in leaf disks is not affected by either PAA or COAM. In intact plants PAA produces a strong antiviral effect on both PVX and red clover mottle virus (RCMV). The effect produced by COAM is much less pronounced, although this substance is less toxic and could be used in a higher concentration than PAA. Neither of these compounds has a significant influence on the development of virus-induced necroses in Nicotiana glutinosa, Gomphrena globosa or Phaseolus vulgaris plants when administered one day before or after virus infection.

  7. Reverse osmosis membrane composition, structure and performance modification by bisulphite, iron(III), bromide and chlorite exposure. (United States)

    Ferrer, O; Gibert, O; Cortina, J L


    Reverse osmosis (RO) membrane exposure to bisulphite, chlorite, bromide and iron(III) was assessed in terms of membrane composition, structure and performance. Membrane composition was determined by Rutherford backscattering spectrometry (RBS) and membrane performance was assessed by water and chloride permeation, using a modified version of the solution-diffusion model. Iron(III) dosage in presence of bisulphite led to an autooxidation of the latter, probably generating free radicals which damaged the membrane. It comprised a significant raise in chloride passage (chloride permeation coefficient increased 5.3-5.1 fold compared to the virgin membrane under the conditions studied) rapidly. No major differences in terms of water permeability and membrane composition were observed. Nevertheless, an increase in the size of the network pores, and a raise in the fraction of aggregate pores of the polyamide (PA) layer were identified, but no amide bond cleavage was observed. These structural changes were therefore, in accordance with the transport properties observed.

  8. Disinfection by-products of chlorine dioxide (chlorite, chlorate, and trihalomethanes): Occurrence in drinking water in Qatar. (United States)

    Al-Otoum, Fatima; Al-Ghouti, Mohammad A; Ahmed, Talaat A; Abu-Dieyeh, Mohammed; Ali, Mohammed


    The occurrence of chlorine dioxide (ClO2) disinfection by-products (DBPs) in drinking water, namely, chlorite, chlorate, and trihalomethanes (THMs), was investigated. Two-hundred-ninety-four drinking water samples were collected from seven desalination plants (DPs), four reservoirs (R), and eight mosques (M) distributed within various locations in southern and northern Qatar. The ClO2 concentration levels ranged from 0.38 to <0.02 mg L(-1), with mean values of 0.17, 0.12, and 0.04 mg L(-1) for the DPs, Rs, and Ms, respectively. The chlorite levels varied from 13 μg L(-1) to 440 μg L(-1), with median values varying from 13 to 230 μg L(-1), 77-320 μg L(-1), and 85-440 μg L(-1) for the DPs, Rs, and Ms, respectively. The chlorate levels varied from 11 μg L(-1) to 280 μg L(-1), with mean values varying from 36 to 280 μg L(-1), 11-200 μg L(-1), and 11-150 μg L(-1) in the DPs, Rs, and Ms, respectively. The average concentration of THMs was 5 μg L(-1), and the maximum value reached 77 μg L(-1) However, all of the DBP concentrations fell within the range of the regulatory limits set by GSO 149/2009, the World Health Organization (WHO), and Kahramaa (KM).

  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


    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. Efficacy of sodium hypochlorite and acidified sodium chlorite in preventing browning and microbial growth on fresh-cut produce. (United States)

    Sun, Shih Hui; Kim, Su Jin; Kwak, Soo Jin; Yoon, Ki Sun


    The use of suitable sanitizers can increase the quality of fresh-cut produce and reduce the risk of foodborne illnesses. The objective of this study was to compare the washing effects of 100 mg/L sodium hypochlorite (SH) and 500 mg/L acidified sodium chlorite (ASC) on the prevention of enzymatic browning and the growth of microbial populations, including aerobic plate counts, E. coli, and coliforms, throughout storage at 4°C and 10°C. Fresh-cut zucchini, cucumbers, green bell peppers, and root vegetables such as potatoes, sweet potatoes, carrots, and radishes were used. Compared to SH washing, ASC washing significantly (pfresh-cut produce and prevented browning of fresh-cut potatoes and sweet potatoes during storage. More effective inhibition of aerobic plate counts and coliforms growth was observed on fresh-cut produce treated with ASC during storage at 10°C. Polyphenol oxidase (PPO) activity of fresh-cut potatoes and sweet potatoes was more effectively inhibited after washing with ASC. The use of 500 mg/L ASC can provide effective antimicrobial and anti-browning treatments of fresh-cut produce, including processed root vegetables.

  11. Slaughterfloor decontamination of pork carcases with hot water or acidified sodium chlorite - a comparison in two Australian abattoirs. (United States)

    Hamilton, D; Holds, G; Lorimer, M; Kiermeier, A; Kidd, C; Slade, J; Pointon, A


    A decontamination trial on the effectiveness of hot water or acidified sodium chlorite (SANOVA) treatment on Salmonella spp., Escherichia coli and Total Viable Count (TVC) was undertaken on pork carcases prior to primary chilling in two large pork abattoirs in Australia using belly-strip excision sampling. A total of 123 samples from Abattoir A and 400 samples from Abattoir B were cultured and analysed. Test pigs were selected from herds with a known high level of on-farm Salmonella infection. At Abattoir A, Salmonella spp. were not isolated from carcases. The prevalence of E. coli on control carcases was 92.9% compared with 9.8% for hot water and 12.5% for SANOVA treated carcases. The mean log(10) E. coli concentration for control carcases was 0.89 cfu/gram, compared with -0.83 cfu/gram from hot water and -0.75 cfu/gram from SANOVA treated carcases. The mean log(10) TVC for control carcases was 4.06 compared with 1.81 cfu/gram for hot water and 2.76 cfu/gram for SANOVA treated carcases. At Abattoir B, the prevalence of Salmonella on control carcases was 16% compared with 2.7% for hot water and 7.0% for SANOVA treated carcases. The prevalence of E. coli on control carcases was 69.3% compared with 22% for hot water and 30% for SANOVA treated carcases. The mean log(10) E. coli concentration for control carcases was 0.45 cfu/gram, compared with -0.65 cfu/gram from hot water and -0.60 cfu/gram from SANOVA treated carcases. The mean log(10) TVC for control carcases was 3.00 cfu/gram compared with 2.10 cfu/gram for hot water and 2.53 cfu/gram for SANOVA treated carcases. The reductions in prevalence and mean log(10) concentrations in the present trial were all found to be statistically significant and indicate that carcases decontamination with either hot water or SANOVA are effective risk management options immediately available to the pork industry.

  12. Coupled Petrological and Geodynamic Models of Mantle Flow in Subduction Zones; the Importance of Chlorite in the Emergence of a Low-Viscosity Channel (United States)

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


    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

  13. Examination of chloritization of biotite as a tool for reconstructing the physicochemical parameters of mineralization and associated alteration in the Zafarghand porphyry copper system, Ardestan, Central Iran: mineral-chemistry and stable isotope analyses (United States)

    Aminroayaei Yamini, Maryam; Tutti, Faramarz; Aminoroayaei Yamini, Mohammad Reza; Ahmadian, Jamshid; Wan, Bo


    The chloritization of biotite and stable isotopes of silicate have been studied for the Zafarghand porphyry copper deposit, Ardestan, Iran. The studied area, in the central part of the Urumieh-Dokhtar magmatic belt, contains porphyry-style Cu mineralization and associated hydrothermal alteration within the Miocene (19-26 Ma, Zircon U-Pb age) granodioritc stock and adjacent andesitic to rhyodacitic volcanic rocks (ca. 56 Ma, zircon U-Pb age). The primary and secondary biotite that formed during potassic alteration in this porphyry and these volcanic host rocks are variably chloritized. Chloritization of biotite pseudomorphically is characterized by an increase in MgO, FeOt, and MnO, with decreasing in SiO2, K2O, and TiO2. Based on the Ti-in-biotite geothermometer of Henry et al. (Am Mineral 90:316-328, 2005) and Al-in-chlorite geothermometer of Cathelineau (Clay Miner 23:417-485, 1988), crystallization temperatures of primary biotite representative of magmatic conditions and later chloritization temperature range from 617° to 675 °C ± 24 °C and 177° to 346 °C, respectively. Calculated isotopic compositions of fluids that chloritized primary and secondary biotite display isotopic compositions of 1.1 to 1.7 per mil for δ18O and -19.9 to -20.5 per mil for δD consistent with meteoric water. Sericite, barren, and A-type-quartz veins from phyllic alteration were produced by mixed magmatic and meteoric water with δ18O values from -2.8 to 2.5 and δD values of ˜ -23 per mil; the narrow range of δD values of the propylitic epidote may be due to a meteoric water with δ18O values from 0.8 to 1.6 and δD values from -14.6 to -16.9 per mil.

  14. Major, trace and REE geochemistry in contrasted chlorite schist weathering profiles from southern Cameroon: Influence of the Nyong and Dja Rivers water table fluctuations in geochemical evolution processes (United States)

    Onana, Vincent Laurent; Ntouala, Roger Firmin Donald; Tang, Sylvie Noa; Effoudou, Estelle Ndome; Kamgang, Veronique Kabeyene; Ekodeck, Georges Emmanuel


    Three weathering profiles developed on chlorite schists, formations on which little studies have been conducted, were chosen to understand the weathering processes prevailing downslope in Southern Cameroon. The materials nearest to Nyong River at Ayos weather under the influence of the fluctuations of groundwater table and acid rain, while those from Bengbis and Mbalmayo weather under the influence of acid rain. The result is the thickening of materials and weathering profiles, without formation of a nodular ferruginous horizon at Ayos. The Ayos weathered materials (CIA ∼ 92) are the most altered and the least lateritised (IOL ∼ 32). The most stable systems are Hf - U - Nb - Ti - Zr - Mo - W (Bengbis), Yb - U - Nb - Ti - Zr - Hf - Mo - W - Th (Mbalmayo) and Th - Nb - Zr - Hf - Mo - Ta (Ayos). Molybdenum accumulations are important in the studied materials. Uranium accumulations are found only in Mbalmayo. Coarse saprolitic materials at Ayos are the most depleted and fractionated in REE ((La/Yb)N = 0.07, Ce/Ce* = 2.24), while superficial clayey materials are less fractionated. This process is reversed at Bengbis and Mbalmayo. By contrast, weathered materials at Ayos do not show any Eu anomalies (as in Bengbis and Mbalmayo). Weathered materials from Bengbis, nearest to the Dja River, have (La/Yb)N < 1 ratios, indicating the relative immobility of HREE relative to LREE due to xenotime abnormally rich in HREE (HREE-PO4). Weak Ce anomalies (1.05-2.24) are ubiquitous in all the studied materials.

  15. Study on abatement of chlorite in drinking water pipe network in north city%北方某城市饮用水管网中亚氯酸盐调查

    Institute of Scientific and Technical Information of China (English)

    李妍; 崔崇威; 许铁夫


    为保证饮用水给水管网的水质安全,通过现场实验对以二氧化氯为惟一消毒剂的典型管网进行连续试验检测,获得实际管网的二氧化氯消毒副产物亚氯酸盐和氯酸盐的变化规律并对其影响因素进行分析.结果表明,氯酸盐在实际管网中的量均小于0.05 mg/L,而亚氯酸盐在连接管、转弯管和支管的质量浓度分布明显偏低,说明实际管网中的管垢和流速是影响亚氯酸盐质量浓度变化的关键因素.实际管网内二氧化氯消毒副产物的调查分析对消毒剂的安全使用以及饮用水品质的提高具有重要意义.%This paper was designed to study the concentration of chlorite and elucidate the factors on concentration of chlorite in drinking water pipe network disinfected by chlorine di -oxide.The result showed that the lowest concentration of chlorite was connecting tube , elbow tube and branch in drinking water pipe network .The most important impact on chlorite was pipe sordes and flow rate .The transformation of chlorine dioxide disinfection byproducts in pipe network considered drinking water from safe to health play an important role .

  16. Simultaneous determination of bromate, chlorite and haloacetic acids by two-dimensional matrix elimination ion chromatography with coupled conventional and capillary columns. (United States)

    Teh, Hui Boon; Li, Sam Fong Yau


    A new, highly sensitive and reliable two-dimensional matrix elimination ion chromatography (IC) method was developed for simultaneous detection of bromate, chlorite and five haloacetic acids. This method combined the conventional IC in first dimension with capillary IC in the second dimension coupled with suppressed conductivity detection. The first dimension utilizes a high capacity column to partially resolve matrix from target analytes. By optimizing the cut window, the target analytes were selectively cut and trapped in a trap column through the use of a six-port valve, while the separated matrix were diverted to waste. The trapped target analytes were delivered on to the capillary column for further separation and detection. Temperature programming was used to improve selectivity in second dimension column to obtain complete resolution of the target analytes. Compared to the performance of one-dimensional IC, the two-dimensional approach resulted in a significant increase in sensitivity for all target analytes with limit of detection ranging from 0.30 to 0.64μg/L and provided more reliable analysis due to second column confirmation. Good linearity was obtained for all the target analytes with correlation coefficients >0.998. The proposed method was successfully applied to the determination of oxyhalides and haloacetic acids in various matrices with recoveries ranging from 90 to 116% and RSD less than 6.1%. The method allows direct injection of samples and the use of columns with different selectivity, thus significantly reduces the level of false positive results. The method is fully automated and simple, making it practical for routine monitoring of water quality. The satisfactory results also demonstrated that the two-dimensional matrix elimination method coupled with capillary IC is a promising approach for detection of trace substances in complex matrices.

  17. Ion chromatographic determination of trace iodate, chlorite, chlorate, bromide, bromate and nitrite in drinking water using suppressed conductivity detection and visible detection. (United States)

    Binghui, Zhu; Zhixiong, Zhong; Jing, Yao


    An ion chromatography method for the simultaneous determination of trace iodate, chlorite, chlorate, bromide, bromate and nitrite in drinking water has been developed using an anion-exchange column and the suppressed conductivity detector, followed by post-column addition of reagent to enhance visible absorbance detection of ions. A high capacity anion exchange Ion Pac9-HC column (250 mm x 4 mm I.D.) was used. Eight millimole per liter sodium carbonate was used as eluent, an auto-suppression external water mode was selected, 0.5 g/l o-dianisidine.2HCl (ODA)+4.5 g/l KBr+25% methanel+5.6% nitric acid was used as post-column reagent. The post-column reaction (PCR) temperature was at 60 degrees C, and the visible absorbance detected wavelength at 450 nm. The sample's pH and coexist anions had no influence on determination. The method enjoyed a wide linear range and a good linear correlation coefficient (r>0.999). The method detection limits were between 0.023 and 2.0 microg/l. The average recoveries ranged from 87.5 to 110.0%, and the relative standard deviations (RSD) were in the range of 1.1-4.6%. The analytical results by the method of post-column addition of reagent to enhance visible absorbance detection of anions was compared with that of the suppressed conductivity detection, and the former was proved to be better in sensitivity and selectivity. The results showed that this method was accurate, sensitive and might be good for application and suitable for trace analysis at the level of mug/l.

  18. Hydrothermal alteration at the Roosevelt Hot Springs Thermal Area, Utah: modal mineralogy, and geochemistry of sericite, chlorite, and feldspar from altered rocks, Thermal Power Company well Utah State 14-2

    Energy Technology Data Exchange (ETDEWEB)

    Ballantyne, J.M.


    Sericites, chlorites, feldspars, biotite and hornblende from hydrothermally altered rocks at several depths in Thermal Power Company well Utah State 14-2, Roosevelt Hot Springs Thermal Area, Utah, have been analyzed using the electron microprobe. Sericites and ferromagnesian minerals have been analyzed for 12 major elements, and feldspars for 3. The results have been used, along with whole rock chemical analyses, to computer calculate modal mineralogy for samples from the drillhole. Calculated modes for hydrothermal minerals are in reasonable agreement with observations from thin sections.

  19. Algal toxicity of the alternative disinfectants performic acid (PFA), peracetic acid (PAA), chlorine dioxide (ClO2) and their by-products hydrogen peroxide (H2O2) and chlorite (ClO2(-)). (United States)

    Chhetri, Ravi Kumar; Baun, Anders; Andersen, Henrik Rasmus


    Environmental effect evaluation of disinfection of combined sewer overflow events with alternative chemical disinfectants requires that the environmental toxicity of the disinfectants and the main by-products of their use are known. Many disinfectants degrade quickly in water which should be included in the evaluation of both their toxicity as determined in standardized tests and their possible negative effect in the water environment. Here we evaluated according to the standardized ISO 8692 test the toxicity towards the green microalgae, Pseudokirchneriella subcapitata, of three disinfectants: performic acid (PFA), peracetic acid (PAA) and chlorine dioxide (ClO2) as well as two by-products of their use: hydrogen peroxide (H2O2) and chlorite. All of the five chemicals investigated showed clear toxicity to the algae with well-defined dose response curves. The EC50 values ranged from 0.16 to 2.9mg/L based on nominal concentrations leading to the labeling of the chemicals as either toxic or very toxic. The five investigated chemicals decreased in toxicity in the order chlorine dioxide, performic acid, peracetic acid, chlorite and hydrogen peroxide. The stability of the chemicals increased in the same order as the toxicity decrease. This indicates that even though ClO2 has the highest environmental hazard potential, it may still be suitable as an alternative disinfectant due to its rapid degradation in water.

  20. 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:, E-mail:, E-mail:, E-mail: [Observatorio Nacional do Brasil (COGE/ON), Rio de Janeiro, RJ (Brazil). Coordenacao de Geofisica


    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)

  1. 饮用水中的亚氯酸盐、氯酸盐和溴酸盐的离子色谱测定法%Determination of Chlorite ,Chlorate and Bromate in Drinking Water by Ion Chromatography

    Institute of Scientific and Technical Information of China (English)

    周虹; 周小新


    Objective To develop an ion chromatography (IC) for simultaneous determination of chlorite, chlorate and bromate in drinking water. Methods The IC separation was carried out with the IonPAC AS23 column by using 4.5 mmol/L Na_2CO_3-0.8 mmol/L NaHCO_3 at the flow rate of 1.0 ml/min. The injection volume was 250 μl.the temperature of conductivity detector cell and column were 30 ℃ and 35 ℃, respectively. The pressure upon the bottle of mobile phase was 40 kPa. The current of auto-regenerating suppressor was 25 mA. Results The results showed that in the range of 0 to 1 000 mg/L, the calibration equation for chlorite was y=0.009 6+1.600 0 x (r=0.999 3),for bromate was y=0.003 2+3.184 7 x (r=0.999 9),for chlorate was y= 0.001 8+1.788 9 x(r=0.999 9).The detection limit of chlorite,chlorate and bromate were all 5 μg/ L,the recovery rates were 89.0% -108.0% and the relative standard deviations (RSD) were 0.21%-2.70%. Conclusion The method is simple,fast,accurate, sensitive, little interference and is applicable to the simultaneous determination of chlorite, chlorate and bromate in drinking water.%目的 建立同时测定饮用水中亚氯酸盐、氯酸盐和溴酸盐的离子色谱法.方法 选择IonPacAS23色谱柱,淋洗液为4.5mmol/L Na_2CO_3-0.8 mmol/L NaHCO_3,流速为1.0 ml/min,进样量为250 μl,电导检测池温度为30℃,色谱柱温度为35 ℃,流动相瓶加压为40 kPa,抑制器抑制模式为自动再生模式,抑制器电流为25 mA.结果 在0~1 000.0 mg/L范围内,亚氯酸盐的线性方程为:y=0.009 6+1.600 0x,r=0.999 3,检出限为5μg/L;溴酸盐的线性方程为:y=0.003 2+3.184 7x,r=0.999 9,检出限为5μg/L;氯酸盐的线性方程为:y=0.001 8+1.788 9x,r=0.999 9,检出限为5μg/L.加标回收试验结果显示,该方法的平均回收率为89.0%~108.0%,RSD为0.21%~2.70%.结论 该法操作简单、快速、准确,灵敏度高、干扰少,适用于饮用水中亚氯酸盐、氯酸盐和溴酸盐的同时测定.

  2. Production and stability of chlorine dioxide in organic acid solutions as affected by pH, type of acid, and concentration of sodium chlorite, and its effectiveness in inactivating Bacillus cereus spores. (United States)

    Kim, Hoikyung; Kang, Youngjee; Beuchat, Larry R; Ryu, Jee-Hoon


    We studied the production and stability of chlorine dioxide (ClO(2)) in organic acid solutions and its effectiveness in killing Bacillus cereus spores. Sodium chlorite (5000, 10,000, or 50,000 microg/ml) was added to 5% acetic, citric, or lactic acid solution, adjusted to pH 3.0, 4.0, 5.0, or 6.0, and held at 21 degrees C for up to 14 days. The amount of ClO(2) produced was higher as the concentration of sodium chlorite was increased and as the pH of the acid solutions was decreased. However, the stability in production of ClO(2) was enhanced by increasing the pH of the organic acid solutions. To evaluate the lethal activity of ClO(2) produced in various acid solutions as affected by acidulant and pH, suspensions of B. cereus spores were treated at 21 degrees C for 1, 3, 5, or 10 min in hydrochloric acid or organic acid solutions (pH 3.0, 4.0, 5.0, or 6.0) containing ClO(2) at concentrations of 100, 50, or 25 microg/ml. Populations of viable spores treated with ClO(2) at concentrations of 100 or 50 microg/ml in organic acid solutions decreased more rapidly than populations treated with the same concentrations of ClO(2) in HCl. Rates of inactivation tended to increase with higher pH of ClO(2) solutions. Results show that ClO(2) formed in organic acid solutions has higher stability and is more lethal to B. cereus spores than ClO(2) formed at the same concentration in HCl solution. This finding emphasizes the benefits of using organic acid solutions to prepare ClO(2) intended for use as an antimicrobial.

  3. Algal toxicity of the alternative disinfectants performic acid (PFA), peracetic acid (PAA), chlorine dioxide (ClO2) and their by-products hydrogen peroxide (H2O2) and chlorite (ClO2-)

    DEFF Research Database (Denmark)

    Chhetri, Ravi Kumar; Baun, Anders; Andersen, Henrik Rasmus


    : performic acid (PFA), peracetic acid (PAA) and chlorine dioxide (ClO2) as well as two by-products of their use: hydrogen peroxide (H2O2) and chlorite. All of the five chemicals investigated showed clear toxicity to the algae with well-defined dose response curves. The EC50 values ranged from 0.16 to 2.9 mg...

  4. 生活饮用水中溴酸盐、氯酸盐和亚氯酸盐的离子色谱测定法%Determination of bromate, chlorate, and chlorite in drinking water by ion chromatography

    Institute of Scientific and Technical Information of China (English)

    孙卫明; 孙建飞; 王权帅


    [ Objective ] To establish a method for determination of bromate, chlorate, and chlorite in drinking water by ion chroma-tography. [ Methods] ] After filtration by 0.22 μm membrane filter, The water samples were put into the ion exchange system of ion chromatography, with the potassium hydroxide eluent. Different ions separated with the different affinity in one separation column and determined quantitatively by the external standard method. [ Results] Recoveries of bromate were 87.5% to 116.0% , and the relative standard deviation (RSD) was 69% ; recoveries of chlorate were 86. 8% to 99.0% , with RSD of 1. 21% ; recoveries of chlorite of 80.1% to 87.0% , with the RSD of 0.93% and the correlation coefficients of all 3 ions were r >0.999 0. [ Conclusion] This method is simple, rapid, can obtain satisfactory separation, with high sensitivity and precision. Also, the recovery meets the methodological requirements. Above all, this method is entirely suitable for the simultaneous determination of bromate, chlorate, and chlorite in drinking water.%目的 建立离子色谱法测定生活饮用水中有溴酸盐、氯酸盐、亚氯酸盐的检测方法.方法 水样经0.22 μm滤膜过滤后,随氢氧化钾淋洗液进入离子色谱的离子交换系统.根据分离柱对不同离子的亲和力不同进行分离,外标法定量.结果 溴酸盐回收率为87.5% ~ 116.0%,相对标准偏差为2.69%;氯酸盐回收率为86.8%~ 99.0%,相对标准偏差为1.21%;亚氯酸盐回收率为80.1% ~ 87.0%,相对标准偏差为0.93%.以上3个项目相关系数均大于0.999 0.结论 该方法检测速度快,样品处理简便,能获得满意的分离效果,具有较高的灵敏度和精密度,回收率也满足方法学要求,完全适合于生活饮用水中有溴酸盐、氯酸盐、亚氯酸盐的同时测定.

  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

    Energy Technology Data Exchange (ETDEWEB)

    Malmstroem, M.; Banwart, S. [Royal Inst. of Technology, Stockholm (Sweden). Dept. of Inorganic Chemistry; Duro, L. [Universidad Politecnica de Cataluna, Barcelona (Spain). Dept. de Ingneria Quimica; Wersin, P.; Bruno, J. [MBT Technologia Ambiental, Cerdanyola (Spain)


    We have studied the kinetics and thermodynamics of biotite and chlorite weathering in the pH range 2

  6. Determination of Chlorite, Bromate, Chlorate in Surface Water and Drinking Water by Ion Chromatography%离子色谱法测定地表水和饮用水中亚氯酸盐、溴酸盐和氯酸盐

    Institute of Scientific and Technical Information of China (English)

    窦艳艳; 杨丽莉; 徐荣; 胡恩宇


    采用KOH梯度淋洗离子色谱法测定地表水和饮用水中ClO2-、BrO3-和ClO3-,在试验确定的条件下,3种离子与F-、Cl-、NO2-、NO3-、SO2-4、Br-、I-等7种离子分离度良好。 ClO2-、BrO3-、ClO3-在50.0μg/L~1000μg/L范围内线性良好,检出限分别为5.2μg/L、8.9μg/L、7.6μg/L,环境水样加标平行测定的RSD分别为2.1%~5.4%、4.1%~5.4%、2.5%~4.8%,两个质量浓度水平加标的平均回收率分别为93.7%~96.5%、90.3%~94.8%、98.7%~111%。%An ion chromatography method for determining chlorite , bromate and chlorate in surface water and drinking water was studied .The separation of the anions was achieved on an IonPac AS 19 Column with KOH as eluent, the chlorite, bromate, chlorate and other 7 kinds of anions could be well separated and determined within 25 min by employing a concentration gradient .The method has good linearity during the concentration 50.0 μg/L ~1 000 μg/L.The method detection limits of chlorite, bromate and chlorate was 5.2 μg/L, 8.9 μg/L and 7.6 μg/L, respectively.The RSD of the samples were 2.1%~5.4% ( chlorite), 4.1%~5.4%(bromate), and 2.5%~4.8% (chlorate).The recoveries of chlorite, bromate and chlorate in water samples were 93.7%~96.5%, 90.3%~94.8%and 98.7%~111%.

  7. 亚氯酸钠对烤烟酶促棕色化反应及烟叶质量的影响%Effects of sodium chlorite on enzymatic browning reaction and curing quality of flue-cured tobacco

    Institute of Scientific and Technical Information of China (English)

    任杰; 李雨江; 包可翔; 赖成连; 冷平; 孙福山


    In order to study the effects of sodium chlorite(SC) on enzyme browning reaction and curing quality,the PPO activity,polyphenol content,chemical composition,smoking quality and economic characters of cured leaves of K326 were investigated.The results indicated that changes of PPO activity of tobacco leaves treated with SC and the control tobacco leaves were similar,but PPO activity of tobacco leaves treated with SC was lower than control tobacco leaves.The scopoletin and chlorogenic acid contents of middle leaves treated with SC were higher than the control leaves,but there was no significant difference of total polyphenol contents between SC treated and the control leaves.The chlorogenic acid,neochlorogenic acid,cryptochlorogenic acid,rutin and total polyphenol contents were higher than the control leaves.SC increased the chlorine and reducing sugar contents obviously,and made the chemical composition more coordinated.SC improved the smoking quality slightly,and increased the economic characters obviously.In conclusion,SC inhibited the enzymatic browning reaction and improved curing quality of flue-cured tobacco.%为研究亚氯酸钠(SC)对烤烟烘烤过程中酶促棕色化反应及烟叶烘烤质量的影响,以K326为试验材料,通过烘烤试验分析了SC对烤烟烘烤过程中多酚氧化酶(PPO)活性、烤后烟叶多酚含量、常规化学成分、感官质量及经济性状的影响。结果表明:SC处理和对照烟叶在烘烤过程中多酚氧化酶(PPO)活性变化表现出基本相同的规律,但SC处理烟叶PPO活性均低于同期对照烟叶。SC处理中部叶莨菪亭和绿原酸含量显著高于对照,但多酚总量与对照无显著差异;SC处理上部叶绿原酸、新绿原酸、隐绿原酸、芸香苷、多酚总量均显著高于对照。SC处理显著提高了烤后烟叶的氯含量和还原糖含量,使化学成分更趋协调。SC处理烤后烟叶感官质量较对照有所改善,经济性状较对照显

  8. Ion chromatography for simultaneous determination of bromate,chlorite and chlorate in drinking water%用离子色谱法同时测定生活饮水中溴酸盐、亚氯酸盐、氯酸盐

    Institute of Scientific and Technical Information of China (English)

    齐春华; 张颖; 王化勇


    Objective; To develop an ion chromatography (IC ) for simultaneous determination of chlorite, chlorate and bromate in drinking water. Methods: The IC separation was carried out with the IonPAC AS19 column by using hydroxide eluent at the flow rate of 1.0 ml/min. The injection volume was 500 jxl. Conductivity detection cell temperature was set at 30℃ , column temperature was set at 35℃. Suppressor was in automatic regeneration mode, suppressor current was 87 mA. Results: The results showed that in the range of 0 μg/L to 500 μg/L, the linear e-quation of chlorite was y =2. 640x -0.027, r =0.9999, the detection limit was 0. 1 μg/L; In the range of 0 μg/L ~ 100 μg/L, the linear equation of bromate was y = 1. 342x - 0. 003 , r - 0. 9999 , detection limit was 0. 5 μg/L; In the range of 0 μg/L -500 μg/L, the linear equation of chlorate was y =2. 157x -0. 043 , r -0. 9999, the detection limit was 0.2 μg/L. The recovery rates were 99. 70% ~102.6% and the relative standard deviations (RSD) were 1. 16% ~3.56%. Conclusion; The method is simple,fast,accurate, sensitive, little interference and applicable to the simultaneous determination of chlorite, chlorate and bromate in drinking water.%目的:建立能够同时测定生活饮用水中亚氯酸盐、氯酸盐和溴酸盐的离子色谱法.方法:选择Ion-PacAS19色谱柱,淋洗液为氢氧根淋洗液,流速为1.0 ml/min,进样量为500μl,电导检测池温度为30℃,色谱柱温度为35℃,抑制器抑制模式为自动再生模式,抑制器电流为87 mA.结果:在0μg/L ~ 500.0 μg/L范围内,亚氯酸盐的线性方程为:y=2.640x-0.027,r=0.9999,检出限为0.1 μg/L;在0μg/L ~ 100.0 μg/L溴酸盐的线性方程为:y=1.342x-0.003,r=0.9999,检出限为0.5 μg/L;在0μg/L~500.0 μg/L氯酸盐的线性方程为:y=2.157x-0.043,r=0.9999,检出限为0.2μg/L.加标回收试验结果显示,该方法的平均回收率为99.7% ~102.6%,RSD为1.16% ~3.56%.结论:该法操作简单、快速、准

  9. Simultaneous Determination of Trace Amount of Chlorite,Chlorate and Common Inorganic Anions in Running Water with kOH Isocratic Elution by Ion Chromatographic Method%KOH等度淋洗IC法同时测定自来水中微量ClO2-、ClO3-及常规阴离子

    Institute of Scientific and Technical Information of China (English)

    陈东; 罗倚坪


    The method to determine a trace of chlorite, chlorate and common inorganic anions in running water with KOH isocratic elution by ion chromatography was investigated. The conditions of method was that the concentration of KOH is 20. 5 mmol/L, the flow rate is 1. 0 mL/min, and the injection volume is 50 μL. The results showed that the concentration of F-,Cl-,NO3 -, SO4 2-,ClO2 -,ClO3 - in water was determined completely only in 12 minutes. The correlation coefficients of calibration curve was 0. 997 0-0. 999 9,while the detection limits was between 0. 05-7. 00 μg/L. The relative standard deviation( RSD) and the recoveries were between 0. 61%-3. 82%and 97. 6%-101. 7%, respectively. The method was sensitive, accurate and rapid, which was favorable to simultaneous quantification of chlorite, chlorate and common inorganic anions in drinking water.%建立了KOH等度淋洗离子色谱法同时测定自来水中微量亚氯酸盐、氯酸盐及氟化物、氯化物、硝酸盐、硫酸盐的分析方法。该方法以20.5 mmol/L KOH为淋洗液,流速1.0 mL/min,进样量50μL。结果表明,6种阴离子可在12分钟内检测完毕,各离子的线性相关系数为0.9970~0.9999;检出限为0.05~7.00μg/L;精密度为0.61%~3.82%;回收率为97.6%~101.7%,能够满足饮用水中这些指标的定量需要,是一种灵敏、准确、快速的理想方法。

  10. [Importance of Chlorite P in prevention and treatment in horticulture]. (United States)

    Szymański, J


    The Polish chlorine preparation for prophilaxis and controlling of bacterial blotch in the champignon culture and in order to carry out the general desinfection in champignon houses has been registered. This preparation is useful to general disinfection in greenhouses and other auxiliary spaces instead formalin having the mutagenic and carcinogenic properties.

  11. 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


    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

  12. Transformações químicas, físicas e enzimáticas de goiabas 'PEDRO SATO' tratadas na pós-colheita com cloreto de cálcio e 1-metilciclopropeno e armazenadas sob refrigeração Chemical, physical and enzymatic transformations of guavas 'PEDRO SATO' treated at post-harvest with calcium chlorite and 1-methylciclopropone and stored under refrigeration

    Directory of Open Access Journals (Sweden)

    Lucilia Alves Linhares


    Full Text Available Com o objetivo de estudar o efeito dos tratamentos com cloreto de cálcio e com 1-MCP associando-se a refrigeração, na conservação e qualidade de goiabas 'Pedro Sato', conduziu-se o experimento em que frutos dessa cultivar foram tratados com solução de CaCl2 a 2% por 5 minutos e com 1-MCP na concentração de 150 nL/L por 12 horas em câmara hermeticamente fechada. Após os tratamentos, os frutos foram armazenados em câmara refrigerada a 10ºC e 90 ± 2% de umidade relativa, por um período de 25 dias. Os resultados indicaram que os tratamentos foram efetivos em manter a qualidade da fruta, salientando-se os frutos tratados com 1-MCP, que mantiveram uma melhor aparência interna e externa, apresentaram menor perda de massa, maior firmeza, menor síntese de vitamina C, menor solubilização de pectinas e menor atividade enzimática, aumentando desta forma a vida pós-colheita das goiabas.With the purpose of investigating the effect of the treatments with calcium chlorite and with 1-methylcyclopropene, associated with refrigeration, on the conservation and quality of guavas 'Pedro Sato', the experiment was carried out in which the fruit of thiscultivar was treated with a solution of 2% CaCl2 for 5 minutes and with 1-MCP at the concentration of 150 nL/L for 12 hours in a tightly sealed chamber. After the treatments, the fruit was stored in a refrigerated chamber at 10ºC and 90 ± 2% of relative humidity for a 25-days period. The results pointed out that the treatments were effective in maintaining fruit quality, stressing the 1-MCP-treated fruit, which kept a better internal and external appearance, presented less loss of mass, greater firmness, less synthesis of vitamin C, less pectin and less activity enzymatic activity, increasing in this way the post-harvest life of guavas.

  13. Spectral Classification of Similar Materials using the Tetracorder Algorithm: The Calcite-Epidote-Chlorite Problem (United States)

    Dalton, J. Brad; Bove, Dana; Mladinich, Carol; Clark, Roger; Rockwell, Barnaby; Swayze, Gregg; King, Trude; Church, Stanley


    Recent work on automated spectral classification algorithms has sought to distinguish ever-more similar materials. From modest beginnings separating shade, soil, rock and vegetation to ambitious attempts to discriminate mineral types and specific plant species, the trend seems to be toward using increasingly subtle spectral differences to perform the classification. Rule-based expert systems exploiting the underlying physics of spectroscopy such as the US Geological Society Tetracorder system are now taking advantage of the high spectral resolution and dimensionality of current imaging spectrometer designs to discriminate spectrally similar materials. The current paper details recent efforts to discriminate three minerals having absorptions centered at the same wavelength, with encouraging results.

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

    DEFF Research Database (Denmark)

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


    The emergence, growth and stabilization of stationary concentration patterns in a continuously fed chemical reation-diffusion system are studied through numerical simulation of the Lengyel-Epstein model. Using the supply of iodine as a control paramter, the regularity of the hexagonal patterns...

  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

    To evaluate the possible changes in petrology within the reservoir sand and across the oil water contact in Rau-1A, Siri Canyon Danish North Sea, 18 samples were selected and studied mainly by electron microscope and XRD. The major diagenetic phases in the well are micro quartz, large syntaxial...


    In an effort to determine the viability of various disinfection alternatives, the Evansville, Ind. Water and Sewer Utility is engaged in a pilot-plant investigation to compare chlorine dioxide and ozone pretreatment. As a result of increased speculation that the total residual c...

  17. Influence of Ligand Architecture in Tuning Reaction Bifurcation Pathways for Chlorite Oxidation by Non-Heme Iron Complexes

    NARCIS (Netherlands)

    Barman, Prasenjit; Faponle, Abayomi S; Vardhaman, Anil Kumar; Angelone, Davide; Löhr, Anna-Maria; Browne, Wesley R; Comba, Peter; Sastri, Chivukula V; de Visser, Sam P


    Reaction bifurcation processes are often encountered in the oxidation of substrates by enzymes and generally lead to a mixture of products. One particular bifurcation process that is common in biology relates to electron transfer versus oxygen atom transfer by high-valent iron(IV)-oxo complexes, whi

  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;


    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...

  19. Determination of Chlorine Dioxide, Chlorine, Chlorite and Chlorate in Water by Ion Chromatography%用离子色谱法测定水中的二氧化氯、氯、亚氯酸根及氯酸根

    Institute of Scientific and Technical Information of China (English)

    田芳; 谢家理



  20. ClO2-—I-—MA化学振荡反应体系的研究%Research on Chlorite-Iodide-Malonic Acid Oscillatory Reaction Systems

    Institute of Scientific and Technical Information of China (English)

    王芳; 施来顺


    目的 探讨出封闭反应器中ClO2-—I-—MA化学振荡体系的振荡规律.方法 采用紫外可见分光光度计在I3-的吸收峰(350 nm)处进行时间扫描,从而得到体系中I3-的浓度随时间的变化规律.结果 检测到比率[ClO2-]0/ [I-]0以及MA的浓度对振荡现象的影响.结论 比率[ClO2-]0/ [I-]0对振荡现象的产生有很大的影响,MA的浓度对振荡现象产生与否影响不大.

  1. 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


    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.

  2. Algal toxicity of the alternative disinfectants performic acid (PFA), peracetic acid (PAA), chlorine dioxide (ClO2) and their by-products hydrogen peroxide (H2O2) and chlorite (ClO2-)

    DEFF Research Database (Denmark)

    Chhetri, Ravi Kumar; Baun, Anders; Andersen, Henrik Rasmus


    Environmental effect evaluation of disinfection of combined sewer overflow events with alternative chemical disinfectants requires that the environmental toxicity of the disinfectants and the main by-products of their use are known. Many disinfectants degrade quickly in water which should...... be included in the evaluation of both their toxicity as determined in standardized tests and their possible negative effect in the water environment. Here we evaluated according to the standardized ISO 8692 test the toxicity towards the green microalgae, Pseudokirchneriella subcapitata, of three disinfectants...... in the same order as the toxicity decrease. This indicates that even though ClO2 has the highest environmental hazard potential, it may still be suitable as an alternative disinfectant due to its rapid degradation in water....

  3. 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; 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. Coso: Example of a Complex Geothermal Reservoir. (United States)


    W Early Barren Magnesian Magnesian Chlorite Dellesite (Mg Chlorite) Mid Barren Argillic Argillic Kaolinite Kaolinite Late Barren Silicification...alteration was quite asymmetric, with the argillic alteration strong on the hanging wall, yet quite limited on the footwall as fractures were crossed. A

  5. Chloriet, chloraat en bromaat in drink- en oppervlaktewater: Voorkomen, herkomst en gezondheidsaspecten

    NARCIS (Netherlands)

    Versteegh JFM; Neele J; Cleven RFMJ


    Chlorate and chlorite exist in surface water especially in the rivers Meuse and Rhine. The average concentration of chlorite and chlorate in river water varies from 10 - 40 mug/l during the six months monitoring program in 1991/1992. The concentrations are lowered during dune infiltration and afte


    Among the 11 disinfection by-products (DBPs) in drinking water that are regulated by the U.S. EPA, (a) 2 DBPs (chloroacetic acid and chlorite) are not carcinogenic-in either of 2 species; (b) chlorite is not carcinogenic in 3 rodent assays and has never been tested for genotoxici...

  7. Study on the removal of NOx from simulated flue gas using acidic NaClO2 solution

    Institute of Scientific and Technical Information of China (English)


    The study on the removal of NOx from simulated flue gas has been carried out in lab-scale bubbling reactor using acidic solutions of sodium chlorite. Experiments were performed at various pH values and inlet NO concentrations in absence as well as presence of SO2 gas at 45oC. The effect of SO2 on NO oxidation and NO2 absorption was critically examined. The oxidative ability of sodium chlorite was investigated at different pH values and it was found to be a better oxidant at a pH less than 4. In acidic medium, sodium chlorite decomposed into ClO2 gas, which is believed to participate in NO oxidation as well as in NO2 absorption. A plausible NOx removal mechanism using acidic sodium chlorite solution has been postulated. A maximum NOx removal efficiency of about 81% has been achieved.

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

    Institute of Scientific and Technical Information of China (English)

    Hui Zhou; Chuanqing Zhang; Zhen Li; Dawei Hu; Jing Hou


    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.

  9. Tests of Rock Cores Scott Study Area, Missouri (United States)


    little potassium feldspar is present in these cores. The bulk composition of this rock is quartz, plagio - clase feldspar (near oligoclase), chlorite...rhyolite porphyry, containing quartz and equal amounts of potassium and plagio - clase feldspar. Piece 22 of PC-2 (Figure 4.8) and Piece 22 of DC-5 (Figure...representative of this type. The bulk composition was Plagio - clase, orthoclase, quartz, biotite, and chlorite. About one-third of the pieces of the core

  10. Improved method generates more chlorine dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, R.W.; Kosinski, A.J.; Baker, R.J.


    The addition of acid can greatly improve the chlorine-chlorite process and enhance the use of chlorine dioxide as an alternative to chlorine for disinfection. The process is economical for use in taste and odor control, and for manganese, oxidation. The maximum yield is obtained using no excess chlorine, and the amount of unreacted sodium chlorite and chlorine in the product stream is reduced. (1 diagram, 4 graphs, 9 references)

  11. Development of a Portable Binary Chlorine Dioxide Generator for Decontamination (United States)


    solutions, but the yields do not vary linearly with increasing chlorite concentrations in the > 50 mM range as predicted by the PFR model, and indeed...the PFR model. We considered two dominant factors. First, kinetic saturation can occur if the chlorite concentration is so high that bromine...Cmax) due to physical flow in large spaces and perhaps other side reactions not yet identified. Thus the poor overall fit of the basic PFR model is

  12. Study on mineralization at Jian copper deposit, Fars province, using petrographical and geochemical data

    Directory of Open Access Journals (Sweden)

    Mohamad Ali Rajabzade


    Full Text Available Jian Cu deposit is hosted by Surian volcano-sedimentary complex of Permo-Triassic age on the eastern edge of the Sanandaj-Sirjan metamorphic zone at a distance of 195 km from Shiraz, southwestern Iran. The complex consists mainly of metabasalt, chlorite-quartz schist, chlorite-muscovite schist, mica schist and graphite schist. Pyrite is the most important sulfide and chalcopyrite is the major Cu-bearing mineral occurring as disseminated grains and veinlets in host chlorite-quartz schist and chlorite-muscovite schist. Chondrite-normalized REE pattern of metabasalt with La/LuN=2/9 indicates mantle tholeiitic basalt as the source of metamorphosed igneous rocks. Geochemical data on the metabasalts, especially the content of immobile elements (e.g., Ti and High Field Strength Elements (HFSE (e.g., Zr، Nb and Y, show low degree of partial melting for parental magma with E-MORB affinity. Chloritic, silicification and minor sericitic assemblages are the main alteration types associated with the Jian Cu deposit. The Y/Ho ratio of Cu ores varies from 29.9 to 32.5, indicating the important role of sea water in the mineralizing system. Petrographical and geochemical data indicate that the Jian Cu deposit was formed as volcano-sedimentary hosted massive sulfide. The Ishikawa alteration index (AI in association with chlorite-carbonate-pyrite index (CCP is useful for the geochemical exploration of Cu deposits in the study area.

  13. In Situ Generation of Chlorine Dioxide for Surface Decontamination of Produce. (United States)

    Hwang, Cheng-An; Huang, Lihan; Wu, Vivian Chi-Hua


    Fresh fruits and vegetables are frequently contaminated with bacterial pathogens and implicated in foodborne illnesses. The objective of this study was to develop a unique surface decontamination method for produce using sodium chlorite and an acid in a sequential treatment. The surfaces of cantaloupe rinds, peels of cucumbers, stem scars of grape tomatoes, and leaves of baby spinach were inoculated with Salmonella or Listeria monocytogenes at 5 to 6 log CFU/g, submerged in 1.6 to 4% sodium chlorite solutions for 10 or 30 min, dried for 20 min, and then soaked in 6 mM hydrogen chloride (HCl) for 10 or 30 min and dried for 20 min. Control samples were treated with deionized water, sodium chlorite, HCl, or a premixed solution of sodium chlorite and HCl for comparison. The control treatments reduced the levels of both pathogens on the samples by only 0.3 to 2.9 log CFU/g, whereas the sequential treatment caused significantly higher reductions (P < 0.05) of 5.1 to 5.6 log CFU/g, effectively eliminating the inoculated pathogens. The more effective decontamination resulting from the sequential treatment was attributed to the in situ formation of chlorine dioxide within the plant tissues under the surface by the reaction between sodium chlorite absorbed by the produce and HCl. These results suggest that the sequential use of sodium chlorite and acid is a potentially effective treatment for elimination of foodborne pathogens on produce.

  14. Reorientation mechanisms of phyllosilicates in the mudstone-to-slate transition at Lehigh Gap, Pennsylvania (United States)

    Ho, Nei-Che; Peacor, Donald R.; van der Pluijm, Ben A.


    The mudstone-to-slate transition of the Martinsburg Formation at Lehigh Gap, Pennsylvania, was re-examined using a new transmission-mode X-ray texture goniometer, supplemented by SEM, XRD, and optical studies. Three mesoscopic zones are recognized in the outcrop: (I) mudstone, (II) transition, and (III) slate zone. In the mudstone zone, the mica basal planes are parallel to bedding whereas the preferred orientation of the chlorite basal planes is up to 30° shallower than bedding. The angular difference between chlorite and mica decreases towards the transition zone, becoming subparallel at ca. 50 m from the contact with the overlying Shawangunk Formation. In the transition zone, the preferred orientations of both mica and chlorite are intermediate to bedding and cleavage orientations, which is consistent with mechanical reorientation of phyllosilicates. This is supported by a decrease in March strain with a minimum at ca. 95 m from the contact for both mica and chlorite. SEM observations similarly show the importance of grain rotation in large detrital grains. In the slate zone, both chlorite and mica orientations are parallel to cleavage. Chlorite and mica in the cleavage orientation of the slate zone have high Fe contents, whereas low-Fe mica and Mg > Fe chlorite dominate in the mudstone and transition zone, which indicates that dissolution-neocrystallization is the dominant mechanism in the slate zone. Thus, mechanical rotation of large detrital grains is important in the early stages of cleavage development, with dissolution—neocrystallization occurring at all stages and becoming dominant in the more evolved stages.

  15. Reactions to define the biotite isograd in the Ryoke metamorphic belt, Kii Peninsula, Japan (United States)

    Wang, Ge-Fan; Banno, Shohei; Takeuchi, Keiji


    Two types of biotite isograd are defined in the low-grade metamorphism of the Wazuka area, a Ryoke metamorphic terrain in the Kii Peninsula, Japan. The first, BI1, is defined by the reaction of chlorite+K-feldspar= biotite+muscovite+quartz+H2O that took place in psammitic rocks, and the second, BI2, by the continuous reaction between muscovite, chlorite, biotite and quartz in pelitic rocks. The Fe/Mg ratios of the host rocks do not significantly affect the reactions. From the paragenesis of pelitic and psammitic metamorphic rocks, the following mineral zones were established for this low-pressure regional metamorphic terrain: chlorite, transitional, chlorite-biotite, biotite, and sillimanite. The celadonite content of muscovite solid solution in pelitic rocks decreases systematically with the grade of metamorphism from 38% in the chlorite zone to 11% in the biotite zone. Low pressure does not prohibit muscovite from showing the progressive change of composition, if only rocks with appropriate paragenesis are chosen. A qualitative phase diagram of the AKF system relevant to biotite formation suggests that the higher the pressure of metamorphism, the higher the celadonite content of muscovite at BI1, which is confirmed by comparing the muscovites from the Barrovian and Ryoke metamorphism.

  16. Stratigraphy and mineralogy of a carbonate-hosted gold deposit: Kings Mountain gold mine, NC

    Energy Technology Data Exchange (ETDEWEB)

    Supplee, J.; Lapoint, D.; Feiss, P.G.


    The Kings Mountain Gold Mine, Cleveland Company, North Carolina, is unique in the Appalachians in that it is carbonate-hosted, with a distinctive ore mineralogy. The mine stratigraphy is upright, younging east to west. The basal unit is a volcanic to subvolcanic chlorite, feldspar, quartz-eye porphyry, cut by a silicic porphyry, interpreted as a shallow level intrusion. Above and gradational to the chloritic porphyry, unless separated by the intrusive silicic porphyry, is a sericitic, quartz-eye porphyry, probably a metatuff. A north-thinning, graphite schists is above the sericitic porphyry. Carbonates overlie the graphite schist except to the north where they are above the sericitic porphyry. The carbonates consist of basal and upper sequences separated by a sericite, quartz-eye schists (metatuff) which is capped by a chlorite-sericite-graphite schist. Mineralization occurs within each carbonate sequence. This is overlain by interbedded chlorite and graphite schists with two horizons of exhalative iron formation (I.F.). Above the I.F. is a thick sequence of sericitic chlorite schists (turbidites). The mineralized carbonates are pervasively silicified with a disseminated assemblage of pyrite, pyrrhotite, sphalerite, chalcopyrite, galena, gold, altaite (PbTe), tetrahedrite, and pyrargyrite in quartz and dolomite +/- fluorite gangue. We suggest that the mineralization is associated with hydrothermal activity during emplacement of the silicic porphyry and following carbonate diagenesis. Mineralization was syn- or post-depositional with respect to the I.F.

  17. Evaluation of Disinfectants Used in Pre-Chilling water Tanks of Poultry Processing Plants

    Directory of Open Access Journals (Sweden)

    BHL Guastalli

    Full Text Available ABSTRACT In poultry processing plants, disinfectants are often added to pre-chilling water tanks to reduce microbial contamination. The present study aimed at evaluating the effect of five disinfectants (acidified sodium chlorite, alkyl dimethyl benzyl ammonium chloride, chlorine dioxide, peracetic acid, and sodium hypochlorite on the populations of food quality indicator microorganisms and on Salmonella Enteritidis (SE in the presence and absence of organic matter. The results showed that chlorine dioxide and sodium hypochlorite did not reduce microbial carcass counts. On the other hand, acidified sodium chlorite, alkyl dimethyl benzyl ammonium chloride and peracetic acid reduced total and fecal coliform counts. Peracetic acid reduced the number of psychrotrophic microorganisms. All products were effective in reducing SE counts only in the absence of organic matter. Acidified sodium chlorite, alkyl dimethyl benzyl ammonium chloride and peracetic acid could be candidates for the replacement of sodium hypochlorite (commonly used in Brazil in pre-chilling tanks.

