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[en] An assessment, based on organic facies characteristics, have been carried out on the middle Cretaceous black shales, in order to determine their hydrocarbon source potential, thermal maturity, and depositional environments. The methods employed include evaluation of organic carbon content, rockeval pyrolysis, extractable organic matter, maceral composition and biomarker distributions.Organic facies criteria such as TOC, HI, Tmax, liptinite content, SOMIFOC and SHC/AHC indicate that Albian to middle Cenomanian shales are could only generate gas. The late Cenomanian to early Turonian shales are characterized by Type I/II kerogen, mature and could generate both oil and characterized by Type III kerogen, immature and could generate gas with little oil. The biomarker distributions indicate immature to mature source rock, moderately biodegraded and with reduced marine environment prevailing during the deposition of the lack shales. The late Cenomanian to early Turonian black shales show the highest source-rock potential
[en] Mercury enrichments in the black shale unit of the Ediacaran Doushantuo Formation are, likely the result of volcanic input or anoxia-driven mercury deposition. If the Hg enrichments are volcanic in origin, or are due to synchronous regional anoxia, then the patterns of Hg enrichment are consistent with the conventional correlation of these units, with the tripartite units equivalent to Member IV black shales. Additionally comparing redox proxy data from the intervals of Hg enrichment could indicate if the enrichments are due to comparable changes in redox conditions, or increased Hg input under differing redox conditions, consistent with volcanic input.
[es]Los enriquecimientos de mercurio en la unidad de esquisto negro de la Formación ediacárica de Doushantuo son probablemente el resultado de la influencia volcánica o del depósito de mercurio mediante anoxia. Si los enriquecimientos de Hg son de origen volcánico, o se deben a una anoxia regional contemporánea, entonces los patrones de enriquecimiento de Hg son consistentes con la correlación convencional de estas unidades, con las unidades tripartitas equivalentes a la pizarra negra del Miembro IV. Además, la comparación de los datos redox de los intervalos de enriquecimiento en Hg podría indicar si los enriquecimientos se deben a cambios comparables en las condiciones redox, o a un aumento de la entrada de Hg bajo diferentes condiciones redox, consistente con la influencia volcánica.
[en] Here we detail the new data acquisition system (DAS) developed for the CSIRO Nuclear Microprobe primarily to handle large detector arrays and to work in tandem with the Maia detector system. Both systems use HYMOD FPGA-based processors. The current DAQ system and its microscopy suite and beam handling have been integrated with the HYMOD system(s) to facilitate easy access to the either system. Examples of the new scanning modes available with the combined system are highlighted on a complex Cambrian black shale sample from the Yangtze basin in Southern China.
[en] An illustration on role of TOC (Total organic carbon) in uranium enrichment is examined in present study from the Jhamarkotra Formation of the Palaeoproterozoic Aravalli Supergroup. The study unravels uranium ion mobility during secondary enrichment process which is governed by the depositional environment. Contrasting black shales facies, though coeval, show selective uranium mineralization. This variability is in discordance with the TOC content of the black shale facies, which in turn are governed by the different microenvironmental conditions. Uranium concentrations in the studied black shales are found to be independent of the TOC. The concentration is dependent on uranium ion carrier during secondary enrichment. (author)
[en] Black shale type uranium deposits, though of low grade (<0.001 to 0.05% U3O8), contain large uranium resources because of their immense volume. The Neoproterozoic-Cambrian Krol-Tal Himalayan sequence covering a cumulative area of about 1000 sq km in five different synclinal basins from Sirmour district, Himachal Pradesh in the west to Nainital district, Uttar Pradesh in east contain such black shale horizons. The uranium mineralisation found in black shale in the Nigalidhar syncline of Himachal Pradesh and its implication of being an indicator for search of such uranium deposits in Himalayas is discussed. (author)
[en] Black shale is the unconventional resource of uranium. Recovery of uranium from black shale has been carried out by the following steps: i) size reduction, ii) leaching of uranium in the aqueous medium, iii) fluoride ion removal, iv) solvent extraction of uranium from the aqueous leach solution, v) scrubbing of the loaded solvent after extraction to remove impurities as much as possible and vi) stripping of uranium from the loaded organic into the aqueous phase. Leaching of black shale has been carried out in hydrochloric acid. Free acidity of the leach solution has been determined by potentiometric titration method. Removal of fluoride ions has been done using sodium chloride. Solvent extraction has been carried out by both tributyl phosphate and alamine-336 as extractants. Scrubbing has been tried with oxalic acid and sulphuric acid. Stripping with sodium carbonate solution has been carried out. Overall recovery of uranium is 95%. (author)
[en] Unconventional uranium resources largely and widely distribute in central-southeastern Guizhou, the samples are of complexity characteristic as black shale series in central-southeastern Guizhou. Due to high selectivity and sensitivity, MUA is used to determine the unconventional uranium with standard samples. The test results are satisfied to ICP-MS method. (authors)
[en] The Late Sinian-Early Cambrian black shales which consist of carbonaceous shale,carbonaceous slate,carbonaceous dolomite, Siliceous dolomite, silicilith, phosphorite and other components in general are widely distributed in the southwest of China. This black shales have been associated with U, Mo, V, Hg, P and other elements enrichment and mineralization.This paper,based on deeply researching into the black shales of southwest of China,suggests that U metallogenesis has the following characteristics 1)The black shales are an important source of U; 2) Various combination of multiple elements mineralization is ccompanied by U mineralization; 3) U mineralization occurs near the center of submarine hydrothermal exhalative in black shales. and 4) U mineralization is obviously related to the Late reformation. (authors)
[en] The Ni–Mo–PGE polymetallic layers, from Southern China (Huangjiawan mine, Zunyi region, northern part of the Guizhou Province), were analyzed by micro-PIXE. These samples are known to be enriched with acidic elements and basic elements. Some of them, like Ag, Au, Pt, Pd, Se and Mo, are of large economic value. The distributions of Fe, Mo, Ni, As, Se and Pd in black shales samples are studied. The correlation among those elements has also been investigated. Trace element data from minerals, the noble metals’ mode of occurrence and correlation with other elements are all significant in mineralogy. Such information can help in understanding the genesis of the deposit and also aid the exploration strategy