  18. Hydrothermal Alteration in the PACMANUS Hydrothermal Field: Implications From Secondary Mineral Assemblages and Mineral Chemistry, OPD Leg 193 (United States)

    Lackschewitz, K. S.; Kummetz, M.; Kummetz, M.; Ackermand, D.; Botz, R.; Devey, C. W.; Singer, A.; Stoffers, P.


    Leg 193 of the Ocean Drilling Program investigated the subsurface nature of the active PACMANUS hydrothermal field in the Manus backarc basin near Papua New Guinea. Drilling in different areas on the felsic neovolcanic Pual Ridge, including the high-temperature black smoker complex of Roman Ruins and the low-temperature Snowcap site with diffusive discharge yielded a complex alteration history with a regional primary alteration being overprinted by a secondary mineralogy. The intense hydrothermal alteration at both sites shows significant differences in the secondary mineralogy. At Roman Ruins, the upper 25 m of hydrothermally altered rocks are characterized by a rapid change from secondary cristobalite to quartz, implying a high temperature gradient. From 10 to 120 mbsf the clay mineralogy is dominated by illite and chlorite. The chlorite formation temperature calculated from oxygen isotope data lies at 250° C in 116 mbsf which is similar to the present fluid outflow temperatures of 240-250° C (Douville et al., 1999, Geochim. Cosmochim. Acta, 63, 627-643). Drilling in the Snowcap field recovered evidence for several stages of hydrothermal alteration. Between 50 and 150 mbsf, cristobalite and chlorite are the most abundant alteration minerals while hydrothermal pyrophyllite becomes abundant in some places At 67 mbsf, the isotopic composition of pyrophyllite gives a temperature for ist formation at 260° C whereas at 77 and 116 mbsf the pyrophyllite displays the highest temperatures of formation (>300° C). These temperatures are close to the maximum measured borehole temperatures of 313° C. The appearance of assemblages of chlorite, chlorite-vermiculite, chlorite-vermiculite-smectite and illite-smectite as well as the local development of corrensite below 150 mbsf suggests that the alteration at Snowcap may be more complex than that beneath Roman Ruins. Detailed geochemical studies of the authigenic clay mineral phases will provide further insights into the

  19. Linking methane oxidation with perchlorate reduction: a microbial base for possible Martian life (United States)

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


    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

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

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


    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Sasao, Eiji [Japan Nuclear Cycle Development Inst., Toki, Gifu (Japan). Tono Geoscience Center


    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

  2. Quaternary clay mineralogy in the northern South China Sea (ODP Site 1146)--Implications for oceanic current transport and East Asian monsoon evolution

    Institute of Scientific and Technical Information of China (English)

    LIU Zhifei(刘志飞); Alain Trentesaux; Steven C. Clemens; WANG Pinxian(汪品先)


    Measurement of clay mineralogy at ODP Site 1146 in the northern South China Sea (SCS) indicates that illite, chlorite, and kaolinite contents increased during glacials and smectite content increased during interglacials. The smectite/(illite+chlorite) ratio and the smectite abundance were determined as mineralogical indicators for the East Asian monsoon evolution. At a 10 ka timescale, prevailing southeasterly surface oceanic currents during interglacials transported more smectite from the south and east areas to the north, showing a strengthened summer monsoon circulation, whereas dominated counter-clockwise surface currents during glacials carried more illite and chlorite from Taiwan as well as from the Yangtze River via the Luzon Strait to the northern SCS, indicating a strongly intensified winter monsoon. Based on a 100 ka timescale, a linear correlation between the smectite/(illite+chlorite) ratio and the sedimentation rate reflects that the winter monsoon has prevailed in the northern SCS in the intervals 2000-1200 ka and 400-0 ka and the summer monsoon did the same in the interval 1200-400 ka. The evolution of the summer monsoon provides an almost linear response to the summer insolation of Northern Hemisphere, implying an astronomical forcing of the East Asian monsoon evolution.

  3. Evidences of climatic variations during Late Pleistocene- Holocene in the eastern Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Chauhan, O.S.; Borole, D.V.; Gujar, A.R.; Mascarenhas, A.; Mislankar, P; Rao, Ch.M.

    of Holocene as deduced from high smectite, reduced chlorite and higher K/C ratio of sediments in 40-73 cm section (LGM-Early Holocene). Between 35 and 40 cm, at the beginning of Holocene, a significant reversal in the climate from humid to arid, and associated...

  4. 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...

  5. Evaluation of an experimental sodium chlorate product, with and without nitroethane, on Salmonella in cull dairy cattle (United States)

    Ruminant animals are natural reservoirs for Salmonella. These bacteria can reduce nitrate to nitrite through the membrane bound enzyme nitrate reductase which also has the ability to reduce chlorate to the cytotoxic end-product chlorite. An experimental product containing sodium chlorate (ECP) has...

  6. Provenance of Holocene sediment on the Chukchi-Alaskan margin based on combined diffuse spectral reflectance and quantitative X-Ray Diffraction analysis (United States)

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


    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.

  7. The composition and evolution of an Oligocene regolith on top of the Sesia–Lanzo Zone (Western Alps)

    DEFF Research Database (Denmark)

    Kapferer, Notburga; Mercolli, Ivan; Berger, Alfons


    temperatures higher than surface conditions. Illite and chlorite thermometry indicates temperatures related to the anchizone (*250–300C). These data are considered as a robust indication of the re-burial of the regolith together with its substrate and its volcanic cover. The burial is closely related...

  8. Viability of Listeria monocytogenes on uncured turkey breast commercially-prepared with and without buffered vinegar during extended storage at 4 degrees and 10 degrees C (United States)

    We determined the viability of Listeria monocytogenes on uncured turkey breast containing buffered vinegar (BV) and surface treated with a stabilized solution of sodium chlorite in vinegar (VSC). Commercially-produced, uncured, deli-style turkey breast was formulated with BV (0.0, 2.0, 2.5, or 3.0%)...

  9. Ultrasound enhanced sanitizer efficacy in reduction of Escherichia coli O157:H7 population on spinach leaves (United States)

    The use of ultrasound to enhance the efficacy of selected sanitizers in reduction of Escherichia coli O157:H7 populations on spinach was investigated. Spot-inoculated spinach samples were treated with water, chlorine, acidified sodium chlorite (ASC), peroxyacetic acid (POAA), and acidic electrolyzed...

  10. Methods for the Selective Oxidation of Cellulose: Preparation of 2,3-Dicarboxycellulose and 6-Carboxycellulose

    NARCIS (Netherlands)

    Besemer, A.C.; Nooy, A.E.J. de; Bekkum, H. van


    Three methods for the selective oxidation of cellulose are described. The classical method consists of consecutive oxidation with sodium periodate, leading to 2,3-dialdehyde cellulose and sodium chlorite, giving 2,3-dicarboxy cellulose. This material, which is obtained in high yield and has a high c

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

    NARCIS (Netherlands)

    Visser, J.P. de


    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

  12. Mineralogy and Sr–Nd isotopes of SPM and sediment from the Mandovi and Zuari estuaries: Influence of weathering and anthropogenic contribution

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, V.P.; Shynu, R.; Singh, S.K.; Naqvi, S.W.A.; Kessarkar, P.M.

    on their distribution. Kaolinite and illite, followed by minor goethite, gibbsite and chlorite were present in SPM and bottom sediment at all stations, both during monsoon and pre-monsoon. Smectite occurred in traces at river end stations but its contents increased...

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

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

    Directory of Open Access Journals (Sweden)

    Miłosz A. Huber


    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.

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

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


    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

  16. Thermal structure of pumpellyite-actinolite facies regions in the Sanbagawa belt, Shikoku, SW Japan (United States)

    Sakaguchi, M.


    On the basis of the mineral assemblages of pelitic rocks, the Sanbagawa belt in Shikoku, SW Japan, has been divided, from low- to high-grade parts, into the chlorite, garnet, albite-biotite and oligoclase-biotite zones (Higashino, 1990). Also, the mineral assemblage of pumpellyite + actinolite + epidote + chlorite or epidote + actinolite + hematite + chlorite, which defines the pumpellyite-actinolite (PA) facies (e.g., Banno, 1998), is widely recognized in metabasites in the chlorite zone (e.g. Banno & Sakai, 1989). However, the detailed study on the PA facies regions has been done only in the Omoiji-Nagasawa area (Nakajima et al., 1977) and Asemigawa-Shirataki area (Nakajima, 1982) in central Shikoku, and thus, it is still hard to solve the regional thermal structure of the PA facies region. This study is aimed to reveal the thermal structure of the PA facies region of the Sanbagawa belt in Shikoku by analyzing the mineral assemblages and mineral chemistries of metabasites from the nine newly studied areas. The studied areas studied belong to the chlorite zone in the Oboke and Besshi units; the Oboke unit structurally underlay the Besshi unit. The mineral assemblages include pumpellyite + epidote + actinolite, epidote + actinolite _ hematite and epidote + Na-amphibole + actinolite + hematite. The metabasites from some areas involve Na-pyroxene-bearing assemblages, but the analyses of the Schreinemakers bundle of Tagiri et al. (1992) show that these assemblages do not define the Na-pyroxene-chlorite subfacies. As the low-grade metamorphic rocks do not have the hematite + pumpellyite paragenesis, its metamorphic temperature is estimated to be higher than the discontinuous reaction temperature of pumpellyite + hematite + quartz = epidote + actinolite + H2O, as shown by Nakajima et al. (1977). It is difficult to detect the difference in temperature in the PA facies regions by analyzing mineral assemblages. To detect the difference in temperature, and then to reveal

  17. Authigenic layer silicate minerals in borehole Elmore 1, Salton Sea Geothermal Field, California, USA (United States)

    McDowell, S. Douglas; Elders, Wilfred A.


    A combined petrographic/X-ray/electron microprobe and energy dispersive system investigation of sandstone cuttings from borehole Elmore # 1 near the center of the Salton Sea Geothermal Field has revealed numerous regular variations in the composition, texture, mineralogy and proportions of the authigenic layer silicate minerals in the temperature interval 185° C (411.5 m depth) to 361° C (2,169 m). At temperatures near 190° C, dolomite/ankerite+calcite-bearing sandstones contain an illite/mixed layer phase with 10% expandable layers (dolomite/ankerite zone). In shale, the percentage of expandable layers in the mixed layer phase changes from 10 15% at 185° C to 5% at 210° C (494 m). In the interval 250° C (620 m) to 325° C (1,135 m), the calcite+pyrite+epidote-bearing sandstones contain a layer silicate assemblage of chlorite and illite (chlorite-calcite zone). In the shallower portions of this metamorphic zone, the illite contains 0 5% expandable layers, while at depths greater than 725 m (275° C) it is completely free of expandable layers. On increasing temperature, the white mica shows regular decreases in SiIV, Mg and Fe, and increase in AlIV, AlVI, and interlayer occupancy, as it changes gradually from fine-grained illite (=textural sericite) to coarse-grained recrystallized phengitic white mica. In the same interval, chlorite shows decreases in AlVI and octahedral vacancies and an increase in total Mg+Fe. The sandstones range from relatively unmodified detrital-textured rocks with porosities up to 20% and high contents of illite near 250° C to relatively dense hornfelsic-textured rocks with trace amounts of chlorite and phengite and porosities near 5% at 325° C. Numerous complex reactions among detrital (allogenic) biotite, chlorite, and muscovite, and authigenic illite and chlorite, occur in the chlorite-calcite zone. Biotite appears, and calcite disappears, at a temperature near 325° C and a depth of 1,135m. The biotite zone so produced persists

  18. 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)



    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.

  19. A study of the properties of chlorine dioxide gas as a fumigant. (United States)

    Shirasaki, Yasufumi; Matsuura, Ayumi; Uekusa, Masashi; Ito, Yoshihiro; Hayashi, Toshiaki


    Chlorine dioxide (ClO2) is a strong oxidant that possesses an antimicrobial activity. We demonstrated here that ClO2 gas is easily generated by mixing 3.35% sodium chlorite solution (Purogene) and 85% phosphoric acid at a 10:1 volume ratio without using an expensive machine. In a test room (87 m(3)), experiments were carried out using various amounts of sodium chlorite solution (0.25 ml/m(3) to 20.0 ml/m(3)). The gas concentration increased in a sodium chlorite volume-dependent manner and reached peak values of from 0.8 ppm to 40.8 ppm at 2 h-3 h, and then gradually decreased. No differences in gas concentrations were observed between 0.1 and 2.5 m above the floor, indicating that the gas was evenly distributed. Under high-humidity (approximately 80% relative humidity), colony formation of both Staphylococcus aureus and Escherichia coli was completely inhibited by ClO2 gas exposure at 1.0 ml/m(3) sodium chlorite solution (mean maximal concentration of 3.0 ppm). Exposure at 4.0 ml/m(3) sodium chlorite solution (mean maximal concentration of 10.6 ppm) achieved complete inactivation of Bacillus atrophaeus spores. In contrast, without humidification, the efficacy of ClO2 gas was apparently attenuated, suggesting that the atmospheric moisture is indispensable. Delicate electronic devices (computer, camera, etc.) operated normally, even after being subjected to more than 20 times of fumigation. Considering that our method for gas generation is simple, reproducible, and highly effective at decontaminating microbes, our approach is expected to serve as an inexpensive alternative method for cleaning and disinfecting animal facilities.

  20. The mineralogy and chemistry of fine-grained sediments, Morphou Bay, Cyprus

    Directory of Open Access Journals (Sweden)

    C. Neal


    Full Text Available The mineralogy and chemistry of the less than 20μm fraction of marine sediments at Morphou Bay, north-west Cyprus, are presented to characterise fine-grained sediment supplies from basic and ultrabasic rocks of the Troodos Massif within a typological setting. The sediments comprise a mixture of smectite, illite, kaolinite and iron rich chlorite. They also contain amorphous iron oxides/hydroxides, calcite (with some magnesium substitution for calcium and an amphibole. Spatial patterns in mineralogy occur: the near-shore sediments are rich in smectite, chlorite, amphibole and amorphous iron oxides/hydroxides, while the offshore sediments are rich in illite and calcite. The sediments are calcium, magnesium, iron, aluminium and potassium bearing, due to the presence of significant amounts of calcite (for Ca, clay minerals and aluminium and iron oxides/hydroxides. Potassium is present within the micaceous mineral illite, but it is also contained within other phases that are difficult to pinpoint. Statistical analysis reveals that the chemical composition of the sediments broadly follows the mineralogy with the dominant feature being related to spatial changes in the mineralogy. The patterns of change reflect a three component mix of clay-sized sediment types: (1 localised lithogenous sources rich in smectite with subsidiary amounts of amorphous iron oxides/hydroxides and amphibole, from Cyprus, the Troodos in particular, (2 illite rich and smectite chlorite and chlorite bearing material of lithogenous origin from other parts of the eastern Mediterranean and (3 calcite, mainly of marine origin. Keywords: smectite, illite, chlorite, kaolinite, calcite, sediments, Morphou Bay, Troodos, Cyprus, Mediterranean, calcium, potassium, magnesium, iron, silicon, phosphorus.

  1. Petrological evolution of subducted rodingite from seafloor metamorphism to dehydration of enclosing antigorite-serpentinite (Cerro del Almirez massif, southern Spain) (United States)

    Laborda-López, Casto; López Sánchez-Vizcaíno, Vicente; Marchesi, Claudio; Gómez-Pugnaire, María Teresa; Garrido, Carlos J.; Jabaloy-Sánchez, Antonio; Padrón-Navarta, José Alberto


    Rodingites are common rocks associated with serpentinites in exhumed terrains that experienced subduction and high pressure metamorphism. However, the response of these rocks to devolatilization and redox reactions in subduction settings is not well constrained. In the Cerro del Almirez ultramafic massif (southern Spain) rodingites constitute about 1-2% of the total volume of exposed rocks. Metarodingites are enclosed in antigorite-serpentinite and chlorite-harzburgite separated by a transitional zone that represents the front of prograde serpentinite-dehydration in a paleo-subduction setting (Padrón-Navarta et al., 2011). Metarodingites occur as boudin lenses, 1 to 20 m in length and 30 cm to 2 m in thickness. During serpentinization of peridotite host rocks, dolerites and basalts precursor of rodingites underwent intense seafloor metasomatism, causing the enrichment in Ca and remobilization of Na and K. Subsequent metamorphism during subduction transformed the original igneous and seafloor metamorphic mineralogy into an assemblage of garnet (Ti-rich hydrogrossular), diopside, chlorite, and epidote. During prograde metamorphism, garnet composition changed towards higher andradite contents. High-pressure transformation of enclosing antigorite-serpentinite to chlorite-harzburgite released fluids which induced breakdown of garnet to epidote in metarodingites. Ti liberation by this latter reaction produced abundant titanite. Released fluids also triggered the formation of amphibole by alkalis addition. Highly recrystallized metarodingites in chlorite-harzburgite present a new generation of idiomorphic garnet with composition equal to 10-30% pyrope, 30-40% grossular and 35-55% almandine + spessartine. This garnet has titanite inclusions in the core and rutile inclusions in the rim. The contact between metarodingites and ultramafic rocks consists of a metasomatic zone (blackwall) with variable thickness (7 to 40 cm) constituted by chlorite, diopside, and titanite

  2. Sorption behavior of U(VI) on phyllite: experiments and modeling (United States)

    Arnold, Thuro; Zorn, T.; Zänker, H.; Bernhard, G.; Nitsche, H.


    The sorption of U(VI) onto low-grade metamorphic rock phyllite was modeled with the diffuse double layer model (DDLM) using the primary mineralogical constituents of phyllite, i.e. quartz, chlorite, muscovite, and albite, as input components, and as additional component, the poorly ordered Fe oxide hydroxide mineral, ferrihydrite. Ferrihydrite forms during the batch sorption experiment as a weathering product of chlorite. In this process, Fe(II), leached from the chlorite, oxidizes to Fe(III), hydrolyses and precipitates as ferrihydrite. The formation of ferrihydrite during the batch sorption experiment was identified by Mössbauer spectroscopy, showing a 2.8% increase of Fe(III) in the phyllite powder. The ferrihydrite was present as Fe nanoparticles or agglomerates with diameters ranging from 6 to 25 nm, with indications for even smaller particles. These Fe colloids were detected in centrifugation experiments of a ground phyllite suspension using various centrifugal forces. The basis for the successful interpretation of the experimental sorption data of uranyl(VI) on phyllite were: (1) the determination of surface complex formation constants of uranyl with quartz, chlorite, muscovite, albite, and ferrihydrite in individual batch sorption experiments, (2) the determination of surface acidity constants of quartz, chlorite, muscovite, and albite obtained from separate acid-base titration, (3) the determination of surface site densities of quartz, chlorite, muscovite, and albite evaluated independently of each other with adsorption isotherms, and (4) the quantification of the secondary phase ferrihydrite, which formed during the batch sorption experiments with phyllite. The surface complex formation constants and the protolysis constants were optimized by using the experimentally obtained data sets and the computer code FITEQL. Surface site densities were evaluated from adsorption isotherms at pH 6.5. The uranyl(VI) sorption onto phyllite was accurately modeled with

  3. Fluid-Dacite Interaction in the PACMANUS Subseafloor Hydrothermal System - Preliminary Results From Secondary Mineral Chemistry and Geochemical Modeling (United States)

    Yeats, C. J.; Bach, W.; Vanko, D. A.; Roberts, S.; Lackschewitz, K.; Paulick, H.


    During Ocean Drilling Program Leg 193, several holes (as deep as 386 meters below sea floor) intersected variably altered and veined dacites on Pual Ridge in the eastern Manus back-arc basin. The hydothermal alteration is complex and multi-stage, and includes pervasive alteration and alteration halos along anhydrite±pyrite±quartz veins. Our preliminary interpretation is that an early pervasive "chloritic" alteration (chlorite, chlorite/smectite, quartz, +/-albite, +/-magnetite) is overprinted locally by illite-pyrophyllite-anhydrite+/-diaspore alteration followed by silica (quartz and cristobalite) flooding. Two drill holes at Snowcap, a site of diffuse venting, reveal alteration profiles of strongly illite-pyrophyllite-anhydrite altered rocks in the shallow parts grading downwards into rocks that show dominant chloritic alteration. At Roman Ruins, a site of discrete venting, K-feldspar and illite-smectite mixed layer phases are abundant and magnetite is rare. K-feldspar appears to be part of the "chloritic" alteration assemblage. Anhydrite is locally abundant but generally less common than at Snowcap. There is a strong lateral heterogeneity in basement alteration as revealed by the differences between sites in the depths of cristobalite-quartz transition and the zones of prevailing alteration styles. Geochemical modeling suggests that the rocks have been altered at temperatures of about 250 to 300° C under variable fluid-to-rock ratios. While all the mineral assemblages are consistent with quartz/cristobalite saturation of the fluids, the formation of diaspore must be related to episodic interaction of the rocks with fluids highly undersaturated in quartz. The early stage of chloritic alteration represents interaction of the dacites with fluids of a fairly high pH ({>}4). In contrast, the occurrence of pyrophyllite and local diaspore suggests lower pH fluid ({hydrothermal stages. A zone of abundant alunite at 350 m deep in the basement at Snowcap may represent

  4. Field-Based Evidence for Devolatilization in Subduction Zones: Implications for Arc Magmatism (United States)

    Bebout, Gray E.


    Metamorphic rocks on Santa Catalina Island, California, afford examination of fluid-related processes at depths of 15 to 45 kilometers in an Early Cretaceous subduction zone. A combination of field, stable isotope, and volatile content data for the Catalina Schist indicates kilometer-scale transport of large amounts of water-rich fluid with uniform oxygen and hydrogen isotope compositions. The fluids were liberated in devolatilizing, relatively low-temperature (400^circ to 600^circC) parts of the subduction zone, primarily by chlorite-breakdown reactions. An evaluation of pertinent phase equilibria indicates that chlorite in mafic and sedimentary rocks and melange may stabilize a large volatile component to great depths (perhaps >100 kilometers), depending on the thermal structure of the subduction zone. This evidence for deep volatile subduction and large-scale flow of slab-derived, water-rich fluids lends credence to models that invoke fluid addition to sites of arc magma genesis.

  5. 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


    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.

  6. Petrography and Diagenesis of Palaeocene -Eocene Sandstones in the Siri Canyon, Danish North Sea

    DEFF Research Database (Denmark)

    Kazerouni, Afsoon Moatari

    small differences in textural and compositional properties, and the lack of depositional structures in deep-water sandstones, the distinction between "in situ" and injected or remobilised sandstones is often indistinct.   Large scale heavy mineral sorting (in 10 m thick units) is observed in several...... of zeolites, pore water chemistry, composition of mineralogical precursors and the host sediments. This study demonstrates also the diagenetic evolution glaucony-rich deep-water sandstones from the Rau-1A well in the Siri Canyon, Danish North Sea.  The major diagenetic phases in the studied well.......  It was transformed to chlorite with depth.    A second phase chlorite is distinguished by its morphology and slightly 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...


    Institute of Scientific and Technical Information of China (English)

    肖志峰; 杨丽清; 等


    The Baoban gold field,located in the area of Hainan Island ,South China ,bears three gold de-posits :Tuwaishan ,Baoban ,and Erjia ,which belong to the wall-rock alteration type.In terms of the petrography data,four alteration zones can be recognized from the ore-vein outwards(1)the silicification zone;(2)the sericitization zone;(3)the chloritization zone;and (4)the calcitization zone.The geochemical kinetic simulation was carried out on sericitization and chloritization .Results of the study showed that the formation of the alteration zones is connected with the properties of hydrothermal fluids:the initial concentration of Al (O H)3,the diffusion coefficient and the velocity of fluid flow.The alteration zones in this field are the result of multiple interaction between hydrothermal fluids and wall rocks.

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

    Directory of Open Access Journals (Sweden)

    C. Lasagna


    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.

  9. Analysis of oxyhalide disinfection by-products and other anions of interest in drinking water by ion chromatography. (United States)

    Hautman, D P; Bolyard, M


    The US Environmental Protection Agency is developing regulations for various drinking water disinfection by-products (DBPs). This effort involves developing analytical methods for the DBPs formed as a result of different disinfection treatments and collecting occurrence data for these species. Ion chromatography is one method being used to analyze drinking water samples for the following inorganic DBPs: chlorite, chlorate and bromate. These anions, however, are difficult to separate from common interfering anions of chloride, carbonate and nitrate. A method is therefore presented by which tetraborate/boric acid is used to separate these anions. Method detection limits of the order of 10 micrograms/l, using conductivity and UV detection were obtained. Stability studies of chlorite showing the effectiveness of ethylenediamine as a preservative and summary data for an occurrence of nitrite, nitrate and the DBP precursor bromide are presented.

  10. Clay mineralogy, grain size distribution and their correlations with trace metals in the salt marsh sediments of the Skallingen barrier spit, Danish Wadden Sea

    DEFF Research Database (Denmark)

    He, Changling; Bartholdy, Jesper; Christiansen, Christian


    metals. The clay assembly of the sediment consists of illite, kaolinite and much less chlorite and smectite. The major clay minerals of illite, kaolinite as well as chlorite correlate very poorly with all the trace metals investigated, due probably to the weak competing strength of these clays compared...... with the other adsorbents and to low availability of the mobile trace metals in the system. Correlation between trace metals and clay minerals may therefore be used as an indicator in environmental assessment. Fine grain fractions of the sediment increased markedly after salt marsh invasion in about 1931......To understand the behavior of trace metals in the salt marsh at Skallingen, Danish Wadden Sea, we investigated a profile from surface to 25 cm depth of the salt marsh sediment, focusing primarily on clay mineralogy and grain size distribution of the sediments and their relationship with trace...

  11. 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

    Directory of Open Access Journals (Sweden)

    Juan Reyes


    Full Text Available 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 structure of rice hull. Nevertheless, this treatment did not favour the subsequent enzymatic process. Photomicrographs obtained from rice hull hydrolysates showed that pre-treatment changed mainly the inner epidermis and parenchyma cell and that they did not change cellular organization of the hull.


    Institute of Scientific and Technical Information of China (English)

    黄文辉; 许光泉; 刑军


    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.

  13. 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


    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.

  14. Diagenetic Sequences Analysis of Fuyu Reservoir in Qijia - Gulong Depression, Northern Songliao Basin

    Institute of Scientific and Technical Information of China (English)

    YAN Jianping; LIU Li; ZHANG Xinrong; MA Yanping


    Five paragenetic associations are recognized in Fuyu reservoir of Qijia - gulong depression of Daqing oil field: 1 )detrital illite permeation, glauconite and pyrite precipitation; 2 ) feldspar dissolution, kaolinite precipitation and the incipient quartz overgrowths; 3 ) early calcite cements; 4 ) postdate quartz overgrowths and pore - filling quartz, authigenetic illite and chlorite formation, feldspar overgrowths, petroleum injections, K - feldspar and calcite cement dissolution; 5) pore - filling calcite and calcite replacement.

  15. Clay mineralogical and geochemical constraints on late Pleistocene weathering processes of the Qaidam Basin, northern Tibetan Plateau (United States)

    Miao, WeiLiang; Fan, QiShun; Wei, HaiCheng; Zhang, XiYing; Ma, HaiZhou


    At the Qarhan Salt Lake (QSL) on the central-eastern Qaidam Basin, northern Tibetan Plateau, Quaternary lacustrine sediments have a thickness of over 3000 m and mainly composed of organic-rich clay and silty clay with some silt halite and halite. In this study, a 102-m-long sediment core (ISL1A) was obtained from the QSL. Combining with AMS 14C and 230Th dating, clay minerals and major-element concentrations of ISL1A were used to reconstruct the weathering process and trend of the QSL since late Pleistocene. The results reveal that the clay mineral from rocks, gneisses and schists of Eastern Kunlun Mountains on the south of the QSL. The abundance of illite mineral displays an opposite fluctuation trending with that of smectite, chlorite and kaolinite mineral in ISL1A, which is significantly different from the monsoon-controlled regions. Moreover, higher values of illite, kaolinite/chlorite and illite/chlorite ratios, and lower values of smectite, chlorite and kaolinite minerals occurred in 83-72.5 ka, 68.8-54 ka, 32-24 ka, corresponding to late MIS 5, late MIS 4, early MIS 3 and late MIS 3, respectively. These three phases were almost similarly changed with oxygen isotopes of authigenic carbonates and pollen records in ISL1A, which implies that stronger chemical weathering corresponds to higher effective moisture periods of source region in the Qaidam Basin. Based on chemical weathering index and (Al2O3-(CaO + Na2O)-K2O) diagram, chemical weathering degree in this study area takes a varying process from low to intermediate on the whole.



    KURT, Hüseyin; Kerim KOÇAK; ASAN, Kürşad; KARAKAŞ, Mustafa


    Biotite granitoid contain mainly quartz, biotite, plagioclase, K-feldspar, muscovite as main phases with minor amphiboles, and apatite, zircon, allanite and chlorite and serisite as accessory components. In contrast, enclaves are composed mainly of plagioclase, amphibole, augite, biotite, with accessory sphene, zircon and calcite and epidote. The granitoids including enclaves with metaluminous composition, display chemical and mineralogical characteristics of S-type granitoids, such as peralu...

  17. 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.


    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.

  18. 40 CFR 141.131 - Analytical requirements. (United States)


    ... Spectrophotometry,” USEPA, May 2005, EPA 815-R-05-008 and EPA Method 552.3, Revision 1.0, “Determination of... 6,7 Chlorite Amperometric titration 4500-ClO2 E 8 4500-ClO2 E-00 8 Spectrophotometry 327.0 Rev 1.1 8... of sample and must be analyzed within 28 days. 8 Amperometric titration or spectrophotometry may...

  19. Conditions of preservation of collectors of pore-type at great depths in Paleozoic deposits of northeast Antipovsko-Shcherbakovskiy zone

    Energy Technology Data Exchange (ETDEWEB)

    Tsygankova, V.A.


    Reasons are explained for preservation of the collectors of pore type in the sandy bed of the Pashiyskiy level stripped by well No. 4-Nikolayevskiy (depth interval 5136-5144 m) in limits of the Antipovsko-Shcherbakovskiy elevated zone of the Volgograd Volga region. A necessary condition for preservation of the collectors is: absence in the bed of considerable catagenetic transformations, presence of clay cement preventing quartz formation, as well as the occurrence of processes of chloritization creating additional secondary porosity.

  20. Alteration and mineralization of an oceanic forearc and the ophiolite-ocean crust analogy (United States)

    Alt, J.C.; Teagle, D.A.H.; Brewer, T.; Shanks, Wayne C.; Halliday, A.


    Mineralogical, chemical, and isotopic (O, C, S, and Sr) analyses were performed on minerals and bulk rocks from a forearc basement section to understand alteration processes and compare with mid-ocean ridges (MOR) and ophiolites. Ocean Drilling Program Hole 786B in the Izu-Bonin forearc penetrates 103 m of sediment and 725 m into volcanic flows, breccias, and basal dikes. The rocks comprise boninites and andesites to rhyolites. Most of the section was affected by low-temperature (Mg, Fe, Sr, and Y, and elevated ??18O and 87Sr/86Sr. Higher temperatures (???150??C) in the basal dikes below 750 m led to more intense alteration and formation of chlorite-smectite, corrensite, albite, K-feldspar, and quartz (??chlorite). A 5 m thick hydrothermally altered and pyritized zone at 815 m in the basal dikes reacted with mixtures of seawater and hydrothermal fluids to Mg-chlorite, albite, and pyrite, and gained Mg and S and lost Si and Ca. Focused flow of hydrothermal fluids produced sericitization halos (Na-K sericite, quartz, pyrophyllite, K-feldspar, and pyrite) along quartz veins at temperatures of 200??-250??C. High 87Sr/86Sr ratios of chloritized (???0.7055) and sericitized (???0.7065) rocks indicate involvement of seawater via mixing with hydrothermal fluids. Low ??34S of sulfide (???2 to -5.5???) and sulfate (12.5???) are consistent with input of magmatic SO2 into hydrothermal fluids and disproportionation to sulfide and sulfate. Alteration processes were generally similar to those at MORs, but the arc section is more intensively altered, in part because of the presence of abundant glassy rocks and mafic phases. The increase in alteration grade below 750 m and the mineralization in the basal dikes are analogous to changes that occur near the base of the volcanic section in MOR and the Troodos ophiolite.

  1. An unusual case of reversible acute kidney injury due to chlorine dioxide poisoning. (United States)

    Bathina, Gangadhar; Yadla, Manjusha; Burri, Srikanth; Enganti, Rama; Prasad Ch, Rajendra; Deshpande, Pradeep; Ch, Ramesh; Prayaga, Aruna; Uppin, Megha


    Chlorine dioxide is a commonly used water disinfectant. Toxicity of chlorine dioxide and its metabolites is rare. In experimental studies, it was shown that acute and chronic toxicity were associated with insignificant hematological changes. Acute kidney injury due to chlorine dioxide was not reported. Two cases of renal toxicity due to its metabolites, chlorate and chlorite were reported. Herein, we report a case of chlorine dioxide poisoning presenting with acute kidney injury.

  2. Two modes of occurrence of garnets from the Tonaru metagabbro mass in the Sambagawa metamorphic belt, central Shikoku, Japan


    蔵谷, 樹; 高須, 晃; カビール, エムデイ ファズレー


    Garnet epidote amphibolite from the central part of the Tonaru metagabbro mass consists mainly of garnet, epidote and amphibole (ferro-hornblende), with small amounts of quartz, plagioclase (albite and oligoclase) and paragonite. Rutile, apatite, hematite, calcite and chlorite occur occasionally. Garnets in the garnet epidote amphibolites exhibit two modes of occurrence. Garnet 1 (Grt 1) occurs as porphyroblast, and garnet 2 (Grt 2) is found as fine grain in the matrix. Porphyroblastic garnet...

  3. Disinfection aboard cruise liners and naval units: formation of disinfection by-products using chlorine dioxide in different qualities of drinking water. (United States)

    Ufermann, Petra; Petersen, Hauke; Exner, Martin


    The world-wide deployment of cruise liners and naval units has caused an increased need for the disinfection of drinking water. The main cause for this is the unknown quality of drinking water in foreign harbours--besides the formation of bio-films due to the climatically disadvantageous conditions in the operational area. Water conduits on board are currently disinfected with calcium hypochlorite in case of microbiological contamination. Chemical and physical analyses after disinfection with calcium hypochlorite have shown that organic by-products consisting of trihalomethanes develop in considerable amounts during disinfection. Furthermore, the method is susceptible to handling errors and thus often leads to insufficient disinfection results. Hitherto, the use of other disinfection methods allowed by government regulations, especially chlorine dioxide, is not widely spread. Unlike disinfection with calcium hypochlorite, chlorine dioxide does not lead to the formation of trihalomethanes. Typical disinfection by-products (DBP) are the anions chlorite and chlorate, which are formed in oxidative processes. The formation conditions of these anions have not yet been elucidated. For this reason, the probability of the generation of inorganic by-products after disinfection with chlorine dioxide has been determined, and their occurrence in drinking water on board has been examined with respect to a possible correlation between water quality and the formation of chlorate and chlorite. Therefore, a chromatographic method was developed and validated in order to determine the periodical development of chlorate and chlorite from chorine dioxide in purified water at different pH-values as well as in actual drinking water samples from water conduits on board. The formation of the by-products chlorite and chlorate after disinfection with chlorine dioxide is influenced neither by pH-value nor by chemical properties of the disinfected water. Considering the examined conditions

  4. Diversity of clay minerals in soils of solonetzic complexes in the southeast of Western Siberia (United States)

    Chizhikova, N. P.; Khitrov, N. B.


    Data on the mineralogical composition of clay in soils of solonetzic complexes of the Priobskoe Plateau and the Kulunda and Baraba lowlands have been generalized. The parent materials predominating in these regions have loamy and clayey textures and are characterized by the association of clay minerals represented by dioctahedral and trioctahedral mica-hydromica, chlorite, kaolinite, and a number of irregular interstratifications. They differ in the proportions between the major mineral phases and in the qualitative composition of the minerals. Mica-hydromica and chlorites with a small amount of smectitic phase predominate on the Priobskoe Plateau and in the Kulunda Lowland; in the Baraba Lowland, the portion of mica-smectite interstratifications is higher. An eluvial-illuvial distribution of clay fraction in solonetzes is accompanied by the acid-alkaline destruction and lessivage of clay minerals, including the smectitic phase in the superdispersed state. This results in the strong transformation of the mineralogical composition of the upper (suprasolonetzic) horizons and in the enrichment of the solonetzic horizons with the products of mineral destruction; superdispersed smectite; and undestroyed particles of hydromica, kaolinite, and chlorite from the suprasolonetzic horizons. A significant decrease in the content of smectitic phase in the surface solodic horizons of solonetzic complexes has different consequences in the studied regions. In the soils of the Priobskoe Plateau and Kulunda Lowland with a relatively low content (10-30%) of smectitic phase represented by chlorite-smectite interstratifications, this phase virtually disappears from the soils (there are only rare cases of its preservation). In the soils of the Baraba Lowland developed from the parent materials with the high content (30-50%) of smectitic phase represented by mica-smectite interstratifications, the similar decrease (by 10-20%) in the content of smectitic phase does not result in its

  5. Heavy minerals and provenance of the paleozoic suffi formation, Western desert, iraq.


    Al Juboury, Ali I. [علي الجبوري; Hassan, Zeki M.


    Heavy minerals analyses were carried out on 10 samples from the clastic Suffi Formation (the Ordovician-Carboniferous unit in the western Iraqi desert). The suite of minerals consists mainly of opaque minerals including pyrite, ilmenite, magnetite and hematite and the non-opaques is represented by zircon, tourmaline, cutile, garnet, epidote, kyanite, staurolite, leucoxene, chlorite and biotite. The nature and occurrence of the above heavy minerals association reflect a source area of the crys...

  6. Willow inner bark as a potential source of fibres and chemicals


    Dou, Jinze


    The aim of this thesis was to acquire basic information on the physical and chemical structure of willow inner bark in order to assess its potential as a raw material for chemicals and fibres. Inner bark from four cultivated willow species/hybrids was studied and compared with their wood tissue. The cell and cell wall structure was studied by optical microscopy, SEM and TEM. The fibres were separated with an acid chlorite treatment and analyzed for their dimensions and morphology. The chemica...

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

    Directory of Open Access Journals (Sweden)

    Miha Mišič


    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.

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

    DEFF Research Database (Denmark)

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


    . 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.......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...

  9. Quantitative mapping and statistical evaluation of fracture minerals in the granitic bedrock at Forsmark, Sweden (United States)

    Löfgren, Martin; Sidborn, Magnus


    This article provides quantitative data on occurrences and amounts of fracture minerals that coat discrete fractures in granitic rock at the Forsmark site in Sweden. The data are useful for retardation modelling of radionuclide and other contaminants, and for groundwater composition calculations. In a unique campaign, 2071 open fractures in groundwater conducting rock have been mapped with respect to chlorite, calcite, and pyrite. In total 767 m of drill core has been studied from very shallow rock down to ~1000 m depth. The occurrences of fracture minerals, their thicknesses, and their fractions of surface coverage have been recorded for up to eight layers for each fracture. Detection limits are, for each layer, 0.1 mm for the thickness and 1 % for the surface coverage, except for pyrite crystals where surface coverages down to 0.01 % are detectable. The abundance of data has permitted statistical treatment, using parametric and non-parametric methods. Parametric fittings have been made to log-normal, truncated log-normal, and beta distributions. Chlorite, calcite, and pyrite were found in 57 %, 52 %, and 10 % of all mapped fractures, respectively. The fracture mineral thickness was 0.1 mm for calcite, 0.2 mm for chlorite, and 2 μm for pyrite, as averaged over the fracture surface area. For 50 % and 99 % of all fractures the total fracture coating thickness was less than 0.1 mm and 1 mm, respectively, which is important for diffusion resistance estimates. Average surface coverages were 18 % for calcite, 38 % for chlorite, and 0.5 % for pyrite. These data may be used for calculating the reaction capacity of flow paths.

  10. 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


    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.

  11. Carboxymethylcellulose Obtained by Ethanol/Water Organosolv Process Under Acid Conditions (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).

  12. 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:; Padmanabhan, E., E-mail: [Department of Geoscience, Faculty of Geosciencs and Petroleum Engineering Universiti Teknologi PETRONAS, Tronoh (Malaysia); Over, Jeffrey, E-mail: [Department of geological sciences, Geneseo, NY (United States)


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

    Directory of Open Access Journals (Sweden)

    Németh Tibor


    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.

  14. Non-heme manganese catalysts for on-demand production of chlorine dioxide in water and under mild conditions. (United States)

    Hicks, Scott D; Kim, Doyeon; Xiong, Silei; Medvedev, Grigori A; Caruthers, James; Hong, Seungwoo; Nam, Wonwoo; Abu-Omar, Mahdi M


    Two non-heme manganese complexes are used in the catalytic formation of chlorine dioxide from chlorite under ambient temperature at pH 5.00. The catalysts afford up to 1000 turnovers per hour and remain highly active in subsequent additions of chlorite. Kinetic and spectroscopic studies revealed a Mn(III)(OH) species as the dominant form under catalytic conditions. A Mn(III)(μ-O)Mn(IV) dinuclear species was observed by EPR spectroscopy, supporting the involvement of a putative Mn(IV)(O) species. First-order kinetic dependence on the manganese catalyst precludes the dinuclear species as the active form of the catalyst. Quantitative kinetic modeling enabled the deduction of a mechanism that accounts for all experimental observations. The chlorine dioxide producing cycle involves formation of a putative Mn(IV)(O), which undergoes PCET (proton coupled electron-transfer) reaction with chlorite to afford chlorine dioxide. The ClO2 product can be efficiently removed from the aqueous reaction mixture via purging with an inert gas, allowing for the preparation of pure chlorine dioxide for on-site use and further production of chlorine dioxide.

  15. Monochloramine and chlorine dioxide for controlling Legionella pneumophila contamination: biocide levels and disinfection by-product formation in hospital water networks. (United States)

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


    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.

  16. Clay mineral association in the salt formation of the Transylvanian Basin and its paleoenvironmental significance

    Directory of Open Access Journals (Sweden)

    Nicoleta Bican-Bris̡an


    Full Text Available The investigated clay fraction was separated from salt samples recovered from three boreholes located in the Praid salt deposit area. For comparison, samples collected from Turda deposit (Franz Josef adit, the Rudolf and Ghizele chambers and from the salt massif from Sărăţel were also analyzed. The qualitative investigations evidenced a clay minerals association dominated by illite and chlorite accompanied by subordinate amounts of kaolinite, smectite, fibrous clays (sepiolite, palygorskite, and in minor amounts, by 14/14 chlorite/vermiculite and chlorite/smectite interstratifications. A quantitative evaluation (% including a standard graphical representation was performed only for the borehole samples (Praid, according to the vertical distribution. The genetical interpretation of the identified clay minerals association took into account the influence of the sedimentation mechanisms and the climate control on the mineral phases. The environment of formation for the salt in the Transylvanian Basin was defined by the presence of specific climatic factors, also suggested by the palynological investigations.

  17. Microbial respiration with chlorine oxyanions: diversity and physiological and biochemical properties of chlorate- and perchlorate-reducing microorganisms. (United States)

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


    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.

  18. Formation mechanism of ferromagnetic minerals in loess of China: TEM investigation

    Institute of Scientific and Technical Information of China (English)

    CHEN Tianhu; XU Huifang; JI Junfeng; CHEN Jun; CHEN Yang


    The results of TEM investigation indicate that magnetite and maghemite are the major ferromagnetic minerals in loess-paleosol sequences. Primary magnetite has the similar morphology and surface characteristics as eolian detrital particles. The magnetite can be classified into two categories, high-titanium and low-titanium, which may be the indicators of magmatic rocks and metamorphic rocks, respectively. TEM investigation at nanometer scale shows that primary detrital magnetite of micron scale had been partially weathered to maghemite of 5~20 nanometer during the pedogenic process, which maintain the pseudomorphism of the aeolian debris. Some chlorite particles were also weathered to nanometer scale magnetite or maghemite in the pedogenic process. So weathering of the two minerals leads to formation of superparamagnetism, which may be the important mechanism of magnetic-susceptibility increase in paleosols. The magnetite or maghemite resulting from the weathering of chlorite contains a small amount of P and S, which is the signal of microbe-mineral interaction, and indicates that microbes may play a certain role in chlorite weathering and formation of superparamagnetic particles.

  19. 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


    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.

  20. Equilibrium and kinetics in metamorphism of pelites in the Nelson aureole, British Columbia (United States)

    Pattison, D. R. M.


    The distribution of metapelitic mineral assemblages in the Nelson aureole, British Columbia, generally conforms to what is predicted from phase equilibria. However, in detail, the mineral textures, mineral compositions and zoning, and sequence and spacing of isograds do not. Two of the main disequilibrium features in the aureole are: (1) delay in the onset and progress of several reactions, ie, thermal overstepping; and (2) unreactivity of staurolite and especially garnet porphyroblasts when they are reactants in higher grade reactions. The thermal overstepping is ascribed primarily to difficulty of nucleation of the product porphyroblasts and sluggishness of dissolution of reactant porphyroblasts required for product mineral growth. The extent to which these barriers to nucleation and growth delay the onset of reaction is related to the reaction affinity of each reaction, which for thermally activated reactions is, in turn, related to the entropy change of the reaction. For a given overstep in temperature, reactions that release large quatities of H2O, such as chlorite-consuming reactions, have a high reaction affinity compared to those which release little or no H2O, such as the chlorite-free staurolite-consuming reaction. Thermal overstepping is consequently expected to be less for the former than for the latter, as was observed in the aureole where ca. 30 °C overstepping was required for garnet growth from a muscovite+chlorite-bearing precursor and ca. 70 °C overstepping was required for growth of Al2SiO5 from a staurolite-bearing, chlorite-free precursor. In all cases reaction progress was strongly influenced by presence or absence of fluid, with fluid presence dramatically lowering kinetic barriers to nucleation and growth, and therefore thermal overstepping. Textural features of rocks from the nearly coincident garnet, staurolite and andalusite isograds are suggestive of a fluid-catalyzed ‘cascade effect' in which reaction took place rapidly and several

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

    KAUST Repository

    Liu, Chao


    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.

  2. Steatite and schist as contenders for the Global Heritage Stone Resource due to their importance in Brazil's natural stone built heritage (United States)

    Gilberto Costa, Antônio


    In Brazil, European natural stones, such as marble and limestone, were used as building material at historically important buildings and monuments, mainly in coastal cities, as well as in contemporary urban centers. However, in the country's central region, these Italian and Portuguese marbles and limestones were scarcely used. Instead, they were substituted for soapstone and several types of schist. As of 1755, the former was employed because of the ease with which it can be worked, essentially in the sculptural art and in the production of ornamental elements. Characterized by the presence of talc, steatite can feature other minerals such as serpentine, chlorite, carbonate, amphiboles, oxides like hematite and magnetite, and sulfites like pyrite, all in broadly variable amounts, which can result in modification of its technological properties (Volumetric Weight, Porosity, Water Absorption, Uniaxial Compression, Abrasion Resistance, Thermal Expansion etc.). In such rocks, talc content will be a decisive factor in their coloration. The higher its talc content is the clearer and softer the stone type will be, which ends up being known as talc stone. In such cases, the rock can display different hues of green, blue and gray. When compared to other rocks, texture patterns containing talc crystals, chlorite and carbonate contribute to low absorption and porosity for steatites. Schists were equally used at historical buildings in the Brazilian inland, especially in constructions in Minas Gerais towns, both in the production of structural elements such as bases, corners, pillars and foundations and in the creation of ornaments. Featuring different compositions, such rocks - which almost always occur interlayered with other ones such as quartzite - display coloration ranging from hues of gray to green to blue. They can be quartz-sericite-albite-chlorite schists featuring great or no amounts of carbonate, magnetite, epidote and tourmaline, sometimes with garnet, such as in

  3. Regional mapping methods using ASTER data to map minerals in the U.S. Basin and Range (United States)

    Mars, J. C.


    The U.S. Geological Survey is currently mapping minerals associated with hydrothermal alteration in a study area that covers most of the U.S. Basin and Range. The study area was mapped using AST_L1B radiance data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). ASTER measures reflected radiation in three bands in the 0.52-0.86 μm wavelength region (VNIR); six bands in the 1.6-2.43 μm wavelength region (SWIR); and five bands of emitted radiation in the 8.125-11.65 μm wavelength region (TIR) with 15 m, 30 m, and 90 m resolution, respectively. ASTER VNIR and SWIR radiance data were calibrated to reflectance data using ACORN atmospheric correction software. TIR radiance data were calibrated to emissivity data using atmospheric removal and emissivity normalization algorithms in ENVI. Rocks containing hydrothermal silica, calcite-dolomite, epidote-chlorite, alunite-kaolinite, and sericite were mapped using Interactive Data Language (IDL) logical operators. IDL logical operators string together band thresholds and band ratios to map spectral features of minerals. ASTER SWIR band ratios are used in IDL logical operators to map Al-O-H spectral absorption features of alunite, kaolinite and sericite. The ASTER SWIR 4/5 ratio maps the 2.165 μm spectral absorption feature in alunite and kaolinite, and the ASTER SWIR 4/6 and 7/6 ratios map the 2.2 μm spectral absorption feature exhibited in alunite, kaolinite and sericite. Hydrothermal silica was mapped using ASTER SWIR and ASTER TIR band ratios. The ASTER SWIR band ratio 4/7 is typically higher for hydrothermal silica-rich rocks which have lower overall SWIR reflectance in the 2.0 to 2.4 μm region than non-hydrothermal silica-rich rocks due to residual molecular water or an O-H absorption feature spanning 2.26 to 2.4 μm. The ASTER TIR band ratio 13/12 maps the 9.09 μm quartz restralen absorption feature. Thus, silica-rich rocks were mapped using the TIR emissivity data and hydrothermal

  4. Fluid-rock interaction controlling clay-mineral crystallization in quartz-rich rocks and its influence on the seismicity of the Carboneras fault area (SE Spain) (United States)

    Jimenez-Espinosa, R.; Abad, I.; Jimenez-Millan, J.; Lorite-Herrera, M.


    The Carboneras Fault zone is one of the longest fault in the Betic Cordillera (SE Spain) and it would be a good candidate to generate large magnitude earthquakes (Gracia et al., 2006). Seismicity in the region is characterised by low to moderate magnitude events, although large destructive earthquakes have occurred, which reveals significant earthquake and tsunami hazards (Masana et al., 2004). Due to the internal architecture of the fault zone, shear lenses of post-orogenic sediments of Miocene and Pliocene age including marls and sandstones sequences are juxtaposed to the predominant slaty gouges of the Alpine basement. Microcataclasites and gouges of the quartz-rich post-orogenic sediments are also developed as cm- to m-scale bands, allowing the comparison between the deformed materials and their protoliths. Red, yellow and white sandstones and their respective cataclasites can be identified. This communication is concerned with the clay mineral crystallization events in these materials and its possible influence on the seismicity model of the region. The presence of phyllosilicates in fault zones as either neoformed or inherited clays is commonly related with fluid circulation and a mechanically weak fault behaviour (e.g., Wang, 1984). A critical factor for the understanding of the mechanical role of clays in fault rocks is to determine the timing of formation of mineral assemblages and microstructure of fault rocks and protolith. The effects of post-faulting alteration limit inferences about fault behaviour that can be made from exhumed rocks. The Carboneras fault zone provides good opportunities to study mineral processes enhanced by deformation, given that it is located in a region of arid climate and shows outcroppings of quartzitic rocks included in slaty rocks. Combined XRD, optical microscopy and SEM analyses reveal that deformed quartzitic rocks are enriched in phyllosilicates, increasing especially the amount of chlorite. The samples strongly damaged

  5. Deposition of talc - kerolite-smectite - smectite at seafloor hydrothermal vent fields: Evidence from mineralogical, geochemical and oxygen isotope studies (United States)

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


    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

  6. Late Quaternary clay minerals off Middle Vietnam in the western South China Sea: Implications for source analysis and East Asian monsoon evolution

    Institute of Scientific and Technical Information of China (English)


    High-resolution clay mineral records combined with oxygen isotopic stratigraphy over the past 450 ka during late Quaternary from Core MD05-2901 off Middle Vietnam in the western South China Sea are reported to reconstruct a history of East Asian monsoon evolution.Variations in Illite,chlorite,and kaolinite contents indicate a strong glacial-interglacial cyclicity,while changes in smectite content present a higher frequency cyclicity.The provenance analysis indicates a mixture of individual clay minerals from various sources surrounding the South China Sea.Smectite derived mainly from the Sunda shelf and its major source area of the Indonesian islands.Illite and chlorite originated mainly from the Mekong and Red rivers.Kaolinite was provided mainly by the Pearl River.Spectral analysis of the kaolinite/(illite+chlorite) ratio displays a strong eccentricity period of 100 ka,implying the ice sheet-forced winter monsoon evolution; whereas higher frequency changes in the smectite content show an ice sheet-forced obliquity period of 41 ka,and precession periods of 23 and 19 ka and a semi-precession period of 13 ka as well,implying the tropical-forced summer monsoon evolution.The winter monsoon evolution is generally in coherence with the glacial-interglacial cyclicity,with intensified winter monsoon winds during glacials and weakened winter monsoon winds during interglacials; whereas the summer monsoon evolution provides an almost linear response to the summer insolation of low latitude in the Northern Hemisphere,with strengthened summer monsoon during higher insolation and weakened summer monsoon during lower insolation.The result suggests that the high-latitude ice sheet and low-latitude tropical factor could drive the late Quaternary evolution of East Asian winter and summer monsoons,respectively,implying their diplex and self-contained forcing mechanism.

  7. Development of chlorine dioxide releasing film and its application in decontaminating fresh produce. (United States)

    Ray, Soumi; Jin, Tony; Fan, Xuetong; Liu, Linshu; Yam, Kit L


    A feasibility study was conducted to develop chlorine dioxide (ClO(2) )-releasing packaging films for decontaminating fresh produce. Sodium chlorite and citric acid powder were incorporated into polylactic acid (PLA) polymer. Films made with different amounts of PLA (100 and 300 mg), percentages of reactant (5% to 60%), and ratios of sodium chlorite to citric acid (1:2 or 2:1) were prepared using a solvent casting method. The release of ClO(2) from the resultant films was activated by moisture. Increase of reactants in the films produced more ClO(2) while higher PLA content in the films resulted in less release of ClO(2) . The ratio of sodium chlorite to citric acid and activation temperature (22 °C compared with 10 °C) did not affect the ClO(2) release from the films. Antimicrobial efficacy of ClO(2) released from the films was evaluated using grape tomato as a model food. The results indicate that the films were activated by moisture from tomatoes in the package and the released ClO(2) reduced Salmonella spp. and Escherichia coli O157:H7 inoculated on the tomatoes to undetectable levels (tomato), achieving more than 3 log reduction. The film-treated tomatoes did not show significant changes in color and texture as compared to controls during storage at 10 °C for 21 d. This study demonstrated the technical feasibility for development of gaseous ClO(2) -releasing packaging system to enhance microbial safety and extend shelf life of fresh produce.

  8. Clay mineralogy in agrochernozems of western Ukraine (United States)

    Papish, I. Ya.; Chizhikova, N. P.; Poznyak, S. P.; Varlamov, E. B.


    The mineralogy of clay fractions separated from deep low-humus deep-gleyic loamy typical agrochernozems on loess-like loams of the Upper Bug and Dniester uplands in the Central Russian loess province of Ukraine consists of complex disordered interstratifications with the segregation of mica- and smectite-type layers (hereafter, smectite phase), tri- and dioctahedral hydromicas, kaolinite, and chlorite. The distribution of the clay fraction is uniform. The proportions of the layered silicates vary significantly within the profile: a decrease in the content of the smectite phase and a relative increase in the content of hydromicas up the soil profile are recorded. In the upper horizons, the contents of kaolinite and chlorite increase, and some amounts of fine quartz, potassium feldspars, and plagioclases are observed. This tendency is observed in agrochernozems developed on the both Upper Bug and Dniester uplands. The differences include the larger amounts of quartz, potassium feldspars, and plagioclases in the clay material of the Upper Bug Upland, while the contents of the smectite phase in the soil profiles of the areas considered are similar. An analogous mineral association is noted in podzolized agrochernozems on loess-like deposits in the Cis-Carpathian region of the Southern Russian loess province developed on the Prut-Dniester and Syan-Dniester uplands. The distribution of particle-size fractions and the mineralogy of the clay fraction indicate the lithogenic heterogeneity of the soil-forming substrate. When the drifts change, the mineral association of the soils developed within the loess-like deposits gives place to minerals dominated by individual smectite with some mica-smectite inter stratifications, hydromicas, and chlorite.

  9. 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


    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.

  10. Weathering of the New Albany Shale, Kentucky, USA: I. Weathering zones defined by mineralogy and major-element composition (United States)

    Tuttle, M.L.W.; Breit, G.N.


    Comprehensive understanding of chemical and mineralogical changes induced by weathering is valuable information when considering the supply of nutrients and toxic elements from rocks. Here minerals that release and fix major elements during progressive weathering of a bed of Devonian New Albany Shale in eastern Kentucky are documented. Samples were collected from unweathered core (parent shale) and across an outcrop excavated into a hillside 40 year prior to sampling. Quantitative X-ray diffraction mineralogical data record progressive shale alteration across the outcrop. Mineral compositional changes reflect subtle alteration processes such as incongruent dissolution and cation exchange. Altered primary minerals include K-feldspars, plagioclase, calcite, pyrite, and chlorite. Secondary minerals include jarosite, gypsum, goethite, amorphous Fe(III) oxides and Fe(II)-Al sulfate salt (efflorescence). The mineralogy in weathered shale defines four weathered intervals on the outcrop-Zones A-C and soil. Alteration of the weakly weathered shale (Zone A) is attributed to the 40-a exposure of the shale. In this zone, pyrite oxidization produces acid that dissolves calcite and attacks chlorite, forming gypsum, jarosite, and minor efflorescent salt. The pre-excavation, active weathering front (Zone B) is where complete pyrite oxidation and alteration of feldspar and organic matter result in increased permeability. Acidic weathering solutions seep through the permeable shale and evaporate on the surface forming abundant efflorescent salt, jarosite and minor goethite. Intensely weathered shale (Zone C) is depleted in feldspars, chlorite, gypsum, jarosite and efflorescent salts, but has retained much of its primary quartz, illite and illite-smectite. Goethite and amorphous FE(III) oxides increase due to hydrolysis of jarosite. Enhanced permeability in this zone is due to a 14% loss of the original mass in parent shale. Denudation rates suggest that characteristics of Zone C

  11. Geochemistry of metamorphosed basaltic and sedimentary rocks from the Smolník Cu-pyrite deposit (Gemeric Superunit, Western Carpathians: a reappraisal of older geochemical data

    Directory of Open Access Journals (Sweden)

    Peter Ivan


    Full Text Available Stratiform chalcopyrite-pyrite deposit of Smolník is located in the low-grade metamorphosed Early Palaeozoic volcano-sedimentary Gelnica Group. Various types of phyllites, mostly sericite and graphite-sericite phyllites with metadolerite bodies build up proximate vicinity of the deposit. The imminent host rocks of sulphide pods are chlorite phyllites with subordinate chlorite-sericite phyllites intercallations. Metadolerites previously interpreted as effusive rocks are probably subvolcanic in origin. Original igneous mineral association of clinopyroxene, plagioclase, ilmenite and probably also olivine were transformed to association of amphiboles, albite, clinozoisite/epidote, titanite ± calcite by metamorphic alteration. Composition of metadolerites is close to basaltic liquids although indices of some fractionation of plagioclase, olivine/chromspinelide or clinopyroxene exist. Trace element distribution points to their similarity to within-plate continental tholeiites (CT and probable relation to the beginning of rifting in the Lower Devonian time. Three possible sources of sedimentary material have been identified in the sedimentary host rocks of the Smolník deposit: (i basalts generated from enriched mantle reservoir; (ii less fractionated calc-alkaline volcanic rocks and (iii fractionated calc-alkaline rhyolites. An additional hydrothermal source for silica and iron is supposed for chlorite phyllites and allows classified them as metaexhalites. The sulphide ores were directly precipitated in the exhalite environment due to reaction hydrothermal solution with hydrogen sulphide produced by thermochemical reduction of the marine sulphate. Geochemical data on metamorphosed dolerites and sediments in combination to other geological characteristics of the Smolník deposit support its classification as the Besshi-type deposit.

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

    Directory of Open Access Journals (Sweden)

    Federica Zaccarini


    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.

  13. Clay Mineralogy of AN Alluvial Aquifer in a Mountainous, Semiarid Terrain, AN Example from Rifle, Colorado (United States)

    Elliott, W. C.; Lim, D.; Zaunbrecher, L. K.; Pickering, R. A.; Williams, K. H.; Navarre-Sitchler, A.; Long, P. E.; Noel, V.; Bargar, J.; Qafoku, N. P.


    Alluvial sediments deposited along the Colorado River corridor in the semi-arid regions of central to western Colorado can be important hosts for legacy contamination including U, V, As and Se. These alluvial sediments host aquifers which are thought to provide important "hot spots" and "hot moments" for microbiological activity controlling organic carbon processing and fluxes in the subsurface. Relatively little is known about the clay mineralogy of these alluvial aquifers and the parent alluvial sediments in spite of the fact that they commonly include lenses of silt-clay materials. These lenses are typically more reduced than coarser grained materials, but zones of reduced and more oxidized materials are present in these alluvial aquifer sediments. The clay mineralogy of the non-reduced parent alluvial sediments of the alluvial aquifer located in Rifle, CO (USA) is composed of chlorite, smectite, illite, kaolinite and quartz. The clay mineralogy of non-reduced fine-grained materials at Rifle are composed of the same suite of minerals found in the sediments plus a vermiculite-smectite intergrade that occurs near the bottom of the aquifer near the top of the Wasatch Formation. The clay mineral assemblages of the system reflect the mineralogically immature character of the source sediments. These assemblages are consistent with sediments and soils that formed in a moderately low rainfall climate and suggestive of minimal transport of the alluvial sediments from their source areas. Chlorite, smectite, smectite-vermiculite intergrade, and illite are the likely phases involved in the sorption of organic carbon and related microbial redox transformations of metals in these sediments. Both the occurrence and abundance of chlorite, smectite-vermiculite, illite and smectite can therefore exert an important control on the contaminant fluxes and are important determinants of biogeofacies in mountainous, semiarid terrains.

  14. Clay mineralogy of the Boda Claystone Formation (Mecsek Mts., SW Hungary) (United States)

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


    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.

  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.


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

    Directory of Open Access Journals (Sweden)

    D. McIlroy


    Full Text Available 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.

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

    Directory of Open Access Journals (Sweden)

    S. J. Needham


    Full Text Available 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.

  18. Distribution and hosts of arsenic in a sediment core from the Chianan Plain in SW Taiwan: Implications on arsenic primary source and release mechanisms. (United States)

    Yang, Huai-Jen; Lee, Chi-Yu; Chiang, Yu-Ju; Jean, Jiin-Shuh; Shau, Yen-Hong; Takazawa, Eiichi; Jiang, Wei-Teh


    High arsenic abundance of 50-700μg/L in the groundwater from the Chianan Plain in southwestern Taiwan is a well-known environmental hazard. The groundwater-associated sediments, however, have not been geochemically characterized, thus hindering a comprehensive understanding of arsenic cycling in this region. In this study, samples collected from a 250m sediment core at the centre of the Chianan Plain were analyzed for arsenic and TOC concentrations (N=158), constituent minerals (N=25), major element abundances (N=105), and sequential arsenic extraction (N=23). The arsenic data show a prevalence of >10mg/kg with higher concentrations of 20-50mg/kg concentrated at 60-80 and 195-210m. Arsenic was extracted mainly as an adsorbate on clay minerals, as a co-precipitate in amorphous iron oxyhydroxide, and as a structural component in clay minerals. Since the sediments consist mainly of quartz, chlorite, and illite, the correlations between arsenic concentration and abundances of K2O and MgO pinpoint illite and chlorite as the major arsenic hosts. The arsenic-total iron correlation reflects the role of chlorite along with the contribution from amorphous iron oxyhydroxide as indicated by arsenic extraction data. Organic matter is not the dominant arsenic host for low TOC content, low arsenic abundance extracted from it, and a relatively low R(2) of the arsenic-TOC correlation. The major constituent minerals in the sediments are the same as those of the upriver metapelites, establishing a sink-source relationship. Composition data from two deep groundwater samples near the sediment core show Eh values and As(V)/As(III) ratios of reducing environments and high arsenic, K, Mg, and Fe contents necessary for deriving arsenic from sediments by desorption from clay and dissolution of iron oxyhydroxide. Therefore, groundwater arsenic was mainly derived from groundwater-associated sediments with limited contributions from other sources, such as mud volcanoes.

  19. Distribution and composition of authigenic minerals in surface sediments of the western Gulf of Thailand

    Institute of Scientific and Technical Information of China (English)

    WANG Kunshan; SHI Xuefa; QIAO Shuqing; KORNKANITNAN Narumol; KHOKIATTIWONG Somkiat


    Generation, morphology, and distribution of authigenic minerals directly reflect sedimentary environment and material sources. Surface sediments were collected from the western Gulf of Thailand during 2011–2012, and 159 samples were analyzed to determine detrital minerals. Authigenic minerals, including siderite, pyrite, and glauconite, are abundant whereas secondary minerals, such as chlorite and limonite, are distributed widely in the study area. Siderite has a maximum content of 19.98 g/kg and appears in three types from nearshore to continental shelf, showing the process of forming-maturity-oxidation. In this process, the MnO content in siderite decreases, but Fe2O3 and MgO content increase. Colorless or transparent siderite pellets are fresh grains generated within a short time and widely distributed throughout the region; high content appears in coastal area where river inputs are discharged. Translucent cemented double pellets appearing light yellow to red are mature grains; high content is observed in the central shelf. Red-brown opaque granular pellets are oxidized grains, which are concentrated in the eastern gulf. Pyrite is mostly distributed in the central continental shelf with an approximately north–south strip. Pyrite are mainly observed in foraminifera shell and distributed in clayey silt sediments, which is similar to that in the Yangtze River mouth and the Yellow Sea. The pyrite in the gulf is deduced from genetic types associated with sulfate reduction and organic matter decomposition. Majority of glauconite are granular with few laminar. Glauconite is concentrated in the northern and southern parts within the boundary of 9.5° to 10.5°N and is affected by river input diffusion. The distribution of glauconite is closely correlated with that of chlorite and plagioclase, indicating that glauconite is possibly derived from altered products of chlorite and plagioclase. The K2O content of glauconite is low or absent, indicating its short

  20. Pinite-cordierite from spotted slate of the Brajkovac contact metamorphic aureole (Dudovica locality, central Serbia

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    Vasković Nada


    Full Text Available The Paleozoic very low to low-grade metamorphic rocks of the Bukulja-Lazarevac Unit designated as Drina, Golija and Birač formations are contact metamorphosed by the intrusion of the Tertiary Brajkovac granodiorite into spotted slates and hornfelses. In some parts, they are slightly migmatized at the contact. In addition to their outcrops found at the western, eastern and northern parts of the formation, these rocks are also found in boreholes near Dudovica at about 8 km south-west from the pluton. There, at a depth of 110 m, the spotted slates comprise oval to ellipsoid pinite-rich spots which can be regarded as incipient cordierite porphyroblasts (up to 5 mm in diameter overgrowing the existing regional foliation. They are composed of cryptocrystalline mixture of a very fine sericitic material ± light glassy orange „film“ (some kind of an amorphous gel-like material often mixed with limonite matter and are abundant in inclusions: minute quartz and dusty ore minerals (magnetite prevail. In addition, within some spots an increased number of xenotime and monazite inclusions are noted. Minute flakes of neobiotite are formed at the expense of quartz-sericite-chlorite matrix. The secondary chlorite occurring as overgrowths on pinite-cordierite spots shows variable composition (brunsvigite to diabandite. The Mg/Fe+Mg ratio of cryptocrystalline pinitic mixture ranges from 0.14-0.67. The Si vs AlIV+AlVI relations deviate from the ideal muscovite-phengite join due to Tschermak substitution towards chloritic composition or a more complex mixture, including clay minerals (which reflected a decrease of Altot and Si with increase of Fe2+. Obtained data indicates that the cordierite-pinite spots can be related to contact metamorphic processes that occurred within the temperature range 300-450°C. [Projekat Ministarstva nauke Republike Srbije, br. 176019 i br. 176016

  1. 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


    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.

  2. Formation of disinfection byproducts upon chlorine dioxide preoxidation followed by chlorination or chloramination of natural organic matter. (United States)

    Yang, Xin; Guo, Wanhong; Lee, Wontae


    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.

  3. Relation between ground-water quality and mineralogy in the coal- producing Norton Formation of Buchanan County, Virginia (United States)

    Powell, John D.; Larson, Jerry D.


    The geochemical processes controlling ground-water chemistry in the coal-producing strata of southwestern Virginia include hydrolysis of silicates, dissolution of carbonates, oxidation of pyrite, cation exchange, and precipitation of secondary minerals, kaolinite and goethite. Core material from the Norton Formation of the Pennsylvania Period is composed of slightly more than one-half sandstone; siltstone and minor amounts of shale, clay, and coal account for the majority of the remainder. Petrographic analyses and x-ray diffraction studies indicate that the sandstone is about 75 percent quartz, 15 percent plagioclase feldspar, 2 percent potassium feldspar, 2 percent muscovite, 4 percent chlorite, and 1 percent siderite. Calcite is present in small amounts and in a few strata as clasts or cement. No limestone strata were identified. The siltstone is about 50 percent quartz, 10 percent plagioclase feldspar, 10 percent mica, 20 percent chlorite, and from 0 to 25 percent siderite. Pyrite is associated with some siltstone and, where present, generally accounts for less than 1 percent. Total sulfur generally constitutes less than 0.1 percent of core samples but about 4 percent in the more pyrite-rich layers. Three reaction models are used to account for the observed water chemistry. The models derive sulfate from pyrite, iron from pyrite and siderite, calcium from plagioclase and calcite, sodium from plagioclase and cation exchange, magnesium from chlorite, and carbon from carbon dioxide, calcite, and siderite. Kaolinite, chalcedony, and goethite are formed authigenically. Carbon-13 data define the relative contributions of carbon sources to models. Comparison of adjacent unmined and mined basins indicates that surface mining significantly increases the weathering reaction of pyrite in contrast to weathering reactions of other minerals. However, in the area studied, reactive pyrite does not appear to be present in sufficient quantities in strata associated with mined

  4. Contact Electrification of Regolith Particles and Chloride Electrolysis: Synthesis of Perchlorates on Mars (United States)

    Tennakone, K.


    Contact electrification of chloride-impregnated martian regolith particles due to eolian agitation and moisture condensation on coalesced oppositely charged grains may lead to spontaneous electrolysis that generates hypochlorite, chlorite, chlorate, and perchlorate with a concomitant reduction of water to hydrogen. This process is not curtailed even if moisture condenses as ice because chloride ionizes on the surface of ice. Limitations dictated by potentials needed for electrolysis and breakdown electric fields enable estimation of the required regolith grain size. The estimated dimension turns out to be of the same order of magnitude as the expected median size of martian regolith, and a simple calculation yields the optimum rate of perchlorate production.

  5. Mineral resource of the month: vermiculite (United States)

    Tanner, Arnold O.


    Vermiculite comprises a group of hydrated, laminar magnesium-aluminum-iron silicate minerals resembling mica. They are secondary minerals, typically altered biotite, iron-rich phlogopite or other micas or clay-like minerals that are themselves sometimes alteration products of amphibole, chlorite, olivine and pyroxene. Vermiculite deposits are associated with volcanic ultramafic rocks rich in magnesium silicate minerals, and flakes of the mineral range in color from black to shades of brown and yellow. The crystal structure of vermiculite contains water molecules, a property that is critical to its processing for common uses.

  6. 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


    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...

  7. Study of the raw materials used in the manufacture of ceramics in Fran Ali (Oued Laou, Marruecos); Estudio de materiales usados en la fabricacion de las ceramicas de Fran Ali (Oued Laou, Marruecos)

    Energy Technology Data Exchange (ETDEWEB)

    Barrios Neira, J.; Martin de la Cruz, J. C.; Montealegre Contreras, L.


    The thermal behaviour, mineralogy, texture and micro-structure of the original rocks used as raw materials in the manufacture of ceramics of the potter community in Fran Ali (Oued Laou, Tetouan, Morocco) were studied. The original rocks of the alteration deposit are metapelites and altered philites from the Units Malaguide-Gomaride in the Baetic-Rifian mountain system. The techniques used by local potters and the water used to prepare the ceramic bodies were also studied. Original rocks are metapelites or filadios and raw materials belong to levels caused by exogenous or supergene alteration (quartz-illite and chlorite type clays). The ceramics studied by microscopy exhibit anisotropy. (Author) 15 refs.

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

    Institute of Scientific and Technical Information of China (English)

    陈友红; 张旗; 等


    This study shows that olivine,serpentine and orthopyroxene 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,grossulatrite is poor in all of these trace elements,except Sr.The trace element composition and distribution in the minearls are heterogeneous.The distributions of trace elements in the minerals further demonstrate that they result from mantle metasomatism under open system.

  9. Les argiles bleues du Cambrien inférieur de Saint-Pétersbourg et leur fissuration. Implications pour des stockages souterrainsLower Cambrian Saint Petersburg blue clays and their fissuration. Implication for underground stages (United States)

    Arnould, Marcel; Boisson, Jean-Yves; Ivanov, Ivan P.


    The Lower Cambrian Saint Petersburg blue clays are composed of predominant illite and chlorite, sometimes accompanied by kaolinite. The <0.1 μm fraction has a high content of illite-smectite mixed layers. Particle-size distribution is more than 50% of clay particles and about 30% of silts. These blue clays correspond to plastic (and soft) clays; they may be compared to the Callovian clays of Bure (France), where storage of natural waste is envisaged. To cite this article: M. Arnould et al., C. R. Geoscience 334 (2002) 1135-1140.

  10. 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) (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.

  11. Mineral assemblages and oxygen and sulphur fugacities in natural water-rock interaction processes (United States)

    D'Amore, F.; Gianelli, G.


    Several mineral assemblages capable of buffering oxygen and sulphur fugacity and theoretical calculations were used to determine the fugacities of these two gas species over a temperature range between 150° and 350°C. Computed values were compared with those calculated from the composition of the geothermal fluids of Larderello, Travale, Bagnore and Piancastagnaio (Italy), The Geysers (USA) and Cerro Prieto (Mexico). The possible hydrothermal mineral assemblages that best fit the field data are those containing minerals frequently found in many geothermal fields: epidote, chlorite, K-feldspar, quartz and pyrite. These assemblages can be used in place of the classical buffers based on iron oxides and sulphides.

  12. Advantages and disadvantages of chemical oxidation and disinfection by ozone and chlorine dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Fiessinger, F.; Richard, Y.; Montiel, A.; Musquere, P.


    Ozone and chlorine dioxide present definite advantages and disadvantages over chlorination. Chlorination, particularly for the removal of ammonia and the maintenance of a disinfectant residual in the distribution system has decisive advantages and will be difficult to replace. Ozone and chlorine dioxide seem to produce fewer carcinogenic by-products but the risk for acute toxicity, especially from the chlorites which follow chlorine dioxide, is higher than with chlorine. Chlorine dioxide and more particularly ozone should be considered as useful complements to chlorination, but no strong oxidative treatment should be applied before most of the organic matter has been removed.

  13. Chlorine dioxide water disinfection: a prospective epidemiology study

    Energy Technology Data Exchange (ETDEWEB)

    Michael, G.E.; Miday, R.K.; Bercz, J.P.; Miller, R.G.; Greathouse, D.G.; Kraemer, D.F.; Lucas, J.B.


    An epidemiologic study of 198 persons exposed for 3 months to drinking water disinfected with chlorine dioxide was conducted in a rural village. A control population of 118 nonexposed persons was also studied. Pre-exposure hematologic and serum chemical parameters were compared with test results after 115 days of exposure. Chlorite ion levels in the water averaged approximately 5 ppM during the study period. Statistical analysis (ANOVA) of the data failed to identify any significant exposure-related effects. This study suggests that future evaluations of chlorine dioxide disinfection should be directed toward populations with potentially increased sensitivity to hemolytic agents.

  14. Contrasting geochemistry and metamorphism of pillow basalts in metamorphic complexes from Aysén, S. Chile (United States)

    Hervé, F.; Aguirre, L.; Sepúlveda, V.; Morata, D.


    The geochemistry of pillow basalts from the Chonos Metamorphic Complex (CMC) and the Eastern Andes Metamorphic Complex of Aysén (EAMC) indicates contrasting tectonic environments for these basic lavas. They have E-MORB and continental alkaline affinities, respectively. The MORB-like basalts are metamorphosed in the pumpellyite-actinolite metamorphic facies, with mineral associations indicative of relatively high P/T metamorphism. The continental alkali basalts exhibit pumpellyite-chlorite assemblages developed in a low to intermediate P/T regime. These contrasting eruptive and metamorphic settings agree with recently established age differences between the complexes, and invalidate direct correlation between them.

  15. Geothermal alteration of clay minerals and shales: diagenesis

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, C.E.


    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.

  16. Relation between the complex Ginzburg-Landau equation and reaction-diffusion System

    Institute of Scientific and Technical Information of China (English)

    Shao Xin; Ren Yi; Ouyang Qi


    The complex Ginzburg-Landau equation(CGLE)has been used to describe the travelling wave behaviour in reaction-diffusion (RD) systems. We argue that this description is valid only when the RD system is close to the Hopf bifurcation,and is not valid when a RD system is away from the onset.To test this,we study spirals and anti-spirals in the chlorite-iodide-malonic acid (CIMA) reaction and the corresponding CGLE.Numerical simulations confirm that the CGLE can only be applied to the CIMA reaction when it is very near the Hopf onset.

  17. Lead isotope compositions as guides to early gold mineralization: The North Amethyst vein system, Creede district, Colorado (United States)

    Foley, Nora K.; Ayuso, Robert A.


    The North Amethyst vein system, which is hosted by approximately 27 Ma Carpenter Ridge Tuff and approximately 26 Ma Nelson Mountain Tuff, has two mineral associations separated by brecciation and sedimentation in the veins. The early association consists of quartz, rhodonite, hematite, magnetite, electrum (Au (sub 0.3-0.5) Ag (sub 0.7-0.5)) , and Mn carbonate, Au-Ag sulfide, Ag sulfosalt, and base metal sulfide minerals. The later mineral association cuts the Mn- and Au-bearing assemblages and consists of quartz, calcite, sericite, chlorite, hematite, adularia, fluorite, base metal sulfides, and Ag-bearing tetrahedrite.

  18. 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


    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.

  19. Mineralogical, geochemical and hydrocarbon potential of subsurface Cretaceous shales, Northern Western Desert, Egypt

    Directory of Open Access Journals (Sweden)

    D.A. Mousa


    Full Text Available Twenty four Cretaceous shale core samples of Gibb Afia-1, Betty-1, Salam-1X and Mersa Matruh-1 wells were mineralogically and geochemically studied using XRD, XRF and Rock Eval Pyrolysis. Kaolinite, smectite and illite are the main clay minerals in addition to rare chlorite, while the non-clay minerals include quartz, calcite, dolomite and rare siderite. The shales were derived through intensive chemical weathering of mafic basement and older sedimentary rocks. These sediments were deposited in a near-shore shallow marine environment with some terrestrial material input. The shales have poor to fair organic content. It is marginally to rarely mature.

  20. Mineral composition of sedimentary matter in the Caspian Sea (United States)

    Lukashin, V. N.; Lisitzin, A. P.; Dara, O. M.; Kozina, N. V.; Klyuvitkin, A. A.; Novigatsky, A. N.


    Data on the mineral composition of sedimentary matter and its fluxes in the sediment system of the Caspian Sea are presented. River runoff, aerosols, particulate matter from sediment traps, and the upper layer (0-1 cm) of bottom sediments are considered. The contents of detrital minerals (quartz, albite, and K-feldspar), clay minerals (illite, chlorite, and kaolinite), and carbonates (calcite, Mg-calcite, dolomite, aragonite, and rhodochrosite) are determined. Gypsum was found in bottom sediments but is absent in the other object of the sediment system.

  1. [First results on the use of chloramines to reduce disinfection byproducts in drinking water]. (United States)

    Azara, Antonio; Muresu, Elena; Dettori, Marco; Ciappeddu, Pierluigi; Deidda, Antonio; Maida, Alessandro


    The presence of disinfection byproducts (DBP) in drinking water raises concerns about the safety of chlorination and is one of the problems inherent the use of surface water as a source of drinking water. In order to reduce the presence of DBP (in particular of chlorites), we evaluated the combined use of chlorine dioxide for primary disinfection and monochloramine for residual disinfection in a water purification plant and distribution system in Sardinia (Italy). The results are very encouraging. Disinfection byproducts were reduced and other parameters were found to be within the recommended standards, indicating further improvements of the purification process.

  2. Silver-cobalt mineralization in the Upper Seymchan ore cluster, Northeastern Russia (United States)

    Goryachev, N. A.; Gamyanin, G. N.; Prokof'ev, V. Yu.; Savva, N. E.; Velivetskaya, T. A.; Ignat'ev, A. V.


    This paper is focused on the Early Cretaceous Ag-Bi-Co-sulfoarsenide mineralization atypical of northeastern Asia, which contains diverse Co-Ni sulfoarsenides, Se-bearing Bi sulfotellurites, and Ag-Bi-Pb sulfosalts. The Upper Seymchan ore cluster is located at the boundary between the Paleozoic Omulevka Terrane of carbonate platform and the In'yali-Debin Synclinorium of the Kular-Nera Terrane. These ore-bearing sequences are represented by the Middle Jurassic terrigenous rocks that rest upon the Upper Triassic sandshale rocks of the upper structural stage. The sedimentary rocks are cut through by high-Al granitic plutons and younger granite-porphyry dikes. The orebodies that are superposed on igneous rocks were formed during (1) the quartz-chlorite-tourmaline stage of metasomatic alteration, (2) the main economic tourmaline-chlorite-quartz-sulfoarsenide vein stage, (3) the polysulfide-quartz stage with Ag, Se, Bi minerals, and (4) the postore quartz-calcite stage with fluorite. The epithermal veins of festoon chalcedony-like quartz with Sb-bearing arsenopyrite occupy a special position. In particular orebodies, the chlorite-quartz ore veins dominate at the upper levels, whereas the quartz-tourmaline veins occur at the lower levels. Wall-rock alteration is represented by metasomatic chloritization and tourmalinization up to the formation of monomineralic metasomatic zones. Sulfides and sulfoarsenides are distinguished by anomalous enrichment of sulfur in the light isotope (δ34S = -12.8 to -16.7‰) in contrast to the sulfur isotopic composition of Sb-asenopyrite (-1.7‰) from the genetically different epithermal veins. The oxygen isotopic composition of calcite (the third stage) is uniform at all studied deposits and reveals a tendency to updip enrichment in δ18O within a vertical interval of 200 m. Quartz from ore-bearing and epithermal veins has an almost identical δ18O value (±2‰) but differs from quartz at the tin deposits related to granites of the

  3. Paleoproterozoic volcanic centers of the São Félix do Xingu region, Amazonian craton, Brazil: Hydrothermal alteration and metallogenetic potential (United States)

    da Cruz, Raquel Souza; Fernandes, Carlos Marcello Dias; Villas, Raimundo Netuno Nobre; Juliani, Caetano; Monteiro, Lena Virgínia Soares; Lagler, Bruno; Misas, Carlos Mario Echeverri


    Geological, petrographic, scanning electron microscopy, and X-ray diffraction studies revealed hydrothermalized lithotypes evidenced by overprinted zones of potassic, propylitic, sericitic, and intermediate argillic alterations types, with pervasive and fracture-controlled styles, in Paleoproterozoic volcano-plutonic units of the São Félix do Xingu region, Amazonian craton, northern Brazil. The Sobreiro Formation presents propylitic (epidote + chlorite + carbonate + clinozoisite + sericite + quartz ± albite ± hematite ± pyrite), sericitic (sericite + quartz + carbonate), and potassic (potassic feldspar + hematite) alterations. The prehnite-pumpellyite pair that is common in geothermal fields also occurs in this unit. The Santa Rosa Formation shows mainly potassic (biotite + microcline ± magnetite), sericitic (sericite + quartz + carbonate ± chlorite ± gold), and intermediate argillic (montmorillonite + kaolinite/halloysite + illite) alterations. These findings strongly suggest the involvement of magma-sourced and meteoric fluids and draw attention to the metallogenetic potential of these volcanic units for Paleoproterozoic epithermal and rare and base metal porphyry-type mineralizations, similar to those already identified in other portions of the Amazonian craton.

  4. Mineralogy of metamorphosed carbonatite of the Vesely occurrence, Northern Transbaikal region, Russia (United States)

    Lastochkin, E. I.; Ripp, G. S.; Doroshkevich, A. G.


    Metamorphism of carbonatite is exemplified in the Vesely occurrence. According to available data, the age of the carbonatite is 596 ± 3.5Ma, whereas metamorphism is dated at 550 ± 14 Ma. The rocks at the Vesely occurrence were metamorphosed under conditions of greenschist facies (epidote-muscovite-chlorite subfacies) under elevated pressure. Microthermometry of fluid inclusions in minerals indicates that the temperature of metamorphism is 377-450°C and the pressure estimated from phengite geobarometer is 6-8 kbar. The low-grade metamorphism led to the partial recrystallization of carbonates and apatite with removal of trace elements. This process resulted in a change of the oxygen isotopic composition of the studied minerals. Metamorphism was accompanied by formation of talc, phengite, chlorite, quartz, tremolite-actinolite, and anthophyllite, which are not typical of carbonatite. The data obtained show that the metamorphism exerted an effect on the mineralogical, isotopic, geochemical, and technological properties of the carbonatite. The effect of metamorphism should be taken into account in determination of the nature of ore mineralization and estimation of ore quality and perspective of the occurrence.

  5. Geochemistry of batch-extract waters derived from spoil material collected at the Cordero coal mine, Powder River basin, Wyoming (United States)

    Naftz, D.L.


    Batch-mixing experiments to evaluate postmining water quality at the Cordero Mine were conducted by the U.S. Geological Survey during 1984 to 1985. Contact of groundwater from the spoil aquifer with fresh spoil material caused only small changes in major-element concentrations and in pH, unless sulfide oxidation or contact with soluble salts, such as epsomite, occurred. In contrast, large changes in major-element concentration resulted when water from the coal aquifer contacted the spoil material. Only three of seven reaction models considered to explain the water quality changes during the batch-mixing experiments were consistent with the thermodynamic and mineralogical data. The three models used to account for the observed water quality changes derived potassium from potassium feldspar; magnesium from chlorite or epsomite or both; sodium from cation exchange and halite; chloride from halite; silica from potassium feldspar and chlorite; sulfate from gypsum, or epsomite or both, and carbon from carbon dioxide. In general, water quality samples obtained from the batch-mixing experiments using water from the coal aquifer had smaller major-ion concentrations than the actual water quality in the spoil aquifer. These differences can be explained by the limited amount of efflorescent salt dissolution and volume of water used in the experiments. Correction ratios calculated for these experiments may be applied to batch-mixing experiments at other mines in the area, to predict postmining water quality. (USGS)

  6. Environmental implication of subaqueous lava flows from a continental Large Igneous Province: Examples from the Moroccan Central Atlantic Magmatic Province (CAMP) (United States)

    El Ghilani, S.; Youbi, N.; Madeira, J.; Chellai, E. H.; López-Galindo, A.; Martins, L.; Mata, J.


    The Late Triassic-Early Jurassic volcanic sequence of the Central Atlantic Magmatic Province (CAMP) of Morocco is classically subdivided into four stratigraphic units: the Lower, Middle, Upper and Recurrent Formations separated by intercalated sediments deposited during short hiatuses in volcanic activity. Although corresponding to a Large Igneous Province formed in continental environment, it contains subaqueous lava flows, including dominant pillowed flows but also occasional sheet flows. We present a study of the morphology, structure and morphometry of subaqueous lava flows from three sections located at the Marrakech High-Atlas (regions of Aït-Ourir, Jbel Imzar and Oued Lhar-Herissane), as well as an analysis of the sediments, in order to characterize them and to understand their environmental meaning. The analysis of clays by the diffraction method X-ray revealed the presence of illite, mica, phengite, céladonite, talc and small amounts of quartz, hematite, calcite and feldspar, as well as two pairs of interbedded irregular (chlorite Smectite/chlorite-Mica). Fibrous minerals such as sepiolite and palygorskite were not detected. The peperite of Herissane region (Central High Atlas) provided an excellent overview on the factors favoring the magma-sediment interaction. These are the products of a mixture of unconsolidated or poorly consolidated sediments, low permeability with a low viscosity magma. The attempt of dating palynology proved unfortunately without results.

  7. 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


    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.

  8. Diagenesis and Its Effect on Reservoir Quality of Silurian Sandstones, Tabei Area, Tarim Basin, China

    Institute of Scientific and Technical Information of China (English)

    Zhang Jinliang; Jia Ying; Du Guilin


    The diagenetic processes of the Tabei sandstones in the Tarim Basin include compaction, cementation (quartz overgrowths, calcite, clay minerals and a minor amount of pyrite), and dissolution of the feldspar and calcite cement.Porosity was reduced by compaction from an assumed original 40% to about 22.1%. Cementation reduced porosity to 26.6%. The Tabei sandstones lost a little more porosity by compaction than by cementation. Quartz cementation,especially syntaxial quartz overgrowth, is a major cause of porosity-loss in many reservoirs in moderately to deeply buried sandstone. Calcite cementation played a key role in the porosity evolution of sandstones. At the early stage of burial, the early calcite cement occupied most of the pore spaces resulting in significant porosity. On the other hand, some primary porosity has been preserved due to incomplete filling or the presence of scattered patches of calcite cement. In addition to calcite, several clay minerals, including illite and chlorite occurred as pore-filling and pore-lining cements.The pore-lining chlorite may have helped in retaining the porosity by preventing the precipitation of syntaxial quartz overgrowths. Illite, which largely occurred as hair-like rims around the grains and bridges on the pore throats, caused a substantial deterioration of penetrability of the reservoir. Calcite cement dissolution was extensive and contributed significantly to the development of secondary porosity.

  9. 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


    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.

  10. Fluid inclusion and stable isotope study of telluride mineralization at Mahd Adh Dhahab, Saudi Arabia

    Energy Technology Data Exchange (ETDEWEB)

    Afifi, A.M.; Kelly, W.C.


    Mahd Adh Dhahab is unique among Precambrian gold deposits in that it displays many characteristics of epithermal precious metal districts. Au-Ag-Cu-Zn-Pb mineralization occurs principally in the third of five generations of quartz veins. Sulfur isotopic equilibrium was generally maintained among sulfides which range in delta/sup 34/S from -1.8 (galena) to 6.4 (pyrite). The narrow range in delta/sup 34/S of sulfides is inconsistent with large variations in f02 calculated from chlorite +/- pyrite +/- hematite assemblages. Galena-sphalerite pairs yield temperatures in the range 160-270/sup 0/C for stage 3 veins, which fall within the 120-300/sup 0/C range defined by fluid inclusion thermometry. Fluid salinities are in the range 0.5 wt.% NaCl equivalent. The trends indicate mixing of delta/sup 18/O approx. = 0 waters with heavier more oxidized waters during stage 4 deposition which led to non-equilibrium oxidation of H/sub 2/S. deltaD values of vein chlorites fall within a narrow range of -65 to -75, while deltaD measurements of inclusion fluids in quartz display a wider spread from -13 to -43; the lighter values may reflect contamination by secondary inclusions. The stable isotope data indicate probable derivation of both sulfur and carbon from igneous sources. District-wide variation in sulfur and oxygen isotopes indicate the presence of several hydrothermal centers, which has possible significance to exploration.

  11. 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


    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.

  12. Sequential flow injection determination of chlorine species using a triiodide-selective electrode detector. (United States)

    Saad, Bahruddin; Wai, Wan Tatt; Ali, Abdussalam Salhin M; Saleh, Muhammad Idiris


    A flow injection analysis (FIA) method for the determination of four residual chlorine species, namely combined available chlorine (CAC), free available chlorine (FAC), total available chlorine (TAC) and chlorite (ClO2-) was developed using a flow-through triiodide-selective electrode as a detector. An important strategy of speciation studies utilized the kinetic discrimination of reactions between the CAC and FAC with Fe2+, which was applied to the speciation of FAC, CAC and TAC. The speciation of available chlorine species and chlorite (an oxychlorine species) was achieved by using the same set-up, but using flow streams of different pH. The effects of the pH of the carrier stream, the flow rate and the sample volume were studied. The method exhibited linearity from 2.8 x 10(-6) to 2.8 x 10(-4) M active chlorine (expressed as OCl-) with a detection limit of 1.4 x 10(-6) M. The selectivity of the method was studied by examining the minimum pH for the oxidation of iodide by other oxidants, and also by assessing the potentiometric selectivity coefficients. The proposed method was successfully applied to the determination of chlorine species in tap water, and disinfecting formulations where good agreement occurred between the proposed and standard methods were found.

  13. Distribution of detrital minerals and sediment color in western Arctic Ocean and northern Bering Sea sediments: Changes in the provenance of western Arctic Ocean sediments since the last glacial period (United States)

    Kobayashi, Daisuke; Yamamoto, Masanobu; Irino, Tomohisa; Nam, Seung-Il; Park, Yu-Hyeon; Harada, Naomi; Nagashima, Kana; Chikita, Kazuhisa; Saitoh, Sei-Ichi


    This paper describes the distribution of detrital minerals and sediment color in the surface sediments of the western Arctic Ocean and the northern Bering Sea and investigates the relationship between mineral composition and sediment provenance. This relationship was used to determine the provenance of western Arctic Ocean sediments deposited during the last glacial period. Sediment color is governed by water depth, diagenesis, and mineral composition. An a*-b* diagram was used to trace color change during diagenesis in the Arctic Ocean sediments. The mineral composition of surface sediments is governed by grain size and provenance. The feldspar/quartz ratio of the sediments studied was higher on the Siberian side than on the North American side of the western Arctic Ocean. The (chlorite + kaolinite)/illite and chlorite/illite ratios were high in the Bering Sea but decrease northwards in the Chukchi Sea. Thus, these ratios are useful for provenance studies in the Chukchi Sea area as indices of the Beaufort Gyre circulation and the Bering Strait inflow. The sediments deposited during the last glacial period have a lower feldspar/quartz ratio and a higher dolomite intensity than Holocene sediments on the Chukchi Plateau, suggesting a greater contribution of North American grains during the last glacial period.

  14. 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)


    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.

  15. Characteristics of fracture in the Takinoue (Kakkonda) goethermal area, iwate prefecture

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, H.; Sato, K.; Miyazaki, S.; Chiba, Y.


    Structural contour maps in the Takinoue geothermal area have been made by using data on net slips of faults and fixed-points of bedding planes as well as on strikes and dips of bedding planes. From the relation between the contour maps and distribution of fractures, characteristics of fractures in this area can be pointed out as follows: (1) fractures oblique to the bedding planes caused by flexural bedding are located at the east flank of anticlinal structure; (2) extension of fractures occurred during the period of buildup operation of production wells has been detected by acceleration-sense long-distance AE measurement equipment. Location of determined AE sources coincide fairly well with fractured layers in the Tertiary formations. The result of AE measurements showed that the newly-made fractures extended along the pre-existing faults planes and horizontal fractures; (3) the result of x-ray analysis of samples collected from 11 production wells showed that aureole of rock alteration can be divided into three subzones: chlorite subzone, laumontite subzone and gypsum subzone. Among them, the gypsum subzone is distributed along faults, then, iron-poor chlorite subzone seems to be formed in the formation with high permeability in the process of hydrothermal activity; and (4) well KD-5 drilled into deeper portion of asymmetric anticline produced much amount of geothermal steam which is supplied through vertical fracture zone with fluid temperature higher than formation temperature.

  16. Thermal evolution of the syn-tectonic Ainsa-Jaca basin (South Pyrenean Zone). New constraints from a multiproxy approach. (United States)

    Lahfid, A.; Lacroix, B.; Hoareau, G.; Meresse, F.; Michel, K.; Buatier, M.


    Constraining the Thermal history of tectonically active basins is of special importance for the petroleum industry. Indeed, the estimation of geothermal gradients and their evolution are basic parameters to understand the tectono-sedimentary evolution of fold-and-thrust belts and associated foreland basins. In this work, we focus on the turbiditic deposits of the Ainsa-Jaca basin (western part of the South Pyrenean Zone) which consist of an accreted foreland basin composed of Eocene syn-tectonic sediments. The aim is to quantify peak temperatures of the basin that underwent late diagenesis and low-grade metamorphism conditions during the Pyrenean activity. For this, turbiditic rocks and calcite veins (extensional and shear veins) were systematically sampled along a section over a thickness of 4 km through the Monte Perdido unit. In order to constrain the structures observed, sampling was accompanied with a detailed structural analysis. We have combined three thermometric indicators to evaluate peak temperature of rocks: Raman thermometry on carbonaceous material, fluid inclusion microthermometry on calcite/quartz shear and extensional veins and compositional chlorite thermometry on Fe-chlorite observed in shear veins. The Raman temperatures obtained show variations ranging from Jaca basin do not seem so obvious and need to be carefully used. In order to better constrain the thermal history of South Pyrenean Zone, we are currently working on the acquisition of more data.

  17. A preliminary investigation of microcracks in the overcored borehole 210-020-RST1, 240 level of the Underground Research Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    McGregor, R.G.


    A section of borehole 210-020-RST1 was sampled and thin sections were cut in order to investigate the occurrence of microcracks within the borehole. The petrology of the sample was described and the presence of microcracks was noted. In total, 1894 microcracks were recorded during the investigation. Microcrack sets were defined on the basis of filling type (or lack of filling) and three-dimensional orientations attributed to the microcrack sets based on structural observations. Many microcrack sets are shown to have similar orientations to mesoscopic fractures observed within the Underground Research Laboratory (URL) lease area and within the URL subsurface. The relative age of observed microcracks, in terms of fillings, is from oldest to youngest: fluid-inclusion-filled fractures; unknown filled fractures; chlorite-filled fractures; and coeval in formation, chlorite-, hematite- and sericite-filled fractures. Fractures without filling are considered the youngest. Plates documenting some observed fractures are included. Biases in the generation and interpretation of the data are discussed and alternatives are mentioned. (auth)

  18. Mass and chemical changes of immobile elements in Yamaghan Occurrence, Zanjan Province, Iran

    Institute of Scientific and Technical Information of China (English)


    Using mass and chemical changes, behavior of some elements have been evaluated in the study area, Yamaghan Occurrence. The techniques using immobile elements can precisely identify altered volcanic rock precursors and measure material changes. The rocks of the study area were affected by hydrothermal alteration. Testing of some compatible-incompatible and compatible-compatible immobile pairs indicates that Al2O3 is the most immobile component in the study area. It means that during the three main stages of hydrothermal alteration (phyllic, intermediate argillic and propylitic) aluminum was the most immobile and titanium was slightly immobile. Increases in mass mostly result from mineralization, silicification or carbonatization as voids and other open space fillings and may have replaced the part of glassy matrix. Mass addition has diluted the immobile elements at constant rates. Mass loss is commonly due to leaching of Si, Ca and Na2O during chloritization and sericitization. The mass loss is recognized by increased proportions of inert minerals such as chlorite and sericite. Mineralographic studies in the study area shows the existence of a supergene zone. Calcocite and covellite are considered enriched minerals. Considering this evidence and mass change results, the enrichment of copper in the circulating fluid is suspected with occasional sulfide precipitation.

  19. Thermal magnetic behaviour of Al-substituted haematite mixed with clay minerals and its geological significance (United States)

    Jiang, Zhaoxia; Liu, Qingsong; Zhao, Xiangyu; Jin, Chunsheng; Liu, Caicai; Li, Shihu


    Clay minerals and Al-substituted haematite (Al-hm) usually coexist in soils and sediments. However, effects of clay minerals on Al-hm during thermal magnetic measurements in argon environment have not been well studied. In order to quantify such effects, a series of Al-hm samples were synthesized, and were then mixed with clay minerals (illite, chlorite, kaolinite and Ca-montmorillonite). The temperature dependence of magnetic susceptibility curves in an argon environment showed that Al-substituted magnetite was produced during the thermal treatment via the reduction of Al-hm by the clay mineral, which leads to a significant magnetic enhancement of the thermal products. In addition, the reductive capacity varies among different types of clay minerals, that is, illite > chlorite > kaolinite > Ca-montmorillonite. Furthermore, the iron content in the clay minerals and Al content of Al-hm are two predominant factors controlling the reduced haematite content. The iron is released from the clay minerals and provides the reducing agent, while Al decreases the crystallinity of haematite and thus facilitates the chemical reaction. Therefore, the thermal magnetic measurements can be used to quantify the Al content of Al-hm in natural samples. Our study provides significant information for palaeomagnetism and environmental magnetism studies, such as thermal magnetic analysis and palaeomagnetic intensity reconstruction using ancient pottery and kilns.

  20. Chlorine dioxide and hemodialysis

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R.P. (Dartmouth Coll., Hanover, NH (USA). Dept. of Pharmacology and Toxicology)


    Because it has little or no tendency to generate carcinogenic trihalomethanes such as chloroform, chlorine dioxide is an attractive alternative to chlorine for drinking water disinfection. There are, however, concerns about its acute toxicity, and the toxic effects of its by-products, chlorite and chlorate. The human experience with chlorine dioxide in both controlled, prospective studies and in actual use situations in community water supplies have as yet failed to reveal adverse health effects. The EPA has recommended standards of 0.06 mg/L for chlorine dioxide and standards of 0.007 mg/L for chlorite and chlorate in drinking water. Among groups who may be at special risk from oxychlorines in drinking water are patients who must undergro chronic extracorporeal hemodialysis. Although even units for home hemodialysis are supposed to be equipped with devices which effectively remove oxychlorines, there is a always a possibility of operator error or equipment failure. When the equipment is adequately maintained, it is likely that dialysis patients will have more intensive exposures from drinking water than from dialysis fluids despite the much larger volumes of water that are involved in dialysis. This paper discusses a hemodialysis and the standards and effects of oxychlorines. 90 refs., 2 tabs.

  1. Formation of disinfection by-products after pre-oxidation with chlorine dioxide or ferrate. (United States)

    Yang, Xin; Guo, Wanhong; Zhang, Xing; Chen, Feng; Ye, Tingjin; Liu, Wei


    The effect of pre-oxidation with chlorine dioxide (ClO2) or ferrate (Fe(VI)) on the formation of disinfection by-products (DBPs) during chlorination or chloramination was tested with natural waters from 12 sources (9 surface waters, 1 groundwater, and 2 wastewater effluents). DBPs investigated included trihalomethanes (THM), chloral hydrate (CH), haloketones (HK), haloacetonitriles (HAN) and trichloronitromethane (TCNM), chlorite and chlorate. Chlorite and chlorate were found in the ClO2-treated waters. Application of 1 mg/L ClO2 ahead of chlorination reduced the formation potential for THM by up to 45% and the formation of HK, HAN and TCNM in most of the samples. The CH formation results were mixed. The formation of CH and HK was enhanced with low doses of Fe(VI) (1 mg/L as Fe), but was greatly reduced at higher doses (20 mg/L Fe). Fe(VI) reduced the formation of THM, HAN and TCNM in most of the samples. Reduced potential for the formation of NDMA was observed in most of the samples after both ClO2 and Fe(VI) pre-oxidation.

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

    Directory of Open Access Journals (Sweden)

    Miloš Miler


    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.

  3. 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


    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.

  4. Independent evolution of four heme peroxidase superfamilies. (United States)

    Zámocký, Marcel; Hofbauer, Stefan; Schaffner, Irene; Gasselhuber, Bernhard; Nicolussi, Andrea; Soudi, Monika; Pirker, Katharina F; Furtmüller, Paul G; Obinger, Christian


    Four heme peroxidase superfamilies (peroxidase-catalase, peroxidase-cyclooxygenase, peroxidase-chlorite dismutase and peroxidase-peroxygenase superfamily) arose independently during evolution, which differ in overall fold, active site architecture and enzymatic activities. The redox cofactor is heme b or posttranslationally modified heme that is ligated by either histidine or cysteine. Heme peroxidases are found in all kingdoms of life and typically catalyze the one- and two-electron oxidation of a myriad of organic and inorganic substrates. In addition to this peroxidatic activity distinct (sub)families show pronounced catalase, cyclooxygenase, chlorite dismutase or peroxygenase activities. Here we describe the phylogeny of these four superfamilies and present the most important sequence signatures and active site architectures. The classification of families is described as well as important turning points in evolution. We show that at least three heme peroxidase superfamilies have ancient prokaryotic roots with several alternative ways of divergent evolution. In later evolutionary steps, they almost always produced highly evolved and specialized clades of peroxidases in eukaryotic kingdoms with a significant portion of such genes involved in coding various fusion proteins with novel physiological functions.

  5. Carbonate cementation as related to the diagenesis of clay in a mixed siliciclastic-carbonate system: Examples from the Centerfield biostrome, east central Pennsylvania

    Energy Technology Data Exchange (ETDEWEB)

    Burns, C.D. (Univ. of North Carolina, Chapel Hill, NC (United States))


    The Middle Devonian Mahantango Formation consists of siliciclastic and mixed carbonate-siliciclastic sediment packages that pulse in and out of the stratigraphy. The formation crops out in several places throughout the folded rocks of eastern Pennsylvania and Maryland. The Centerfield Member is one of the mixed siliciclastic-carbonate packages in the Mahantango Fm. This member crops out in east central Pennsylvania. The Centerfield Mbr. has been interpreted as a series of biostromes and contain abundant rugosan corals, crinoids, bryozoans, and brachiopods. The biostromes have undergone a complex diagenetic history. Illite, smectite, chlorite and muscovite have been found with the use of powder x-ray diffraction and petrographic analysis. The smectite and some of the illite are depositional clays, while, the remaining illite, chlorite and muscovite represent recrystallization of the depositional clays. There are six phases of cement in the biostrome. The paragenetic sequence of the cements is as follows: non-ferroan low magnesian calcite (LMC), intermediate ferroan LMC, ferroan LMC, non-ferroan dolomite, ferroan baroque dolomite, and quartz cement in the form of chert and blocky cement. Staining shows that the iron content of the cement changes within individual crystals and between cement phases. Preliminary data suggest that the cements may be directly related to the steady release of ions during the diagenesis of the surrounding clays in the shale.

  6. Nucleation and growth of strike slip faults in granite. (United States)

    Segall, P.; Pollard, D.P.


    Fractures within granodiorite of the central Sierra Nevada, California, were studied to elucidate the mechanics of faulting in crystalline rocks, with emphasis on the nucleation of new fault surfaces and their subsequent propagation and growth. Within the study area the fractures form a single, subparallel array which strikes N50o-70oE and dips steeply to the S. Some of these fractures are identified as joints because displacements across the fracture surfaces exhibit dilation but no slip. The joints are filled with undeformed minerals, including epidote and chlorite. Other fractures are identified as small faults because they display left-lateral strike slip separations of up to 2m. Slickensides, developed on fault surfaces, plunge 0o-20o to the E. The faults occur parallel to, and in the same outcrop with, the joints. The faults are filled with epidote, chlorite, and quartz, which exhibit textural evidence of shear deformation. These observations indicate that the strike slip faults nucleated on earlier formed, mineral filled joints. Secondary, dilational fractures propagated from near the ends of some small faults contemporaneously with the left-lateral slip on the faults. These fractures trend 25o+ or -10o from the fault planes, parallel to the direction of inferred local maximum compressive stress. The faults did not propagate into intact rock in their own planes as shear fractures. -from Authors

  7. Clay mineralogical and geochemical proxies of the East Asian summer monsoon evolution in the South China Sea during Late Quaternary (United States)

    Chen, Quan; Liu, Zhifei; Kissel, Catherine


    The East Asian summer monsoon controls the climatic regime of an extended region through temperature and precipitation changes. As the East Asian summer monsoon is primarily driven by the northern hemisphere summer insolation, such meteorological variables are expected to significantly change on the orbital timescale, influencing the composition of terrestrial sediments in terms of both mineralogy and geochemistry. Here we present clay mineralogy and major element composition of Core MD12-3432 retrieved from the northern South China Sea, and we investigate their relationship with the East Asian summer monsoon evolution over the last 400 ka. The variability of smectite/(illite + chlorite) ratio presents a predominant precession periodicity, synchronous with the northern hemisphere summer insolation changes and therefore with that of the East Asian summer monsoon. Variations in K2O/Al2O3 are characterized by eccentricity cycles, increasing during interglacials when the East Asian summer monsoon is enhanced. Based on the knowledge of sediment provenances, we suggest that these two proxies in the South China Sea are linked to the East Asian summer monsoon evolution with different mechanisms, which are (1) contemporaneous chemical weathering intensity in Luzon for smectite/(illite + chlorite) ratio and (2) river denudation intensity for K2O/Al2O3 ratio of bulk sediment. PMID:28176842

  8. 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


    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.

  9. 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


    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 (western China are transformed into ferrihydrite by atmospheric chemical processes during their long-range transport to eastern China and Japan based on the speciation by X-ray absorption fine structure (XAFS and other methods such as X-ray diffraction and chemical extraction. Moreover, it was found that iron in the dust after the transport becomes more soluble in our leaching experiments conducted for 24 h compared with those for initial dusts possibly due to the formation of ferrihydrite in the atmosphere. Our findings suggested that ferrihydrite secondarily formed during the transport is an important source of soluble iron species, which can be more soluble than clay minerals initially contained in the mineral dust such as illite and chlorite.

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

    Directory of Open Access Journals (Sweden)

    Fereshteh Bayat


    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.

  11. Mass Concentration and Mineralogical Characteristics Aerosol Particles Collected at Dunhuang During ACE-Asia

    Institute of Scientific and Technical Information of China (English)


    Measurements were performed in spring 2001 and 2002 to determine the characteristics of soil dust in the Chinese desert region of Dunhuang, one of the ground sites of the Asia-Pacific Regional Aerosol Characterization Experiment (ACE-Asia). The mean mass concentrations of total suspended particle matter during the spring of 2001 and 2002 were 317 μg m-3 and 307 μg m-3, respectively. Eleven dust storm events were observed with a mean aerosol concentration of 1095 μg m-3, while the non-dusty days with calm or weak wind speed had a background aerosol loading of 196 μg m-3 on average in the springtime.The main minerals detected in the aerosol samples by X-ray diffraction were illite, kaolinite, chlorite, quartz,feldspar, calcite and dolomite. Gypsum, halite and amphibole were also detected in a few samples. The mineralogical data also show that Asian dust is characterized by a kaolinite to chlorite (K/C) ratio lower than 1 whereas Saharan dust exhibits a K/C ratio larger than 2. Air mass back-trajectory analysis show that three families of pathways are associated with the aerosol particle transport to Dunhuang, but these have similar K/C ratios, which further demonstrates that the mineralogical characteristics of Asian dust are different from African dust.

  12. Remote sensing and GIS prospectivity mapping for magmatic-hydrothermal base- and precious-metal deposits in the Honghai district, China (United States)

    Wang, Gongwen; Du, Wenhui; Carranza, Emmanuel John M.


    In this paper, we constructed an exploration target model for volcanogenic massive sulfide and hydrothermal deposits in Honghai district (China) using moderate resolution ETM+, ASTER, and hyperspectral Hyperion images and high resolution ZY-3 images, and weights-of-evidence (WofE) analysis and concentration-area (C-A) fractal modeling. The methodology and mapping steps were: (1) ETM + images were used to extract hydroxyl and iron-oxide alterations for identification of linear and ring fault structures and prospective zones in regional scale; (2) ASTER images were used to extract SiO2 index, kaolinite, chlorite, propylite, potassium, carbonate, and limonite alterations for identification of mineralization zones in district scale; (3) hyperspectral Hyperion images were analyzed to identify mineral components for identification of Cusbnd Au deposit zones in district scale; (4) high resolution ZY-3 images were used to extract geological objects (e.g., volcanic rocks, integration, and linear and ring fault structures) and cross-validate multiple type alterations and their associations with lithological strata based on interpretation of ETM+ and ASTER images; (5) alteration/structural factors and geological objects were integrated for mineral prospectivity mapping by WofE analysis, and mineral prospectivity was classified by (C-A) fractal modeling. Ring faults, iron-oxide alteration, chlorite alteration and silicification are important exploration factors, whereas carbonate alteration, potassic alteration, and linear faults are secondary exploration factors. Ten exploration targets were recognized in the Honghai district.

  13. Chemical modification of cellulose extracted from sugarcane bagasse: Preparation of hydroxyethyl cellulose

    Directory of Open Access Journals (Sweden)

    E.S. Abdel-Halim


    Full Text Available Cellulose was extracted from sugarcane bagasse by alkaline extraction with sodium hydroxide followed by delignification/bleaching using sodium chlorite/hexamethylenetetramine system. Factors affecting extraction process, including sodium hydroxide concentration, hexamethylenetetramine concentration and temperature were studied and optimum conditions for alkaline extraction were found to be boiling finely ground bagasse under reflux in 1 N sodium hydroxide solution and then carrying out the delignification/bleaching treatment at 95 °C using 5 g/l sodium chlorite together with 0.02 g/l hexamethylenetetramine. The extracted cellulose was used in the preparation of hydroxyethyl cellulose through reaction with ethylene oxide in alkaline medium. Factors affecting the hydroxyethylation reaction, like sodium hydroxide concentration during the alkali formation step, ethylene oxide concentration, reaction temperature and reaction duration were studied. Optimum conditions for hydroxyethylation reaction were using 20% NaOH solution and 200% ethylene oxide (based on weight of cellulose, carrying out the reaction at 100 °C for 60 min.

  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 (United States)

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


    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. 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


    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.

  16. 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


    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.

  17. Geomorphological stability of Permo-Triassic albitized profiles - case study of the Montseny-Guilleries High (NE Iberia) (United States)

    Parcerisa, D.; Casas, L.; Franke, C.; Gomez-Gras, D.; Lacasa, G.; Nunez, J. A.; Thiry, M.


    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

  18. Unbiased isotope equilibrium factors from partial isotope exchange experiments in 3-exchange site systems (United States)

    Agrinier, Pierre; Javoy, Marc


    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

  19. Two-stage fluid flow and element transfers in shear zones during collision burial-exhumation cycle: Insights from the Mont Blanc Crystalline Massif (Western Alps) (United States)

    Rolland, Y.; Rossi, M.


    The Mont-Blanc Massif was intensely deformed during the Alpine orogenesis: in a first stage of prograde underthrusting at c. 30 Ma and in a second stage of uplift and exhumation at 22-11 Ma. Mid-crustal shear zones of 1 mm-50 m size, neighbouring episyenites (quartz-dissolved altered granite) and alpine veins, have localised intense fluid flow, which produced substantial changes in mineralogy and whole-rock geochemistry. Four main metamorphic zones are oriented parallel to the strike of the massif: (i) epidote, (ii) chlorite, (iii) actinolite-muscovite ± biotite and (iv) muscovite ± biotite. In addition, phlogopite-bearing shear zones occur in the chlorite zone, and calcite-bearing shear zones are locally found in the muscovite zone. The initial chemical composition of the granitic protolith is relatively constant at massif scale, which allows investigating compositional changes related to shear zone activity, and subsequent volume change and elements mobility. The variations of whole-rock composition and mineral chemistry in shear zones reflect variations in fluid/rock ratios and fluid's chemistry, which have produced specific mineral reactions. Estimated time-integrated fluid fluxes are of the order of 106 m3/m2. The mineral assemblages that crystallised upon these fluid-P-T conditions are responsible for specific major and trace element enrichments. The XFe (Fe/Fe + Mg) pattern of shear zone phyllosilicates and the δ13C pattern of vein calcite both show a bell-type pattern across the massif with high values on the massif rims and low values in the centre of the massif. These low XFe and δ13C values are explained by down temperature up-flow of a Fe-Mg-CO2-rich and silica-depleted fluid during stage 1, while the massif was underthrusting. These produced phlogopite, chlorite and actinolite precipitation and quartz hydrolysis, resulting in strong volume losses. In contrast, during stage 2 (uplift), substantial volume gains occurred on the massif rims due to the

  20. Recent and Late Quaternary sedimentation processes in the area of the SE Mediterranean Sea (United States)

    Hamann, Y.; Ehrmann, W.; Schmiedl, G.; Dulski, P.; Kuhnt, T.


    The present distribution of clay minerals in the southeastern Levantine Sea reveals a complex pattern of different source areas and dispersions of the main clay minerals smectite, illite, kaolinite, chlorite, and palygorskite. Smectite dominates the suspension load of the Nile River and rivers of the Near East. Sources of illite are dust- bearing winds blowing from the Saharan desert and the northern mainland of the Levantine Sea. Kaolinite is prevalent in the sediment yield of rivers which drain the Sinai, in sediments of wadis which discharge into the Nile River, and in dust loads of African storms. Palygorskite and chlorite are mainly derived from several dust bearing wind systems of the North and Central African continent, whereas chlorite is also provided by dust-bearing winds of the northeastern Mediterranean mainland. The clay mineral distributions and XRF element data of a sediment core from the southeastern Levantine Sea, spanning the last 27,000 years, show that the sediments are mainly affected by the discharge of the Nile River. The provenance of clay minerals provides a sensitive recorder of changes in the Nile River discharge and therefore in the climate conditions in the catchment of its tributaries. The glacial section of the core is characterized by low smectite concentrations, high K/Al ratios and low linear sedimentation rates when compared to the Holocene suggesting a low influence by the Nile outflow. Subsequently, during the early and middle Holocene, when the North African continent was influenced by more humid conditions during the African Humid Period, our record shows high proportions of smectite and low K/Al ratios which likely reflect higher discharge rates of the River Nile. In contrast to the sharp beginning and end of the African Humid Period as recorded in West African records at 15 and 5.5 kyr BP, our record in the southeastern Levantine Sea shows more transitional patterns and trend towards slightly lower Nile discharge rates at


    Institute of Scientific and Technical Information of China (English)

    蓝先洪; 张宪军; 刘新波; 李日辉; 张志珣


    通过对南黄海表层沉积物295个站位的黏土矿物含量分析,研究了南黄海表层沉积物黏土矿物的组合特征、分布规律及与物质来源的关系.南黄海表层沉积物中伊利石含量最高,蒙脱石和高岭石含量次之,绿泥石含量最低;黏土矿物的组合类型以伊利石-蒙脱石-高岭石-绿泥石型为主,伊利石-高岭石-蒙脱石-绿泥石型次之;南黄海表层沉积物黏土矿物主要为陆源成因,物质主要来源于黄河和长江的供给.现代黄河物质及老黄河物质主要沉积于南黄海的西部和中部;长江物质主要在南黄海的西南和中北部区域沉积,东部物质反映来自朝鲜半岛的物质对南黄海东部的作用.%The clay minerals composition of the surface sediments in the South Yellow Sea from 295 stations were studied with focus on clay assemblages and their distribution pattern as well as provenance. The research results show that illite dominates in surface sediments of the South Yellow Sea with smectite or kao-linite as the second and chlorite the lowest. The assemblage of illite-smectite-kaolinete-chlorite is the main type of the clay minerals assemblage in the area, followed by the illite-kaolinete-smectite-chlorite assemblage. Clay minerals are mainly from the Yellow River and Yangtze River. Materials from both the recent and the ancient Yellow River deposited mainly in the western, middle part of the South Yellow Sea, while the substance from the Yangtze River deposited mainly in the southwestern and southern parts. In the eastern part of the study area, an influence of the material from the Korean peninsula was observed.

  2. HFSE (High Field Strength Elements)-transport and U-Pb-Hf isotope homogenization mediated by Ca-bearing aqueous fluids at 2.04 Ga: Constraints from zircon, monazite, and garnet of the Venetia Klippe, Limpopo Belt, South Africa (United States)

    Zeh, A.; Gerdes, A.


    Results from laser-ablation inductively-coupled-plasma mass spectrometry (LA-ICP-MS) and isotope dilution (ID) analyses of minerals and rocks from a single outcrop of the Venetia Klippe of the Limpopo Belt indicate that the U-Pb and Hf isotope system homogenized on the decimetre scale under amphibolite-facies conditions of ⩽645 ± 25 °C and ⩽7.0 ± 1.1 kbar, i.e. in the presence of an aqueous fluid phase. For a metabasite sample, homogenization is supported by isotope analyses of metamorphic zircon, garnet, and whole rock, which yield a six-point Lu-Hf isochron age of 2039.7 ± 3.4 Ma, with initial 176Hf/177Hf of 0.28126 ± 0.00001, and a U-Pb zircon age of 2042 ± 10 Ma. The occurrence of a few inherited magmatic zircon cores with ages up to 2705 Ma, and with significantly lower initial 176Hf/177Hf of 0.28112, however, indicate that homogenization was incomplete. For a chlorite-biotite-garnet schist isotope homogenization is reflected by within error identical zircon and monazite U-Pb ages of 2045 ± 10 Ma and 2041 ± 8 Ma, respectively, and by a zircon-garnet-whole rock Lu-Hf isochron age of 2083 ± 63 Ma, with an initial 176Hf/177Hf of 0.28140 ± 0.00003. Contemporaneous formation of metamorphic zircon, monazite and garnet in the chlorite schist is not only supported by the isotope data, but also by chlorite inclusions in all three minerals, and by inclusions of metamorphic zircon in garnet. The inclusion textures and the identical initial 176Hf/177Hf support the conclusion that metamorphic zircon grains precipitated from an aqueous fluid phase, after dissolution of zirconium-bearing phases elsewhere, followed by a major HFSE transport, and Hf isotope homogenization. This fluid perhaps was Ca-bearing, as is suggested by the fact that garnet in the schist sample is the only Ca-bearing phase, and that metamorphic monazite, dating the metamorphic peak, is partially replacement by apatite. The fact that the metamorphic zircon rims in the metabasite sample have

  3. Reversibility of soil forming clay mineral reactions induced by plant - clay interactions (United States)

    Barré, P.; Velde, B.


    Recent data based upon observations of field experiments and laboratory experiments suggest that changes in phyllosilicate mineralogy, as seen by X-ray diffraction analysis, which is induced by plant action can be reversed in relatively short periods of time. Changes from diagenetic or metamorphic mineral structures (illite and chlorite) to those found in soils (mixed layered minerals in the smectite, hydroxy-interlayer mineral and illites) observed in Delaware Bay salt marsh sediments in periods of tens of years and observed under different biologic (mycorhize) actions in coniferous forests in the soil environment can be found to be reversed under other natural conditions. Reversal of this process (chloritisation of smectitic minerals in soils) has been observed in natural situations over a period of just 14 years under sequoia gigantia. Formation of smectite minerals from illite (potassic mica-like minerals) has been observed to occur under intensive agriculture conditions over periods of 80 years or so under intensive zea mais production. Laboratory experiments using rye grass show that this same process can be accomplished to a somewhat lesser extent after one growing season. However experiments using alfalfa for 30 year growing periods show that much of the illite content of a soil can be reconstituted or even increased. Observations on experiments using zea mais under various fertilizer and mycorhize treatments indicate that within a single growing season potassium can be extracted from the clay (illite layers) but at the end of the season the potassium can be restored to the clay structures and more replaced that extracted. Hence it is clear that the change in clay mineralogy normally considered to be irreversible, illite to smectite or chlorite to smectite observed in soils, is a reversible process where plant systems control the soil chemistry and the soil mineralogy. The changes in clay mineralogy concern mostly the chemical composition of the interlayer

  4. Fluid-induced Blueschist Preservation on Syros, Cyclades, Southern Greece (United States)

    Kleine, B. I.; Huet, B.; Skelton, A. D. L.


    Local examples of preservation of high-pressure, low-temperature (HP-LT) mineral assemblages within retrograde metamorphosed greenschist are recorded from the Cyclades, Greece. Several models have been proposed to explain the preservation of HP-LT rocks in these areas. On Sifnos, a capping effect of impermeable marble units below the preserved blueschists caused diversion of the upward, cross-layer infiltration of retrograde fluids [1]. On Tinos, blueschist preservation occurred due to retrograde fluid flow channelization along lithological contacts with high flux rates [2]. HP-LT minerals were preserved in regions adjacent to these contacts where fluid fluxes were smaller. We propose a different mechanism of blueschist preservation based on observations from a costal section near Fabrika on Syros. At this locality a high strain zone cuts through a retrograde greenschist. Along the fault a dark blue halo occurs within the greenschist. Whole rock analyses along a profile from the fault into the greenschist show that only the areas directly adjacent to the deformation zone show chemical evidence of metasomatism, whereas the areas further away are chemically similar to greenschist. Point counting of 1000 evenly spaced points in thin sections of the profile shows a clear blueschist to greenschist transition with a blueschist mineral assemblage (glaucophane+phengite+calcite) nearer to the metasomatic zone and a typical greenschist mineral assemblage (epidote+chlorite+albite) farther away. We propose the following model to explain preservation of HP-LT mineral assemblage in this locality. During retrograde metamorphism a water-rich fluid infiltrated the blueschist rock from below. This occurred close to the brittle-ductile transition. This fluid caused a reaction front to propagate into the overlying blueschist at which its mineral assemblage glaucophane+phengite+calcite was replaced by the greenschist mineral assemblage epidote+albite+chlorite. Upwards-flowing fluid

  5. Climatic control of sediment transport from the Himalayas to the proximal NE Bengal Fan during the last glacial-interglacial cycle (United States)

    Joussain, Ronan; Colin, Christophe; Liu, Zhifei; Meynadier, Laure; Fournier, Léa; Fauquembergue, Kelly; Zaragosi, Sébastien; Schmidt, Frédéric; Rojas, Virginia; Bassinot, Franck


    Clay mineralogy, siliciclastic grain-size, major elements, 87Sr/86Sr, and εNd analyses of deep-sea sediments cored in the north-eastern Bay of Bengal are used to reconstruct evolution of detrital sources and sediment transport to the proximal part of the Bengal deep-sea fan during the last climatic cycle. εNd values (-13.3 to -9.7) and 87Sr/86Sr ratios (0.721-0.733) indicate a mixture of sediments originating from the Ganges-Brahmaputra rivers and the Indo-Burman ranges. Interglacial Marine Isotopic Stages (MIS) 5 and 1 are associated with a higher contribution of sediments from the Ganges-Brahmaputra river system than is the case for glacial MIS 6, 4, 3, and 2. Siliciclasitic grain-size combined with Si/Al and Si/Fe ratios indicate coarser glacial sediments with numerous turbidite layers. Glacial turbidite layers display similar clay mineralogical compositions to hemipelagic sediments. Only few of turbidite layers (MIS 6, 4, and 2) are slightly unradiogenic (εNd -13.3), suggesting a higher contribution of Ganges-Brahmaputra river sediments. Independently of changes in the sedimentary sources, the smectite/(illite + chlorite) ratio of cores located on the NE Bengal Fan indicates higher inputs of primary minerals (illite and chlorite) from the highlands of the river basins (relief) during glacial MIS 6, 4, 3, and 2 and an increased contribution of pedogenic minerals (smectite and kaolinite) during interglacial MIS 5 and 1. Maximum smectite/(illite + chlorite) ratios during the warm sub-stages of MIS 5 suggest an intensification of summer monsoon rainfall associated with higher rates of physical erosion of the Indo-Gangetic flood-plain and/or dominant summer hydrological conditions transporting a higher proportion of sediments deriving from the Ganges-Brahmaputra rivers to the NE Bengal Fan. In addition, a higher production of smectite in soils of the Indo-Gangetic flood-plain during periods of intensification of monsoon rainfall cannot be excluded.

  6. Brittle tectonothermal evolution in the Forsmark area, central Fennoscandian Shield, recorded by paragenesis, orientation and 40Ar/ 39Ar geochronology of fracture minerals (United States)

    Sandström, Björn; Tullborg, Eva-Lena; Larson, Sven Åke; Page, Laurence


    In this paper, we show how studies of fracture mineral paragenesis, their orientation and 40Ar/ 39Ar geochronology can be applied in order to recognise the brittle tectonothermal evolution in an area. Samples were selected from nearly 18 km of drill cores from the upper 1 km of the Fennoscandian Shield obtained during the site investigation for a repository of spent nuclear fuel in Forsmark, central Sweden. Four major events of fracturing and/or reactivation of fractures associated with fracture mineralisation have been distinguished. The first event was characterised by precipitation of epidote, quartz and chlorite, along preferably sub-horizontal and gently-dipping fractures or steep, WNW-ESE to NW-SE fractures. Precipitation occurred between 1.8 and 1.1 Ga, possibly during the late stage of the Svecokarelian orogeny close to 1.8-1.7 Ga. The second event is associated with precipitation of hematite-stained adularia and albite, prehnite, laumontite, calcite and chlorite, preferably along steep, ENE-WSW to NNE-SSW and NNW-SSE fractures. Precipitation occurred around 1107 ± 7 to 1034 ± 3 Ma, probably due to effects from the Sveconorwegian orogeny. This event was followed by a period with dissolution of fracture minerals and subsequent precipitation of mainly calcite, quartz, pyrite and asphaltite during the Palaeozoic. The formation fluid emanated from an overlying organic-rich sedimentary cover. Precipitation occurred during reactivation of Proterozoic fractures, but formation of new fractures is also inferred, possibly due to far-field effects of the Caledonian orogeny, or elevated hydrostatic pressure due to its foreland basin. The latest event is dominated by clay minerals, chlorite and calcite along hydraulically conductive fractures. These minerals are prominent along sub-horizontal and gently-dipping fractures, but also occur in sets of steeply-dipping fractures. It is inferred that the hydraulically conductive fractures are Proterozoic structures in which

  7. 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


    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

  8. Physiological and genetic description of dissimilatory perchlorate reduction by the novel marine bacterium Arcobacter sp. strain CAB. (United States)

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


    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




    The presented studies were carried out in order to check the usefulness of subfossil wood for stable isotope analysis. The aim of research was also to define the optimal method of subfossil samples preparation. Subfossil samples used during the presented studies are a part of the multi-century dendrochronological scale. This chronology originates in an area situated around a small mountain lake — Schwarzersee, in Austria. The obtained results of stable carbon isotope measurements confirmed that the method of α-cellulose extraction by the application of acidic sodium chlorite and sodium hydroxide solutions removes resins and other mobile compounds from wood. Therefore, in the case of the analysed samples, the additional chemical process of extractives removing was found to be unnecessary. Studied wood samples contained an adequate proportion of α-cellulose similar to the values characteristic for the contemporary trees. This proved an adequate wood preservation which is essential for the conduction of isotopic research. PMID:26346297

  10. Effect of Steam Explosion Pretreatment on Bamboo for Enzymatic Hydrolysis and Ethanol Fermentation

    Directory of Open Access Journals (Sweden)

    Zhiqiang Li


    Full Text Available Based on the steam explosion pretreatment that has been applied to other types of lignocellulosic biomass, the steam explosion pretreatment of bamboo, along with a study of the chemical compositions and enzymatic hydrolyzability of substrates, was conducted. The results show that steam explosion pretreatment can greatly enhance the cellulose-to-glucose conversion yield after enzymatic hydrolysis, which is sometimes affected by bamboo age and steam explosion conditions. When the steam explosion pretreatment conditions were 2.0 MPa (pressure and 4 min (time, the cellulose-to-glucose conversion yield of 2-year-old bamboo substrate was 62.5%. However, the cellulose-to-glucose conversion yield of bamboo substrates after direct (without steam explosion pretreatment sodium chlorite/acetic acid delignification was 93.1%. Fermentation of enzymatic hydrolyzates with Saccharomyces cerevisiae resulted in about 88.1% to 96.2% of the corresponding theoretical ethanol yield after 24 h.

  11. PIXE analysis of museum soapstone sculptures from Esie, South-West Nigeria (United States)

    Olabanji, Simon O.; Olarewaju, Victor O.; Onabajo, Opeolu


    The PIXE technique was employed for the study of Esie Museum stone sculptures using 2.55 MeV protons from the 3 MeV tandem accelerator (NEC 3 UDH) in Lund, coupled with geological and archaeological findings. The aim is to elucidate and decipher the prodigious but rather enigmatic and bewildering stone sculptures. PIXE results show that the composition of the stone sculptures is approximately 41% talc-tremolite schist, 31% talc-chlorite schist, 15% talc-tremolite-anthophyllite schist and 13% talc-amphibolite schist. Thus the composition of Esie sculptures is found to be the same as the locally available talc schists present around Esie. The geological evidence (mineralogical results) corroborated this, as there was no textural or mineralogical difference between the talc-bearing country rock (outcrop) in Esie and the museum soapstone samples studied. Consequently, there is a very high probability that the sculptures were carved using the locally available talc schists.

  12. Sédimentologie et géochimie organique des sédiments superficiels de la lagune de Nador (Maroc nord-oriental) (United States)

    El-Alami, M.; Mahjoubi, R.; Damnati, B.; Kamel, S.; Icole, M.; Taieb, M.


    The Nador lagoon is situated at the eastern end of the Moroccan Rift along the Mediterranean coast. The superficial deposits are characterised by three types of litho-facies: sand, clay-sand and clay-silt-sand. The clay minerals show a homogeneous distribution with abundant illite and, in decreasing order, kaolinite, chlorite and smectite. The highest organic matter content does not exceed 10%. Organic C, total N, humic components analysis and "Rock-Eval" pyrolysis characterise the organic matter, compared to the superficial sediments. Most of the organic matter occurs as humic-acid and humin. Its distribution is controlled by the physico-chemical conditions and by the importance and composition of the detrital inputs.

  13. 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)


    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.


    Institute of Scientific and Technical Information of China (English)

    郑建华; 韩舞鹰


    The preparation method of ClO2, its some present products and application are introduced in this paper. Its preparation methods mainly include chemical and electrolysis methods, and their raw materials are mainly sodium chlorate, sodium chlorite and table salt. The present chloride dioxide products are mainly the stable ClO2 aqueous solution and solid chloride dioxide; the solid chloride dioxide has adsorbing type, gelatifying type and mono-packing type etc. due to different preparation technique. They are extensively applied to the aspects of disinfection, sterilization, algue removal, pulp-bleaching, air purification, food antisepsis and retaining freshness etc. of drinking water, industrial wastewater, hospital sewage, industrial cycle cooling water, fowl slaughter, indoor hygiene, beer production and aquiculture etc.%本文详细地介绍了二氧化氯的制备方法和现有的几种二氧化氯制品及其应用。

  15. 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)


    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.

  16. High resolution remote sensing information identification for characterizing uranium mineralization setting in Namibia (United States)

    Zhang, Jie-Lin; Wang, Jun-hu; Zhou, Mi; Huang, Yan-ju; Xuan, Yan-xiu; Wu, Ding


    The modern Earth Observation System (EOS) technology takes important role in the uranium geological exploration, and high resolution remote sensing as one of key parts of EOS is vital to characterize spectral and spatial information of uranium mineralization factors. Utilizing satellite high spatial resolution and hyperspectral remote sensing data (QuickBird, Radarsat2, ASTER), field spectral measurement (ASD data) and geological survey, this paper established the spectral identification characteristics of uranium mineralization factors including six different types of alaskite, lower and upper marble of Rössing formation, dolerite, alkali metasomatism, hematization and chloritization in the central zone of Damara Orogen, Namibia. Moreover, adopted the texture information identification technology, the geographical distribution zones of ore-controlling faults and boundaries between the different strata were delineated. Based on above approaches, the remote sensing geological anomaly information and image interpretation signs of uranium mineralization factors were extracted, the metallogenic conditions were evaluated, and the prospective areas have been predicted.

  17. An oxygen isotope and geochemical study of meteoric-hydrothermal systems at Pilot Mountain and selected other localities, Carolina slate belt (United States)

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


    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

  18. Identificación de metabasaltos alterados mediante datos ASTER Identification of altered metabasalts from ASTER data

    Directory of Open Access Journals (Sweden)

    Silvia Castro Godoy


    Full Text Available Los datos del sensor ASTER permitieron desarrollar una metodología sencilla, utilizando las bandas del infrarrojo de onda corta (subsistema SWIR, para prospectar cuerpos ígneos alterados que manifiestan diferencias espectrales con respecto a la roca de caja. A modo de ejemplo se detectó la alteración clorítica presente en metabasaltos intercalados en metasedimentitas de la Formación Puntilla de Uspallata en la Precordillera mendocina.ASTER data allowed developing a simple methodology, using the Short Wave Infrared spectral bands (SWIR, in order to detect alteration minerals that affect igneous bodies and have spectral differences with the country rock. As an example chloritic alteration was detected in metabasalts interbedded in metasediments of Puntilla de Uspallata Formation, Precordillera Mendocina.

  19. Development of the Extra-low Permeability Oilfield of Ansai

    Institute of Scientific and Technical Information of China (English)

    Hu Wenrui


    @@ Reservoir Characteristics Ansai Oilfield is located in Ordos Basin. Its regional structure is a large westward-dipping monocline with dip angle less than 1°. The main producing interval is in Yanchang formation,Triassic, and the depositional environment is a delta deposit of inland fresh water lake. This oilfield is distributed in distributary channel sandstone of delta plain,front underwater distributary channel sandstone and front river mouth bar sandstone of flowershape. Lithologic trap is the primary trap type and shows complex rhythm with average reservoir thickness of 11 to 15 m and Average porosity of 11% to14%. It is fine grained and well sorted sandy arkose. The cementing material is predominantly secondary chlorite, secondary laumontite and calcite with content of 11% to 14%.

  20. Analysis of the Importance of Oxides and Clays in Cd, Cr, Cu, Ni, Pb and Zn Adsorption and Retention with Regression Trees (United States)

    González-Costa, Juan José; Reigosa, Manuel Joaquín; Matías, José María; Fernández-Covelo, Emma


    This study determines the influence of the different soil components and of the cation-exchange capacity on the adsorption and retention of different heavy metals: cadmium, chromium, copper, nickel, lead and zinc. In order to do so, regression models were created through decision trees and the importance of soil components was assessed. Used variables were: humified organic matter, specific cation-exchange capacity, percentages of sand and silt, proportions of Mn, Fe and Al oxides and hematite, and the proportion of quartz, plagioclase and mica, and the proportions of the different clays: kaolinite, vermiculite, gibbsite and chlorite. The most important components in the obtained models were vermiculite and gibbsite, especially for the adsorption of cadmium and zinc, while clays were less relevant. Oxides are less important than clays, especially for the adsorption of chromium and lead and the retention of chromium, copper and lead. PMID:28072849

  1. Mineralogy of a mudstone at Yellowknife Bay, Gale crater, Mars. (United States)

    Vaniman, D T; Bish, D L; Ming, D W; Bristow, T F; Morris, R V; Blake, D F; Chipera, S J; Morrison, S M; Treiman, A H; Rampe, E B; Rice, M; Achilles, C N; Grotzinger, J P; McLennan, S M; Williams, J; Bell, J F; Newsom, H E; Downs, R T; Maurice, S; Sarrazin, P; Yen, A S; Morookian, J M; Farmer, J D; Stack, K; Milliken, R E; Ehlmann, B L; Sumner, D Y; Berger, G; Crisp, J A; Hurowitz, J A; Anderson, R; Des Marais, D J; Stolper, E M; Edgett, K S; Gupta, S; Spanovich, N


    Sedimentary rocks at Yellowknife Bay (Gale crater) on Mars include mudstone sampled by the Curiosity rover. The samples, John Klein and Cumberland, contain detrital basaltic minerals, calcium sulfates, iron oxide or hydroxides, iron sulfides, amorphous material, and trioctahedral smectites. The John Klein smectite has basal spacing of ~10 angstroms, indicating little interlayer hydration. The Cumberland smectite has basal spacing at both ~13.2 and ~10 angstroms. The larger spacing suggests a partially chloritized interlayer or interlayer magnesium or calcium facilitating H2O retention. Basaltic minerals in the mudstone are similar to those in nearby eolian deposits. However, the mudstone has far less Fe-forsterite, possibly lost with formation of smectite plus magnetite. Late Noachian/Early Hesperian or younger age indicates that clay mineral formation on Mars extended beyond Noachian time.

  2. 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) (United States)

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


    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

  3. Oolitic ores in the Bakchar iron-ore cluster (Tomsk Oblast) (United States)

    Rudmin, M. A.; Mazurov, A. K.


    Oolitic iron ores are typified, and their morphology and composition are studied. Special attention is focused on the character of distribution of valuable and harmful admixtures and determination of the principal minerals concentrating these elements. As a result of this study, three types of ores are identified, such as "loose" ores, cemented ores with glauconite-chlorite-clay cement, and well-cemented ores with siderite cement. The morphology and composition of the ore oolites are characterized. The forms of occurrence of calcium phosphates (anapaite) and phosphates of rare-earth elements (monazite, cularite) that are related to the harmful phosphorus admixture are described. According to the analysis of the elemental composition, the fractions of (-1…+0.2) and (-1…+0.1) mm in the western and eastern segments, respectively, may be promising for processing.

  4. Soluble salt deposit in the Nihewan beds and its environmental significance

    Institute of Scientific and Technical Information of China (English)

    李容全; 乔建国; 邱维理; 翟秋敏; 李永良


    Observation and experimental analysis of soluble salt deposit along four profiles across the strata deposited in Nihewan paleolake basin enabled us to recognize the nature and evolution stages of the Nihewan paleolake and its significance in stratigraphical division and pa-leo-environmental reconstruction. The Nihewan paleolake was at least a weak-saline to semi-saline lake and represents an intracontinental lake in the semi-arid region. The lower member of sedimentary strata in the paleolake contains gypsum layer and gypsum lamellae. Soluble salt is mainly composed of SO42- and Ca2+ ions, representing a trend of the paleolake evolvinginto a stage of sulfate lake. The upper member of the strata has predominantly Cl-, K+, and Na+ ions in soluble salt, indicating a starting development of the paleolake to chlorite lake, but no salt rock was deposited, indicating a drying trend of the area.

  5. Evaluation methods for ceramic suitability of raw clays

    Directory of Open Access Journals (Sweden)

    Hajjaji M.


    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.

  6. Progress of Chlorine Dioxide Preparation Method%二氧化氯制备方法研究进展

    Institute of Scientific and Technical Information of China (English)

    吴建春; 杨佳财


    二氧化氯是一种具有高氧化性和强消毒性的化合物,本论文介绍了二氧化氯制备的化学法、电解法以及电化学法,并对几种工艺方法的优缺点进行了分析和比较,适合工业化生产的工艺主要是化学法中的氯酸钠法和亚氯酸钠法。%Chlorine dioxide is a high oxidation resistance and strong disinfection compound.This paper introduces the chemical preparation method of dioxide chlorine,electrolysis method and electrochemical method.The advantages and disadvantages of several processing methods were discussed and compared.The process suitable for industrial production is mainly sodium chlorate and sodium chlorite method.

  7. Dehydration-driven topotaxy in subduction zones (United States)

    Padrón-Navarta, José Alberto; Tommasi, Andréa; Garrido, Carlos J.


    Mineral replacement reactions play a fundamental role in the chemistry and the strength of the lithosphere. When externally or internally derived fluids are present, interface-coupled dissolution-precipitation is the driving mechanism for such reactions [1]. One of the microstructural features of this process is a 3D arrangement of crystallographic axes across internal interfaces (topotaxy) between reactant and product phases. Dehydration reactions are a special case of mineral replacement reaction that generates a transient fluid-filled porosity. Among others, the dehydration serpentinite is of special relevance in subduction zones because of the amount of fluids involved (potentially up to 13 wt.%). Two topotatic relationships between olivine and antigorite (the serpentine mineral stable at high temperature and pressure) have been reported in partially hydrated mantle wedge xenoliths [2]. Therefore, if precursor antigorite serpentine has a strong crystallographic preferred orientation (CPO) its dehydration might result in prograde peridotite with a strong inherited CPO. However for predicting the importance of topotactic reactions for seismic anisotropy of subduction zones we also need to consider the crystallization orthopyroxene + chlorite in the prograde reaction and, more importantly, the fact that this dehydration reaction produces a transient porosity of ca. 20 % vol. that results in local fluctuations of strain during compaction and fluid migration. We address this issue by a microstructural comparison between the CPO developed in olivine, orthopyroxene and chlorite during high-pressure antigorite dehydration in piston cylinder experiments (at 750ºC and 20 kbar and 1000ºC and 30 kbar, 168 h) and that recorded in natural samples (Cerro del Almirez, Betic Cordillera, Spain). Experimentally developed CPOs are strong. Prograde minerals show a significant inheritance of the former antigorite foliation. Topotactic relations are dominated by (001)atg//(100)ol

  8. Do suspended sediment and bedload move progressively from the summit to the sea along Magela Creek, northern Australia? (United States)

    Erskine, W. D.; Saynor, M. J.; Turner, K.; Whiteside, T.; Boyden, J.; Evans, K. G.


    Soil erosion rates on plots of waste rock at Ranger uranium mine and basin sediment yields have been measured for over 30 years in Magela Creek in northern Australia. Soil erosion rates on chlorite schist waste rock are higher than for mica schist and weathering is also much faster. Sediment yields are low but are further reduced by sediment trapping effects of flood plains, floodouts, billabongs and extensive wetlands. Suspended sediment yields exceed bedload yields in this deeply weathered, tropical landscape, but the amount of sand transported greatly exceeds that of silt and clay. Nevertheless, sand is totally stored above the topographic base level. Longitudinal continuity of sediment transport is not maintained. As a result, suspended sediment and bedload do not move progressively from the summit to the sea along Magela Creek and lower Magela Creek wetlands trap about 90.5% of the total sediment load input.

  9. Spinifex-textured komatiites in the south border of the Carajas ridge, Selva Greenstone belt, Carajás Province, Brazil (United States)

    Siepierski, Lincoln; Ferreira Filho, Cesar Fonseca


    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

  10. 云龙锡矿独特的矿床地质特征

    Institute of Scientific and Technical Information of China (English)



    The Yunlong tin deposit is controlled by a NNW tectonic zone. The primary ore bodios occur mainly in migmatized granites, occasionally in their external contact zones.The extending direction of tin ore bodies is approximately consistent with that of the regional tectonic line. Ore bodies in the three tin ore belts of the studied region fall into three typos: cassiterite-quartz tourmaline veins, cassiterite-quartz veinlets and cassiterite-quartz sulfide veins. The mineral compositions of the ore bodies are rather simple. The principal minerals are quartz, elbaite, schori, dravite, cassiterite,pyrrotite, pyrite and arsenopyrite.Wail-rock alteration is oharaeterized by silicification, tourmalinization, chloritization,etc. Tin ore veins are rich in boron and fluorine as mineralizing elements. The Yunlong deposit is a hypothermul tin deposit associated with migmatization,and ira metallogenetic epoch is Himalayan.

  11. Palaeoproterozoic Volcanic Massive Sulphides (VMS) in the Lithuanian crystalline basement: evidences for a back-arc tectonic setting (United States)

    Skridlaite, Grazina; Siliauskas, Laurynas


    In the southwestern part of the East European Craton (EEC), several events of Palaeoproterozoic volcanic arc magmatic activity were recognized in the concealed crystalline basement. In Lithuania, the TTG suites of 1.89 Ga and 1.86-1.84 Ga were later metamorphosed in amphibolite and granulite facies conditions. Remnants of a volcano-sedimentary sequence metamorphosed in green schist and amphibolite facies conditions were discovered in central and southern Lithuania. In southern Lithuania, the upper part of the Lazdijai 13 (Lz13) drilling (at c. 493 m depth) consists of exhalitic quartz chlorite cherts mixed with andesitic rocks. The rocks are impregnated with magnetite in some places replacing calcite. Most of the magnetite grains are overgrown by a dendritic kovelite, which may have formed while magnetite was still in aqueous surrounding. Other accessory minerals are xenotime, zircon, apatite, Sr-Ba sulphates etc. The cherts are underlain by a metaandesite which volcanic structures were obscured by hydrothermal alteration, i.e. the idiomorphic magnetite crystals and porphyritic plagioclase grains were replaced by clay minerals and quartz or muscovite in many places. Thin metamorphosed mudstone layers turned into garnet, biotite (+/-staurolite) and chlorite schists. The rocks were affected by silicification, chloritization, argilitization and carbonatization. Taking into account the rock composition, micro and macro scale alteration zones and absence of breccia, the whole package resembles an outer part of the VMS stockwork. The lower boundary at 526 m is sharp, marked by a quartz vein, below which lies quartz, biotite (+/- chlorite) bearing schist with minor tremolite (former sandstone). It was intensely affected by silicification, and was enriched in Na, K and Ca. Accessory minerals are monazite, xenotime, apatite and detrital zircon. The schist exhibits fine mineral foliation, and is fine-grained. A 4 m thick granitic vein cuts the rock at 654 m depth, below

  12. Rayleigh-type parametric chemical oscillation. (United States)

    Ghosh, Shyamolina; Ray, Deb Shankar


    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.

  13. Parametric spatiotemporal oscillation in reaction-diffusion systems. (United States)

    Ghosh, Shyamolina; Ray, Deb Shankar


    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.

  14. A Lattice Boltzmann Model for Oscillating Reaction-Diffusion (United States)

    Rodríguez-Romo, Suemi; Ibañez-Orozco, Oscar; Sosa-Herrera, Antonio


    A computational algorithm based on the lattice Boltzmann method (LBM) is proposed to model reaction-diffusion systems. In this paper, we focus on how nonlinear chemical oscillators like Belousov-Zhabotinsky (BZ) and the chlorite-iodide-malonic acid (CIMA) reactions can be modeled by LBM and provide with new insight into the nature and applications of oscillating reactions. We use Gaussian pulse initial concentrations of sulfuric acid in different places of a bidimensional reactor and nondiffusive boundary walls. We clearly show how these systems evolve to a chaotic attractor and produce specific pattern images that are portrayed in the reactions trajectory to the corresponding chaotic attractor and can be used in robotic control.

  15. Paragenesis and chemistry of multistage tourmaline formation in the sullivan Pb-Zn-Ag deposit, British Columbia (United States)

    Jiang, S.-Y.; Palmer, M.R.; Slack, J.F.; Shaw, D.R.


    Detailed petrographic study, scanning electron microscope imaging, and electron microprobe analyses of tourmalines from the Sullivan Pb-Zn-Ag massive sulfide deposit (British Columbia, Canada) document multiple paragenetic stages and large compositional variations. The tourmalines mainly belong to two common solid-solution series: dravite-schorl and dravite-uvite. Ca- and Fe-rich feruvite and alkali-deficient tourmalines are present locally. Products of tourmaline-forming stages include (from oldest to youngest): (1) rare Fe-rich dravite-schorl within black tourmalinite clasts in footwall fragmental rocks; (2) widespread Mg-rich, very fine grained, felted dravite in the footwall (the main type of tourmaline in the footwall tourmalinite pipe); (3) recrystallized, Fe-rich dravite-schorl (locally Ca-Fe feruvite) in the tourmalinite pipe, which preferentially occurs near postore gabbroic intrusions; (4) Mg-rich dravite or uvite associated with chlorite-pyrrhotite and chlorite-albite-pyrite-altered rocks in the shallow footwall and hanging wall; (5) discrete Mg-rich tourmaline grains associated with chlorite and discordant Mg-rich tourmaline rims which occur on disseminated Fe-rich schorl in the bedded Pb-Zn-Ag ores. The timing of rare Fe-rich schorl in the bedded ores is uncertain, but it most likely occurred during or between stages 2 and 3. The different paragenetic stages and their respective tourmaline compositions are interpreted in terms of a multistage evolution involving contributions from: (1) variable mixtures of synsedimentary, Fe-rich hydrothermal fluids and entrained seawater; (2) postore, Fe-rich, gabbro-related hydrothermal fluids; and (3) postore metamorphic reactions. Early synsedimentary, Fe-rich hydrothermal fluids which contained little or no entrained seawater formed Fe-rich black tourmalinite clasts locally in the footwall. The major type of tourmaline in the footwall tourmalinite pipe is Mg rich, recording seawater entrainment under high water

  16. Nature minéralogique et rôle nutritionnel des argiles de sols céréaliers en région subhumide à semi-aride (Tunisie) (United States)

    Ben Hassine, Habib


    The cereal soils of the Northwest of Tunisia derive most of the time, from alluvial deposits or altered remains of carbonated and clayey rocks. Extraction of the clayey fraction permitted to reveal the presence of the following clayey minerals: kaolinite, illite, smectite, chlorite, as well as an illite-smectite interstratified layer, which is present in the deep horizons of the vertisol and in the isohumic soil. The presence of such types of clays shows that the evolution mechanism of soils is weathering of primary minerals inherited from the sedimentary rocks of the Northwest of Tunisia. These clays ensure to soils most of their cationic exchange capacity. Thanks to these clays, which have Ca ++, Mg ++ and K + as exchangeable cations, the chemical fertility of these soils is ensured. It may be improved by increasing contents of organic matter, which is naturally few abundant in these soils. To cite this article: H. Ben Hassine, C. R. Geoscience 338 (2006).

  17. Petrography and U-Pb Zircon Geochronology of Geological Units of the Mesa de Cocodite, Península de Paraguaná, Venezuela (United States)

    Mendi, D.; Baquero, M. L.; Oliveira, E. P.; Urbani, F.; Pinto, J.; Grande, S.; Valencia, V.


    Several continental crust units crop out in The Mesa de Cocodite, central Paraguaná Peninsula, Northwestern Venezuela, including a newly mapped quartz-feldspar gneiss that intruded the El Amparo Pluton, a major low-graded metamorphic unit of Permian age. It is unconformably overlying by Late Jurassic phyllites of the Pueblo Nuevo Formation. All these units are cross-cut by narrow dykes. This contribution focuses on the petrography and LA-ICP-MS U-Pb zircon dating of the igneous units, with the aim of constraining magmatism and its tectonic significance in the area. The quartz-feldspar gneiss consists of albite, bluish-smoked quartz, muscovite-chlorite, epidote and zircon. The enclosing El Amparo Pluton is typically a coarse-grained and thick-banded metagranodiorite, containing andesine, quartz, hornblende, epidote, K-feldspar, biotite, chlorite, titanite and zircon. The younger dykes consist of fine-grained, porphyritic hornblende diorites that contain numerous hornblende phenocrysts. The main minerals are andesine, hornblende, quartz, and chlorite. Accessory minerals include zircon, epidote and opaques. A felsic gneiss xenolith collected from the dykes contain quartz, K-feldspar, chlorite, epidote, albite and zircon. Zircon population in the quartz-feldspar gneiss displays a discordia trend, ranging in age from 1050-750 Ma but mostly around 950-900 Ma, which may represent a peak high-grade metamorphism in the area. The El Amparo Pluton provides a concordant Permian age (271.3±6.5 Ma), which is comparable with previous reported U-Pb ages in titanite. Because the porphyry dykes cross-cut all the units in the area, they should be post-Late Jurassic in Age; however, all dated zircons from the dykes are in the range of 1200-750 Ma. The absence of younger ages can be attributed to either formation during a relatively low temperature magmatic event, which generated very narrow younger zircon rims only and thus undetectable with the technique used, or a completely lack

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

    DEFF Research Database (Denmark)

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


    Soil organic carbon (SOC) storage and turnover is influenced by interactions between organic matter and the mineral soil fraction. However, the influence of clay content and type on SOC turnover rates remains unclear, particularly in tropical soils under natural vegetation. We examined the lability...... 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....... Basal soil respiration rates were determined from bulk soils and soil fractions. Substrate induced respiration rates were determined from soil fractions. SOC lability was significantly influenced by clay mineralogy, but not by clay content when compared across contrasting clay minerals. The lability...

  19. Electric plasma discharge combustion synthesis of chlorine dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Dotson, R. L.; Geren, G. W.


    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.

  20. Selective chlorine dioxide determination using gas-diffusion flow injection analysis with chemiluminescent detection

    Energy Technology Data Exchange (ETDEWEB)

    Hollowell, D.A.; Gord, J.R.; Gordon, G.; Pacey, G.E.


    An automated chemiluminescent technique has been developed utilizing the advantages of gas-diffusion flow injection analysis. A gas-diffusion membrane separates the donor (sampling) stream from the acceptor (detecting) stream and removes ionic interferences. A novel chemiluminescence flow-through detector cell is used to measure the concentration of chlorine dioxide as a function of the intensity of the chemiluminescence produced from its reaction with luminol. The chemiluminescent reagent merges with the analyte directly in front of the photomultiplier tube in order to maximize the sensitivity of the system. The detection limit for chlorine dioxide is approximately 5 ppb. The method is over 1500 times more selective for chlorine dioxide than for chlorine on a mole basis. This method eliminates interference from iron and manganese compounds, as well as other oxychlorinated compounds such as chlorite ion and chlorate ion.


    Directory of Open Access Journals (Sweden)

    M. Sarwar Jahan


    Full Text Available Bleaching of soda-anthraquinone jute pulp by chlorine dioxide (ClO2 was studied to reach a target brightness of above 88% for the purpose of using less bleaching chemicals. The performance of either chlorine dioxide or peroxide in the final bleaching to boost brightness was also studied. The experimental results revealed that the final brightness depended on ClO2 charge in the Do and D1 stages. The brightness reversion was lower when the final stage brightening was done by peroxide. The use of Mg(OH2 in the D1 and D2 stages improved the final brightness due to the formation of less chlorate and chlorite during the Mg(OH2- based ClO2 brightening stages. The strength properties of pulp bleached by peroxide in the final stage was slightly better than that from ClO2 as the final ClO2 bleaching stage.

  2. Selective determination of chlorine dioxide using gas diffusion flow injection analysis

    Energy Technology Data Exchange (ETDEWEB)

    Hollowell, D.A.; Pacey, G.E.; Gordon, G.


    An automated absorbance technique for the determination of aqueous chlorine dioxide has been developed by utilizing gas diffusion flow injection analysis. A gas diffusion membrane is used to separate the donor (sampling) stream from the acceptor (detecting) stream. The absorbance of chlorine dioxide is monitored at 359 nm. The first method uses distilled water as the acceptor stream and gives a detection limit of 0.25 mg/L chlorine dioxide. This system is over 550 times more selective for chlorine dioxide than chlorine. To further minimize chlorine interference, oxalic acid is used in the acceptor stream. The detection limit for this system is 0.45 mg/L chlorine dioxide. This second system is over 5400 times more selective for chlorine dioxide than chlorine. Both methods show excellent selectivity for chlorine dioxide over iron and manganese compounds, as well as other oxychlorinated compounds such as chlorite and perchlorate ions. 18 references, 7 figures, 3 tables.

  3. 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)


    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.

  4. The geology, structure and mineralisation of the Oyu Tolgoi porphyry copper-gold-molybdenum deposits, Mongolia: A review

    Directory of Open Access Journals (Sweden)

    T.M. (Mike Porter


    Mineralisation is characterised by varying, telescoped stages of intrusion and alteration. Early A-type quartz veined dykes were followed by Cu-Au mineralisation associated with potassic alteration, mainly K-feldspar in quartz-monzodiorite and biotite-magnetite in basaltic hosts. Downward reflux of cooled, late-magmatic hydrothermal fluid resulted in intense quartz-sericite retrograde alteration in the upper parts of the main syn-mineral intrusions, and an equivalent chlorite-muscovite/illite-hematite assemblage in basaltic host rocks. Uplift, facilitated by syn-mineral longitudinal faulting, brought sections of the porphyry deposit to shallower depths, to be overprinted and upgraded by late stage, shallower, advanced argillic alteration and high sulphidation mineralisation. Key controls on the location, size and grade of the deposit cluster include (i a long-lived, narrow faulted corridor; (ii multiple pulses of overlapping intrusion within the same structure; and (iii enclosing reactive, mafic dominated wall rocks, focussing ore.

  5. Rayleigh-type parametric chemical oscillation

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Shyamolina; Ray, Deb Shankar, E-mail: [Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India)


    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.

  6. The differences in clay minerals between the northern and southern Chelungpu fault, Taiwan (United States)

    Hashimoto, Y.


    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

  7. Genesis of hydrothermal alterations using stable isotope geochemistry in Takestan area (Tarom zone

    Directory of Open Access Journals (Sweden)

    Batool Taghipou


    Full Text Available Hydrothermal alteration processes are extensively took place on volcanic and pyroclstics of Takestan area. Existence of abundant, deep fracturing and subvolcanic intrusions are enhanced extend hydrothermal alteration zones. The following alteration zones are determined: propylitic, argillic, advanced argillic and sillicic. There are outcropped and widespread in different size and limit. Formation of siliceous sinter, silicified tuffs with preserved primary sedimentary layering including pure mineralized alunite patches are most outstanding. Quartz, sussoritic plagioclase, chlorite, sericite and alunite are main mineral constituents in the volcanics. On the basis of geochemical data volcanic rocks are rhyolite, dacite, andesite, andesitic-basalt and basalt in composition. Acid-sulfate zone is the type of alteration in Tarom area and alunite is an index mineral of this zone. Results of 18O, D and 34S stable isotope geochemistry on altered minerals (muscovite, kaolinite and alunite, revealed that alteration fluids are magmatic in origin.


    Directory of Open Access Journals (Sweden)

    Vasile Rusu


    Full Text Available 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 alumosilicates, aluminum and iron hydroxides. The applied procedure for separation of clay fractions by sizing settling in liquid media proves to be very useful, enabling possibilities for more accurate identification of the clay constituents of diatomic material. Procedure allows to separate very clean clay fraction especially rich in montmorillonite, which can be utilized itself as mineral adsorbent for practical purposes.

  9. Petrography and geochemistry of basaltic rocks from the Conrad fracture zone on the America-Antarctica Ridge (United States)

    le Roex, Anton P.; Dick, Henry J. B.


    Intrusive and extrusive basaltic rocks have been dredged from the Conrad fracture zone (transecting the slow-spreading America-Antarctica Ridge). The majority of rocks recovered are holocrystalline with the dominant mineral assemblage being plagioclase plus clinopyroxene with or without minor Fe-Ti oxides (olivine occurs in only three samples) and many of the samples show evidence of extensive alteration. Secondary minerals include chlorite, actinolite, K- and Na-feldspar, analcite and epidote. In terms of bulk chemistry the rocks are characterized by their generally evolved and highly variable compositions (e.g. Mg *=0.65-0.35;TiO 2=0.7-3.6%;Zr=31-374ppm;Nb=differentiation observed in the Conrad fracture zone basalts implies some additional constraint other than spreading rate on the formation of ferrobasalt and reaffirms the importance of extensive crustal differentiation during the production of this basalt type.

  10. Radon measurements in soil and water and its relation with geology, Garhwal Himalaya, India

    Energy Technology Data Exchange (ETDEWEB)

    Choubey, V.M. [Wadia Institute of Himalayan Geology, Dehra Dun (India)


    Radon concentrations were measured in soil and spring water in the Garhwal Himalaya using radon emanometer. The measurements were made in the Berinag, Bhatwari and Munsiari Formations. The main rock types in the area are sheared granitic gneiss, porphyritic gneiss, chlorite schist, mica schist, mylonite, slate, phyllite, quartzite and metabasic. The radon concentrations were found to vary from 1.2 kBq/m{sup 3} to 56.5 kBq/m{sup 3} in soil and 0.4 Bq/l to 887 Bq/l in water. The results suggest that the radon emanation is controlled not only by uranium content of the rock and soil but also by structural zones (thrust, fault, etc.) which help in the easy migration of radon from the deeper parts of the earth crust. (author)

  11. The effects of hemicelluloses and lignin removal on water uptake behavior of hemp fibers. (United States)

    Pejic, Biljana M; Kostic, Mirjana M; Skundric, Petar D; Praskalo, Jovana Z


    This study investigated the individual influences of hemicelluloses and lignin removal on the water uptake behavior of hemp fibers. Hemp fibers with different content of either hemicelluloses or lignin were obtained by chemical treatment with 17.5% sodium hydroxide or 0.7% sodium chlorite. Various tests (capillary rise method, moisture sorption, water retention power) were applied to evaluate the change in water uptake of modified hemp fibers. The obtained results show that when the content of either hemicelluloses or lignin is reduced progressively by chemical treatment, the capillary properties of hemp fibers are improved, i.e. capillary rise height of modified fibers is increased up to 2.7 times in relation to unmodified fibers. Furthermore, hemicelluloses removal increases the moisture sorption and decreases the water retention values of hemp fibers, while lignin removal decreases the moisture sorption and increases the water retention ability of hemp fibers.

  12. Ion chromatography in the manufacture of multilayer circuit boards (United States)

    Smith, Robert E.


    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.

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

    Institute of Scientific and Technical Information of China (English)


    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.

  14. 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


    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.

  15. Catalysis of aluminosilicate clay minerals to the formation of the transitional zone gas

    Institute of Scientific and Technical Information of China (English)

    雷怀彦; 师育新; 关平; 房玄


    It has been shown that the major clay minerals of the biothermocatalytic transitional zone source rock are montmorillonite, illite/montmorillonite (I/M) interlayer mineral, illite, kaolinite and chlorite. Within the depth of the transitional zone, montmorillonite could convert to the I/M ordered interlayer mineral via the I/M disordered one, i.e. in the intercrystalline layer of montmorillonite, Al3+ replaces Si4+ abundantly, resulting in a surface charge imbalance and the occurrence of a surface acidity. By means of the pyridine analytic method, the surface acidity of these aluminosilicate clay minerals is measured. The catalysis of aluminosilicate clay minerals, such as montmorillonite, illite and kaolinite to the thermo-degraded gas formation of the transitional zone is simulated in the differential thermal analysis-gas chromatography system and the alcohol dehydration catalyzed by clay minerals is employed to discuss this catalytic mechanism. Experiments have shown that montmorillonite is the major


    Institute of Scientific and Technical Information of China (English)

    Byung-HoYoon; Li-JunWangI; Se-JongKim


    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

  17. Hydrochemical measures and salinity studies in Inhanhuns` waters, Ceara State, Brazil; Medidas hidroquimicas e estudo da salinizacao das aguas nos Inhamuns

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Carlos Henrique; Santiago, Marlucia Freitas; Mendes Filho, Josue; Frischkorn, Horst [Ceara Univ., Fortaleza, CE (Brazil)


    The Inhamuns region is one of the most arid in Ceara Waters exhibit very high salinity. Here we evaluate measurements of chemical parameters (electrical conductivity, EC, and major ions) and {delta}{sup 18} O for waters from wells, springs and surface reservoirs. Results show that springs, with EC of up to nearly 5000 {mu}S/cm, are fed by pluvial water, exchange through dams can be excluded. Electrical conductivity is well correlated with Na{sup +} Mg{sup ++} and Cl{sup -} for waters of various origins, whereas Ca{sup ++} correlates reasonably only for wells. We conclude that aerosol deposition is a major source of salt, Enrichment through evaporation constitutes the most important process for surface water salination. Dissolution of chlorite-silicates is the cause for the magnesian character of underground water. (author) 1 ref., 1 tab.

  18. Soap-stone in architecture of North European cities. A nomination as a candidate for a Global Heritage Stones Resource (United States)

    Bulakh, Andrey


    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).

  19. Metamorphism, argon depletion, heat flow and stress on the Alpine fault (United States)

    Scholz, C. H.; Beavan, J.; Hanks, T. C.


    The Alpine fault of New Zealand is a major continental transform fault which was uplifted on its southeast side 4 to 11 km within the last 5 m.y. This uplift has exposed the Haast schists, which were metamorphosed from the adjacent Torlesse graywackes. The Haast schists increase in metamorphic grade from prehnite-pumpellyite facies 9-12 km from the fault through the chlorite and biotite zones of the greenschist facies to the garnet-oligoclase zone amphibolite facies within 4 km of the fault. These metamorphic zone boundaries are subparallel to the fault for 350 km along the strike. The K-Ar and Rb-Sr ages of the schists increase with distance from the fault: from 4 m.y. within 3 km of the fault to approximately 110 m.y. 20 km from the fault. Field relations show that the source of heat that produced the argon depletion aureole was the fault itself.

  20. The Extraction of Altered Minerals by use of Hyperspectral and Aster Data and Their Comparison Research in Beketan, Altyn (United States)

    Yi, H.; Li, J. Q.; Ren, G. L.; Yang, M.; Han, H. H.; Gao, T.; Yang, J. L.


    Hyperspectral remote sensing technology has played an important role in the field of geological application in recent years. Based on the reflectance of typical altered minerals and the spectral characteristics of rocks, we tried to identify and extract the altered minerals such as calcite, dolomite, epidote, chlorite, moscovite, limonite, hematite, etc. by using of CASI/SASI data in Beketan, Altyn. Moreover, we extracted Mg-OH/CO32-/Al-OH/Fe3+/Ferric oxide from Aster data by the ratio method. Combined with known geological background and the field investigation, we found that the extracted altered mineral information was consistent with the actual distribution of the field. The altered mineral information extracted by Hyperspectral data dispalyed more mineral distribution in details. It showed that the hyperspectral remote sensing technology could provide accurate hydrothermal altered mineral information which is helpful for geological mapping work.


    Directory of Open Access Journals (Sweden)

    Vladimir Majer


    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.

  2. Study of removal effect on Mesocyclops leukarti with oxidants

    Institute of Scientific and Technical Information of China (English)


    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


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

    Directory of Open Access Journals (Sweden)

    Juan C Martínez


    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.

  5. The Synthesis of Natural Cinnamic Acid and Its Esters%天然肉桂酸及其酯类的制备

    Institute of Scientific and Technical Information of China (English)

    谷运璀; 宦月琴; 钱莉群; 陶骅


    以天然肉桂醛为原料,采用亚氯酸钠氧化法制备天然肉桂酸,并以制得的天然肉桂酸与天然来源的甲醇、乙醇、异戊醇等进行酯化反应制备天然肉桂酸甲酯、肉桂酸乙酯、肉桂酸异戊酯.%Using natural cinnamic aldehyde as raw material,the natural cinnamic acid was synthesized via oxidation with sodium chlorite.Then,the natural methyl cinnamate,ethyl cinnamate and isoamyl cinnamate were obtained through esterification between natural cinnamic acid and natural methanol,ethanol and isoamyl alcohol.

  6. Petrology of Impact-Melt Rocks at the Chicxulub Multiring Basin, Yucatan, Mexico (United States)

    Schuraytz, Benjamin C.; Sharpton, Virgil L.; Marin, Luis E.


    Compositions and textures of melt rocks from the upper part of the Chicxulub structure are typical of melt rocks at other large terrestrial impact structures. Apart from variably elevated iridium concentrations (less than 1.5 to 13.5 +/- 0.9 ppb) indicating nonuniform dissemination of a meteoritic component, bulk rock and phenocryst compositions imply that these melt rocks were derived exclusively from continental crust and platform-sediment target lithologies. Modest differences in bulk chemistry among samples from wells located approximately 40 km apart suggest minor variations in relative contributions of these target lithologies to the melts. Subtle variations in the compositions of early-formed pyroxene and plagioclase also support minor primary differences in chemistry between the melts. Evidence for pervasive hydrothermal alteration of the porous mesostasis includes albite, K-feldspar, quartz, epidote, chlorite, and other phyllosilicates, as well as siderophile element-enriched sulfides, suggesting the possibility that Chicxulub, like Sudbury, may host important ore deposits.

  7. Weathering Characteristics of Wood Plastic Composites Reinforced with Extracted or Delignified Wood Flour

    Directory of Open Access Journals (Sweden)

    Yao Chen


    Full Text Available This study investigated weathering performance of an HDPE wood plastic composite reinforced with extracted or delignified wood flour (WF. The wood flour was pre-extracted with three different solvents, toluene/ethanol (TE, acetone/water (AW, and hot water (HW, or sodium chlorite/acetic acid. The spectral properties of the composites before and after artificial weathering under accelerated conditions were characterized by Fourier transform infrared (FTIR spectroscopy, the surface color parameters were analyzed using colorimetry, and the mechanical properties were determined by a flexural test. Weathering of WPC resulted in a surface lightening and a decrease in wood index (wood/HDPE and flexural strength. WPCs that were reinforced with delignified wood flour showed higher ΔL* and ΔE* values, together with lower MOE and MOR retention ratios upon weathering when compared to those with non-extracted control and extracted WF.

  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)

    WANG; Yurong; HU; Shouxi


    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.

  9. Mid amphibolite facies metamorphism of harzburgites in the Neoproterozoic Cerro Mantiqueiras Ophiolite, southernmost Brazil

    Directory of Open Access Journals (Sweden)



    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.

  10. Cross fertilization: a means of obtaining a better performing breed of investigator

    Energy Technology Data Exchange (ETDEWEB)

    Creelman, R.A. [R.A. Creelman and Associates, Epping, NSW (Australia)


    Coals in a Queensland coal deposit have high iron in ash contents. These are high enough to indicate, on the basis of Ash Fusion tests and slagging indices, that they are slagging coals. However, in practice, these coals do not produce problem deposits in test furnaces. Previous investigations into the mineralogy of the mineral matter in these coals were unable to detect the presence of any quantities of iron bearing minerals. X-ray diffraction showed the presence of chlorite (with iron bonded with alumino-silicate) which is usually area in coals. A second case study showed the importance of smectite in determining the use of coal in coal-water mixtures. 15 figs., 2 tabs.

  11. Ultramafic rocks in the Namurian C series in the Zebrzydowice area (Rybnik coal region)

    Energy Technology Data Exchange (ETDEWEB)

    Jochemczyk, L.


    The chemical and physical properties as well as origin of ultramafic rock samples from the Zebrzydowice area in the Rybnik coal region are evaluated. The ultramafic rocks detected by drilling were situated at depths of 1035 m in the top of dacite-andesite system and thermally alterated claystones. Chemical analyses and X-ray examination show that the ultramafic rock consists of secondarily alterated peridotite. The peridotite consists of chlorite-serpentite, phlogopite, bastite, nepheline and opaque minerals. Its chemical composition is characterized by reduced content of silica and a high content of ferric oxide. The ultramafic rock in the Zebrzydowice area differs from mineral and chemical composition of igneous rocks which occur in Carboniferous strata in the west and the southwest of the Upper Silesia basin. Rock of this type has been recorded in the Upper Silesia basin for the first time. 12 references.

  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


    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....../K and Cl/K ratios) did not change and the resulting ages can be interpreted unambiguously. In mineral separates containing two white micas, Ca/K and Cl/K ratios were variable, reflecting non-simultaneous laboratory degassing of the two heterochemical Ar-reservoirs. These ratios were used to identify each...... Ar reservoir and to unravel the age. In a chlorite-margarite-biotite-calcschist equilibrated near 560 °C and 0.65 GPa, biotite, margarite, and muscovite all yield ages around 18 Ma. At slightly higher grade (560-580 °C, 0.8-0.9 GPa), the assemblage muscovite-paragonite-plagioclase is at equilibrium...

  13. Metabolism and pharmacokinetics of alternate drinking water disinfectants. (United States)

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


    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 tract following the administration of 36ClO2 orally, and the half-life for the elimination of 36Cl from the rat was 44 hr, corresponding to a rate constant of 0.016/hr. After 72 hr, radioactivity was highest in plasma, followed by kidney, lung, and stomach. 36Cl in plasma reached a peak at 2 hr and 1 hr after oral administration of 36ClO2- and 36ClO3-, respectively. 36Cl excretion was greatest 24 hr after the administration of 36ClO3-, but in the case of 36ClO2-, the excretion probably represented saturation of the biotransformation and excretion pathway. A low activity in packed cells compared to plasma was detected in chlorate ingestion, rather than an even distribution in chlorite treatment. Chloroform determinations in rat blood after one year indicated that chloroform was significantly higher than control in the 100 and 1000 mg/l. ClO2 groups. However, no significant values were observed in the 1 or 10 mg/l. ClO2 and ClO2 metabolites groups. ClO2 and its metabolites are eliminated from the body more rapidly than chlorine, and they do not appear to increase trihalomethane concentrations at low dosages.

  14. Clay mineralogy of the malmian source rock of the Vienna Basin: Effects on shale gas exploration? (United States)

    Schicker, Andrea; Gier, Susanne; Herzog, Ulrich


    In an unique opportunity the diagenetic changes of clay minerals of a marlstone formation with only minor differences in provenance and depositional environment was studied from shallow (1400 m) to very deep (8550 m) burial. The clay mineralogy of 46 core samples from ten wells was quantified with X-ray diffraction in applying the mineral intensity factor (MIF)-method of Moore and Reynolds (1997). The clay fraction of the marlstone contains a prominent illite/smectite (I/S) mixed-layer mineral (20 to 70 wt%), illite (20 to 70 wt%), chlorite (0.5 to 12 wt%) and kaolinite (2 to 17 wt%). The amounts of I/S and kaolinite decrease with depth, whereas illite and chlorite increase. A gradual transformation of smectite to illite through mixed-layer I/S intermediates is recognized. With increasing depth the illite content in I/S intermediates increases from 25% to 90% in parallel the ordering of the mixed layer I/S changes from R0 (25% illite in I/S) to R1 (60-80% illite in I/S) to R3 (90% illite in I/S). R3 ordering prevails at depths greater than 4000 m and implies that the effect of the expandable mineral smectite is negligible. This paper covers a part of a shale gas feasibility study on the main Vienna Basin hydrocarbon source rock (Mikulov Formation, a Malmian marlstone) recently performed by OMV. Shale gas production usually is enabled by pumping fluids (mainly water) into a gas-mature source rock in order to generate fracture permeability. Expandable clays within the source rock can dramatically reduce stimulation effectiveness and gas production. Moore and Reynolds (1997) X-ray diffraction and the identification and analysis of clay minerals. Oxford University Press, New York, 378 p.

  15. Evolution of clay mineral assemblages in the Tinguiririca geothermal field, Andean Cordillera of central Chile: an XRD and HRTEM-AEM study (United States)

    Vázquez, M.; Nieto, F.; Morata, D.; Droguett, B.; Carrillo-Rosua, F. J.; Morales, S.


    HRTEM textural evidence shows that clay minerals in the Tinguiririca geothermal field (Andean Cordillera, central Chile) are the result of direct alteration of former volcanic glass and minerals by hydrothermal fluids at similar temperatures to the present day. They show the classical pattern of diagenetic transformation from smectite at the top to illite at the bottom, with the progressive formation of corrensite and chlorite. The high fluid/rock ratio, disposability of necessary cations and absence of previous detrital phyllosilicates allow the consideration of this area as a natural laboratory to establish the extreme ideal conditions for very low-T reactions. Transformations from smectite to R1 illite-smectite (I-S) and from these to R3 mixed-layers occur respectively at 80-120 °C and 125-180 °C. In spite of ideal genetic conditions, the new-formed minerals show all the defective character and lack of textural and chemical equilibrium previously described in the literature for diagenetic and hydrothermal low-temperature assemblages. Chemistry of smectite-illite phases evolves basically through a diminution of the pyrophyllitic component toward a theoretical muscovite (Si4 + + □ -> Al3 ++ K+). However, a second chemical vector (Si4 ++ Mg2 + → Al3 ++ Al3 +), that is, decreasing of the tschermack component, also contributes to the evolution toward the less Si-more Al rich muscovite in relation to the original smectite. Residual Mg (and Fe) from the latter reaction is consumed in the genesis of chloritic phases. Nevertheless, as a consequence of the lack of chemical equilibrium (probably because of the short time-scale of the geothermal alteration processes), the composition of clay minerals is highly heterogeneous at the level of a single sample. Consequently, the respective fields of smectite, R1 I-S and R3 I-S overlap each other, making the distinction among these three phases impossible based exclusively on chemical data.

  16. Oxygen-isotope exchange and mineral alteration in gabbros of the Lower Layered Series, Kap Edvard Holm Complex, East Greenland

    Energy Technology Data Exchange (ETDEWEB)

    Fehlhaber, K.; Bird, D.K. (Stanford Univ., CA (United States))


    Multiple intrusions of gabbros, mafic dikes, and syenites in the Kap Edvard Holm Complex gave rise to prolonged circulation of meteoric hydrothermal solutions and extreme isotope exchange and mineral alteration in the 3,600-m-thick Lower Layered Series gabbros. In the Lower Layered Series, {delta}{sup 18}O of plagioclase varies from +0.3{per thousand} to {minus}5.8{per thousand}, and it decreases with an increase in the volume of secondary talc, chlorite, and actinolite. In the same gabbros, pyroxenes have a more restricted range in {delta}{sup 18}O, from 5.0{per thousand} to 3.8{per thousand}, and values of {delta}{sup 18}O{sub pyroxene} are independent of the abundance of secondary minerals, which ranges from 14% to 30%. These relations indicate that large amounts of water continued to flow through the rocks at temperatures of < 500-600C, altering the gabbros to assemblages of talc + chlorite + actinolite {plus minus}epidote {plus minus}albite and causing significant oxygen-isotope exchange in plagioclase, but not in pyroxene. The extensive low-temperature secondary mineralization and {sup 18}O depletion of plagioclase in the Lower Layered Series are associated with the later emplacement of dikes and gabbros and syenites, which created new fracture systems and provided heat sources for hydrothermal fluid circulation. This produced subsolidus mineral alteration and isotope exchange in the Lower Layered Series that are distinct from those in the Skaergaard and Cuillin gabbros of the North Atlantic Tertiary province, but are similar to those observed in some oceanic gabbros.

  17. Porosity evolution, contact metamorphism, and fluid flow in the host basalts of the Skaergaard magma-hydrothermal system

    Energy Technology Data Exchange (ETDEWEB)

    Manning, C.E.


    Temporal and spatial variations in porosity during contact metamorphism of the basaltic country rocks to the Skaergaard intrusion in East Greenland resulted in a complex hydrological evolution of the metamorphic aureole. Contrasts in macroscopic porosities in different lithologies led to differences in mineralogical, bulk chemical, and oxygen isotopic alteration, and units with greater macroscopic porosities record larger fluid flux during metamorphism. Calculated Darcy velocities indicate that the horizontal component of fluid flow in the aureole was toward the intrusive contact. In the actinolite + chlorite zone time-integrated fluid flux was higher in aa units ({approximately} 300 kg cm{sup {minus}2}) than in massive units ({approximately} 130 kg cm{sup {minus}2}). Approximately equal time-integrated fluxes of respectively 4 and 5 kg cm{sup {minus}2} in aa and massive units in the pyroxene zone indicate that the volume of fluid flow in the higher grade rocks was independent of primary porosity. These results are consistent with inward fluid migration in the actinolite + chlorite zone through an open network of pores whose abundance varied as a function of primary lava morphology. At higher metamorphic grades fluid fluxes were lower and were independent of primary porosity, probably as a consequence of (1) channelization of fluids due to more extensive pore filling and (2) decreasing horizontal component of flow due to upward migration of fluids near the contact. The results of this study indicate that explicit provision for rock porosity aids interpretation of the nature of fluid flow during contact metamorphism in magma-hydrothermal systems.

  18. 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


    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.

  19. 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 (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


    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.

  20. Petrology and radiogeology of the Stripa pluton

    Energy Technology Data Exchange (ETDEWEB)

    Wollenberg, H.; Flexser, S.; Andersson, L.


    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.

  1. Quartz-sericite and argillic alterations at the Peschanka Cu-Mo-Au deposit, Chukchi Peninsula, Russia (United States)

    Marushchenko, L. I.; Baksheev, I. A.; Nagornaya, E. V.; Chitalin, A. F.; Nikolaev, Yu. N.; Kal'ko, I. A.; Prokofiev, V. Yu.


    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.

  2. Studies on the preparation of value-added products for limestone

    Energy Technology Data Exchange (ETDEWEB)

    Chae, Young Bae; Jeong, Soo Bok; Ko, Won Sik; Park, Je Shin; Oh, Jung Whan [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)


    Most of limestone in our country was consumed by the cement and iron/steel making industries and the amount of that was up to 72 million ton in 1996. Recently, importation of high grade limestone that have properties of high whiteness and grade are increased with diversification of chemical products and powder as various qualified filler, because high grade limestone are limited and of few deposit in our country. Therefore, the purpose of this study has investigated to raise to high grade by economical processes with low grade of domestic limestone. In this year, first of all, we investigated the status of application utilize and related industries with the domestic limestone, and then being consideration with condition selected the adequate sample from Andong, Jungsun and Kumsan area. Magnetic materials were involved in impurities of sample, so magnetic separation method was applied in elimination of the ferro-magnetic materials and para-magnetic materials, such as chlorite, muscovite, quartz, dolomite, magnetite, feldspar and so on. The limestone sample has many kinds of impurity. Investigation of flotation was undertaken to eliminate impurities from limestone crude ore and the tests were performed to get a optimum condition adding oleic acid as a promoter, sodium silicate and sodium carbonate as a conditioning agents and MIBC as a frother, while to float the sulfide minerals added amyl xanthate as a promoter, and sulfuric acid as a pH regulator. And most of the impurities involving in flotation sink contained such as quartz, chlorite, muscovite, feldspar, dolomite and so on. Selective crushing and classification methods were performed to eliminate impurities depends on the mineral properties and should be the selective crushing methods are very useful at the manufacturing factory of heavy calcium carbonate with the dry milling system. (author). 36 refs., 46 tabs., 33 figs.

  3. A microstructural and argon laserprobe study of shear zone development at the western margin of the Nanga Parbat-Haramosh Massif, western Himalaya (United States)

    Reddy, Steven M.; Kelley, Simon P.; Magennis, Lochlann

    A sample of banded amphibolite from the western margin of the Nanga Parbat-Haramosh Massif as Sassi has been studied using microstructural and 40Ar/39Ar laserprobe techniques to investigate the relationship between deformation and argon isotope variations in a natural system. Amphibolite-grade deformation occurred during south-directed overthrusting of the Kohistan arc over India along the Main Mantle Thrust and was overprinted by extensional reactivation of the earlier fabric and the formation of biotite-rich shear zones. Subsequent deformation along discrete fine-grained fault zones was characterised by the formation of scapolite, chlorite and K-feldspar, early plastic deformation and later cataclasis. Different minerals developed during this history show a wide range in apparent 40Ar/39Ar ages. Biotite, chlorite and scapolite exhibit much lower concentrations of excess argon, indicating their equilibration in a fluid relatively poor in excess argon. A `true' age of ca. 8 Ma from biotite represents a minimum age for deformation associated with formation of the Nanga Parbat Syntaxis and also precludes Pliocene metamorphism in this area of the syntaxis. Both high- and low-closure temperature minerals (amphiboles and feldspars) record apparent ages which are associated with the incorporation of excess argon within the mineral lattice. Although differential thermal resetting of minerals at different closure temperatures is important, variations in the inherited 40Ar/36Ar ratio throughout the sample is dominated by deformation and fluid infiltration. Consequently it appears that within deforming metamorphic rocks, areas with significantly different argon isotope compositions may be present and need not be homogenised by diffusion.

  4. Mineralogy, morphology, and textural relationships in coatings on quartz grains in sediments in a quartz-sand aquifer. (United States)

    Zhang, Shouliang; Kent, Douglas B; Elbert, David C; Shi, Zhi; Davis, James A; Veblen, David R


    Mineralogical studies of coatings on quartz grains and bulk sediments from an aquifer on Western Cape Cod, Massachusetts, USA were carried out using a variety of transmission electron microscopy (TEM) techniques. Previous studies demonstrated that coatings on quartz grains control the adsorption properties of these sediments. Samples for TEM characterization were made by a gentle mechanical grinding method and focused ion beam (FIB) milling. The former method can make abundant electron-transparent coating assemblages for comprehensive and quantitative X-ray analysis and the latter technique protects the coating texture from being destroyed. Characterization of the samples from both a pristine area and an area heavily impacted by wastewater discharge shows similar coating textures and chemical compositions. Major constituents of the coating include Al-substituted goethite and illite/chlorite clays. Goethite is aggregated into well-crystallized domains through oriented attachment resulting in increased porosity. Illite/chlorite clays with various chemical compositions were observed to be mixed with goethite aggregates and aligned sub-parallel to the associated quartz surface. The uniform spatial distribution of wastewater-derived phosphorus throughout the coating from the wastewater-contaminated site suggests that all of the coating constituents, including those adjacent to the quartz surface, are accessible to groundwater solutes. Both TEM characterization and chemical extraction results indicate there is a significantly greater amount of amorphous iron oxide in samples from wastewater discharge area compared to those from the pristine region, which might reflect the impact of redox cycling of iron under the wastewater-discharge area. Coating compositions are consistent with the moderate metal and oxy-metalloid adsorption capacities, low but significant cation exchange capacities, and control of iron(III) solubility by goethite observed in reactive transport

  5. Hydrothermal alteration in oceanic ridge volcanics: A detailed study at the Galapagos Fossil Hydrothermal Field (United States)

    Ridley, W.I.; Perfit, M.R.; Josnasson, I.R.; Smith, M.F.


    The Galapagos Fossil Hydrothermal Field is composed of altered oceanic crust and extinct hydrothermal vents within the eastern Galapagos Rift between 85??49???W and 85??55???W. The discharge zone of the hydrothermal system is revealed along scarps, thus providing an opportunity to examine the uppermost mineralized, and highly altered interior parts of the crust. Altered rocks collected in situ by the submersible ALVIN show complex concentric alteration zones. Microsamples of individual zones have been analysed for major/minor, trace elements, and strontium isotopes in order to describe the complex compositional details of the hydrothermal alteration. Interlayered chlorite-smectite and chlorite with disequilibrium compositions dominate the secondary mineralogy as replacement phases of primary glass and acicular pyroxene. Phenocrysts and matrix grains of plagioclase are unaffected during alteration. Using a modification of the Gresens' equation we demonstrate that the trivalent rare earth elements (REEs) are relatively immobile, and calculate degrees of enrichment and depletion in other elements. Strontium isotopic ratios increase as Sr concentrations decrease from least-altered cores to most-altered rims and cross-cutting veins in individual samples, and can be modeled by open system behaviour under low fluid-rock ratio (< 10) conditions following a period of lower-temperature weathering of volcanics within the rift zone. The complex patterns of element enrichment and depletion and strontium isotope variations indicate mixing between pristine seawater and ascending hot fluids to produce a compositional spectrum of fluids. The precipitation of base-metal sulfides beneath the seafloor is probably a result of fluid mixing and cooling. If, as suggested here, the discharge zone alteration occurred under relatively low fluid-rock ratios, then this shallow region must play an important role in determining the exit composition of vent fluids in marine hydrothermal systems

  6. Inactivation of Yersinia pseudotuberculosis, as a surrogate for Yersinia pestis, by liquid biocides in the presence of food residue. (United States)

    Hilgren, J; Swanson, K M J; Diez-Gonzalez, F; Cords, B


    The efficacy of liquid biocides is influenced by surface cleanliness, treatment time, and temperature. Experiments were completed to measure the impact of these variables on the ability of commercial biocides to inactivate Yersinia pseudotuberculosis ATCC 29910, as a surrogate for Yersinia pestis, in the presence of food residues. The test organism was mixed with water, milk, flour, or egg yolk and then dried onto stainless steel coupons. Coupons were then exposed to sodium hypochlorite, acidified sodium chlorite, a quaternary ammonium compound, an iodophor, hydrogen peroxide, peroxyacetic acid, or a peroxy-fatty acid mixture, for 10 or 30 min at 10, 20, or 30 degrees C. For all biocides except the iodophor, manufacturer-recommended disinfection levels applied for 10 min at 20 degrees C resulted in 5-log reductions of the test organism dried alone or with flour. However, in the presence of whole milk or egg yolk residue, markedly higher sodium hypochlorite, peroxyacetic acid, peroxy-fatty acid mixture, quaternary ammonium compound, and iodophor concentrations were needed to achieve the 5-log reductions. Further, the quaternary ammonium compound was incapable of achieving 5-log reductions in 10 min in the presence of milk and egg yolk residues. Hydrogen peroxide and acidified sodium chlorite disinfection levels (7.5% and 2500 ppm, respectively) achieved 5-log reductions under all test conditions. These results suggest that commercial disinfectants can adequately decontaminate clean surfaces contaminated with Y. pseudotuberculosis and Y. pestis. These results also provide guidance on the feasibility of overcoming the negative influence of food residues on disinfection by adjusting biocide exposure time, temperature, and concentration.

  7. Gaseous, chlorine-free chlorine dioxide for drinking water

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, G. [Miami Univ., Oxford, OH (United States); Rosenblatt, A. [CDG Technology Inc., New York, NY (United States)


    The benefits of applying chlorine dioxide (ClO{sub 2}) for the oxidative treatment of drinking water are well established. Chlorine dioxide treated finished water typically has substantially lower trihalomethane (THM) levels because ClO{sub 2} will not form chlorinated organic species as a by-product of disinfection. The THMs that are formed are probably due to chlorine from the generator or chlorine used to maintain a post-disinfection residual. An emerging regulatory issue concerning the formation of disinfection by-products (DBPs) is causing the water industry to set standards for the generation and delivery of ClO{sub 2}. The Federal Register (11 February 1994) contains language developed to limit the production of the unwanted inorganic by-products chlorite (ClO{sub 2}{sup -}), chlorate (ClO{sub 3}{sup -}), and bromate (BrO{sub 3}{sup -}) ions by requiring utilities to maintain high (95%) generation efficiencies and by limiting the amount of excess Cl{sub 2} that can be used during the generation process. The efficiency and excess Cl{sub 2} regulations may be problematic for utilities that over-chlorinate to attain chlorine dioxide high yields. Many utilities will have to decide either to reduce the amount of Cl{sub 2} used to react with sodium chlorite (NaClO{sub 2}), thereby increasing the ClO{sub 2}{sup -} residual in finished water, or over-chlorinate to increase yields and surpass the excess Cl{sub 2} limits.

  8. Miocene fossil hydrothermal system associated with a volcanic complex in the Andes of central Chile (United States)

    Fuentes, Francisco; Aguirre, Luis; Vergara, Mario; Valdebenito, Leticia; Fonseca, Eugenia


    Cenozoic deposits in the Andes of central Chile have been affected by very low-grade burial metamorphism. At about 33°S in the Cuesta de Chacabuco area, approximately 53 km north of Santiago, two Oligocene and Miocene volcanic units form a ca. 1300-m-thick rock pile. The Miocene unit corresponds to a volcanic complex composed of two eroded stratovolcanoes. Secondary mineral assemblages in both units were studied petrographically and using X-ray diffraction and electron microprobe analyses. Most of the igneous minerals are wholly or partially preserved, and the ubiquitous secondary minerals are zeolites and mafic phyllosilicates. The alteration pattern observed is characterized by a lateral zonation in secondary mineralogy related to a lateral increase in temperature but not to stratigraphic depth. The following three zones were established, mainly based on the distribution of zeolites: zone I comprises heulandite, thomsonite, mesolite, stilbite and tri-smectite; zone II contains laumontite, yugawaralite, prehnite, epidote and chlorite; and zone III comprises wairakite, epidote, chlorite, diopside, biotite and titanite. For each zone, the following temperature ranges were estimated: zone I, 100-180 °C; zone II, 180-270 °C; and zone III, 245-310 °C. The alteration episode was characterized by a high Pfluid/ Ptotal ratio (ca. 1.0), although slightly variable, a high geothermal gradient of ca. 160 °C km -1 and fluid pressures below 500 bars. Although temperature was the main control on the mineral zonation, several interrelated parameters, mainly fluid composition, porosity and permeability, were also important. Hot, near neutral to slightly alkaline pH, alkali chloride hydrothermal fluids with very low dissolved CO 2 contents deposited the secondary minerals. The alteration pattern is the result of depositing fluids in outflow regions from a hydrothermal system developed inside a volcanic complex during the Miocene. The hydrothermal system has been eroded to a

  9. Episodic subgreenschist facies metamorphism in the Andes of Chile - is it a valid model? (United States)

    Bevins, R. E.; Robinson, D.; Aguirre, L.; Vergara, M.


    The Central Andes of Chile are characterized by subgreenschist facies burial metamorphism that is reported as having developed in up to seven episodic cycles of some 40Myr duration. The main evidence in support of the model is reported as mineralogical breaks at major stratigraphic boundaries that are interpreted as documenting sharp breaks in metamorphic grade. Here we test this model by examination of the progressive secondary mineral development, reaction progress in mafic phyllosilicates, and topological variations of the low-grade assemblages in metabasites for Jurassic to Miocene sequences east of Santiago. The mafic phyllosilicates (smectite - mixed-layer chlorite/smectite - chlorite) show increasing reaction progress with stratigraphic age and there is a continuum across the main stratigraphic boundaries, such there is no offset or gap in the reaction progress at these boundaries. There are some differences in mineral assemblages between the various stratigraphic units, such as between prehnite+pumpellyite+/-laumonite or amphibole-bearing and non amphibole bearing rocks, from which contrasting subgreenschist facies can be recognised. However, consideration of the controls on mineral parageneses at subgreenschist facies conditions demonstrates that these different facies cannot be used solely as evidence of sharp breaks in metamorphic grade at unconformities, as has been reported in many previous publications for the Andes. The presently accepted model for the Central Andes, involving repeated cycles of episodic metamorphism developing in extensional basins, is, therefore, partly unfounded. Consideration of the overall tectonic evolution of this part of the Andes concurs that the burial metamorphism developed in extensional settings, but in only two events, namely in mid-late Cretaceous and Late Miocene times respectively. The results from this work suggest that the record of sharp metamorphic breaks and the episodic model of metamorphism reported for many

  10. Complex patterns in fossilized stromatolites revealed by hyperspectral imaging (400-2496 nm). (United States)

    Murphy, R J; Van Kranendonk, M J; Kelloway, S J; Wainwright, I E


    Hyperspectral imaging (400-2496 nm) was used to quantitatively map surface textures and compositional variations in stromatolites to determine whether complexity of textures could be used as evidence to support biogenicity in the absence of preserved biomarkers. Four samples of 2.72-2.4 Ga stromatolites from a variety of settings, encompassing marine and lacustrine environments, were selected for hyperspectral imaging. Images of the sawn surfaces of samples were processed to identify reflectance and mineral absorption features and quantify their intensity (as an index of mineral abundance) using automated feature extraction. Amounts of ferrous iron were quantified using a ratio of reflectance at 1650 and 1299 nm. Visible near infrared imagery (400-970 nm) did not reveal additional textural patterns to those obtained from visual inspection. Shortwave infrared imagery (1000-2496 nm), however, revealed complex laminar and convoluted patterns, including a distinctive texture of sharp peaks and broad, low troughs in one sample, similar to living tufted microbial mats. Spectral analysis revealed another sample to be composed of dolomite. Two other samples were dominated by calcite or chlorite ± illite. Large variations in amounts of ferrous iron were found, but ferric iron was exclusively located in the oxidation crust. Hyperspectral imaging revealed large differences between parts of a sample of biogenic and non-biogenic origin. The former was characterized by calcite with varying amounts of ferrous iron, distributed in lenticular, convoluted patterns; the latter by Mg-Fe chlorite with large amounts of aluminium silicate, distributed as fine laminar layers. All minerals identified by hyperspectral imaging were confirmed by thin section petrography and XRD analyses. Spatial statistics generated from quantitative minerals maps showed different patterns between these different parts of the sample. Thus, hyperspectral imaging was shown to be a powerful tool for

  11. Petrography and geochemical study of Nezam-Abad area, Southwest of Shazand, Arak

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    Robabeh Jafari


    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.

  12. Reduction of Surrogates for Escherichia coli O157:H7 and Salmonella during the Production of Nonintact Beef Products by Chemical Antimicrobial Interventions. (United States)

    Ulbrich, Carson J; Lucia, Lisa M; Arnold, Ashley N; Taylor, T Matthew; Savell, Jeffrey W; Gehring, Kerri B


    The efficacy of chemical antimicrobials for controlling Escherichia coli O157:H7 and Salmonella during production of marinated nonintact beef products was evaluated using nonpathogenic surrogates. Boneless beef strip loins were inoculated with either approximately 5.8 or 1.9 log CFU/cm(2) (high and low inoculation levels, respectively) of nonpathogenic rifampin-resistant E. coli. Inoculated strip loins were chilled at 2°C for 24 h, vacuum packaged, and aged for 7 to 24 days at 2°C. After aging, strip loins received no treatment (control) or one of five antimicrobial spray treatments: 2.5% L-lactic acid (pH 2.6), 5.0% L-lactic acid (pH 2.4), 1,050 ppm of acidified sodium chlorite (pH 2.8), 205 ppm of peroxyacetic acid (pH 5.2), or tap water (pH 8.6). Mean application temperatures were 53, 26, 20, and 18°C for lactic acid, water, peroxyacetic acid, and acidified sodium chlorite treatments, respectively. Treated and control strip loins were vacuum tumbled in a commercial marinade. Samples were collected throughout the experiment to track the effects of antimicrobial treatment and processing on inoculated surrogates. For high-inoculation strip loins, the 5.0% L-lactic acid treatment was most effective for reducing surrogates on meat surfaces before marination, producing a 2.6-log mean reduction. Peroxyacetic acid treatment resulted in the greatest reduction of surface-located surrogate microorganisms in marinated product. Water treatment resulted in greater internalization of surrogate microorganisms compared with the control, as determined by enumeration of surrogates from cored samples. Producers of nonintact beef products should focus on use of validated antimicrobial sprays that maximize microbial reduction and minimize internalization of surface bacteria into the finished product.

  13. Influences of petrographic parameters on technological properties of greywackes used for crushed stone production (United States)

    Prikryl, Richard; Cermak, Martin; Krutilova, Katerina


    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

  14. Very low-temperature metamorphism in Ordovician metasedimentary rocks above and below the Sardic unconformity, SW Sardinia, Italy (United States)

    Franceschelli, M.; Battaglia, S.; Cruciani, G.; Pasci, S.; Puxeddu, M.


    In the Iglesiente region, the Cabitza and Monte Argentu Formations are separated by an angular unconformity known as the Sardic unconformity. This is related to an early Ordovician mild compressional phase, known as the "Sardic phase". The pelitic samples from the structurally lower Cabitza Formation consist of alternating reddish phyllosilicate-rich and whitish phyllosilicate-poor, sialic layers, whose S0 bedding plane is parallel to a pre-Variscan S1P schistosity overprinted by the Variscan S1V schistosity. Pelitic samples from the Monte Argentu Formation are characterized by a Variscan S1V axial plane schistosity. Samples from the two formations consist of quartz and phyllosilicates. The latter are potassic white mica, chlorite, paragonite, locally kaolinite, and pyrophyllite. The illite crystallinity values determined for the Cabitza samples are 0.25-0.31, with an average of 0.29; meanwhile, the Monte Argentu samples produce values of 0.33-0.38, with an average of 0.35. The chlorite crystallinity and b0 of potassic white mica values show greater heterogeneity in the Cabitza than the Monte Argentu samples. The b0 values and P-T pseudosections allow us to confirm that there is no significant difference in the P-T metamorphism conditions between the Cabitza and Monte Argentu samples. The Iglesiente region, which is considered to be the rift zone behind the Middle Ordovician Sarcidano-Barbagia volcanic arc, underwent the "Sardic phase", giving rise to E-W folds. These were first overprinted by weak E-W, and then by stronger N-S-oriented Variscan deformation events.

  15. Geological and geochemical studies of the Shujiadian porphyry Cu deposit, Anhui Province, Eastern China: Implications for ore genesis (United States)

    Wang, Shiwei; Zhou, Taofa; Yuan, Feng; Fan, Yu; White, Noel C.; Lin, Fengjie


    Most porphyry deposits in the world occur in magmatic arc settings and are related to subduction of oceanic plates. A small proportion of porphyry deposits occur in intracontinental settings, however they are still poorly understood. Shujiadian, a newly-discovered porphyry Cu deposit, is located in the Middle-Lower Yangtze River Valley metallogenic belt and belongs to the intracontinental class. The deposit has classic alteration zones defined by a core of potassic alteration and local Ca-silicate alteration, which is overprinted by a feldspar-destructive alteration zone and cut by veins containing epidote and chlorite. Wallrocks of the deposit are unreactive quartz-rich sedimentary rocks. Three main paragenetic stages have been recognized based on petrographic observations; silicate stage, quartz-sulfide stage, and sulfide-carbonate stage. Quartz + pyrite + chalcopyrite ± molybdenite veins, and quartz + chalcopyrite + pyrite veins of the quartz-sulfide stage contribute most of the copper, and chalcopyrite + chlorite ± pyrite ± pyrrhotite ± quartz ± illite veins of the sulfide-carbonate stage also contribute part of the copper; all the mineralized veins are associated with feldspar-destructive alteration. Investigations on the fluid inclusions in Shujiadian indicate that the ore-forming fluids had four evolutionary episodes: immiscibility and overpressure in the silicate stage, boiling in the quartz-sulfide stage and mixing with meteoric water in the sulfide-carbonate stage. Sulfur and strontium isotope studies suggest that ore metals were mainly derived from magmatic-hydrothermal fluids, and combined with our study of fluid inclusions, we infer that decompression, changes in oxygen fugacity and sulfur content were the main factors that caused Cu precipitation. Compared with porphyry deposits in magmatic arc settings, there are some differences in the ore-bearing rock, alteration, and the composition of ore-forming fluids.

  16. Hydrogeothermal characteristics of groundwater from Ribarska Banja spa, central Serbia

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    Dragišić Veselin S.


    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

  17. The Canastra Group in the type-area, Tapira region, southwest of Minas Gerais State, Brazil

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    Carlos Humberto da Silva


    Full Text Available This work aimed at describing the Neoproterozoic evolution of a Southern Brasília Fold Belt segment, in Tapira area(southwest of Minas Gerais state, Brazil, using detailed geologic mapping. This area, the Canastra Group type-area, hasshowed great tectonic and stratigraphic complexities unlike the simplicity suggested in previous works. From recognizingthe main tectonic discontinuities, it was possible to subdivide the area into some domains. In the west domain, they wereindividualized in tectonic sheet I, marked by pelitic rocks and pelitic-graphite rocks with psammitic intercalations, and II,pelitic rocks with psammitic and mafic-ultramafic intercalations overlapped by gneisses. In the east domain, a group ofthree tectonic sheets was defined, in which, in the two lower tectonic sheets, pelitic and pelitic-graphite rocks with psammiticrock intercalations prevailed, which is different in metamorphic conditions. The lower tectonic sheet is marked bymineralogical associations with muscovite + chlorite + quartz ± graphite ± albite, without biotite; however, the superior oneis with muscovite + quartz + garnet ± chlorite ± biotite ± chloritoid ± graphite ± albite. In the upper tectonic sheet, peliticrocks with local contributions of psammitic and ultramafics rocks occur. In the south domain, psammitic rocks basically occur with contributions of pelitics and rudaceous rocks, where the preservation of textures and sedimentary structures is common.Rocks of the several domains are interpreted as part of a passive continental margin basin, located in the western margin of the SãoFrancisco paleocontinent. Thus, the south domain rocks would represent the facies of proximal platform; rocks of the lower and middle tectonic sheets (east domain and of the tectonic sheet I (west domain are of facies distal platform; and the ones from the upper tectonic sheet (east domain and tectonic sheet II (west domain were acknowledged as deposited in an environment

  18. Karakteristik mineralisasi epitermal di Daerah Taran, Hulu Kahayan, Kalimantan Tengah berdasarkan studi mikroskopis, X-Ray Diffraction (XRD, dan inklusi fluida

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    Danny Zulkifli Herman


    Full Text Available area is occupied predominantly by piroclastic rocks and locally intercalations of lenticular claystones and sandstones. The pyroclastic rocks are intruded by diorite, dacite and andesite, leading alteration and mineralization within the host rocks. Mineralization occurs as a vein type and is associated with a number of pervasive alteration types named respectively: quartz-illite- montmorillonite-kaolinite ± pyrite, quartz-illite ± pyrite, quartz-illite-chlorite ± pyrite and quartz- kaolinite-illite ± pyrite. On the other hand, a propylitic alteration also occurs within the andesite intrusion composed of calcite-epidote-chlorite-sericite-quartz ± pyrite. The mineralization is characterized by several zones of quartz stockwork containing gold and associated ore minerals of chalcopyrite, sphalerite, galena, pyrite and argentite. The quartz veins occurs as fi llings of structural openings in the form of milky quartz and amethyst with textures of sugary, comb, and dogteeth. Evaluation work on results of microscopic (petrography and mineragraphy, X-Ray Diffraction (XRD, and fl uid inclusion studies, and chemical analysis of entirely altered rock/quartz vein samples shows that the alteration and mineralization process were closely related to a change of hydrothermal fl uids, from near neutral into acid conditions at a temperature range of >290o – 100oC. The appearances of quartz variation indicate a relationship with repeated episodes of boiling in an epithermal system, as ground water mixed with hot vapor originated from a remained post-magmatic solution. Corresponding to a salinity of average 1,388 equiv.wt.% NaCl, it indicates that the ore minerals bearing quartz veins were deposited at a depth range of 640 – 1020 m beneath paleosurface.  

  19. Mass change calculations of hydrothermal alterations within the volcanogenic metasediments hosted Cu-Pb (-Zn) mineralization at Halilar area, NW Turkey (United States)

    Kiran Yildirim, Demet; Abdelnasser, Amr; Doner, Zeynep; Kumral, Mustafa


    The Halilar Cu-Pb (-Zn) mineralization that is formed in the volcanogenic metasediments of Bagcagiz Formation at Balikesir province, NW Turkey, represents locally vein-type deposit as well as restricted to fault gouge zone directed NE-SW along with the lower boundary of Bagcagiz Formation and Duztarla granitic intrusion in the study area. Furthermore, This granite is traversed by numerous mineralized sheeted vein systems, which locally transgress into the surrounding metasediments. Therefore, this mineralization closely associated with intense hydrothermal alteration within brecciation, and quartz stockwork veining. The ore mineral assemblage includes chalcopyrite, galena, and some sphalerite with covellite and goethite formed during three phases of mineralization (pre-ore, main ore, and supergene) within an abundant gangue of quartz and calcite. The geologic and field relationships, petrographic and mineralogical studies reveal two alteration zones occurred with the Cu-Pb (-Zn) mineralization along the contact between the Bagcagiz Formation and Duztarla granite; pervasive phyllic alteration (quartz, sericite, and pyrite), and selective propylitic alteration (albite, calcite, epidote, sericite and/or chlorite). This work, by using the mass balance calculations, reports the mass/volume changes (gain and loss) of the chemical components of the hydrothermal alteration zones associated with Halilar Cu-Pb (-Zn) mineralization at Balikesir area (Turkey). It revealed that the phyllic alteration has enrichments of Si, Fe, K, Ba, and LOI with depletion of Mg, Ca, and Na reflect sericitization of alkali feldspar and destruction of ferromagnesian minerals. This zone has high Cu and Pb with Zn contents represents the main mineralized zone. On the other hand, the propylitic zone is characterized by addition of Ca, Na, K, Ti, P, and Ba with LOI and Cu (lower content) referring to the replacement of plagioclase and ferromagnesian minerals by albite, calcite, epidote, and sericite

  20. Alteration of Crystalline and Glassy Basaltic Protolith by Seawater as Recorded by Drill Core and Drill Cutting Samples (United States)

    Fowler, A. P.; Zierenberg, R. A.; Schiffman, P.


    The major and trace element composition of hydrothermally altered basaltic drill core and drill cutting samples from the seawater recharged Reykjanes geothermal system in Iceland are compared to unaltered surface flows from the Reykjanes Peninsula compiled from the literature. Trace element characteristics of deep (>2000 m) core samples record bimodal compositions similar to trace element enriched and trace element depleted Reykjanes Ridge basalts. Drill cuttings (350-3000 m) overwhelmingly reflect the more common trace element enriched igneous precursor. Crystalline protoliths (dolerite dykes and pillow lava cores) are depleted in Cs, Rb, K, and Ba (± Pb and Th) relative to an unaltered equivalent, despite variations in the extent of alteration ranging from from minor chloritization with intact igneous precursor minerals through to extensive chloritization and uralitization. Glassy protoliths (dyke margins, pillow edges, and hyaloclastites) show similar depletions of Cs, Rb, K, and Ba, but also show selective depletions of the light rare earth elements (LREE) La, Ce, Pr, Nd and Eu due to extensive recrystallization to hydrothermal hornblende. Lower grade alteration shows less pronounced decoupling of LREE and is likely controlled by a combination of Cl complexation in the seawater-derived recharge fluid, moderated by anhydrite and epidote precipitation. These results suggest that alteration of glassy protolith in seawater-recharged systems is an important contribution to the consistently light rare earth and Eu enriched patterns observed in seafloor hydrothermal fluids from basaltic systems. An important conclusion of this study is that that drill cuttings samples are strongly biased toward unaltered rock and more resistant alteration minerals including epidote and quartz potentially resulting in misidentification of lithology and extent of alteration.

  1. Geology of the Early Archean Mid-Ocean Ridge Hydrothermal System in the North Pole Dome, Pilbara Craton, Western Australia (United States)

    Kitajima, K.; Maruyama, S.


    An Archean hydrothermal system in the North Pole Dome, Pilbara Craton is associated with extensive fluid circulation driven by numerous extensional fracture systems and the underlying heat source. The fracture system is now occupied by abundant fine-grained quartz aggregate, hence we call this as silica dikes. Some of the fracture system extends deeper structural levels as listric normal faults down to 1000 m depth in the MORB crust. Barite-bearing fine-grained quartz predominant mineralogy indicates the extensive development of fracturing and quenching in a short time. Accompanying the fluid circulation, the extensive metasomatism proceeded to form the four different chemical courses, (1) silicification, (2) carbonation, (3) potassium-enrichment, and (4) Fe- enrichment. Silicification occurs along the silica dikes, carbonated greenstones are distributed relatively shallower level. Potassium-enriched (mica-rich) greenstones occur at the top of the greenstone sequence, and Fe-enriched (chlorite-rich) greenstones are distributed at lower part of the basaltic greenstones. The down going fluid precipitated carbonate-rich layer at shallow levels, whereas depleted in SiO2. Then, the fluid went down to more deeper level, and was dissolved SiO2 at high temperature (~350°C) and chlorite-rich greenstone was formed by water-rock interaction. The upwelling fluid precipitated dominantly SiO2 and formed silica dikes. Silica dikes cement the fractures formed by extensional faulting at earliest stage of development of oceanic crust. Therefore, the hydrothermal system must have related to normal fault system simultaneously with MORB volcanism. Particularly the greenish breccia with cherty matrix (oregano chert) was formed at positions by upwelling near ridge axis. After the horizontal removal of MORB crust from the ridge-axis with time, the propagating fracture into deeper levels, transports hydrothermal fluids into 500-1000 m depth range where metasomatic element exchange between

  2. Mineralogical, geochemical and radiological characterisation of Selmo Formation in Batman area, Turkey. (United States)

    Isik, Umit; Damla, Nevzat; Akkoca, Dicle Bal; Cevik, Uğur


    This work deals with the mineralogical, geochemical and radiological characterisations of Selmo Formation in Batman neighbourhood. The upper Miocene-Pliocene Selmo Formation is common in the centre of Batman and composed of carbonated sandy claystones and silty-sandy stone lenses. The common whole minerals of the samples are quartz, feldspars, calcite and dolomite. The clay minerals are smectite, illite, chlorite and mixed-layer clay (chlorite-smectite). The geochemical mean values of the samples are 51.7% SiO(2); 12.6% Al(2)O(3); 6.2% Fe(2)O(3); 3.6% MgO; 6.3% CaO; 1.1% Na(2)O; 1.7% K(2)O; 0.8% TiO(2); 0.2% P(2)O(5); 0.1% MnO; and 0.03% Cr(2)O(3). In addition, baseline maps for the concentrations of each radionuclide, the radium equivalent activity and the outdoor gamma dose rate distributions have been plotted for the study area. The mean activity concentrations of (226)Ra, (232)Th, (40)K and (137)Cs were determined to be 32, 24, 210 and 9 Bq kg(-1), respectively. The assessments of the radiological hazard indices, such as radium equivalent activity, absorbed dose rate in air, annual effective dose equivalent, excess lifetime cancer risk, external hazard index and internal hazard index, were calculated and compared with the internationally accepted reference values. This study shows that the concentrations of radioactivities in the measured samples were within the recommended safety limits and did not pose to be any significant source of radiation hazard.

  3. Dating slate belts using 40Ar/39Ar geochronology and zircon ages from crosscutting plutons: A case study from east-central Maine, USA (United States)

    Ghanem, Hind; Kunk, Michael J.; Ludman, Allan; Bish, David L.; Wintsch, Robert P.


    We report the ages of cleavage development in a normally intractable lower greenschist facies slate belt, the Central Maine-Aroostook-Matapedia belt in east-central Maine. We have attacked this problem by identifying the minimum ages of muscovite in a regional Acadian cleavage (S1) and in a local ductile fault zone cleavage (S2) using 40Ar/39Ar geochronology and the ages of crosscutting plutons. Our success stems from the regional low-grade metamorphism of the rocks in which each crystallization event preserves a40Ar/39Ar crystallization age and not a cooling age. Evidence for recrystallization via a pressure solution mechanism comes from truncations of detrital, authigenic, and in some rocks S1 muscovite and chlorite grains by new cleavage-forming muscovite and chlorite grains. Low-blank furnace age spectra from meta-arkosic and slaty rocks climb from moderate temperature Devonian age-steps dominated by cleavage-forming muscovite to Ordovician age-steps dominated by a detrital muscovite component. S1- and S2-cleaved rocks were hornfelsed by granitoids of ∼407 and 377 Ma, respectively. The combination of these minimum ages with the maximum metamorphic crystallization ages establishes narrow constraints on the timing of these two cleavage-forming events, ∼410 Ma (S1) and ∼380 Ma (S2). These two events coincide in time with a change in the plate convergence kinematics from the arrival of the Avalon terrane (Acadian orogeny), to a right-lateral transpression arrival of the Meguma terrane in the Neoacadian orogeny.

  4. Mineral Sequestration of Carbon Dixoide in a Sandstone-Shale System

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    Xu, Tianfu; Apps, John A.; Pruess, Karsten


    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.

  5. Secondary mineralization and hydrothermal alteration in the Reydarfjordur drill core, eastern Iceland (United States)

    Mehegan, James M.; Robinson, Paul T.; Delaney, John R.


    Deep crustal drilling in eastern Iceland has allowed study of a fossil hydrothermal system at a constructive plate margin. The drilled sequence consists of partly to completely altered subaerial lava flows, basaltic dikes, and minor clastic material. Alteration and secondary mineralization are most intense in the flow top breccias where water/rock ratios are presumed to have been the highest. In the upper portion of the cored sequence (to a depth of about 1200 m) alteration is characterized by the deposition of clay minerals ± calcite ± quartz ± laumontite into open spaces such as vugs and vesicles. Low-temperature zeolites, such as stilbite, epistilbite, mordenite, and heulandite, are also present but are restricted to the upper 500 m of the drill core. Below 1200 m, alteration is characterized by the dissolution and replacement of both primary minerals and earlier authigenic minerals, followed by partial filling of dissolution cavities. Early mineral assemblages consist of epidote ± quartz ± prehnite ± chlorite ± albite, and a later superimposed assemblage consists of calcite + laumontite ± anhydrite. Authigenic sphene, pyrite, chalcopyrite, pumpellyite, actinolite, and wairakite also occur sporadically in the cored sequence. Secondary mineral assemblages and temperature measurements of fluid inclusions suggest a maximum temperature of alteration of about 300°C. Fluid inclusion compositions indicate that the geothermal fluid was meteoric water with very low salinities and high calcium activities. Iron activities and oxygen fugacities were highest in the deeper portions of the systems. The mineral paragenesis suggests that the fluid composition, temperature, and PCO2 varied significantly with time. The thermal energy for the geothermal system was probably derived from a high-level magma chamber associated with nearby Thingmuli volcano. Local contact metamorphism, indicated by the formation of garnet, occurred during late stage emplacement of dikes into

  6. The geological setting and style of copper mineralization at the Bushman group of deposits, northeastern Botswana (United States)

    Barton, J. M.; Blaine, J. L.; Doig, R.; Byron, C. L.


    The Bushman group of CuPbZn deposits occur within the north-northeasterly trending Bushman shear zone in northeastern Botswana. The deposits are hosted by a sliver of sheared and altered, carbonate rocks and chloritic and graphitic schists that resemble and are presumed correlative with metasedimentary rocks of the Matsitama schist belt to the east. This sliver is surrounded by sheared and altered granitic gneisses. Within the sliver, the mineralized zones are a chalcopyrite and pyrite bearing quartz-calcite±alkali feldspar vein breccias near the sheared contact between the carbonate rocks and the chloritic and graphitic schists. Elsewhere within the granitic gneisses, those zones are marked by barren quartz breccias surrounded by a zone dominated by red, turbid orthoclase in turn surrounded by a zone dominated by green epidote. Initially hydrothermal alteration propylitized the host rocks and then porphyroblasts of orthoclase, albite and quartz grew with the introduction of calcite. Away from the mineralized zones, four generations of veins occur, the first two directly traceable to CuPbZn mineralization and the third carrying galena and sphalerite. Isotopic data suggest that the protolith of the granitic gneisses was emplaced sometime between about 2.57 Ga and 2.3 Ga ago. After this protolith was deformed and metamorphosed, CuPbZn mineralization occurred about 1926 Ma ago from fluids at a temperature of about 360°C. The Pb isotopic compositions of the sulfide minerals indicate that the fluids giving rise to the CuPbZn mineralization were possibly the same as those giving rise to Pb and Zn mineralization. In both instances, however, the Pb came from several sources. More recently, shear zones parallel to the Bushman shear zone may have controlled in part the emplacement of kimberlite pipes.

  7. 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


    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

  8. Silicification of pelitic schist in the Iwakuni-Yanai area of the Ryoke belt, southwest Japan: Origin of competent layers in the deep crust (United States)

    Terabayashi, M.; Yamamoto, H.


    Bright-layer reflections have been imaged at about 15-20 km depth in fore-arc region of southwest Japan, and most of the epicenter distributes above the bright-layer (Ito, 1999). To understand the cause of a seismic bright-layer with the mechanism of large inland earthquake, we studied the low-P/T metamorphic rocks in the Ryoke belt, southwest Japan. The Ryoke belt in the Iwakuni-Yanai area is underlain by Jurassic accretionary complex and their metamorphosed equivalents. They were intruded by Cretaceous granitic rocks. Five metamorphic zones can be difined by mineral assemblages of pelitic rocks as a regional metamorphism before the intrusion; chlorite, chlorite-biotite, biotite, cordierite and sillimanite zones from north to south (Ikeda, 1993). Silicified rocks have been found in pelitic schist of the biotite zone and northernmost part of the cordierite zone. The pelitic schist is dark in color but silicification turned it to be pale gray or milky white. Silicified pelitic schist is mainly composed of fine-grained quartz and minor muscovite and biotite. The silicified pelitic schist forms layers or lenticular bodies several to fifty meters in thickness. The boundary between silicified rock layer and underlying pelitic schist is fairly distinct but that between the overlying pelitic schist is gradual. Quartz veins crossing high angles with schistosity were preferentially developed in the silicified rock layers, while schistosity-parallel quartz veins, which underwent plastic flow, were observed in the pelitic schist. En echelon quartz vein and fishnet-like quartz veins are characteristic of silicified rock layers. This mode of occurrence of quartz veins indicates competence of silicified rock layers relative to pelitic schist. Rock boundary with high competence contrast is probably a good reflector of seismic waves. Bright-layer reflections would arise from silicified rock layers if those are distributed in the deep crust to a considerable extent.

  9. Investigation on type and origin of iron mineralization at Mesgar occurrence, south of Zanjan, using petrological, mineralogical and geochemical data

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    Mohammad Ebrahimi


    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

  10. The "green stones" of Valtellina and Valchiavenna (central Alps, northern Italy) (United States)

    Cavallo, Alessandro


    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

  11. 可可西里盐湖表层沉积物中粘土矿物的环境信息%Environmental information of clay minerals in salt lake surface sediments of Hol Xil area

    Institute of Scientific and Technical Information of China (English)

    高翔; 彭强; 蔡敏; 邸迎伟; 方勤方; 马鸿文; 鲁安怀


    通过对可可西里盐湖表层沉积物中粘土矿物的研究,以期获得近年来湖区的某些环境信息.研究结果表明:沉积物中的粘土矿物主要为伊利石和绿泥石,非粘土矿物主要为石英、方解石和长石以及少量白云石、文石、闪石和石膏等.样品中<2μm的粘土矿物以伊利石和绿泥石为主,局部样品含少量有序伊/蒙混层.根据样品分布特点和粘土矿物的组合类型,将样品划分为3个区域:1区和3区的矿物组合为伊利石、绿泥石和有序伊/蒙混层;2区为伊利石和绿泥石,无伊像混层矿物.其中1区和3区样品的结晶度(IC)范围为0.41~0.59,均值为0.51;2区样品的结晶度范围为0.25~0.40,均值为0.34,明显低于1区和3区,说明2区样品中的伊利石具有更高的结晶度.样品的伊利石化学指数(CI)均小于0.5,表明该伊利石为富Fe-Mg伊利石,主要是物理风化作用的结果.伊利石和绿泥石作为主要粘土矿物反映了近年来整个湖区的环境以干冷为主,局部区域(1区和3区)出现的少量有序I/S混层矿物则指示在短期内曾经历过短暂的干湿交替环境.此外,在酸性介质条件下,少量伊利石发生弱水解作用导致晶格中的K+淋失,并转化为伊/蒙混层矿物,同时也降低了伊利石的结晶度.%Clay minerals of surface sediments in the salt lakes of Hoi Xil area were studied in this paper with the purpose of obtaining some recent environmental information of the lakes. The results show that clay minerals are illite and chlorite in surface sedimentary samples, whereas non-clay minerals mainly include quartz, calcite and feldspar together with small amounts of dolomite, aragonite, amphibole and gypsum. Clay minerals with particle sizes smaller than 2 μm in samples are illite (65% ~82% ) and chlorite (13% ~35% ), and small amounts of ordered Illite/Smectite (I/S) mixed layer (4%~15%) also exists in local areas. According to the distribution of

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

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    Loefgren, Martin (Niressa AB, Norsborg (Sweden)); Sidborn, Magnus (Kemakta Konsult AB, Stockholm (Sweden))


    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

  13. Facies metamórficas y edades relativas de las rocas del extremo oriental del Brazo Huemul, provincia de Neuquén Metamorphic facies and relative ages of rocks on the eastern part of Brazo Huemul, Neuquén province

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    M.F. Gargiulo


    exposed in the study area are mainly of tonalitic composition and have been correlated with the Subcordilleran Patagonian Batholith because they are crosscut by two different types of dikes. One group of dikes shows an albite - chlorite - epidote - cummingtonite/ grunerite - hornblende mineral assemblage as a consequence of a thermal metamorphic event transitional between albite - epidote hornfels facies and hornblende hornfels conditions. This process has been attributed to the emplacement of the Cordilleran Patagonian Batholith of Cretaceous age. Because of this, the hornfels dikes were correlated with Montes de Oca Formation. The other group of dikes shows a chlorite + pumpellyite + laumontite + chlorite/esmectite + iron oxides assemblage indicating metamorphism in zeolite facies of high temperature or, sometimes shows propilitic alteration and these dikes have been correlated with the Ventana Formation. The differences between these two types of dikes allow the discussion of the relative age of the tonalitic rocks that host them. In this paper it is proposed that this tonalitic body is of Low to Middle Jurassic age.

  14. Geologic and mineralogic controls on acid and metal-rich rock drainage in an alpine watershed, Handcart Gulch, Colorado (United States)

    Bove, Dana J.; Caine, Jonathan S.; Lowers, Heather


    The surface and subsurface geology, hydrothermal alteration, and mineralogy of the Handcart Gulch area was studied using map and drill core data as part of a multidisciplinary approach to understand the hydrology and affects of geology on acid-rock drainage in a mineralized alpine watershed. Handcart Gulch was the locus of intense hydrothermal alteration that affected an area of nearly 3 square kilometers. Hydrothermal alteration and accompanied weak mineralization are spatially and genetically associated with small dacite to low-silica rhyolite stocks and plugs emplaced about 37-36 Ma. Felsic lithologies are commonly altered to a quartz-sericite-pyrite mineral assemblage at the surface, but alteration is more variable in the subsurface, ranging from quartz-sericite-pyrite-dominant in upper core sections to a propylitic variant that is more typical in deeper drill core intervals. Late-stage, hydrothermal argillic alteration [kaolinite and(or) smectite] was superimposed over earlier-formed alteration assemblages in the felsic rocks. Smectite in this late stage assemblage is mostly neoformed resulting from dissolution of chlorite, plagioclase, and minor illite in more weakly altered rocks. Hydrothermally altered amphibolites are characterized by biotitic alteration of amphibole, and subsequent alteration of both primary and secondary biotite to chlorite. Whereas pyrite is present both as disseminations and in small veinlets in the felsic lithologies, it is mostly restricted to small veinlets in the amphibolites. Base-metal sulfides including molybdenite, chalcopyrite, sphalerite, and galena are present in minor to trace amounts in the altered rocks. However, geologic data in conjunction with water geochemical studies indicate that copper mineralization may be present in unknown abundance in two distinct areas. The altered rocks contain an average of 8 weight percent fine pyrite that is largely devoid of metals in the crystal structure, which can be a significant

  15. 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 (United States)

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


    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

  16. Mineralogical and Geochemical Characteristics of Detrital Rocks in the Mengyejing Formation and Evolution of the Sedimentary Environment of Paleolake in Simao Basin,Yunnan Province%云南思茅盆地勐野井组碎屑岩矿物学、地球化学特征及古盐湖沉积环境演化

    Institute of Scientific and Technical Information of China (English)

    苗卫良; 马海州; 张西营; 石海岩; 李永寿; 容志明


    Clay mineralogy and geochemistry of detrital sediment samples collected in a core of the Mengyejing Potash salt mining of Simao basin,Yunnan were used to evaluate the provenance and sedimentary environment evolution of paleolake.The clay mineral assemblages,La/Th-Hf,La/Sc-Th/Co,La-Th-Sc diagrams and values of Cr/Th,Al2 O3/TiO2 indicate that the provenance of the detrital sediment is mainly granodiorites.And the major element results indicate that the formation of clay minerals is accompanied by leaching of Ca and Na first and enrichment of K and Mg.Fe and Mn,is deplete because of the limitations provenance.Combined with the formation conditions of clay minerals,we suggest that the paleolake experienced a variable paleoclimate evolution process which characterized by warm and wet to warm and dry (the stage of salt-forming and sylvite-forming )to warm and wet (the desalination stage).The hypersaline environment and burial diagenesis affected the clay mineral assemblages significantly, documented by the widespread occurrence of illitization and chloritization in core samples.Thus,the clay mineral assemblages of illite + chlorite, combined with the abundance of Mg-rich chlorite and the abnormally high value of MgO of detrital sediments at the corresponding stage are indictive of the evolution of salt-forming and sylvite-forming stage.%通过对云南思茅盆地勐野井钾盐矿区钻孔岩心的碎屑沉积物进行粘土矿物分析和元素地球化学分析探讨了研究区晚白垩世碎屑岩的物源属性及古盐湖沉积环境演化特征。粘土矿物组合特征及 La/Th-Hf、La/Sc-Th/Co、La-Th-Sc 图解,Cr/Th、Al2 O3/TiO2比值等表明该孔碎屑岩的物源主要为长英质花岗闪长岩。主量元素活动性分析表明化学风化过程中随着粘土矿物的形成首先发生 Ca 和 Na 的淋失,K、Mg 则在这一过程中呈富集态势,而 Fe、Mn 主要受物源限制而总体上表现为亏损。结合粘土矿物形

  17. 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))


    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

  18. Caldera complex, hosted rocks and alteration of the Yandong porphyry copper deposit in Eastern Tianshan, Xinjiang%新疆延东斑岩铜矿床火山机构、容矿岩石及热液蚀变

    Institute of Scientific and Technical Information of China (English)

    申萍; 潘鸿迪; 董连慧; 杨俊弢; 沈远超; 代华五; 关维娜; 赵云江


    alteration assemblages, including ihe central fiericile-chlorite assemblage and chlorite-sericite assemblage and distal propylitic assemblage. Cu-Fe sulfldes are closely associated with the sericite-chlorite assemblage. Plagiogranite porphyry, cutting ihe early-stage diorite porphyry, has undergone the central phyllic and surrounding strong and weak sericite alteration. Intense phyllic alteration produced the high-grade copper ore at Yandong. The two alteration systems at Yandong were characterized by rare potassic alteration and widespread sericite alteration.

  19. 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 (United States)

    Kampmann, Tobias C.; Jansson, Nils J.; Stephens, Michael B.; Majka, Jarosław


    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

  20. Fluid-related modifications of Cr-spinel and olivine from ophiolitic peridotites by contact metamorphism of granitic intrusions in the Ablah area, Saudi Arabia (United States)

    Ahmed, Ahmed Hassan; Surour, Adel Abdullah


    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

  1. The geological and metallogenic setting of stratabound carbonate-hosted Zn-Pb mineralizations in the West Asturian Leonese Zone, NW Spain (United States)

    Tornos, F.; Ribera, F.; Shepherd, T. J.; Spiro, B.


    Several carbonate-hosted stratabound zinc-lead ores in the Ponferrada-Caurel area (NW Spain) are hosted by the Lower to Middle Cambrian Vegadeo Formation. Two clearly distinct groups of mineralizations occur in different stratigraphic positions. The stratiform disseminated ore is located in the Lower Member as irregular and millimetre-thick layers of sphalerite and galena replacing earlier pyrite. The lack of hydrothermal alteration and the heavy C., O and S isotopic signatures suggest that this ore is of premetamorphic origin, the sulphur and fluids being derived from the host carbonates. The more likely source of the sulphide is the abiogenic thermal reduction of sulphate derived from sulphate beds intercalated with the carbonates. The second group of mineralizations is located at the top of the Vegadeo Fm, always along its contact with the overlaying shales and sandstones of the Cabos Series. This group is economically more important and include three styles of strata-bound mineralizations. The more common one is the ‘silica ore’, a hydrothermal rock that traces the contact between the carbonate and the detrital rocks along more than 50 km. Locally, a ‘carbonate-rich ore’ is found along the contact between the silica ore and the Vegadeo Fm. Laterally to these rocks, there are large bodies of the ≪breccia ore≫, made up of sulphides and calcite in a matrix of chlorite. The ore assemblage is composed of sphalerite and galena with minor amounts of chalcopyrite and pyrite. Co-Ni-As sulphides, bismuthinite, tetrahedrite and Pb-Bi sulphosalts are also found as trace minerals. The geological relationships and the isotopic signatures suggest that the three ores are synchronous and of late Hercynian age. They are interpreted as linked with a tectonically driven fluid flow along the stratigraphic contact between the carbonate and the detrital rocks. The model of ore genesis involves the circulation of fluids in likely equilibrium with the detrital rocks that

  2. Geology and porphyry copper-type alteration-mineralization of igneous rocks at the Christmas Mine, Gila County, Arizona (United States)

    Koski, Randolph A.


    igneous rocks is progressively more alkaline and silicic from basalt to granodiorite. Early (Stage I) chalcopyrite-bornite (-molybdenite) mineralization and genetically related K-silicate alteration are centered on the Christmas stock. K-silicate alteration is manifested by pervasive hornblende-destructive biotitization in the stock, biotitization of basaltic volcanic wall rocks, and a continuous stockwork of K-feldspar veinlets and quartz-K-feldspar veins in the stock and quartz-sulfide veins in volcanic rocks. Younger (Stage II) pyrite-chalcopyrite mineralization and quartz-sericite-chlorite alteration occur in a zone overlapping with but largely peripheral to the zone of Stage I stockwork veins. Within the Christmas intrusive complex, K-silicate-altered rocks in the central stock are flanked east and west by zones of fracture-controlled quartz-sericite alteration and strong pyritization. In volcanic rocks quartz-chlorite-pyrite-chalcopyrite veins are superimposed on earlier biotitization and crosscut Stage I quartz-sulfide veins. Beyond the zones of quartz-sericite alteration, biotite rhyodacite porphyry dikes contain the propylitic alteration assemblage epidote-chlorite-albite-sphene. Chemical analyses indicate the following changes during pervasive alteration of igneous rocks: (1) addition of Si, K, H, S, and Cu, and loss of Fe 3+ and Ca during intense biotitization of basalt; (2) loss of Na and Ca, increase of Fe3+/Fe2+, and strong H-metasomatism during sericitization of quartz diorite; and (3) increase in Ca, Na, and Fe3+/Fe2+, and loss of K during intense propylitization of biotite rhyodacite porphyry dikes. Thorough biotitization of biotite granodiorite porphyry in the Christmas stock was largely an isochemical process. Fluid-inclusion petrography reveals that Stage I veins are characterized by low to moderate populations of moderate-salinity and gas-rich inclusions, and sparse but ubiquitous halite-bearing inclusions. Moderate-salinity an

  3. Influence of the angle between cleavage and bedding on the anisotropy of magnetic susceptibility and the degree of phyllosilicate preferred orientation (United States)

    Debacker, T. N.; Sintubin, M.


    Due to the common scarcity of strain markers and the often fine-grained lithologies, performing strain analyses in slate belts may be difficult. As an alternative, one may use methods such as phyllosilicate preferred orientation (X-ray pole figure goniometry) and anisotropy of magnetic susceptibility (AMS). However, a large number of factors influence the results of these analytical methods. One of the factors is the angle between cleavage and bedding. The study area is the Brabant Massif, a single-phase deformed, low-grade slate belt in N-Belgium consisting of a steep Cambrian core surrounded by Ordovician-Silurian sequences. In the southern part of the Cambrian core, the transition between steeply plunging folds, considered typical for the steep core, and gently plunging folds, considered characteristic for the peripheral Ordovician-Silurian sequences, occurs in homogeneous mudstones of the Lower Cambrian Oisquercq Formation. In these deposits mica and chlorite show a similar degree of preferred orientation. Mica is always aligned along the cleavage, whereas chlorite is aligned along the bedding. Clear intersection pole figure patterns characterise samples with large cleavage/bedding angles, whereas flattening fabrics only become apparent for samples with small cleavage/bedding angles. For both mica and chlorite, the degree of preferred orientation is higher for samples with small cleavage/bedding angles. The magnetic fabric shows prolate susceptibility ellipsoids for samples with large cleavage/bedding angles and oblate susceptibility ellipsoids for samples with small cleavage/bedding angles (cf. Housen et al., 1993). The short axis of the susceptibility ellipsoid is generally oriented perpendicular to bedding, occasionally perpendicular to cleavage or with an intermediate orientation. The long axis of the susceptibility ellipsoid is always parallel to the cleavage/bedding intersection. The shape parameter T shows an almost linear relationship with respect to

  4. 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.


    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

  5. Mineralogy and microstructure of roofing slate: thermo-optical behaviour and fissility

    Directory of Open Access Journals (Sweden)

    García-Guinea, J.


    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. Bedout basement rise, offshore northwestern Australia: evidence of an unshocked mafic volcanic hyaloclastite volcanic breccia (United States)

    Glikson, A.


    Core samples from Bedout-1 (3035.8-3044.95 m.), Bedout basement rise, offshore northwestern Australia, were examined by optical microscopy, SEM, EDS and WDS spectrometry. At this stratigraphic depth level Becker et al. (2004) interpret cryptocrystalline alteration zones around and within plagioclase in terms of shock-induced transformation of feldspar into diaplectic maskelynite glass _u postulating a ~200 km-large impact structure and thereby an impact connection of the Permian-Triassic boundary mass extinction. However, the breccia is dominated by fragments of microlitic basalt and ophitic-textured dolerite with well preserved igneous textures, showing no evidence of shock metamorphism. Euhedral pseudomorphs of chlorite and amphibole, probably after pyroxene, protrude into or are enveloped by euhedral albite-twinned calcic plagioclase (andesine to bytownite). Minor phases include euhedral ilmenite needles and subhedral magnetite grains. Plagioclase is altered by cryptocrystalline albite and microcrystalline albite-chlorite matrix along crystal boundaries, along twin lamella and within internal oscillatory crystal zones, consistent with burial metamorphosed hydrovolcanic basalts and spilites (e.g. Amstutz, 1974). The volcanic fragments are set within, and injected by, microcrystalline intergranular mesostasis of mixed mineral fragments and volcanic meta-glass. Becker et al. (2004) refer to the breccia in part as product of Mg-rich sediments (e.g. dolomites). However, apart from the pristine igneous textures of the breccia, the transition element levels (chlorite in dolerite fragment "C Ni 97-160 ppm; Co 75-152 ppm; Cu 69-204 ppm; mesostasis "C Ni 29-45 ppm; Co 18-52 ppm; Cu 26-110 ppm) are consistent with Fe-rich basalts but exceed common abundances in carbonates and marls (BVTP, 1981; Wedepohl, 1978). No shock metamorphic features, such as planar deformation features (PDF), are observed in the feldspar or in any other phases. No criteria for discriminating

  7. Pervasive, high temperature hydrothermal alteration in the RN-17B drill core, Reykjanes Geothermal System-Iceland Deep Drilling Project (United States)

    Zierenberg, R. A.; Schiffman, P.; Marks, N. E.; Reed, M. H.; Elders, W. A.; Fridleifsson, G. O.


    In November 2008, 9.5 m of core were recovered from Reykjanes production well RN-17B at a depth of 2800m. The core consists mainly of hyaloclastite breccias, hetrolithic breccias with clasts of crystalline basalt, and volcaniclastic sandstones/siltstones. Much of the material appears to have been transported and redeposited, but homolithic breccias and hyaloclastites, some with upright flow lobes of basalt with quenched rims, are interpreted to have erupted in situ. Fine-scale features (glass rims, quench crystals, vesicles, phenocrysts) are well preserved, but all lithologies are pervasively hydrothermally altered such that primary clinopyroxene is ubiquitously uralitized and primary plagioclase (An42-80) is replaced by albite and/or more calcic plagioclase. In contrast, cuttings of similar lithologies, recovered by rotary drilling in intervals immediately above and below the core, exhibit much lesser degrees of hydrothermal alteration and commonly contain igneous plagioclase and clinopyroxene. Vitric clasts in the core are recrystallized into aggregates of chlorite and actinolite. In some breccias, cm-scale metadomains are composed of patchy albite or actinolite/magnesiohornblende giving the core a green and white spotted appearance. Minor amounts (<1%) of disseminated pyrite occur throughout the core, but two intervals with more abundant sulfide contain chalcopyrite and sphalerite in addition to pyrite. Amygdales and vugs in the breccias, initially filled with chlorite, actinolite, epidote, and/or albite, have been partly overprinted with hornblende and anorthite. The core is cut in places by < 1 cm- wide veins composed of early epidote + actinolite + titanite and later anorthite + magnesiohornblende/pargasite. Quartz is not present in any alteration domains observed in the core, although it is reported from virtually all of the cutting intervals above and below the cored section. Seawater-basalt reaction calculations suggest that albite formed during early

  8. Initiating intermediate-depth earthquakes: Insights from a HP-LT ophiolite from Corsica (United States)

    Deseta, N.; Ashwal, L. D.; Andersen, T. B.


    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

  9. The Freyenstein Shear Zone - Implications for exhumation of the South Bohemian Batholith (Moldanubian Superunit, Strudengau, Austria) (United States)

    Griesmeier, Gerit; Iglseder, Christoph; Konstantin, Petrakakis


    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

  10. Origins of chromite and magnetite in sedimentary rocks deposited in a shallow water environment in the 3.2 Ga Moodies Group, South Africa (United States)

    Otake, T.; Sakamoto, Y.; Itoh, S.; Yurimoto, H.; Kakegawa, T.


    *Otake, T. Div. of Sustainable Resources Engineering, Hokkaido Univ., Sapporo, Japan Sakamoto, Y. Dep. of Earth Science, Tohoku Univ., Sendai, Japan Itoh, S. Dep. of Natural History Sciences, Hokkaido Univ., Sapporo, Japan Yurimoto. H. Dep. of Natural History Sciences, Hokkaido Univ., Sapporo, Japan Kakegawa, T. Dep. of Earth Science, Tohoku Univ., Sendai, Japan Geochemical data from ferruginous chemical sedimentary rocks (e.g., Banded Iron Formation: BIF) have been used to reconstruct the surface environments of early Earth. However, only a few studies have investigated the geochemical characteristics of BIFs deposited in a shallow water environment during the Archean, which may have differed from those deposited in a deep water environment. Therefore, we investigated geological, petrographic and geochemical characteristics of ferruginous rocks deposited in a shallow water environment in the Moodies group, in the Barberton Greenstone Belt, South Africa. We obtained ferruginous rock samples in the Moodies group from both an outcrop and underground gold mine, and compared the characteristics of these samples. The 70 sedimentary rock samples were divided into groups based on the dominant Fe minerals they contain: Hematite-rich jaspilite (HM group), Magnetite-rich iron formation/shale/sandstone (MT group), and Siderite-rich sandstone (SD group). Samples in the HM group are predominantly composed of fine-grained quartz (< 20 μm) and hematite (< 5 μm), which are interpreted to be chemical precipitates. Samples in the MT group contain quartz, magnetite, siderite, ankerite, chlorite, biotite and chromite. The grain size of magnetite is much larger (20-150 μm) than that of hematite in the HM group. The magnetite is interpreted as a secondary mineral transformed from hematite during early diagenesis. Results of in situ oxygen isotope analysis by

  11. A-type and I-type granitoids and mylonitic granites of Hassan Salaran area of SE Saqqez, Kurdistan, Iran (United States)

    Abdullah, Fakhraddin Mohammad; Saeed Ahmad, Sheler


    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. Geochemical, microtextural and petrological studies of the Samba prospect in the Zambian Copperbelt basement: a metamorphosed Palaeoproterozoic porphyry Cu deposit. (United States)

    Master, Sharad; Mirrander Ndhlovu, N.


    , 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.

  13. Bioreduction of Fe-bearing clay minerals and their reactivity toward pertechnetate (Tc-99)

    Energy Technology Data Exchange (ETDEWEB)

    Bishop, Michael E.; Dong, Hailiang; Kukkadapu, Ravi K.; Liu, Chongxuan; Edelmann, Richard E.


    99Technetium (99Tc) is a fission product of uranium-235 and plutonium-239 and poses a high environmental hazard due to its long half-life (t1/2 = 2.13 x 105 y), abundance in nuclear wastes, and environmental mobility under oxidizing conditions [i.e., Tc(VII)]. Under reducing conditions, Tc(VII) can be reduced to insoluble Tc(IV). Ferrous iron [Fe(II)], either in aqueous form or in mineral form, has been used to reduce Tc(VII) to Tc(IV). However, the reactivity of Fe(II) from clay minerals, other than nontronite, toward immobilization of Tc(VII) and its role in retention of reduced Tc(IV) have not been investigated. In this study the reactivity of a suite of clay minerals toward Tc(VII) reduction and immobilization was evaluated. The clay minerals chosen for this study included five members in the smectite-illite (S-I) series, (montmorillonite, nontronite, rectorite, mixed layered I-S, and illite), chlorite, and palygorskite. Fe-oxides were removed from these minerals with a modified dithionite-citrate-bicarbonate (DCB) procedure. The total Fe content of these clay minerals, after Fe-oxide removal, ranged from 0.7 to 30.4% by weight, and the Fe(III)/Fe(total) ratio ranged from 44.9 to 98.5%. X-ray diffraction (XRD) and Mössbauer spectroscopy results showed that after Fe oxide removal the clay minerals were free of Fe-oxides. Scanning electron microscopy (SEM) revealed that little dissolution occurred during the DCB treatment. Bioreduction experiments were performed in bicarbonate buffer (pH-7) with Fe(III) in the clay minerals as the sole electron acceptor, lactate as the sole electron donor, and Shewanella Putrifaciens CN32 cells as mediators. In select tubes, anthraquinone-2,6-disulfate (AQDS) was added as electron shuttle to facilitate electron transfer. The extent of Fe(III) bioreduction was the highest for chlorite (~43 wt%) and the lowest for palygorskite (~4.17 wt%). In the S-I series, NAu-2 was the most reducible (~31 %) and illite the least (~0.4 %). The

  14. 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 (United States)

    Irino, T.; Yamamoto, M.; Ikehara, K.; Kuwae, M.; Takemura, K.


    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

  15. Mineralogy, chemistry of magnetite and genesis of Korkora-1 iron deposit, east of Takab, NW Iran

    Directory of Open Access Journals (Sweden)

    Mohammad Maanijou


    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

  16. Mineralogy of the silica-epidote mineralized zone (SEMZ) in the Cerro Prieto geothermal reservoir, B.C., Mexico; Mineralogia de la zona mineralizada de silice-epidota (ZMSE) del yacimiento geotermico de Cerro Prieto, B.C., Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Izquierdo, Georgina; Aragon, Alfonso; Portugal, Enrique; Arellano; Victor M [Instituto de Investigaciones Electricas, Gerencia de Geotermia, Cuernavaca, Morelos (Mexico)]. E-mail:; Leon, Jesus de; Alvarez, Julio [Comision Federal de Electricidad, B.C. (Mexico)


    The distribution of hydrothermal minerals, mineral assemblages and fluid inclusion data were taken from drill cuttings from the production zone of wells all over the Cerro Prieto geothermal field. The production zone has been termed the silica-epidote mineralized zone (SEMZ), and is located in the deep part of the gray shale where thick layers of sandstone are found. Common mineral assemblages show three temperature ranges in the SEMZ: <200 degrees Celsius, 200-250 degrees Celsius and 250-300 degrees Celsius. The first range is characterized by clays, calcite and quartz; the second by quartz, epidote, chlorite and mica, and the third by epidote, amphibole, illite and chlorite. The study of fluid inclusions in authigenic grain quartz has shown two-phase fluid inclusions (liquid + vapor) of different salinities. A wide range exists of homogenization temperatures (Th) and for some wells there is a good agreement between Th and direct temperature measurements. [Spanish] Se determino la distribucion de minerales hidrotermales y las asociaciones parageneticas y se realizo el estudio microtermometrico de inclusiones fluidas a partir de recortes de perforacion de pozos de las distintas areas del campo geotermico de Cerro Prieto. Las muestras de recortes y nucleos de perforacion estudiados provienen de la zona de produccion a la que se le ha denominado Zona Mineralizada de Silice-Epidota (ZMSE), que se encuentra en la parte profunda de la lutita gris con importantes horizontes de areniscas. En esta zona las asociaciones parageneticas mas comunes han mostrado tres intervalos de temperatura para la ZMSE: <200 degrees Celsius, 200-250 degrees Celsius, 250-300 degrees Celsius. El primer intervalo esta caracterizado principalmente por arcillas, calcita y cuarzo; el segundo por cuarzo, epidota, clorita y micas, y el tercero por epidota, anfiboles, illita y clorita. El estudio de inclusiones fluidas en fragmentos de cuarzo autigenico mostro la presencia de inclusiones de dos fases

  17. Depression and dispersion effect of carboxy methyl cellulose on flotation of layered magnesium-silicates%羧甲基纤维素对层状镁硅酸盐矿物浮选的抑制与分散作用

    Institute of Scientific and Technical Information of China (English)

    龙涛; 冯其明; 卢毅屏; 张国范; 欧乐明; 潘高产


    通过浮选实验、润湿接触角测量和Zeta电位测试,考察滑石、绿泥石和蛇纹石3种层状镁硅酸盐矿物的可浮性及其对金川镍矿中的硫化矿物-黄铁矿浮选的影响,并研究羧甲基纤维素(CMC)对3种层状镁硅酸盐矿物浮选的抑制与分散作用.结果表明;3种镁硅酸盐矿物表面性质与可浮性不同,对硫化矿浮选的影响方式与机理也存在区别:蛇纹石天然可浮性较差,但由于静电作用易与黄铁矿发生异相凝聚,降低黄铁矿的可浮性进而影响其回收率,CMC可通过调整矿物表面电性而起到分散作用;滑石与绿泥石并不影响黄铁矿的可浮性,但由于其天然可浮性相对较好,易进入精矿增加MgO杂质含量,CMC能调整矿物表面润湿性而抑制其浮选.%The floatability of three types of layered magnesium-silicates (talc, chlorite and serpentine), the negative effect of magnesium-silicates on the flotation of pyrite (one sulfide mineral of Jinchuan nickel mine) and the depression and dispersion effect of carboxy methyl cellulose (CMC) on the flotation of magnesium-silicates were investigated through flotation tests, contact angle measurements and zeta potential measurements. The results show that the surface properties and floatability of these magnesium-silicates different, and the way how the magnesium-silicates affecting the flotation of sulfides are also different: the natural floatability of serpentine is poor, but electrostatic aggregation occurred between serpentine and pyrite, thus reducing the fioatability of pyrite. CMC can disperse serpentine and pyrite by changing the surface electrical property of minerals. Although talc and chlorite cannot affect the recovery of pyrite, they mix in concentrate and then increase the impurity contents of MgO due to their good floatability. CMC depresses their flotation by changing the surface wettability.

  18. Applicability of the RSCM geothermometry approach in a complex tectono-metamorphic context: The Jebilet massif case study (Variscan Belt, Morocco) (United States)

    Delchini, Sylvain; Lahfid, Abdeltif; Plunder, Alexis; Michard, André


    The Raman Spectroscopy of Carbonaceous Materials (RSCM) geothermometry approach allows determining the peak temperature recorded by metasediments through their metamorphic history. This technique, however, has been calibrated using Meso-Cenozoic metapelitic rocks that underwent a single metamorphic cycle. Until now, the reliability of the RSCM method has never been demonstrated for contexts with superposition of regional and contact metamorphism, such as many Variscan contexts. The present study aims at testing the applicability of the RSCM method to these polyphased metamorphism terrains and at investigating the cumulative molecular transformations of carbonaceous materials related to metamorphic superposition. To address the above issues, samples were collected in the Variscan Jebilet massif of the Moroccan Meseta. This massif was first affected by a regional, greenschist facies metamorphic event (D1 phase), and then by a higher-T, regional and contact metamorphism that reached the hornfels/amphibolite facies conditions (D2 and D2/D3 phases). Mineralogical, thermobarometric and RSCM methods have been used in this study to determine the peak T recorded by the studied rocks. The results obtained for greenschist facies metapelitic rocks show a good agreement between the mineralogical assemblage Chlorite-Phengite-Felspar-Quartz and the Raman temperatures ranging from 330 to 394 ± 50 °C. In the metapelitic rocks that underwent higher metamorphism grades (hornfels/amphibolite facies), four dominant mineral assemblages were observed: (1) Chlorite-Biotite, (2) Cordierite-Biotite, (3) Andalusite-Garnet-Bt, and (4) Andalusite-Cordierite-Biotite. The corresponding Raman temperatures vary respectively between 474 ± 50 °C and 628 ± 50 °C. The pseudo-sections generated for samples from the hornfels/amphibolite facies confirmed the peak temperatures measured by the RSCM method. Our results do not support clear evidence of potential molecular cumulative effect on CM

  19. Radiation chemical effects in the near-field environment of a radwaste repository: {gamma} radiolysis in 6 molal NaCl solutions; Strahlenchemische Effekte im Endlagernahbereich: {gamma}-Radiolyse in 6 molarer NaCl-Loesung

    Energy Technology Data Exchange (ETDEWEB)

    Kelm, M.; Bohnert, E.


    The radiation emitted from high-level radioactive wastes in a radwaste repository causes radiolysis products to be formed in brines resulting from water intrusion. The products may alter via redox and complexing reactions the mobilisation processes of radionuclides. The major products of {gamma} radiolysis determined in 6 molal NaCl solution as a function of radiation dose are hydrogen, oxygen, and chlorate. Hypochlorite and chlorite were found to have concentrations in the {mu}Mol/kg range. There was no dependence on dose rate. For the experiments under atmospheric pressure, which allowed radiolytic gas to escape from the solution, the G values measured are 0.46 (H{sub 2}), 0.16 (O{sub 2}), and 0.074 (ClO{sub 3}). In pressurized experiments, with radiolytic gas remaining contained in the solution, the radiolytic effect was much smaller. After approx. 100 days, at a dose of about 2 MGy, gas equilibrium concentrations of some mMol/kg were measured. The results can be qualitatively described by a system of parallel running reaction rate equations. As to quantitative analysis, the reaction model needs to be refined. (orig./CB) [Deutsch] Die Strahlung von hochradioaktiven Abfaellen in einem Endlager im Salz hat zur Folge, dass bei einem Wasserzutritt in den entstehenden Laugen Radiolyseprodukte gebildet werden. Die Radiolyseprodukte koennen durch Redox- und Komplexierungsreaktionen die Mobilisierbarkeit von Radionukliden veraendern. Als Hauptprodukte der {gamma}-Radiolyse wurden in 6 molaler NaCl-Loesung Wasserstoff, Sauerstoff und Chlorat in Abhaengigkeit von der Dosis bestimmt. Hypochlorit und Chlorit erreichten nur Konzentrationen im {mu}Mol/kg-Bereich. Eine Dosisleistungsabhaengigkeit war nicht festzustellen. Bei den Experimenten unter Normaldruck, bei denen die Radiolysegase aus der Loesung entweichen konnten, betrugen die G-Werte 0.46 (H{sub 2}), 0,16 (O{sub 2}) und 0,074 (ClO{sub 3}{sup -}). Bei den Experimenten unter Druck wurden die Radiolysegase in Loesung

  20. 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)


    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

  1. Geology, alteration, and lithogeochemistry of the Hood volcanogenic massive sulfide (VMS) deposits, Nunavut, Canada (United States)

    Mills, Hannah K.; Piercey, Stephen J.; Toole, Trish


    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.


    Directory of Open Access Journals (Sweden)

    Vanny Hertanto Vahyu


    Nichols, 2009, and Packstone (Dunham, 1962; inNichols, 2009. Carbonate sandstones predominantly feldspar and quartz minerals and the lihtology names areCarbonate quartz wackes (Pettijhon, 1975; in Nichols, 2009, and Carbonate feldspathic arenite (Pettijhon, 1975;in Nichols, 2009. There are three minerals type of cement showed in carbonate sandstones which are calcite,chlorite and pyrite cements.The results of this research indicate that the diagenesis stages of carbonate sandstones showed cementation,dissolution, replacement, bioturbation, and compaction processes, and the more stages of diagenesis that occurs incarbonate sandstones will result in reduced porosity and progressively up at for formation stratigraphy excelsiorsediment rock assess its porosity is equal to 1%, 5%, 7% and 15% respectively. The type of cement minerals in thecarbonate sandstone influence porosity, especially in carbonate sandstone which there are chlorite cement that havesmall porosity value of 1%, 5% and 7%. The environment of diagenesis in carbonate sandstones that is phreatic andburial experienced of eogenesis process, mesogenesis process and telogenesis process.

  3. Breakdown of Clays by Ectomycorrhizal Fungi Through Changes in Oxidation State of Iron (United States)

    Arocena, J. M.; Velde, B.


    Organisms are known to play a significant role in the transformation of clay minerals in soils. In our earlier work on canola, barley and alfalfa, we reported that Glomus, an arbuscular mycorrhizae, selectively transformed biotite into 2:1 expanding clays through the oxidation of Fe (II) in biotite to Fe(III). In this presentation, we will share similar results on clay transformations mediated by ectomycorrhizal fungi colonizing the roots of coniferous trees. Clay samples were isolated from rhizosphere soils of sub-alpine fir (Abies lasiocarpa (Hook.) Nutt.) in northern British Columbia (Canada). Chemical and mineralogical properties of these soils had been reported in our earlier paper. In this study, we subjected the clay samples to iron X-ray Absorption Near Edge Spectroscopy (Fe-XANES) at the Canadian Light Source synchrotron facility in Saskatoon (Canada). Our initial results showed relatively higher amounts of Fe (III) than Fe(II) in clays collected from rhizosphere of Piloderma (an ectomycorrhizal fungus) compared to soils influenced by non-Piloderma species and Control (non-rhizosphere soil). Coupled with the results of X-ray diffraction (XRD) analysis, there seems to be a positive relationship between the relative amounts of Fe(III) and the 2:1 expanding clays. This relationship is consistent with our results on agricultural plants in laboratory experiments on biotites where we suggested that oxidation of Fe(II) to Fe(III) results in the formation of 2:1 expanding clays. In a related data set on chlorite alteration we observed that after dithionite-citrate-bicarbonate (DCB) treatment, the d-spacing of a slight portion of chloritic expanding clays shifted to higher angles indicating decreased d-spacing towards micaceous clays. The reductive process initiated through the action of the DCB treatment seems to indicate the collapsed of expandable clays upon the reduction of Fe(III) to Fe(II). Initial results from the Fe-XANES and XRD analysis of DCB

  4. Dismantling processes of basaltic shield volcanoes - origin of the Piton des Neiges breccias - Reunion Island (United States)

    Arnaud, A.; Bachèlery, B.; Cruchet, C.


    Reunion Island is mainly composed by two volcanic massifs: the active Piton de la Fournaise to the southeast and the Piton des Neiges to the northwest that has been inactive for about 12000 years. The latter corresponds to a dismantled volcanic massif, deeply cut by valleys and by three vast depressions, called “cirques” around the centre of the volcano. They offer the opportunity to observe the inside of a basaltic shield volcano. The first work dealing with the origin of the “cirques” very quickly showed the existence of a significant cover of breccia deposits. These breccias were often interpreted as the result of a major stage of erosion considered as partly at the origin of the “cirques” formation. Geological campaigns mainly achieved in the “cirque de Salazie” (eastern of the Piton des Neiges), allow to establish a first typology based on morphological, phenomenological and sedimentary features of the deposits. Two main complexes of breccias have been distinguished. An old complex outcropping in the internal parts of the cirque and an upper complex generally overlaying the lower complex. The old complex comprises two main units of breccias. These units show a strong alteration marked by the presence of clays, chlorites, serpentines and zeolites. In the inner part of the cirque, these breccias are closely related to the old lava formations from which they come. These units show frequent jigsaw-cracks, a chaotic stratigraphy, as well as large amounts of chlorite. The upper complex is constituted by four main units which are more or less geographically separated in the cirque of Salazie. Their limits are not yet well identified because of the significant relief and a strong vegetable cover. Several units display a very strong fracturation, jigsaw-cracks and a chaotic stratigraphy whereas many lava flows are pulverised and locally injected in scoria levels. Recent work on Saint-Gilles breccias (Fèvre et al., this meeting) allowed to identify

  5. A- to B-Type Olivine Fabric Transitions Associated with Hydration, Dehydration and Shear Above the Farallon Flat Slab (United States)

    Behr, W. M.; Smith, D.


    We investigate mantle rocks associated with hydration, dehydration and shear above the Farallon flat-slab at its contact with the base of North America. The rocks we focus on are ultramafic inclusions hosted within serpentinized ultramafic microbreccia diatremes of the Navajo Volcanic Field (New Mexico) that erupted to the surface at the waning stages of the Laramide orogeny. A large number of petrological and geochronological studies have pinpointed the origin of these rocks to the hydrated mantle wedge above the Farallon slab as well as tectonically eroded and entrained fragments of the plate interface. We combine petrological observations and EBSD measurements of olivine grainsize and LPO to examine the effects of hydration on olivine fabric development in different parts of the supra-subduction zone mantle. The rocks examined include weakly deformed to strongly foliated tectonites we interpret to represent partially hydrated fragments of the upper plate mantle; and mylonites and ultramylonites we interpret to represent deformed fragments of the plate interface. The rocks deformed at temperatures ranging from 500-900°C based on thermometry, and olivine compositions in some record heating just before incorporation in the diatreme mix. We observe the following: Tectonites exhibit A-type bulk olivine LPOs, but show transitions to B-type LPO in local, fine-grained, dynamically recrystallized regions associated with hydrous minerals. Mylonites and ultramylonites with stable chlorite and/or antigorite and recrystallized grainsizes of less than 10μm show strong B-type olivine LPOs. A single mylonite with recrystallized grainsizes of ~35μm shows evidence for prograde metamorphism and dehydration through the chlorite breakdown reaction at temperatures above ~770°C. It contains no hydrous minerals and shows a strong A-type olivine LPO. Together these rocks demonstrate a strong correlation between hydration under high stress conditions, and B-type olivine LPO

  6. 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


    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

  7. 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


    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

  8. Petrology and radiogeology of the Stripa pluton

    Energy Technology Data Exchange (ETDEWEB)

    Wollenberg, Harold; Flexser, Steve; Andersson, Lennart


    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

  9. Biogenic versus metamorphic origins of diverse microtubes in 2.7 Gyr old volcanic ashes: Multi-scale investigations (United States)

    Lepot, Kevin; Benzerara, Karim; Philippot, Pascal


    Titanite-bearing microtubes in metabasalts have been interpreted as evidence for early microbial life thriving in the oceanic crust up to 3.5 Ga ago based on similarities with microtubular pitting occurring in modern volcanic glass. An alternative abiogenic origin as ambient inclusions trails (AITs) has been debated but textural evidence such as the absence of diagnostic terminal inclusions was used to discard this possibility. Here, we describe a variety of microtubes occurring in pyroclastic tuff of the 2.72 Ga Tumbiana Formation, Western Australia, some of which resemble titanite-filled microtubes reported in metamorphosed Archean pillow basalts. To assess the origin of the Tumbiana microtubes, we investigated their structure and chemistry and their root zone down to the sub-micrometer scale using a combination of Raman microspectroscopy, scanning electron microscopy (SEM), focused ion beam (FIB) milling and scanning transmission electron microscopy (STEM) coupled with energy dispersive X-ray spectrometry (EDXS). We report four types of microtubes. Type 1 comprises calcite microtubes. Type 2 comprises AITs showing terminal pyrite and trails with negative crystal shapes. Type 3 comprises titanite microtubes in chlorite displaying morphologies similar to those reported in ~ 3.5 Ga old Archean lavas. At the sub-micrometer scale, they display a dendritic structure. Depending on their localization, Type 3 microtubes have been divided in three main sub-types: i) Type 3A extends in pores filled by chloritized cement, ii) Type 3B occurs in pyroclasts, and iii) Type 3C overgrows and thus post-dates Type 2 AITs. Type 4 comprises titanite microtubes confined to quartz and calcite rims. Types 3 and 4 microtubes are terminated by sub-micrometric carbonaceous and/or mineral inclusions. Altogether, these features suggest that the Tumbiana titanite microtubes have formed as dendritic AITs associated with displacement of mineral and/or organic inclusions in pyroclasts and in

  10. Kuh-e Dom Fe-Cu-Au prospect, Anarak Metallogenic Complex, Central Iran: a geological, mineralogical and fluid inclusion study (United States)

    Tale Fazel, Ebrahim; Mehrabi, Behzad; Tabbakh Shabani, Amir Ali


    The Kuh-e Dom Fe-Cu-Au prospect is located in the Urumieh-Dokhtar Magmatic Belt, and is characterized by copper-iron oxide and gold veins, stockworks and breccias hosted by the Eocene Kuh-e Dom arc intrusion. Mineralization is located within NE-SW to WNW-ESE sinistral faults and likely formed in a subduction-related continental margin that is typical of IOCG deposit systems. The deposits have a distinct metal composition of Fe, Cu, Bi, Co, Mo and LREE with gold (up to 3 g/t), and the mineral assemblages are quartz, hematite, pyrite, chalcopyrite, emplectite, magnetite, free gold, calcite, barite, chlorite, and tourmaline. Three paragenetic stages of mineralized quartz veins are distinguished in the Kuh-e Dom prospect, including: (i) hematite-bearing quartz veins, (ii) quartz-sulfide stockwork and breccia veins, and (iii) quartz-calcite±sulfide infilling veins. Sodic (albitization), potassic, and quartz-calcite±chlorite pervasive alterations are commonly associated with these three mineralization stages. Three types of fluid inclusions have been identified at Kuh-e Dom, including: aqueous two-phase (H2O-NaCl-CaCl2±FeCl2), halite-saturated aqueous (H2O-NaCl±KCl), and CO2-bearing (H2O-CO2±CH4 and CO2±CH4) fluid inclusions. A hypersaline (~35 wt% NaCl equiv.), aqueous magmatic fluid was released at about 400 °C and a pressure of nearly 4 kbar, forming early hematite-bearing quartz veins. These high salinity fluids were progressively diluted further away from Kuh-e Dom intrusion due to substantial input of meteoric water and mixing with the magmatic components during the middle and late stages of mineralization. The mineralogy, alteration, and fluid composition of the Kuh-e Dom Fe-Cu-Au prospect compared well with Fe oxide Cu-Au (IOCG) deposits worldwide.

  11. Deglacial Record in the Illinois River Valley Explains Asynchronous Phases of Meltwater Pulses and Clay Mineral Excursions in the Gulf of Mexico (United States)

    Wang, H.


    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

  12. Relationship Between Minerals and Mineral Nutrients of Soil Weathering from Different Rocks in Guizhou Province%贵州不同岩石背景土壤矿物与矿质养分的关系

    Institute of Scientific and Technical Information of China (English)

    任明强; 于晓红


    The mineral nutrients of two different soils developed from different soil parent materials were determined to scientifically guide crop cultivation in different soils in Guizhou. The results showed that the soil developed from clastic rocks with higher feldspar and mica content in soil powder minerals and high chlorite content and lower kaolmite content in soil clay mineral, a lower weathering degree and relative abundant soil nutrients had strong sustained release capacity of mineral nutrient. However, the soil developed from carbonatite rocks with lower feldspar and mica content in soil powder minerals and lower chlorite content and higher kaolinite content in soil clay mineral, a higher weathering degree and relative poor nutrients had poor sustained release capacity of mineral nutrient.%为了更好地了解优质农作物生长与不同岩石背景土壤养分的关系,科学指导农业种植,叶两种不同岩石背景土壤中矿物与土壤主要矿质养分的关系进行研究.结果表明:碎屑岩背景区土壤粉粒矿物中长石、云母含量较碳酸盐岩背景区土壤中的高,土壤粘粒矿物中绿泥石含量较碳酸盐岩背景区土壤中的高,高岭石含量较低,土壤风化程度较低,持续释放矿质养分的能力较强,土壤养分相对充裕;而碳酸盐岩背景区土壤粉粒矿物中长石、云母含量较碎屑岩背景区土壤中的低.土壤粘粒矿物中绿泥石含量较碎屑岩背景区土壤中的低,高岭石含量较高,土壤风化程度较高.持续释放矿质养分的能力弱,土壤养分相对缺乏.

  13. Re-equilibration history and P- T path of eclogites from Variscan Sardinia, Italy: a case study from the medium-grade metamorphic complex (United States)

    Cruciani, Gabriele; Franceschelli, Marcello; Groppo, Chiara; Oggiano, Giacomo; Spano, Maria Elena


    Retrogressed eclogites are hosted within the Variscan low- to medium-grade metamorphic complex near Giuncana, north-central Sardinia. These rocks are medium to fine grained with garnet and amphibole as the most abundant mineral phases along with clinopyroxene, plagioclase, quartz, biotite, chlorite, epidote, ilmenite, rutile and titanite. Four stages of mineralogical re-equilibration have been distinguished. The stage I is characterized by the occurrence of omphacite, epidote, quartz, amphibole, rutile and ilmenite in garnet poikiloblasts. The stage II is characterized by two types of symplectitic microstructures: (1) amphibole + quartz symplectite and (2) clinopyroxene + plagioclase ± amphibole symplectite. The first symplectite type replaces omphacite included in garnet, whereas the second one is widespread in the matrix. Biotite droplets and/or lamellae intimately growing with fine-grained plagioclase resemble biotite + plagioclase symplectite after phengite. The stage III is characterized by the widespread formation of amphibole: (1) as zoned porphyroblasts in the matrix, (2) as corona-type microstructure replacing garnet. Subordinate plagioclase (oligoclase) is also present in the amphibole corona. The stage IV is characterized by the local formation of biotite replacing garnet, actinolite, chlorite, albite and titanite. P- T pseudosections calculated with Perple_X give P- T conditions 580 < T < 660 °C, 1.3 < P < 1.8 GPa for the stage I. After the stage I, pressure decrease and temperature increase led to the breakdown of omphacite with the formation of clinopyroxene + plagioclase ± amphibole symplectite at ~1.25-1.40 GPa and 650-710 °C (stage II). P- T conditions of the amphibolite-facies stage III have been defined at 600-670 °C, P = 0.65-0.95 GPa. P- T conditions of the latest stage IV are in the range of greenschist facies. The P- T path of the retrogressed eclogite hosted in the medium-grade micaschist and paragneiss of Giuncana recalls the P- T

  14. 黑龙江金厂金矿床18号矿体围岩蚀变及短波红外光谱特征%Characteristics of Wall-Rock Alteration and the Shortwave Infrared Spectra for Minerals in the 18th Orebody, Jinchang Gold DepositHeilongjiang Province

    Institute of Scientific and Technical Information of China (English)

    孙雨沁; 许虹; 李胜荣; 张岩


    金厂金矿18号矿体围岩蚀变发育顺序从早到晚为:钾化、硅化、绿泥石化、绢云母化、碳酸盐化、高蛉土化,从内往外依次发育青磐岩化带、绢英岩化带和钾化带.矿化出现在泥化和绢英岩化叠加处,以及泥化和青磐岩化叠加处.通过短波红外光谱测试技术,识别出本矿区有26种蚀交矿物,其中白云母含量与金矿体呈正相关,说明绢云母化与金矿化关系密切;青磐岩化带蚀变矿物组合为绿泥石+绿帘石+伊利石±埃洛石±蒙脱石±石英;钾化带蚀变矿物组合为钾长石+高岭石+埃洛石±蒙脱石±石英;绢英岩化带蚀变矿物组合为绢云母+埃洛石±蒙脱石±高岭石±石英.%The wall-rock alteration sequence of the 18th orebody in the Jinchang gold deposit is feldspathization, si-licification, chloritization, sericitization, calcitization and kaolinite, including propylitic, phyllic and potassic alteration zones from central to outword parts of the complex. The gold mineralization occurs mainly in the overlapped parts of argillization and phyllic alteration zones and of argillization and propylitic alteration zones. 26 species of hy-drothermal alteration minerals were identified by the short-wave infrared spectroscope technique. The positive correlation of muscovite and Au contents in these minerals suggested that the gold mineralization is closely related with the sericitization. The minerals associated with the propylitic alteration zone are chlorite + epidote + illite ± hal-loysite ± montmorillonite ± quartz, the minerals in the potassic alteration zone are K-feldspar + kaolinite + hal-loysite ± montmorillonite ± quartz and the minerals in the phyllic alteration zone are muscovite + halloysite ± montmorillonite ± kaolinite ± quartz.

  15. Dynamics of mineral crystallization at inclusion-garnet interface from precipitated slab-derived fluid phase: first in-situ synchrotron x-ray measurements (United States)

    Malaspina, Nadia; Alvaro, Matteo; Campione, Marcello; Nestola, Fabrizio


    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

  16. Provenance and composition of unusually chrome and nickel-rich bucket-shaped pottery from Rogaland (southwestern Norway) (United States)

    Zimmermann, Udo; Kristoffersen, Elna Siv; Fredriksen, Per Ditlef; Bertolino, Silvana A. R.; Andò, Sergio; Bersani, Danilo


    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.

  17. Slab melting and magma formation beneath the southern Cascade arc (United States)

    Walowski, K. J.; Wallace, P. J.; Clynne, M. A.; Rasmussen, D. J.; Weis, D.


    The processes that drive magma formation beneath the Cascade arc and other warm-slab subduction zones have been debated because young oceanic crust is predicted to largely dehydrate beneath the forearc during subduction. In addition, geochemical variability along strike in the Cascades has led to contrasting interpretations about the role of volatiles in magma generation. Here, we focus on the Lassen segment of the Cascade arc, where previous work has demonstrated across-arc geochemical variations related to subduction enrichment, and H-isotope data suggest that H2O in basaltic magmas is derived from the final breakdown of chlorite in the mantle portion of the slab. We use naturally glassy, olivine-hosted melt inclusions (MI) from the tephra deposits of eight primitive (MgO > 7 wt%) basaltic cinder cones to quantify the pre-eruptive volatile contents of mantle-derived melts in this region. The melt inclusions have B concentrations and isotope ratios that are similar to mid-ocean ridge basalt (MORB), suggesting extensive dehydration of the downgoing plate prior to reaching sub-arc depths and little input of slab-derived B into the mantle wedge. However, correlations of volatile and trace element ratios (H2O/Ce, Cl/Nb, Sr/Nd) in the melt inclusions demonstrate that geochemical variability is the result of variable addition of a hydrous subduction component to the mantle wedge. Furthermore, correlations between subduction component tracers and radiogenic isotope ratios show that the subduction component has less radiogenic Sr and Pb than the Lassen sub-arc mantle, which can be explained by melting of subducted Gorda MORB beneath the arc. Agreement between pMELTS melting models and melt inclusion volatile, major, and trace element data suggests that hydrous slab melt addition to the mantle wedge can produce the range in primitive compositions erupted in the Lassen region. Our results provide further evidence that chlorite-derived fluids from the mantle portion of the

  18. Chloroxyanion Residue Quantification in Cantaloupes Treated with Chlorine Dioxide Gas. (United States)

    Kaur, Simran; Smith, David J; Morgan, Mark T


    Previous studies show that treatment of cantaloupes with chlorine dioxide (ClO2) gas at 5 mg/liter for 10 min results in a significant reduction (P < 0.05) in initial microflora, an increase in shelf life without any alteration in color, and a 4.6- and 4.3-log reduction of Escherichia coli O157:H7 and Listeria monocytogenes, respectively. However, this treatment could result in the presence of chloroxyanion residues, such as chloride (Cl(-)), chlorite (ClO2(-)), chlorate (ClO3(-)), and perchlorate (ClO4(-)), which, apart from chloride, are a toxicity concern. Radiolabeled chlorine dioxide ((36)ClO2) gas was used to describe the identity and distribution of chloroxyanion residues in or on cantaloupe subsequent to fumigation with ClO2 gas at a mean concentration of 5.1 ± 0.7 mg/liter for 10 min. Each treated cantaloupe was separated into rind, flesh, and mixed (rind and flesh) sections, which were blended and centrifuged to give the corresponding sera fractions. Radioactivity detected, ratio of radioactivity to mass of chlorite in initial ClO2 gas generation reaction, and distribution of chloroxyanions in serum samples were used to calculate residue concentrations in flesh, rind, and mixed samples. Anions detected on the cantaloupe were Cl(-) (∼ 90%) and ClO3(-) (∼ 10%), located primarily in the rind (19.3 ± 8.0 μg of Cl(-)/g of rind and 4.8 ± 2.3 μg of ClO3(-)/g of rind, n = 6). Cantaloupe flesh (∼ 200 g) directly exposed to(36)ClO2 gas treatment showed the presence of only Cl(-) residues (8.1 ± 1.0 μg of Cl(-)/g of flesh, n = 3). Results indicate chloroxyanion residues Cl(-) and ClO3(-) are only present on the rind of whole cantaloupes treated with ClO2 gas. However during cutting, residues may be transferred to the fruit flesh. Because Cl(-) is not toxic, only ClO3(-) would be a toxicity concern, but the levels transferred from rind to flesh are very low. In the case of fruit flesh directly exposed to ClO2 gas, only nontoxic Cl(-) was detected. This

  19. Chemical mobility during low-grade metamorphism of a Jurassic lava flow: Río Grande Formation, Peru (United States)

    Aguirre, L.

    Chemical and mineralogical changes produced by very low-grade metamorphism in a 40 meter thick, K-rich, calc-alkaline andesite flow of the marine Jurassic Río Grande Formation of southern coastal Peru are discussed. This metamorphism (=spilitization) was non-deformational and generated spilitic domains at (and near) both vesicular margins of the flow, whereas the massive central zone remained relatively unaltered. The metadomains are characterized by mineral associations of the zeolite facies. Primary minerals are Ca-plagioclase, augitic pyroxene, iron-titanium oxides, and (pseudomorphs after) olivine. Metamorphic minerals are: albite (three generations), K-feldspar, pumpellyite, chlorite, interlayered chlorite-celadonite, celadonite, various mixed-layer Si- and Fe-rich phyllosilicates, "iddingsite," calcite, analcime, titanite, and white mica. The effect of the metamorphism on the rock chemistry is reflected in changes especially observed at the marginal zones of the flow which affect major, trace, and RE elements: 1) strong increase of the iron oxidation ratio (Fe 2O 3/FeO); 2) enrichment in Na 2O accompanied by a concomitant depletion of CaO in non-amygdaloidal domains; 3) depletion of SiO 2; 4) strong enrichment in H 2O and CO 2; 5) marked depletion of Sr and Rb; 6) enrichment in Cl and S; and 7) slight depletion in RE elements, notably in the top zone of the flow. Conversely, elements such as Ti, P, Nb, and Y were fairly immobile, whereas Zr and K were only slightly mobilized. The effect of the metamorphism on the mineral chemistry is expressed by the predominance of metastable equilibrium evidenced by the existence of wide compositional ranges in the phyllosilicates, the incomplete albitization of the Ca-plagioclase, and the Al-rich character of the pumpellyites. The metamorphism is considered to be of hydrothermal-burial type, which takes place at low temperature and pressure — probably about 125-230°C and less than 3 kb, and is produced mainly through

  20. Alteration processes in igneous rocks of the michilla mining area, coastal range, northern chile, and their relation with copper mineralisation (United States)

    Oliveros, V.; Aguirre, L.; Townley, B.


    A 10 km thick homoclinal sequence of intermediate volcanic and sedimentary Jurassic rocks crops out in the Michilla mining area, Coastal Range, northern Chile (22-22°45S, 70-70°15W). Cretaceous plutons, intermediate to acid in composition, intrude this sequence together with numerous small basic to acid dykes and stocks. Main deposits are stratabound Cu-(Ag) with the ore minerals emplaced at the porous tops of the volcanic flows. However, some discordant orebodies, e.g. hydrothermal breccias, exist within the manto-type deposits. The volcanic sequence, and a minor part of the plutonic rocks, have been affected by three different alteration processes, each of them with their distinct mineral assemblages reflecting that every process was developed under different physicochemical conditions. The volcanic rocks far from the mining area are affected by a regional scale alteration process, basically isochemical. Its products are typical of a low-grade event: chl + ep +qtz + ttn (+- ab +- cal) with no ore minerals associated. The temperature interval, estimated by the chlorite geothermometer, ranges between 250 and 350°C. This alteration is either due to very low grade burial metamorphism or to hydrothermalism related to the Late Jurassic - Cretaceous plutonism. Inside the mining district the volcanic rocks are affected by a local scale alteration process originated by the intrusion of small stocks and dykes. This event is characterized by strong sodic metasomatism and minor Mg mobility. Two stages probably occurred as suggested by the two main mineral assemblages present, a propylitic (ab + ep + chl + act + ttn + qtz) and a quartz-sericitic one (ab + ser + qtz + tnn). They would reflect the changes in temperature, water/rock ratio and pH conditions during the whole process. Ore minerals related to this alteration are chalcopyrite, chalcocite and minor bornite and native silver. A temperature interval of 200-300°C is indicated by the chlorite geothermometer for the

  1. 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)


    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

  2. Can the dissolution rates of individual minerals be used to describe whole rock dissolution? (United States)

    Critelli, Teresa; Marini, Luigi; Schott, Jacques; Mavromatis, Vasileios; Apollaro, Carmine; Rinder, Thomas; De Rosa, Rosanna; Oelkers, Eric H.


    There have been an exhaustive number of laboratory studies determining the dissolution rates of individual minerals, but few have focused on the dissolution rates of minerals in multi-mineralic rocks. As a result, geochemical modeling of the temporal evolution of water-rock interaction is generally based on the assumption that the dissolution rate of minerals within a rock is equal to that measured in the laboratory on individual minerals. To verify this hypothesis, we have determined experimentally the dissolution rates of a well characterized metabasalt rock (Apollaro et al., 2011; Bloise et al., 2012) from the Mt. Reventino area (Southern Italy) at 25°C in mixed flow reactors. From these experiments and rock modal analysis we have deduced the dissolution rates of the minerals present in the rock (actinolite, albite, chlorite, epidote, and phengite). The major observation of this effort include: (i) only small differences in the dissolution rates of the individual minerals were observed; these rates are close to the whole-rock dissolution rate and (ii) the dissolution rates of albite and chlorite are in close agreement with laboratory rates obtained from individual mineral dissolution experiments, whereas those of actinolite, phengite, and epidote are not consistent with those reported in literature by 1-2 orders of magnitude. These results demonstrate that the dissolution rate of a given mineral in a multi-phase rock can be affected by the presence of the other minerals. Rock dissolution kinetics are likely constrained by the dissolution rates of the more abundant, lesser reactive mineral or minerals in the rock. These unreactive minerals can prevent the dissolution of the more rapidly dissolving mineral grains by keeping them out of contact with the aqueous phase. This implies that the overall weathering rate of rocks cannot be modelled from the measured dissolution rates of its individual minerals. If confirmed through further studies, this conclusion may

  3. 鄂尔多斯盆地华池地区长6储层成岩相及其对物性的控制作用%The diagenetic facies and its control over physical property of Chang6 reservoir in Huachi, Ordos Basin

    Institute of Scientific and Technical Information of China (English)

    王永东; 张创; 徐岗; 夏海英; 温亮


    在储层特征分析和成岩作用研究的基础上,划分了华池地区长6储层成岩相,探讨了成岩相对储层物性的控制作用.储层主要经历了压实、压溶、碳酸盐胶结、黏土矿物胶结、硅质胶结和长石溶蚀作用;根据不同的成岩作用特征,该区长6储层可划分为绿泥石薄膜弱溶蚀成岩相、长石溶蚀成岩相、伊利石充填成岩相和碳酸盐致密胶结成岩相;由于不同成岩相具有不同成岩特征和岩石组构,因此其孔隙、喉道的类型和分布特征各不相同,由此决定了不同类型成岩相的物性存在差异,该区绿泥石薄膜弱溶蚀成岩相物性最好,长石溶蚀成岩相次之,伊利石充填成岩相和碳酸盐致密胶结成岩相物性较差.%Based on reservoir characteristic analysis and diagenesis research,diagenetic facies of Chang6 reservoir in Huachi,is classified,and its control over physical property is studied.Chang6 reservoir mainly experienced compaction,pressolution,carbonate cementation,clay mineral cementation,siliceous cementation and feldspar dissolution.According to the different diagenesis characteristics,the diagenetic facies can be classified into four types,which are chlorite rim facies,feldspar dissolution facies,illitefilling facies,and carbonate dense cementation facies.Because of the different diagenesis characteristics and petrologic makeup in four diagenesis facies,the types and distribution of pores and pore-throats are different.Furthermore,their physical properties are different,of which chlorite rim facies is best,and illite-filling facies,and carbonate dense cementation facies is worst.

  4. 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.


    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

  5. Hydrofracturing of Sediment and Hydrated MORB's during Subduction of Ocean Crust (United States)

    Nabelek, P. I.


    Dehydration accompanying metamorphism of sediment and hydrated mafic ocean crust during ocean plate subduction can potentially lead to fracturing and intraplate tremors. As rocks are buried, they lose porosity and permeability and eventually pass into the lithostatic pressure regime where the porosity and permeability are thought to be very small. Pore fluid pressure generation stemming from metamorphic reactions was modeled using the program SUTRAMET (Nabelek et al., 2014), which is a modified version of the program SUTRA (Voss & Provost, 2002). The program allows modeling of metamorphic reactions at high pressures and temperatures and incorporates transient porosity and permeability changes due to overpressure and changing volumes of metamorphic assemblages. Permeabilities (k) of 10-18 and 10-20 m2 within the brittle regime were modeled. The model assumes continuous subduction with fluids generated at horizons where specific P-T conditions for reactions exist. Temperature gradient was assumed to be 10°C/km and the vertical component of subduction velocity to be at 0.85 cm/y. The model reactions in sediment (Campito Formation of western California as a proxy) and average MORB were generated by the program Theriak-Domino (de Capitani and Petrakakis, 2010). The initial sediment mineralogy includes albite, K-feldspar, phengite, chlorite, and lawsonite. The final mineralogy for the 10°C/km gradient is quartz, phengite, garnet, and pyroxene with jadeite and acmite components. The initial mineralogy of MORB includes chlorite, amphibole, pumpelyite, albite and quartz and the final eclogite mineralogy includes garnet, cpx, kyanite and quartz. Calculations show that at k = 10-18 m2, pore fluid pressure can reach 450 MPa. Pore pressure is reduced by negative ∆V of mineral assemblages stemming from reactions; nevertheless, for the garnet-forming reaction, pore pressure is about 110 MPa. Assuming a tensile strength of 15 MPa and fracture aperture given by rock

  6. Petrology of HP/LT metapelitic rocks of an accretionary wedge, the Central Pontides, Turkey: evidence for tectonic stacking and syn-subduction exhumation (United States)

    Aygül, Mesut; Okay, Aral; Oberhänsli, Roland


    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

  7. Environmentálne aspekty transformácie nízko-sulfidického postflotačného kalu na antropogénnu pôdu (Smolník, Slovensko

    Directory of Open Access Journals (Sweden)

    Mangová Kristína


    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

  8. Site investigation SFR. Boremap mapping of core drilled borehole KFR106

    Energy Technology Data Exchange (ETDEWEB)

    Winell, Sofia (Geosigma AB (Sweden))


    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

  9. Numerical Simulation of Extent of Carbon Dioxide Plume Injected in the Gyeongsang Basin, Korea (United States)

    Kihm, J.; Park, S.; Kim, J.


    A series of thermo-hydro-chemical numerical simulations was performed to evaluate extent of carbon dioxide plume injected in the Gyeongsang Basin, which is one of the prospective onshore sedimentary basins for geologic storage of carbon dioxide in Korea. The carbon dioxide plume extent is an important factor in estimating storage efficiency and thus storage capacity of carbon dioxide in a storage formation because it represents an actual volume of the storage formation, which is occupied by injected carbon dioxide. The carbon dioxide plume extent is also an essential component in risk analysis of geologic storage of carbon dioxide because most of thermo-hydro-mechanical-chemical responses to carbon dioxide injection occur within it. To evaluate impacts of injection scenarios (i.e., injection rate and period) of carbon dioxide and geological conditions (i.e., thickness and depth) and hydrogeochemical properties (i.e., porosity, intrinsic permeability, salt concentration in groundwater, and volume fraction of chlorite) of a storage formation on the carbon dioxide plume extent, a series of sensitivity tests was also performed. The numerical simulation results show that the carbon dioxide plume extent is significantly affected by such injection scenarios, geological conditions, and hydrogeochemical properties. The carbon dioxide plume extent increases as the injection rate (with a constant injection period) increases, and this trend does not change with time. The carbon dioxide plume extent decreases as the injection period (with a constant total injection amount) increases until about 50 years, while it is not sensitive to the injection period after about 50 years. The carbon dioxide plume extent also decreases as the thickness increases until about 100 years, while it is not sensitive to the thickness after about 100 years. In contrast, the carbon dioxide plume extent decreases as the depth increases, and this trend is intensified with time. On the other hand, the

  10. Reconstruction of seawater chemistry from deeply subducted oceanic crust; hydrogen and oxygen isotope of lawsonite eclogites preserving pillow structure (United States)

    Hamabata, D., VI; Masuyama, Y.; Tomiyasu, F.; Ueno, Y.; Yui, T. F.; Okamoto, K.


    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

  11. 2.9-1.9 Ga paleoalterations of Archean granitic basement of the Franceville basin (Gabon) (United States)

    Mouélé, Idalina Moubiya; Dudoignon, Patrick; El Albani, Abderrazak; Meunier, Alain; Boulvais, Philippe; Gauthier-Lafaye, François; Paquette, Jean-Louis; Martin, Hervé; Cuney, Michel


    The Archean granitoids in the Kiéné area, Gabon, are overlained by the Paleoproterozoic sediments of the Franceville basin (2.1 Ga). The basin is known for its high-grade uranium deposits among which some have been forming natural nuclear fission reactors. Most of the studies were dedicated to the FA-FB Paleoproterozoic sediments hosting these uranium deposits. Little is known on the Archean basement itself and specifically on the hydrous alteration events it experienced before and after the sediment deposition. The present work is focused on their petrographical, mineralogical and geochemical characterization. Dating the successive alteration events has been attempted on altered monazite crystals. Rocks in different alteration states have been sampled from eight drill cores crosscutting the Archean - Paleoproterozoic unconformity. The Archean granitoids observed in the deepest levels exhibit typical petrographical features of a propylitic alteration while they are intensely illitized up to the unconformity. The propylitic alteration is mainly pervasive but the original texture of the granitoïds is conserved in spite of the formation of new minerals: Mg-chlorite, allanite and epidote forming a typical paragenesis. The illitic alteration is much more invasive near the unconformity. The illitization process leads to the replacement of feldspars and the corrosion of quartz crysals by an illitic matrix while the ferromagnesian minerals are pseudomorphosed by a Fe-chlorite + phengite + hematite assemblage. The final fluid-rock interaction step is marked by fissural deposits of calcite and anhydrite. The δ13C isotopic data show that the fissural carbonates precipitated from diagenetic fluids enriched carbon products deriving from the maturation of organic matter. The U-Pb isotopic analyzes performed on monazite crystals have dated three distinct events: 3.0-2.9 Ga (magmatic), 2.6 Ga (propylitic alteration) and 1.9 Ga (diagenetic illitization). The calculation of

  12. Biogenic smectite clay formation in subsurface granitic environments (United States)

    Tuck, V.; Edyvean, R.; West, J.; Bateman, K.; Coombs, P.; Milodowski, A.


    Many bacteria and biofilms in groundwater environments are able to adsorb and accumulate soluble components from an aqueous environment and exert a strong influence on the attenuation and transport of a significant range of dissolved species including many pollutants. They can also act as catalysts or nucleation sites for authigenic mineral phases such as metal sulphides or complex silicates. The processes involved are not well defined, but appear to range from large-scale interactions altering bulk groundwater chemistry to very small-scale interactions involving geochemical and physical alterations within biofilms and at the mineral surface. The purpose of this research program is to investigate biologically-induced and unusually rapid formation of smectite and chlorite clays. The work expands on experiments conducted by the British Geological Survey designed to simulate rock-water/microbial interactions, radionuclide mobility and groundwater redox-buffering capacity in the vicinity of the Äspö Underground Research Laboratory (URL) in Sweden. Packed-columns were set up containing crushed Äspö granodiorite, saline groundwater (simulating Äspö’s) and either single or combined inoculations of two bacteria species isolated from the Äspö URL, an iron-reducer Shewanella putrefaciens and a sulphate-reducer Desulfovibrio aespoeensis. Flow was maintained at 12ml/day to mimic that in the Äspö region, and strict anaerobic/reducing conditions were maintained throughout the experiments. Results showed that the iron-reducing bacteria S. putrefaciens quickly attached to surfaces and formed extensive filamentous biofilm meshes across porespaces. Neoformed smectite and chlorite clays also appeared on or near the biofilaments along with a calcium sulphate precipitate. Both of these processes (clay formation and the production of a mesh-like biofilm) served to cause total blockage of the pores, rendering the aggregate impermeable and thus cutting off the flow of

  13. Glass shards, pumice fragments and volcanic aerosol particles - diagenesis a recorder of volcanic activity? (United States)

    Obenholzner, J. H.; Schroettner, H.; Poelt, P.; Delgado, H.


    Detailed SEM/EDS studies of Triassic (Southern Alps, A, I, Sl) and Miocene (Mixteca Alta, Mexico) tuffs revealed that volcanic glass shards can be replaced by zeolites (analcite), chlorites and smectites preserving the shape of primary shards (1). The Triassic pyroclastic deposits have been incorporated in the pre-Alpine burial diagenesis, the Miocene pyroclastic deposits are bentonites. The volcanologist is impressed by the circumstances that million years old pyroclast relict textures can be sized. Shape parameters obtained by image analysis can be compared with much younger pyroclastic deposits (2). Both deposits have not been effected by shearing. The alteration of pumice fragments of Triassic age is not a simple replacement process. Intergrowth of different illites and chlorites and probably vesicle filling by SiO2 and subsequent overgrowth make a reconstruction sometimes difficult. These processes are accompanied by the formation of REE-, Y- and Zr-bearing minerals as well as with the alteration of zircons. Studies of recently erupted ash from Popocatepetl volcano reveal the presence of a variety of µm-sized contact-metamorphosed clasts being a part of the volcanic ash (3). Such clasts should be present in many older pyroclastic deposits, especially where volcanoes had been situated on massive sedimentary units providing contact metamorphism in the realm of a magma chamber or during magma ascent. Volcanic aerosol particles collected in 1997 from the passively degassing plume of Popocatepetl volcano revealed in FESEM/EDS analysis (H. Schroettner and P. Poelt) a wide spectrum of fluffy, spherical and coagulated spherical particles (µm-sized). Under pre-vacuum conditions they remained stable for ca. 3 years (3). In nature the fate of these particles in the atmosphere is unknown. Are there relicts in marine, lacustrine sediments and ice cores, which could be used as proxies of volcanic activity? (1) Obenholzner &Heiken,1999. Ann.Naturhist.Mus.Wien, 100 A, 13

  14. Diagenetic characteristics and reservoir quality of the Lower Cretaceous Biyadh sandstones at Kharir oilfield in the western central Masila Basin, Yemen (United States)

    Hakimi, Mohammed Hail; Shalaby, Mohamed Ragab; Abdullah, Wan Hasiah


    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

  15. Paleoenvironmental Implications of Clay Minerals at Yellowknife Bay, Gale Crater, Mars (United States)

    Bristow, Thomas F.; Blake, David F.


    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

  16. Metamorphic constraints on the Caledonian Upper Allochthon of Central Norway - the Gula Complex staurolite-garnet-kyanite mica schist (United States)

    Engvik, A. K.; Grenne, T.; Lutro, O.; Meyer, G. B.


    Petrological studies of staurolite-garnet-kyanite-biotite schist and garnet-muscovite schist of the Gula Complex provide constraints on the metamorphic evolution of the Caledonian Upper Allochthon in the eastern Trondheim Region, Central Norway. The biotite schist contains conspicuous porphyroblasts of Fe-rich staurolite (Mg#=0.21-0.24), garnet (Alm64-71Prp13-19Grs3-11Sps7-20) and kyanite, set in a fine-grained, well foliated matrix of biotite (Mg#=0.57- 0.62), quartz, minor plagioclase (An19-31) and locally muscovite. The muscovite schist is fine to medium grained with a muscovite-quartz dominated matrix, including garnet (Alm54-70Prp10-14Grs12-25Sps1-11), biotite (Mg#=0.56-0.57), minor plagioclase (An31-45) and clinozoisite. P-T modeling based on thermobarometric calculations and construction of P-T pseudosections illustrates that significant mineralogical heterogeneity in the high grade mica schists arise from only modest geochemical heterogeneities in the original pelitic rocks. Based on garnet ±staurolite ±kyanite ±muscovite +biotite +plagioclase +quartz-assemblages, peak metamorphism reached 680 °C with pressures estimated to 1.01 ±0.11 GPa for the garnet-muscovite schist, and 0.86 ±0.12 GPa for the staurolite-garnet-kyanite-biotite schist. A clockwise P-T path is constrained by secondary mineral reactions; the replacement of kyanite to fibrous sillimanite indicates decompression below 0.65 GPa at elevated temperatures. Growth of foliation-parallel chlorite reflects cooling below 640 °C. Chlorite formation proceeded during cooling and decompression towards 550 °C and 0.4 GPa. Peak metamorphic conditions are associated with a strong N-S trending regional foliation, and the initial uplift continued within the same strain regime. The documented high grade metamorphism and subsequent decompression and retrogression of the Gula Complex metapelites prevailed during the mid-Silurian continent-continent collision and Caledonian burial and exhumation of the

  17. Raman Spectroscopy Study on the Mineral Composition of the Guatemalan Jade%拉曼光谱在危地马拉翡翠矿物组成中的应用研究

    Institute of Scientific and Technical Information of China (English)

    陈全莉; 尹作为; 卜玥文; 钟增球


    危地马拉是缅甸之外的另一个翡翠的商业性产地,危地马拉翡翠通常是多种矿物成分的集合体,其矿物组成具有特色,与缅甸翡翠的不同.以危地马拉紫色和灰绿色翡翠为研究对象,通过激光拉曼光谱测试分析,对其结构特征及共生矿物组成特点进行了研究.结果表明,危地马拉翡翠中的主要组成矿物为硬玉,并伴有多种共生矿物.危地马拉翡翠的共生矿物包括五类,其中深色共生矿物为角闪石,白云石,绿辉石和绿泥石,浅色共生矿物为磷灰石.其中角闪石,白云石,绿辉石和绿泥石也是缅甸翡翠中常见的共生矿物,而磷灰石在缅甸翡翠中几乎不可见.%Guatemala is another jade commercial origin in addition to the Myanmar. The Guatemalan jade is usually an assemblage of a variety of mineral compositions, and the mineral composition is unique and different from the Myanmar jade. The characteristics of the structures and paragenetic minerals of the purple and gray-green jade from Guatemala were studied by laser Raman spectroscopy analysis. The results show that the jadeite is a major constituent mineral in Guatemala jade, associated by a variety of coexisting minerals. The paragenetic minerals in Guatemalan jade can be divided into five categories, including the dark minerals hornblende, dolomite, omphacite, chlorite, and light-colored mineral apatite. The hornblende, dolomite, omphacite and chlorite are also the paragenetic minerals in the Myanmar jade, but the apatite is almost invisible in the Myanmar jadeite.

  18. Grain-rimming kaolinite in Permian Rotliegend reservoir rocks (United States)

    Waldmann, Svenja; Gaupp, Reinhard


    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. Metamorphism of mineral matter in coal from the Bukit Asam deposit, south Sumatra, Indonesia

    Energy Technology Data Exchange (ETDEWEB)

    Susilawati, Rita; Ward, Colin R.


    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

  20. TEM analysis of the internal structures and mineralogy of Asian dust particles and the implications for optical modeling

    Directory of Open Access Journals (Sweden)

    G. Y. Jeong


    Full Text Available Mineral dust interacts with incoming/outgoing electromagnetic radiation in the atmosphere. This interaction depends on the microphysical properties of the dust particles, including size, mineral composition, external morphology, and internal structure. Ideally all these properties should be accounted for in dust remote sensing, the modeling of single-scattering properties, and radiative effect assessment. There have been many reports on the microphysical characterizations of mineral dust, but no investigations of the internal structures or mineral composition of individual dust particles. We explored the interiors of Asian dust particles using the combined application of focused ion beam thin-slice preparation and high-resolution transmission electron microscopy. The results showed that individual dust particles consisted of numerous mineral grains, which were organized into several types of internal structure: single and polycrystalline cores of quartz, feldspars, calcite, and amphibole often with oriented clay coatings; individual clay agglomerates of nano-thin clay platelets showing preferred to random orientations commonly with coarser mineral inclusions; and platy coarse phyllosilicates (muscovite, biotite, and chlorite. Micron to submicron pores were scattered throughout the interior of particles. Clays in the coatings and agglomerates were dominated by nano-thin platelets of the clay minerals of illite-smectite series including illite, smectite, and their mixed layers with subordinate kaolinite and clay-size chlorite. Submicron iron oxide grains, dominantly goethite, were distributed throughout the clay agglomerates and coatings. Unlike the common assumptions and simplifications, we found that the analyzed dust particles were irregularly shaped with birefringent, polycrystalline, and polymineralic heterogeneous compositions. Accounting for this structural and mineralogical makeup may improve the remote sensing retrieval of dust and the

  1. Episyenites in meta-granitoids of the Tauern Window (Eastern Alps): unpredictable? (United States)

    Pennacchioni, Giorgio; Ceccato, Alberto; Fioretti, Anna Maria; Mazzoli, Claudio; Zorzi, Federico; Ferretti, Patrizia


    The core of the Tauern tectonic window (Eastern Alps) consists of pre-Alpine granitoids (∼295 Ma) variably deformed during Alpine (∼30 Ma) amphibolite-facies metamorphism. Episyenites occur as local alteration haloes (as wide as a few meters) surrounding steeply dipping, strike-slip faults, with offsets meta-granodiorite) and 13% (meta-aplite), mainly derived from dissolution of quartz. Glacier-polished outcrops allow the detailed investigation of the relationships between the episyenites and the structure of the associated faults. Field mapping indicates that episyenites: (i) are spatially linked to pre-existing faults and statically overprinted these structures; (ii) are discontinuous along faults; (iii) have a thickness (of as much as a few meters) that does not correlate with either the amount of slip along the pre-existing faults or the spatial density of the fracture network; (iv) developed with a similar extent in rocks with conspicuous variations of the original quartz grain size and structure. The studied outcrop includes a relatively large volume of episyenite associated with faults. However, despite the pervasiveness of faulting, episyenites are rare in the Tauern meta-granitoids. This localized occurrence of episyenite is inferred to represent a section of a vertical pipe structure exploiting a portion of the fault network. Our study indicates that the location and the extent of episyenite alteration cannot be simply predicted from the geometry and the fracturing patterns of the pre-existing cataclastic faults. Quartz dissolution during episyenitization was accompanied and/or followed by: (i) pervasive substitution of oligoclase and biotite/chlorite of the meta-granodiorite by albite and vermicular chlorite, respectively; and (ii) precipitation of adularia, albite, anatase, calcite, hematite and zeolites within pores. Isotopic data from the calcite filling of the pores suggest a surficial source of fluids associated with this calcite precipitation

  2. 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.


    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

  3. Reduction and immobilization of hexavalent chromium by microbially reduced Fe-bearing clay minerals (United States)

    Bishop, Michael E.; Glasser, Paul; Dong, Hailiang; Arey, Bruce; Kovarik, Libor


    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

  4. Structural and alteration controls on gold mineralization the of the amphibolite facies Detour Lake Deposit, Canada (United States)

    Dubosq, Renelle; Schneider, David


    The 15M oz Detour Lake deposit is a Neoarchean orogenic gold ore body located in the northern most region of the Abitibi district within the Superior Province. The mine is an open pit design in the high strain zone of the Sunday Lake Deformation Zone (SLDZ). The ductile-brittle SLDZ parallels the broadly E-W Abitibi greenstone belt and the deposit is situated in a dilation zone between volcanoclastic rocks of the Caopatina Assemblage and Lower Detour Lake Formation, consisting of ultramafic talc-chlorite-sericite schist. The Upper Detour Lake Formation consists of pillowed and massive flows and hyloclastic units crosscut by minor felsic to intermediate dykes. All of the formations are sub-vertical, north-dipping units with stretching lineations indicating dip-slip motion. The Detour deposit differs from other classic ore deposits in the dominantly greenschist facies Abitibi Subprovince by possessing an amphibolite facies metamorphic assemblage of actinolite-biotite-plagioclase-almandine. Consequently, the typical indicator minerals used to identify alteration and mineralization, such as secondary biotite, may not be useful. Petrological and geochemical analyses have revealed at least four populations of biotite: 1) large euhedral crystals located within quartz-carbonate veins, 2) small, euhedral zoned crystals present as alteration haloes, 3) very small, anhedral to subhedral indistinct crystal present in mafic volcanic host rock, and 4) large euhedral crystals defining the main metamorphic foliation in the metasediments. Extensive examination of mineral assemblages, alteration products, and vein structure in rock core across barren and mineralized zones has documented over a dozen vein types which can be grouped into two main categories: 1) sulfidized quartz-carbonate veins associated with biotite alteration and 2) late carbonate veins. Gold grades do not prove to be dependent on vein type but rather on the host rock composition: the highest ore grades are present

  5. Clay minerals and geochemistry of the bottom sediments in the northwestern East China Sea

    Institute of Scientific and Technical Information of China (English)


    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

  6. Coupled mass transfer through a fluid phase and volume preservation during the hydration of granulite: An example from the Bergen Arcs, Norway (United States)

    Centrella, Stephen; Austrheim, Håkon; Putnis, Andrew


    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

  7. The influence of critical zone processes on the Mg isotope budget in a tropical, highly weathered andesitic catchment (United States)

    Chapela Lara, María; Buss, Heather L.; Pogge von Strandmann, Philip A. E.; Schuessler, Jan A.; Moore, Oliver W.


    In order to assess the effects of critical zone processes on Mg concentrations and isotopic signatures of tropical streams, we studied a well constrained, highly weathered andesitic volcaniclastic catchment in the Luquillo Critical Zone Observatory, Puerto Rico. Our results indicate that dissolved Mg concentrations and isotope ratios in the regolith pore water are mainly controlled by rain input, with weathering inputs being more important at sites with thinner regolith (2.7-0.9 m deep) and at depth (>8 m) on a thick ridgetop regolith (∼10 m). In addition to mixing of precipitation and weathering-sourced Mg, an isotopic fractionation process is taking place between dissolved Mg and the regolith, likely during dissolution or recrystallisation of Fe(III)-(hydro)oxides under alternating redox conditions. Bulk regolith is isotopically heavier than both the bedrock and the exchangeable fraction (δ26Mgregolith-bedrock = +0.03 to +0.47‰), consistent with the preferential incorporation of heavy 26Mg into secondary minerals with some exchange of sorbed Mg with isotopically lighter pore water. Magnesium concentrations in the stream show a typical dilution behaviour during a storm event, but the [Mg] - δ26Mg pattern cannot be explained by mixing of rain and pore water; the data are best explained by a steady-state fractionation model with α = 1.00115. During baseflow the stream has δ26Mg = +0.01‰, higher than any of the water samples or the bedrock. In-situ analysis of the Mg isotopic composition of bedrock minerals points at the dissolution of Mg-rich chlorite (δ26Mg = +0.19‰) as the most likely source of this isotopically heavy Mg, with mass balance calculations indicating chlorite dissolution is also the main source of Mg to the stream. Overall, our study highlights the importance of atmospheric input of nutrients to the vegetation in tropical areas covered by thick, highly leached regolith, whereas the Mg flux and Mg isotopic signature of watershed exports

  8. Source and evolution of ore-forming hydrothermal fluids in the northern Iberian Pyrite Belt massive sulphide deposits (SW Spain): evidence from fluid inclusions and stable isotopes (United States)

    Sánchez-España, Javier; Velasco, Francisco; Boyce, Adrian J.; Fallick, Anthony E.


    A fluid inclusion and stable isotopic study has been undertaken on some massive sulphide deposits (Aguas Teñidas Este, Concepción, San Miguel, San Telmo and Cueva de la Mora) located in the northern Iberian Pyrite Belt. The isotopic analyses were mainly performed on quartz, chlorite, carbonate and whole rock samples from the stockworks and altered footwall zones of the deposits, and also on some fluid inclusion waters. Homogenization temperatures of fluid inclusions in quartz mostly range from 120 to 280 °C. Salinity of most fluid inclusions ranges from 2 to 14 wt% NaCl equiv. A few cases with Th=80-110 °C and salinity of 16-24 wt% NaCl equiv., have been also recognized. In addition, fluid inclusions from the Soloviejo Mn-Fe-jaspers (160-190 °C and ≈6 wt% NaCl equiv.) and some Late to Post-Hercynian quartz veins (130-270 °C and ≈4 wt% NaCl equiv.) were also studied. Isotopic results indicate that fluids in equilibrium with measured quartz (δ18Ofluid ≈-2 to 4‰), chlorites (δ18Ofluid ≈8-14‰, δDfluid ≈-45 to -27‰), whole rocks (δ18Ofluid ≈4-7‰, δDfluid ≈-15 to -10‰), and carbonates (δ18Oankerite ≈14.5-16‰, δ13Cfluid =-11 to -5‰) evolved isotopically during the lifetime of the hydrothermal systems, following a waxing/waning cycle at different temperatures and water/rock ratios. The results (fluid inclusions, δ18O, δD and δ13C values) point to a highly evolved seawater, along with a variable (but significant) contribution of other fluid reservoirs such as magmatic and/or deep metamorphic waters, as the most probable sources for the ore-forming fluids. These fluids interacted with the underlying volcanic and sedimentary rocks during convective circulation through the upper crust.

  9. Fault-zone structure and weakening processes in basin-scale reverse faults: The Moonlight Fault Zone, South Island, New Zealand (United States)

    Alder, S.; Smith, S. A. F.; Scott, J. M.


    The >200 km long Moonlight Fault Zone (MFZ) in southern New Zealand was an Oligocene basin-bounding normal fault zone that reactivated in the Miocene as a high-angle reverse fault (present dip angle 65°-75°). Regional exhumation in the last c. 5 Ma has resulted in deep exposures of the MFZ that present an opportunity to study the structure and deformation processes that were active in a basin-scale reverse fault at basement depths. Syn-rift sediments are preserved only as thin fault-bound slivers. The hanging wall and footwall of the MFZ are mainly greenschist facies quartzofeldspathic schists that have a steeply-dipping (55°-75°) foliation subparallel to the main fault trace. In more fissile lithologies (e.g. greyschists), hanging-wall deformation occurred by the development of foliation-parallel breccia layers up to a few centimetres thick. Greyschists in the footwall deformed mainly by folding and formation of tabular, foliation-parallel breccias up to 1 m wide. Where the hanging-wall contains more competent lithologies (e.g. greenschist facies metabasite) it is laced with networks of pseudotachylyte that formed parallel to the host rock foliation in a damage zone extending up to 500 m from the main fault trace. The fault core contains an up to 20 m thick sequence of breccias, cataclasites and foliated cataclasites preserving evidence for the progressive development of interconnected networks of (partly authigenic) chlorite and muscovite. Deformation in the fault core occurred by cataclasis of quartz and albite, frictional sliding of chlorite and muscovite grains, and dissolution-precipitation. Combined with published friction and permeability data, our observations suggest that: 1) host rock lithology and anisotropy were the primary controls on the structure of the MFZ at basement depths and 2) high-angle reverse slip was facilitated by the low frictional strength of fault core materials. Restriction of pseudotachylyte networks to the hanging-wall of the

  10. Reaction Rind Formation in Mèlange in the Catalina Schist, California (United States)

    Penniston-Dorland, S. C.; Bebout, G. E.; Sorensen, S. S.; Piccoli, P. M.; Walker, R. J.


    Reaction rinds between differing lithologies are commonly considered the result of fluid-assisted metasomatic alteration, however, enrichments in relatively fluid-immobile elements such as Cr and Ni seemingly reflect other processes such as volume strain or tectonic mixing. Eleven samples along a 30 cm traverse of an amphibolite grade block and its reaction rind adjacent to ultramafic-rich matrix, show dramatic change in mineral abundance and whole-rock major and trace element and Li isotope composition. Samples of the rind are enriched in whole-rock SiO2, K2O, Rb, Ba, Li, MgO, Cr, Ni, and also Os, Ir and Ru relative to samples of the block core, and are depleted in FeO, Al2O3, TiO2, CaO, and Zr. δ7LiL-SVEC ranges from -3 to +1% and the distribution of Li concentrations and δ7Li is consistent with diffusion on the scale of nearly the entire profile. FeO content of garnets in the rind is lower than that of garnets in the block core, reflecting whole-rock FeO concentrations, and suggesting garnet growth after the depletion in whole-rock FeO. Garnets in the rind show extensive pseudomorphing by decussate chlorite, suggesting post-garnet growth infiltration by H2O-rich fluid. Rind concentrations of Cr, Ni, Zr, Al2O3, TiO2, FeO, and possibly CaO, MgO, Na2O, and Sr can be most simply explained by mechanical mixing of mafic block with mèlange matrix. Such mixing cannot explain the increases in SiO2, K2O, Li, and Ba, and we propose that the concentrations of these elements in the rind reflect element mobility during relatively late-stage fluid infiltration. We propose an early episode of mechanical mixing during which mixing of material derived from the mafic block and mèlange matrix produced rind-like material which then accreted onto the basaltic block. Garnet growth in both the block core and the rind occurred after this mechanical mixing. Fluid infiltration in the rind occurred after peak metamorphism of the block, causing alteration of garnet to chlorite and the

  11. An integrated multidisciplinary re-evaluation of the geothermal system at Valles Caldera, New Mexico, using an immersive three-dimensional (3D) visualization environment (United States)

    Fowler, A.; Bennett, S. E.; Wildgoose, M.; Cantwell, C.; Elliott, A. J.


    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

  12. The Cedrolina Chromitite, Goiás State, Brazil: A Metamorphic Puzzle

    Directory of Open Access Journals (Sweden)

    Yuri de Melo Portella


    Full Text Available The Cedrolina chromitite body (Goiás-Brazil is concordantly emplaced within talc-chlorite schists that correspond to the poly-metamorphic product of ultramafic rocks inserted in the Pilar de Goiás Greenstone Belt (Central Brazil. The chromite ore displays a nodular structure consisting of rounded and ellipsoidal orbs (up to 1.5 cm in size, often strongly deformed and fractured, immersed in a matrix of silicates (mainly chlorite and talc. Chromite is characterized by high Cr# (0.80–0.86, high Fe2+# (0.70–0.94, and low TiO2 (av. = 0.18 wt % consistent with variation trends of spinels from metamorphic rocks. The chromitite contains a large suite of accessory phases, but only irarsite and laurite are believed to be relicts of the original igneous assemblage, whereas most accessory minerals are thought to be related to hydrothermal fluids that emanated from a nearby felsic intrusion, metamorphism and weathering. Rutile is one of the most abundant accessory minerals described, showing an unusually high Cr2O3 content (up to 39,200 ppm of Cr and commonly forming large anhedral grains (>100 µm that fill fractures (within chromite nodules and in the matrix or contain micro-inclusions of chromite. Using a trace element geothermometer, the rutile crystallization temperature is estimated at 550–600 °C (at 0.4–0.6 GPa, which is in agreement with P and T conditions proposed for the regional greenschist to low amphibolite facies metamorphic peak of the area. Textural, morphological, and compositional evidence confirm that rutile did not crystallize at high temperatures simultaneously with the host chromitite, but as a secondary metamorphic mineral. Rutile may have been formed as a metamorphic overgrowth product following deformation and regional metamorphic events, filling fractures and incorporating chromite fragments. High Cr contents in rutile very likely are due to Cr remobilization from Cr-spinel during metamorphism and suggest that Ti was

  13. Grain size distribution, clay mineralogy and chemistry of bottom sediments from the outer Thermaikos Gulf, Aegean Sea, Greece

    Directory of Open Access Journals (Sweden)



    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

  14. A thermal investigation on coals from Assam (India)

    Energy Technology Data Exchange (ETDEWEB)

    Saikia, Binoy K.; Boruah, Rajani K.; Baruah, Bimala P. [North-East Institute of Science and Technology (CSIR), Jorhat-785 006 (India); Gogoi, Pradip K. [Department of Chemistry, Dibrugarh University, Dibrugarh-786 004 (India)


    A thermal characterization of two coal samples from Ledo and Tikak collieries of Makum coalfield, Assam, India using XRD, FT-IR, and TGA was reported in this paper. The coal samples were heated for 20, 40 and 60 min in a 1000-watt heater (temperature {proportional_to} 250 C) in presence of air and characterized by XRD and FT-IR spectroscopy. Both the coals contain amorphous and crystalline phases. The raw coals also contain very small peaks due to quartz, calcite, gypsum, pyrite, and chlorite. The XRD patterns were found to change upon heating. In the coals heated for 20 and 40 min, it was observed that both amorphous and crystalline parts are common in them; crystalline part being the major one in the 40 min heated samples. The XRD patterns of the samples heated for 60 min indicate the presence of major quantities of {alpha}-quartz, hematite, and chlorite in them. They also show some new peaks, which are assigned to be kaolinite, illite, magnetite and very small in comparison to the amorphous portion in raw coals. {alpha}-quartz was found to be most stable crystalline phase of silica in the coals. The crystallinity % (X-ray) of the coals heat-treated for different times was determined and found to be increasing with time of heating. The FT-IR spectra of raw and heat-treated coal samples at 250 C were also recorded and compared. The spectra were observed to be almost similar and it was observed that few functional groups disappear on heating at 250 C. The same coal samples were also characterized by thermogravimetric analysis (TGA) and differential thermal analysis (DTA) techniques. On heat treatment in air atmosphere up to 800 C, 20-27% weight loss occurs due to removal of various volatile materials. DTA results indicate the chemical reactivity of the coal sample initially at 80-110 C due to loss of water, and two other major reactions at around 420 and 530 C due to primary and secondary volatization. (author)

  15. Constraining the thermal structure beneath Lusi: insights from temperature record in erupted clasts (United States)

    Malvoisin, Benjamin; Mazzini, Adriano; Miller, Stephen


    Sedimentary units beneath Lusi from surface to depth are the Pucangan formation, the Upper Kalibeng formation where shales and then volcanoclastic clasts are found, the Kujung-Propuh-Tuban formation composed of carbonates and the Ngimbang formation composed of shales. Water and gas geochemistry as well as surface deformation indicate that Lusi is a hydrothermal system rooted at >4 km depth. However, the thermal structure beneath Lusi is still poorly constrained whereas it has first-order impacts on the physical and chemical processes observed during the eruption. In the framework of the Lusi Lab project (ERC grant n° 308126) and of a project of the Swiss National Science Foundation (n°160050) we studied erupted clasts collected at the crater site to determine their source and temperature record. Three types of clasts were studied based on morphological and mineralogical basis. The first type is limestones mainly composed of Ca- and Fe-bearing carbonates. The clasts of the second type are light grey shales (LGS) containing carbonaceous matter, illite/smectite mixture, plagioclase and quartz. The third type is also a shale with a black colour containing hydrocarbons (black shales, BS) and with the additional presence of Na-rich plagioclase, biotite and chlorite. The presence of these latter minerals indicates hydrothermal activity at relatively high temperature. Better constraints on temperature were obtained by using both Raman spectroscopic carbonaceous material thermometry (RSCM) and chlorite geothermometry. Temperatures below 200°C were determined for the LGS with RSCM. BS recorded two temperatures. The first one, around 170°C, is rather consistent with an extrapolation of the geothermal gradient measured before the eruption up to 4,000 m depth. Combined with mineralogical observations, this suggests that BS originate from the Ngimbang formation. The second recorded higher temperature around 250°C indicates heating, probably through interaction with high

  16. In search of early life: Carbonate veins in Archean metamorphic rocks as potential hosts of biomarkers (United States)

    Peters, Carl A.; Piazolo, Sandra; Webb, Gregory E.; Dutkiewicz, Adriana; George, Simon C.


    The detection of early life signatures using hydrocarbon biomarkers in Precambrian rocks struggles with contamination issues, unspecific biomarkers and the lack of suitable sedimentary rocks due to extensive thermal overprints. Importantly, host rocks must not have been exposed to temperatures above 250 °C as at these temperatures biomarkers are destroyed. Here we show that Archean sedimentary rocks from the Jeerinah Formation (2.63 billion yrs) and Carawine Dolomite (2.55 billion yrs) of the Pilbara Craton (Western Australia) drilled by the Agouron Institute in 2012, which previously were suggested to be suitable for biomarker studies, were metamorphosed to the greenschist facies. This is higher than previously reported. Both the mineral assemblages (carbonate, quartz, Fe-chlorite, muscovite, microcline, rutile, and pyrite with absence of illite) and chlorite geothermometry suggest that the rocks were exposed to temperatures higher than 300 °C and probably ∼400 °C, consistent with greenschist-facies metamorphism. This facies leads to the destruction of any biomarkers and explains why the extraction of hydrocarbon biomarkers from pristine drill cores has not been successful. However, we show that the rocks are cut by younger formation-specific carbonate veins containing primary oil-bearing fluid inclusions and solid bitumens. Type 1 veins in the Carawine Dolomite consist of dolomite, quartz and solid bitumen, whereas type 2 veins in the Jeerinah Formation consist of calcite. Within the veins fluid inclusion homogenisation temperatures and calcite twinning geothermometry indicate maximum temperatures of ∼200 °C for type 1 veins and ∼180 °C for type 2 veins. Type 1 veins have typical isotopic values for reprecipitated Archean sea-water carbonates, with δ13CVPDB ranging from - 3 ‰ to 0‰ and δ18OVPDB ranging from - 13 ‰ to - 7 ‰, while type 2 veins have isotopic values that are similar to hydrothermal carbonates, with δ13CVPDB ranging from - 18

  17. The Alteration History of Clovis Class Rocks in Gusev Crater as Determined by Ti-Normalzed Mass Balance Analysis (United States)

    Sutter, Brat; Ming, Douglas W.; Niles, P. B.; Golden, D. C.


    The West Spur Clovis class rocks in Gusev Crater are some of the most altered rocks in Gusev Crater and likely contain a mixed sulfate and phyllosilicate mineralogy [1,2]. The high S and Cl content of the Clovis rocks suggests that acidic vapors or fluids of H2SO4 and HCl reacted with the Clovis parent rock to form Ca, Mg,- sulfates, iron-oxyhydroxides and secondary aluminosilicates (approx.60 wt.%) of a poorly crystalline nature (e.g., allophane) [1]. Up to 14-17 wt.% phyllosilicates (e.g., kaolinite, chlorite, serpentine) are hypothesized to exist in the Clovis materials suggesting that Clovis parent materials while possibly exposed to acidic pHs were likely neutralized by basalt dissolution which resulted in mildly acidic pHs (4-6) [1, 2]. This work proposes that subsequent to the alteration of the Clovis rocks, alteration fluids became concentrated in ions resulting in the addition of silicate and salts. The objective of this work is to utilize Ti-normalized mass balance analysis to evaluate (1) mineral gains and losses and (2) elemental gains and losses in the Clovis rocks. Results of this work will be used evaluate the nature of geochemical conditions that affect phyllosilicate and sulfate formation at Gusev crater.

  18. Regional tectonics, geology, magma chamber processes and mineralisation of the Jinchuan nickel-copper-PGE deposit, Gansu Province, China: A review

    Directory of Open Access Journals (Sweden)

    T.M. (Mike Porter


    The Jinchuan ultramafic intrusion was injected into three interconnected sub-chambers, each containing a separate orebody. It essentially comprises an olivine-orthopyroxene-chromite cumulate, with interstitial orthopyroxene, clinopyroxene, plagioclase and phlogopite, and is predominantly composed of lherzolite (∼80%, with an outer rim of olivine pyroxenite and cores of mineralised dunite. Mineralisation occurs as disseminated and net-textured sulphides, predominantly within the dunite, with lesser, PGE rich lenses, late massive sulphide accumulations, small copper rich pods and limited mineralised diopside skarn in wall rock marbles. The principal ore minerals are pyrrhotite (the dominant sulphide, pentlandite, chalcopyrite, cubanite, mackinawite and pyrite, with a variety of platinum group minerals and minor gold. The deposit underwent significant post-magmatic tremolite-actinolite, chlorite, serpentine and magnetite alteration. The volume of the Jinchuan intrusion accounts for <3% of the total parental magma required to generate the contained olivine and sulphide. It is postulated that mafic melt, intruded into the lower crust, hydraulically supported by density contrast buoyancy from below the Moho, ponded in a large staging chamber, where crystallisation and settling formed a lower sulphide rich mush. This mush was subsequently injected into nearby shallow dipping faults to form the Jinchuan intrusion.

  19. (Per)chlorate reduction by an acetogenic bacterium, Sporomusa sp., isolated from an underground gas storage.

    KAUST Repository

    Balk, Melike


    A mesophilic bacterium, strain An4, was isolated from an underground gas storage reservoir with methanol as substrate and perchlorate as electron acceptor. Cells were Gram-negative, spore-forming, straight to curved rods, 0.5-0.8 microm in diameter, and 2-8 microm in length, growing as single cells or in pairs. The cells grew optimally at 37 degrees C, and the pH optimum was around 7. Strain An4 converted various alcohols, organic acids, fructose, acetoin, and H(2)/CO(2) to acetate, usually as the only product. Succinate was decarboxylated to propionate. The isolate was able to respire with (per)chlorate, nitrate, and CO(2). The G+C content of the DNA was 42.6 mol%. Based on the 16S rRNA gene sequence analysis, strain An4 was most closely related to Sporomusa ovata (98% similarity). The bacterium reduced perchlorate and chlorate completely to chloride. Key enzymes, perchlorate reductase and chlorite dismutase, were detected in cell-free extracts.

  20. Geochemistry of Kasnau-Matasukh lignites, Nagaur Basin,Rajasthan (India)

    Institute of Scientific and Technical Information of China (English)

    Prakash K.Singh; Pramod K.Rajak; Mahendra P.Singh; Vijay K.Singh; Amiya S.Naik


    The distribution and verticals variation of geochemical components in the Kasnau-Matasukh lignites of Nagaur Basin,Rajasthan,were investigated using microscopy,proximate and ultimate analyses,Rock-Eval Pyrolysis,X-ray diffraction and Fourier Transform Infrared analyses,and major/minor/trace element determination.The relationship of elements with ash content and with macerals have also been discussed.These lignites are stratified,black,dominantly composed of huminite group macerals with subordinated amounts of liptinite and inertinite groups.They are classified as type-Ⅲ kerogen and are mainly gas prone in nature.The concentration (in vol%) of mineral matter is seen to increase towards upper part of seam and so is the concentration (in wt%) of the volatile matter,elemental carbon and sulphur.The common minerals present in these lignitesare mixed clay layer,chlorite,and quartz as identified by X-ray diffraction study.Compared with world average in brown coal,the bulk concentration of Cu is anomalously high in most of the samples while Cd is 2-3 times high and Zn is high in one band.Based on interrelationship,different pyrite forms are noticed to have different preferential enrichment of various elements.The concentration of disseminated pyrite is more than the other pyrite forms and is followed by discrete pyrite grains and massive pyrite.

  1. Growth of bultfonteinite and hydrogarnet in metasomatized basalt xenoliths in the B/K9 kimberlite, Damtshaa, Botswana: insights into hydrothermal metamorphism in kimberlite pipes (United States)

    Buse, Ben; Schumacher, John C.; Sparks, R. Stephen J.; Field, Matthew


    Metamorphic assemblages within Karoo basalt xenoliths, found within volcaniclastic kimberlite of the B/K9 pipe, Damtshaa, Botswana, constrain conditions of kimberlite alteration. Bultfonteinite and chlorite partially replace the original augite-plagioclase assemblage, driven by the serpentinisation of the kimberlite creating strong chemical potential gradients for Si and Mg. Hydrogarnet and serpentine replace these earlier metamorphic assemblages as the deposits cool. The bultfonteinite (ideally Ca2SiO2[OH,F]4) and hydrogarnet assemblages require a water-rich fluid containing F-, and imply hydrothermal alteration dominated by external fluids rather than autometamorphism from deuteric fluids. Bultfonteinite and hydrogarnet are estimated to form at temperatures of ca. 350-250°C, which are similar to those for serpentinisation. Alteration within the B/K9 kimberlite predominantly occurs between 250 and 400°C. We attribute these conditions to increased efficiency of mass transfer and chemical reactions below the critical point of water and a consequence of volume-increasing serpentinisation and metasomatic reactions that take place over this temperature range. A comparison of the B/K9 kimberlite with kimberlites from Venetia, South Africa suggests that the composition and mineralogy of included xenoliths affects the alteration assemblages within kimberlite deposits.

  2. Mineralogía de los materiales de la Formación de La Viñuela (Cordilleras Béticas

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    Galán, E.


    Full Text Available Mineralogy of several samples from the Viñuela Formation,Lower Burdigalian (Vélez Málaga, Cordilleras Béticas, has been studied. Materials are composed of abundant microfauna. and pebbles of micaschits, quartzites and other materials, from the Alpujárrides and Maláguides Nappes, cemented by a micritic matrix . Most samples contain zeolites (clinoptilolite, mordenite and analcime, and illite chlorite, interstratified clay minerals, montmorillonite and opal C-T. A diagenetic genesis for zeolites is suggested.

    Se ha estudiado la composición mineralógica de unas muestras de la serie tipo de la Formación de La Viñuela (norte de Vélez Málaga, Cordilleras Béticas, datadas como Burdigaliense inferior. Se trata de sedimentos marinos carbonatados micríticos, con abundante microfauna. que cementan cantos de micaesquistos, cuarcitas y otros materiales procedentes de los mantos alpujárrides y maláguides. En gran parto de estas muestras se han encontrado zeolitas (clinoptilolita, mordenita y analcima, así como illita, clorita, interestratificados, montmorillonita y ópalo C-T. Se atribuye a las zeolitas un origen diagenético.

  3. A Petrographic Study of the Three Forks Formation (Upper Devonian, Williston Basin, North Dakota: Based on Thin Section Analysis, XRD and SEM

    Directory of Open Access Journals (Sweden)

    Richard Ashu


    Full Text Available Deeply buried below 8,000 ft, the Three Forks Formation in North Dakota displays a variety of interesting diagenetic characteristics including dolomitization and hematite precipitation. Samples from three lithofacies are analyzed by thin section and SEM petrography and combined bulk and clay XRD analyses. Key aspects controlling the porosity and permeability of this formation are revealed by focusing on the detail mineralogy, rock type and diagenetic mineral distribution, and overall reservoir quality. Results prove that the Three Forks mineralogy is dominated by dolomite, along with substantial hematite, monocrystalline quartz, and mica flakes with trace feldspar, calcite, and pyrite. Clays mainly consist of illite together with minor chlorite and kaolinite and are associated with the scattered clasts. The reservoir quality is controlled by intercrystalline, rare microvuggy, and microporosity types that result from diagenetic and depositional events. Three stages of the dolomitization process are identified and discussed. Our hypothesis is that dolomitization commenced soon after deposition and was pervasive as no original carbonate texture is detectable.

  4. Alkali-etched heated clay: Microstructure and physical/mechanical properties

    Directory of Open Access Journals (Sweden)

    Kenza El Hafid


    Full Text Available The microstructure of alkali-etched heated kaolinitic-illitic clay, which was cured in wet atmosphere at different temperatures and times, was investigated by using X-ray diffraction, Fourier-transform infrared spectroscopy, thermal analysis and scanning electron microscope. The flexural strength, density and water absorption of the cured samples were correlated to curing time, ageing temperature and alkaline solution concentration by using the response surface methodology. It was found that hydro-sodalite and zeolite P were essentially formed from metakaolinite, the products of chlorite and illite. The geopolymer was almost absent mainly because of excessive hydration. The assemblage of neoformed zeolites differed partially from that predicted using the stability diagram Na2O–SiO2–Al2O3. Polynomial models described well the change of the physical/mechanical properties against the experimental factors. Based on the results of the models, the increase of any factor among the studied ones had an adverse effect on the mechanical strength and contributed to the increase of water absorption. The weight of the effect of the factors on density was less significant. These results were discussed in relation to the microstructure investigation.

  5. Magmatism, sedimentation and stratigraphy of the northern region of the Santos Basin; Magmatismo, sedimentacao e estratigrafia da porcao norte da Bacia de Santos

    Energy Technology Data Exchange (ETDEWEB)

    Moreira, Jobel Lourenco Pinheiro [PETROBRAS S.A., Rio de de Janeiro, RJ (Brazil). E e P. Grupo de Interpretacao Exploratoria da Bacia de Santos], E-mail:; Esteves, Carlos Augusto; Rodrigues, Jose Joaquim Goncalves; Vasconcelos, Claudemir Severiano de


    The Santos Basin, passive margin basin, had its sedimentary history disrupted by intra and extra-basinal tectonic activity that took place during the Eocene and Santonian-Campanian. Many authors have identified these events; however this matter still deserves an integrated study including basement and basin areas. Recent Ar/Ar geochronological data from intrusive and extrusive rocks in the Santos basin have identified two events precisely at 82 {+-} 1 Ma and 48,9 Ma. Among the depositional sequences individualized from seismic and well data in the Santos Basin, the K90 depositional sequence - of Santonian- Campanian age - is the best example to investigate magmatism, sedimentation and stratigraphy. Substantial volcanic building, intrusive and extrusive rocks can be observed in this sequence and have a strong impact on in the mineralogical and sedimentary composition of the siliciclastic deposits (sandstones and shales). Subaerial and subaqueous volcanisms are well identified and its characteristics are described herein in terms of seismic facies, log facies and lithofacies. Siliciclastic depositional systems from the transgressive tract (shallow marine) and from lowstand (deep marine) of this sequence are lithic arkosean sandstones, composed mainly by quartz, Kfeldspar, plagioclase and fragments of igneous rocks. An intensive diagenetic chloritization, probably due to the presence of ferromagnesian minerals, has a strong impact on the reservoir quality. (author)

  6. Mineral composite assessment of Kelkit River Basin in Turkey by means of remote sensing

    Indian Academy of Sciences (India)

    Hakan Mete Dogan


    Utilizing remote sensing (RS) and geographic information systems (GIS) tools, mineral composite characteristics (ferrous minerals (FM), iron oxide (IO), and clay minerals (CM)) of the Kelkit River Basin (15913.07 km2) in Turkey were investigated and mapped. Mineral composite (MC) index maps were produced from three LANDSAT-ETM+ satellite images taken in 2000. Resulting MC index maps were summarized in nine classes by using ‘natural breaks’ classification method in GIS. Employing bi-variety correlation analysis, relationships among index maps were investigated. According to the results, FM and IO index maps showed positive correlation, while CM index map is negatively correlated with FM and IO index maps. Negative correlations between iron and clay variables suggested that the dominant clay minerals of the study area might be smectite, illite, kaolinite, and chlorite, which have little or no iron content. Using field data for which their geographic coordinates had been determined by global positioning system (GPS), developed MC maps were verified, and found dependable for environmental and ecological modeling studies.

  7. Thermal evolution of the Sisters shear zone, southern New Zealand; Formation of the Great South Basin and onset of Pacific-Antarctic spreading (United States)

    Kula, Joseph; Tulloch, Andy J.; Spell, Terry L.; Wells, Michael L.; Zanetti, Kathleen A.


    The separation of Zealandia from West Antarctica was the final stage in the Cretaceous breakup of the Gondwana Pacific margin. Continental extension resulting in formation of the Great South Basin and thinning of the Campbell Plateau leading to development of the Pacific-Antarctic spreading ridge was partially accommodated along the Sisters shear zone. This east-northeast striking brittle-ductile structure exposed along the southeast coast of Stewart Island, New Zealand, is a greenschist facies extensional shear zone that separates a hanging wall of chloritic, brecciated granites, and undeformed conglomerate from a footwall of mylonitic Carboniferous and Early Cretaceous granites. This complex structure exhibits bivergent kinematics and can be subdivided into a northern and southern segment. The 40Ar/39Ar thermochronology indicates that cooling of the shear zone footwall began at ˜94 Ma with accelerated cooling over the interval ˜89-82 Ma. Structural and thermochronological data indicate a spatial and temporal link between the Sisters shear zone, initial sedimentation within the offshore Great South Basin, extension of the Campbell Plateau, and initiation of the Pacific-Antarctic spreading ridge.

  8. Hyperspectral surface materials map of quadrangle 3262, Farah (421) and Hokumat-e-pur-Chaman (422) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials (United States)

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Johnson, Michaela R.; Giles, Stuart A.


    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  9. Oxygen and hydrogen isotope study of the Skaergaard intrusion and its country rocks: a description of a 55-M. Y. old fossil hydrothermal system

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, H.P. Jr. (California Inst. of Tech., Pasadena); Forester, R.W.


    Oxygen isotope analyses have been obtained on rocks and coexisting minerals, principally plagioclase and clinopyroxene, from about 400 samples of the Skaergaard layered gabbro intrusion and its country rocks. The delta/sup 18/O values of plagioclase decrease upward in the intrusion, from normal values of about +6.0 to +6.4 in the Lower Zone and parts of the Middle Zone, to values as low as -2.4 in the Upper Border Group. The /sup 18/O depletions of the plagioclase all took place under subsolidus conditions, and were produced by the Eocene meteoric-hydrothermal system established by this pluton. Clinopyroxene, which is more resistant to /sup 18/O exchange than is plagioclase, also underwent depletion in /sup 18/O, but to a lesser degree. The /sup 18/O-depleted rocks typically show reversed 18/O/sub plag-px/ fractionations, except at the top of the Upper Zone, where the pyroxenes are very fine-grained aggregates pseudomorphous after ferrowollastonite; these inverted pyroxenes were much more susceptible to subsolidus /sup 18/O exchange. D/H analyses of the chloritized basalt country rocks and of the minor quantities of alteration minerals in the pluton (delta D = -116 to -149) confirm these interpretations, indicating that the rocks interacted with meteoric groundwaters.

  10. Mineralogy and composition of chromitites and host peridotites from the Colkahan ultramafic complex (Nazdasht mine), Kerman, southeastern Iran (United States)

    Najafzadeh, Ali Reza


    Several chromitite pods of variable sizes are hosted in dunite-harzburgite of the about 14 km2 mining district of Nazdasht, in the Colkahan ultramafic complex, located in the Haji Abad-Esfandagheh district in the Kerman province, southeastern Iran. Olivine, orthopyroxene, and to a lesser extent clinopyroxene of a highly refractory nature, are the primary silicates found in the dunites and harzburgites. The matrix minerals between chromian spinel grains are serpentinized olivine and pyroxene, Cr-rich chlorite (kaemmererite), uvarovite, and veins of magnesite. Chromian spinel mainly occurs as massive chromitite pods and as thin massive chromitite bands together with minor disseminations in dunites and harzburgites. Chromian spinels in massive chromitites show relatively high Cr-numbers (0.60-0.82), Mg-numbers (0.54-0.74) and very low TiO2 contents (averaging 0.16 wt.%) which may reflect the crystallization of chromite from a boninitic magma. The Fe3+-number is very low, down to discrimination diagrams based on mineral chemistry of peridotites are consistent with the differentiation of arc related magmas with boninitic affinity and support the supra-subduction paleogeodynamic setting of Haji Abad-Esfandagheh district previously proposed by some authors.

  11. Distribution characteristics and source analysis of clay minerals contents in surface sediments of the northwestern South China Sea%南海北部西侧海域粘土矿物的含量分布特征及来源分析

    Institute of Scientific and Technical Information of China (English)

    张晓飞; 陈坚; 徐勇航; 赖志坤


    Clay components <2 )i,m of 315 surface sediment samples are analyzed by XRD. The results indicate that clay minerals consist of illite, chlorite, smectite and kaolinite. Distribution character of the clay minerals is signifi cantly different in different parts of the research area. Based on the distribution character of clay minerals and topography of the research area, the research area can be divided into three parts; A area is the continental shelf off Pearl River; B area is the eastern continental shelf and the slope off the Hainan Island; C area is from Xisha Trough to the Xisha Islands waters. Based on the distribution characteristics of the clay minerals in the research area and surrounding rivers, it is found that kaolinite(mean 19% )of A area is from Pearl River, illite(mean 53% ) and chlorite(mean 18% ) mainly from Taiwan, with low amount of smectite( mean 10% ). Kaolinite( mean 13% ) of B area is mainly from Hainan Island, smectite( mean 16% ) mainly from Luzon Island. Smectite( mean 14% ) of C area is mainly from rivers of middle Vietnam and the Red River, with low (mean 12% ) kaolinite content. Illite and chlorite of west B and C area are mainly from rivers of middle Vietnam and the Red River, while illite and chlorite of east B and C area are mainly from Taiwan rivers.%应用X射线衍射(XRD)方法对南海北部西侧海域315个表层沉积物<2μm的粘土组分进行分析.结果表明,本研究区粘土矿物有伊利石、绿泥石、蒙脱石和高岭石,其组合特征在不同区域表现出明显的差异.根据粘土矿物的空间分布特征以及研究区的海底地形特征,研究区大致可以分为3个不同区块:A区是珠江口外的大陆架区域;B区是海南岛以东陆架陆坡区域;C区为西沙海槽至西沙群岛附近区域.根据研究区表层粘土矿物分布特征、周围河流供给的主要粘土成分以及洋流搬运作用,发现A区高岭石(平均含量为19%)主要来自珠江,伊利石与绿

  12. Insights into the P–T evolution path of TsoMorari eclogites of the north-western Himalayas: Constraints on the geodynamic evolution of the region

    Indian Academy of Sciences (India)

    Preeti Singh; Ashima Saikia; Naresh Chandra Pant; Pramod Kumar Verma


    The present study is on the Ultra High Pressure Metamorphic rocks of the Tso Morari Crystalline Complex of the northwestern Himalayas. Five different mineral associations representative of five stages of P–T (pressure–temperature) evolution of these rocks have been established based on metamorphic textures and mineral chemistry. The pre-UHP metamorphic association 1 of Na-Ca-amphibole + epidote ± paragonite ± rutile ± magnetite with T–P of ∼500° C and 10 kbar. This is followed by UHP metamorphic regime marked by association 2 and association 3. Association 2 (Fe< Mg< Ca-garnet + omphacite + coesite + phengite + rutile ± ilmenite) marks the peak metamorphic conditions of atleast 33 kbar and ∼750° C. Association 3 (Fe< Mg< Ca-garnet + Na-Ca amphibole + phengite ± paragonite ± calcite ± ilmenite ± titanite) yields a P–T condition of ∼28 kbar and 700°C. The post-UHP metamorphic regime is defined by associations 4 and 5. Association 4 (Fe< Ca< Mg-garnet + Ca-amphibole + plagioclase (An05) + biotite + epidote ± phengite yields a P–T estimate of ∼14 kbar and 800°C) and association 5 (Chlorite + plagioclase (An0.5) + quartz + phengite + Ca- amphibole ± epidote ± biotite ± rutile ± titanite ± ilmenite) yields a P–T value of ∼7 kbar and 350°C.

  13. Geochemical characteristics of Mesoproterozoic metabasite dykes from the Chhotanagpur Gneissic Terrain, eastern India: Implications for their emplacement in a plate margin tectonic environment

    Indian Academy of Sciences (India)

    Rajesh K Srivastava; Anup K Sinha; Suresh Kumar


    A number of mafic intrusive bodies (mostly dykes) are exposed in the Chhotanagpur Gneissic Terrain (CGT). Most dykes trend in ENE–WSW to E–W following major structural trends of the region. These metabasite dykes show granoblastic to grano-nematoblastic textures and contain hornblende, plagioclase, chlorite, quartz and epidote which suggest their metamorphism under amphibolite grade P–T conditions. Although no radiometric age is available for the metabasite dykes, field relationships with host rock and available geochronology on granitoids suggest their emplacement during Mesoproterozoic. Geochemical characteristics of these dykes classify them as low-K tholeiite to medium-K calcalkaline type. At least two types of metabasite dykes are recognized on the basis of their HFSE contents; one group shows entirely calc-alkaline nature, whereas the other group has rocks of tholeiite-calc-alkaline series. High Mg#observed in a number of samples indicates their derivation from primary melt. Multielement spidergrams and rare-earth element patterns observed in these samples also corroborate their derivation from different magma batches. Trace element patterns observed for Nb–Ta, Hf–Zr, Sr and Y suggesting involvement of subduction related processes in the genesis of CGT metabasite dykes. Perceived geochemical characteristics suggest that metamorphism did not affect much on the chemistry of metabasites but source region, responsible for the generation of CGT metabasites, was possibly modified during subduction process. This study suggests that magma generated in a destructive plate setting fed the Mesoproterozoic mafic dykes of the CGT.

  14. Age determination of nephrite by in-situ SIMS U-Pb dating syngenetic titanite: A case study of the nephrite deposit from Luanchuan, Henan, China (United States)

    Ling, Xiao-Xiao; Schmädicke, Esther; Li, Qiu-Li; Gose, Jürgen; Wu, Rui-Hua; Wang, Shi-Qi; Liu, Yu; Tang, Guo-Qiang; Li, Xian-Hua


    Nephrite is a kind of valuable jade which forms during metamorphism under greenschist facies conditions. Most investigations focus on the genesis of nephrite, however, the formation age of nephrite remains poorly constrained due to the lack of suitable dating methods. In this paper, the petrological, chemical characteristics, and mineral inclusions of nephrite collected from Luanchuan, Henan, China have been studied by optical and electron microscopy and wavelength-dispersive electron microprobe (EMP). The petrological observations show that nephrite consists mainly of tremolite, minor calcite and titanite, occasionally with rutile, quartz, serpentine, chlorite, pyrite, and apatite. The titanite and tremolite which are intergrown with each other share low-energy grain boundaries. It indicates that the two phases are equilibrated and can be considered as cogenetic. The chemical composition of tremolite is high in Si, Mg, Ca, but low in Fe, Cr, and Ni, which indicates that the nephrite from Luanchuan belongs to the dolomite type rather than the serpentinite type. The petrography of different nephrite structures suggests that the grain size of tremolite was determined by the stress intensity undergone during the nephrite formation progress. In-situ Secondary Ion Mass Spectrometer (SIMS) U-Pb dating of titanite from nephrite yielded an age of 361 ± 4 Ma, which is the first estimate for the time of formation of the Luanchuan nephrite deposit. This investigation provides a powerful in-situ dating method to unravel the age of nephrite, which could be served as a tool for future research on other nephrite deposits.

  15. Fe K-edge XANES and pre-edge polarization dependance for the determination of the oxidation state of iron in antigorite and other phyllosilicates (United States)

    Munoz, M.; Vidal, O.; Marcaillou, C.; Pascarelli, S.; Mathon, O.; Farges, F.


    Iron oxidation state in minerals is often a crucial indicator for the understanding of mineralogical reactions related to hydrothermalism, or various natural processes. We investigated here the influence of the linear polarization of the synchrotron X-ray beam on the determination of the iron oxidation state in phyllosilicates. Fe K-edge XANES spectra and pre-peaks of biotite (Bt), chlorite (Chl), talc (Tlc) and antigorite (Atg) crystals have been recorded at different crystal orientations. As a function of the crystal orientation, the experimental results show, 1) important changes both for XANES and pre-peaks, 2) typical changes of spectral signatures for all mineral species, 3) uncorrelated changes between XANES and pre-peaks, 4) important changes of the pre-peak energies, but no significant change of the integrated areas. Ab initio XANES calculations, performed for 6 orientations of the Bt structure are consistent with the experimental measurements. The energy position of the pre-peak centroids changes with crystal orientation by 0.4 eV for Bt and Tlc crystals, and by 0.2 eV for Chl and Atg, which correspond to XFe(apparent)3+ variations (2δ) of 0.22 and 0.15, respectively. Measurements on powdered crystals show that - (2/3)2δ

  16. Mineralogical Zonation of Wall-Rock Alteration in Jiaodong Gold Province, North China

    Institute of Scientific and Technical Information of China (English)


    Mineralogical zonation of wall-rock alterations in Mesozoic granitoids is summarized from 18 gold deposits in Jiaodong gold province on the Asian mobile continental margin of the west circum-Pacific rim. This paper deals with wall-rock alterations developed around gold mineralizations of the quartz-vein type in granitoids and the wall-rock alteration type in granitoid-basement contacts alongMesozoic fault zones trending mostly NNE-SSW and NE-SW. Five alteration zones are distinguished from host rock to ore zone, namely the chloritization and sericitization zone, the hematitization-rutilization and microclinization zone, the quartz-sericitization zone, the pyrite-quartz-sericitization zone and the pyrite-silicification zone. The former two are outer zones marked by incomplete alteration of first mafic and then felsic minerals of the granitoids, while the later three are inner zones marked by complete alteration of both mafic and felsic minerals of the granitoids leading to retrogressive sericitization and progressive silicification with participation of ore elements. The whole process proceeds under dynamometamorphism with high fugacity of volatiles. Wall-rock alteration is the intermediate link between unaltered host rock and ore mineralization both in time and space. Development of the alteration zonation and its mineral composition controls genetic type of mineralization, size and grade of the deposit and location of the ore zones.

  17. Final report of the rock sealing project. Sealing of zones disturbed by blasting and stress release

    Energy Technology Data Exchange (ETDEWEB)

    Boergesson, L.; Pusch, R.; Fredriksson, A.; Hoekmark, H.; Karnland, O.; Sanden, T. (Clay Technology AB, Lund (Sweden))


    Test 2 and 3 of the rock sealing project comprised determination of the hydraulic properties of the disturbed rock around tunnels and drifts and the possibilities of decreasing the hydraulic conductivity of the disturbed zones by an attempt to seal the very fine excavation-induced fractures that cause an increase in conductivity. This report deals with the grouting procedures and their effect while the hydraulic testing before grouting is described in volume 2. The macro flow test of the BMT drift before grouting showed that the disturbed zone around the drift has a highly increased hydraulic conductivity reaching more than 1 m into the rock from the periphery of the drift. The most conductive shallow part of this zone was grouted by 350 1 m long 'hedgehog' holes. The holes were injected with cement using dynamic as well as static techniques. The injections were preceded by laboratory investigations of the rheological properties of different cement mixtures, by theoretical modelling of grout penetration in factures, and by full scale injections in an artificial fracture. The macro flow test was repeated after the grouting and the results evaluated by using the same finite element models as before the grouting. The conclusion was that the effect of the grouting was very small. Excavation of the rock after grouting showed that the grout penetration has been very poor into chlorite-coated fractures and a conclusion was that such fractures are hardly groutable due to debris hindering the grout from penetrating. (au).

  18. Structure and metamorphism of the Gran Paradiso massif, western Alps, Italy (United States)

    Brouwer, F. M.; Vissers, R. L. M.; Lamb, W. M.


    The pressure-temperature-time trajectory and structural history of high-pressure rocks presently exposed in the Gran Paradiso massif provide constraints on the processes that caused their thermal evolution and exhumation. High-pressure metamorphism of the rocks is found to have culminated at temperatures around 525 °C and pressures of 12 to 14 kbar. After high-pressure metamorphism, the rocks cooled during initial decompression, while undergoing top-to-the-west shear on chlorite-bearing shear bands and larger scale shear zones. Biotite-bearing shear bands and larger shear zones related to top-to-the-east deformation affected the Gran Paradiso massif during reheating to temperatures of around 550 °C at 6 to 7 kbar. Further exhumation occurred at relatively high temperatures. A potentially viable explanation of the observed stage of reheating before final cooling and exhumation is breakoff of a subducting slab in the upper mantle, allowing advective heat transfer to the base of the crust. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at

  19. Differential effects on innate versus adaptive immune responses by WF10. (United States)

    Giese, Thomas; McGrath, Michael S; Stumm, Susanne; Schempp, Harald; Elstner, Erich; Meuer, Stefan C


    Oxidative compounds that are physiologically generated in vivo can induce natural defense mechanisms to enhance the elimination of pathogens and to limit inflammatory tissue damage in the course of inflammation. Here, we have investigated WF10, a chlorite-based non-toxic compound for its functional activities on human PBMC in vitro. WF10 exerts potent immune-modulatory effects through generating endogenous oxidative compounds such as taurine chloramine. Proliferation and IL-2 production of anti-CD3 stimulated PBMC were inhibited by WF10, as was the nuclear translocation of the transcription factor NFATc. In PBMC and monocytes, however, WF10 induced pro-inflammatory cytokines like IL-1beta, IL-8, and TNF-alpha. In the monocytic cell line THP-1, the activation of the transcription factors AP-1 and NFkappaB by WF10 was demonstrated. Inhibition of NFAT regulated genes in activated lymphocytes in concert with the induction of several myeloid cell associated pro-inflammatory genes in monocytes represents a novel mechanism of immune modulation.

  20. Quantification of Tremolite in Friable Material Coming from Calabrian Ophiolitic Deposits by Infrared Spectroscopy

    Directory of Open Access Journals (Sweden)

    Antonella Campopiano


    Full Text Available The aim of this study is to identify the infrared absorption band suitable for quantifying tremolite in three powdered samples (fine, medium, and large size classes coming from a quarry of ophiolitic friable rocks in the western part of the Calabria region of Italy. Three IR bands were considered: OH stretching band between 3700 and 3650 cm−1, the stretching bands of the Si-O-Si linkage between 1200 and 900 cm−1, and the absorbance band at 756 cm−1 attributable to tremolite. The amount of tremolite in the test samples was quantified by using the curve parameters of the three analytical bands. The quantitative analysis of tremolite using the band due to OH stretchings (3700–3650 cm−1 and the bands attributed to the Si-O-Si stretchings (1200–900 cm−1 showed high values for all test samples. Their use overestimated the tremolite amount because both bands were affected at the interfering mineral silicates such as talc, kaolinite, chlorite, and serpentinites. The abundant presence of antigorite in studied samples mainly in medium size class sample had a key role in our findings. The band at 756 cm−1 was not affected at the interfering minerals and can be used for quantitative analysis of tremolite in sample coming from ophiolitic deposits.

  1. Correlation of wireline log characteristics with hydrothermal alteration and other reservoir properties of the Salton Sea and Westmorland geothermal fields, Imperial Valley, California, USA

    Energy Technology Data Exchange (ETDEWEB)

    Muramoto, F.S.; Elders, W.A.


    A detailed study of wireline logs from 11 wells in the Salton Sea and Westmorland geothermal systems was undertaken in order to determine the effects of hydrothermal alteration on the response of electrical and gamma-gamma density well logs. For the Salton Sea geothermal field, definite correspondence between log responses and hydrothermal mineralogy is evident, which in turn is related to the physical properties of the rocks. Three hydrothermal and one unaltered zone can be identified from log data on shales. These are: (1) the unaltered montmorillonite zone (<100/sup 0/ to 190/sup 0/C); (2) the illite zone (100/sup 0/ to 190/sup 0/C to 230/sup 0/ to 250/sup 0/C); (3) the chlorite zone (230/sup 0/ to 250/sup 0/C to 290/sup 0/ to 300/sup 0/C); and (4) the feldspar zone (>290/sup 0/ to 300/sup 0/C). The characteristic responses on well logs by which these zones are identified result primarily from changes in clay mineralogy of the shales and increases in density with progressive hydrothermal metamorphism. In the Westmorland geothermal field, differentiating mineral zones from log responses was only partially successful. However, analyses of both well log and petrologic data for wells Landers 1 and Kalin Farms 1 suggest that the former is heating up and the latter is cooling.

  2. Oil and gas reservoir exploration based on hyperspectral remote sensing and super-low-frequency electromagnetic detection (United States)

    Qin, Qiming; Zhang, Zili; Chen, Li; Wang, Nan; Zhang, Chengye


    This paper proposes a method that combined hyperspectral remote sensing with super-low-frequency (SLF) electromagnetic detection to extract oil and gas reservoir characteristics from surface to underground, for the purpose of determining oil and gas exploration target regions. The study area in Xinjiang Karamay oil-gas field, China, was investigated. First, a Hyperion dataset was used to extract altered minerals (montmorillonite, chlorite, and siderite), which were comparatively verified by field survey and spectral measurement. Second, the SLF electromagnetic datasets were then acquired where the altered minerals were distributed. An inverse distance weighting method was utilized to acquire two-dimensional profiles of the electrical feature distribution of different formations on the subsurface. Finally, existing geological data, field work, and the results derived from Hyperion images and SLF electromagnetic datasets were comprehensively analyzed to confirm the oil and gas exploration target region. The results of both hyperspectral remote sensing and SLF electromagnetic detection had a good consistency with the geological materials in this study. This paper demonstrates that the combination of hyperspectral remote sensing and SLF electromagnetic detection is suitable for the early exploration of oil and gas reservoirs, which is characterized by low exploration costs, large exploration areas, and a high working efficiency.

  3. Relation between facies, diagenesis, and reservoir quality of Rotliegende reservoirs in north Germany

    Energy Technology Data Exchange (ETDEWEB)

    David, F.; Gast, R.; Kraft, T. (BEB Erdgas Erdol GmbH, Hannover (Germany))


    In north Germany, the majority of Rotliegende gas fields is confined to an approximately 50 km-wide east-west-orientated belt, which is situated on the gently north-dipping flank of the southern Permian basin. Approximately 400 billion m[sup 3] of natural gas has been found in Rotliegende reservoir sandstones with average porosities of depths ranging from 3500 to 5000 m. Rotliegende deposition was controlled by the Autunian paleo-relief, and arid climate and cyclic transgressions of the desert lake. In general, wadis and large dunefields occur in the hinterland, sebkhas with small isolate dunes and shorelines define the coastal area, and a desert lake occurs to the north. The sandstones deposited in large dunefields contain only minor amounts of illite, anhydrite, and calcite and form good reservoirs. In contrast, the small dunes formed in the sebkha areas were affected by fluctuations of the desert lake groundwaters, causing the infiltration of detrital clay and precipitation of gypsum and calcite. These cements were transformed to illite, anhydrite, and calcite-II during later diagenesis, leading to a significant reduction of the reservoir quality. The best reservoirs occur in the shoreline sandstones because porosity and permeability were preserved by early magnesium-chlorite diagenesis. Since facies controls diagenesis and consequently reservoir quality, mapping of facies also indicates the distribution of reservoir and nonreservoir rocks. This information is used to identify play area and to interpret and calibrate three-dimensional seismic data.

  4. Coupled modelling (transport-reaction) of the fluid-clay interactions and their feed back on the physical properties of the bentonite engineered clay barrier system; Modelisation couplee (transport - reaction) des interactions fluides - argiles et de leurs effets en retour sur les proprietes physiques de barrieres ouvragees en bentonite

    Energy Technology Data Exchange (ETDEWEB)

    Marty, N


    The originality of this work is to process feed back effects of mineralogical and chemical modifications of clays, in storage conditions, on their physical properties and therefore on their transport characteristics (porosity, molecular diffusion, permeability). These feed back effects are modelled using the KIRMAT code (Kinetic of Reaction and MAss Transfer) developed from the kinetic code KINDIS by adding the effect of water renewal in the mineral-solution reactive cells. KIRMAT resolves mass balance equations associated with mass transport together with the geochemical reactions in a 1D approach. After 100 000 years of simulated interaction at 100 C, with the fluid of the Callovo-Oxfordian geological level (COX) and with iron provided by the steel overpack corrosion, the montmorillonite of the clay barrier is only partially transformed (into illite, chlorite, saponite...). Only outer parts of the modelled profile seem to be significantly affected by smectite dissolution processes, mainly at the interface with the geological environment. The modifications of physical properties show a closure of the porosity at the boundaries of the barrier, by creating a decrease of mass transport by molecular diffusion, essentially at the interface with the iron. Permeability laws applied to this system show a decrease of the hydraulic conductivity correlated with the porosity evolution. Near the COX, the swelling pressure of the clays from the barrier decreases. In the major part of the modelled profile, the engineered clay barrier system seems to keep its initial physical properties (porosity, molecular diffusion, permeability, swelling pressure) and functionalities. (author)

  5. Geochemistry of abyssal peridotites from the super slow-spreading Southwest Indian Ridge near 65°E: Implications for magma source and seawater alteration

    Indian Academy of Sciences (India)

    Zhigang Zeng; Qiaoyun Wang; Xiaomei Wang; Shuai Chen; Xuebo Yin; Zhaoxue Li


    The geochemical characteristics of abyssal peridotite samples from one dredge station (27° 49.74′S, 65° 02.14′E, water depth 4473 m) on the super slow-spreading Southwest Indian Ridge (SWIR) near 65°E were investigated. Abyssal peridotites recovered from this site were comprised mainly of lizardite, chlorite, carbonate and magnetite with minor amounts of talc, pyroxene phenocrysts and sparse olivines. Serpentinites exhibit talc veins and major serpentine derived from serpentinization with relict olivine granuloblasts. Olivine grains in serpentinites display exsolution lamellae, indicating the occurrence of talc reduction or decompression during seawater–rock interaction. Pyroxene shows clear cleavage in t