Black shales
The paleoenvironment during the Early Cambrian is closely related to the accumulation mechanism of organic matter (OM) from the Lower Cambrian black shales. However, paleoenvironment remains a controversial issue. Here, we reported a lot of detailed data of sedimentary stratigraphy and geochemistry of the Lower Cambrian Yuertusi Formation in the Aksu area, Tarim Basin. The Yuertusi Formation ..."Schistes carton", Jurassic black shale rocks occurring in the south-western part of the Grand Duchy of Luxembourg, were investigated, based on a combined mineralogical and geochemical approach. The major aim of this study was to understand the lateral and vertical variation in mineralogy, and the distribution of major and trace elements ...
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A recent drilling operation in the Triassic Yanchang Formation (Tongchuan District of the Ordos Basin, north-central China) reached a black shale bed with an average in-situ gas content of 1.11 g/ml. Subsequent total organic carbon (TOC) content measurements and rock-eval analysis showed that the black shale section was generally classified as excellent source rock, with TOC contents commonly ...High thermal maturities raise questions about gas storage potential in lower Paleozoic shales. Given these uncertainties, a new look at Sichuan Basin shale gas ...Early Cambrian black shales display strongly enriched Se, Ga, and As, significantly enriched Ba, Bi, and Rb, weakly enriched Mo, Cs, Cd, V, U, Be, In, and Tl, normal Sc, Th, Cr, Li, Cu, Ni, and Pb and depleted Co, Zn, and Sr. Moreover, Se is the most enriched trace element in the Ediacaran and early Cambrian black shales: concentrations vary ...May 1, 2019 · Abstract. Black shales are sedimentary rocks containing >0.5% of organic carbon. They host polymetallic deposits which have been mined for Cu, Ni, Zn, Mn, P, Mo, V, U, Au and PGE (platinum group elements). Even sub-economic occurrences provide potential risk of acid rock drainage when exposed to oxic surface environment. Sep 1, 2017 · Introduction. The deposition of black shales and the accumulation of organic matter in black shales not only involves the basic biogeochemical processes on Earth, including photosynthesis, oxidation, bacterial sulfate reduction and humification, etc., but also makes an important contribution to the primary source of hydrocarbons and other economic mineral deposits (Arthur and Sageman, 1994 ... The Bodaibo District (the Irkutsk Region of Russia) is a world-class gold-mining subprovince comprising a total of 13 large-and medium-scale black-shale-hosted orogenic gold deposits known as the ...The specific surface area and pore volume of OM in black shales follow a parabolic pattern with increasing thermal maturity (quantified via vitrinite reflectance, Ro). The initial increase reflects development of OM-hosted pores, and the subsequent decrease is due to denser stacking of aromatic units in the macromolecular structure of OM, with ...May 30, 2006 · The Lower Cambrian black shale sequence of the Niutitang Formation in the Yangtze Platform, South China, hosts an extreme metal-enriched sulfide ore bed that shows >10,000 times enrichment in Mo, Ni, Se, Re, Os, As, Hg, and Sb and >1,000 times enrichment in Ag, Au, Pt, and Pd, when compared to average upper continental crust. We report in this paper trace- and rare-earth-element concentrations ... 1. Introduction. Black shale (BS) is a dark-colored, usually thinly laminated and organic rich fine-grained rock with characteristics associated to specific sedimentology, paleoecology and geochemistry conditions formed within bottom water poor in oxygen (Wignall, 1994; Tyson, 2004).A wide range of sedimentary environments are favorable for the formation of BS and most ancient BS appear to ...'Black shales' is an old term for argillaceous rocks rich in organic matter. The characteristics of the depositional environment of such deposits have long intrigued geologists, particularly the extent to which actualistic models can be applied. The revived interest in the last few years stems principally from the wide-spread recognition ...Using the modern Black Sea as an analogue, ancient black shales may record the Mo isotope composition of contemporaneous seawater if conversion of MoO 4 2− (molybdate) to MoS 4 2− (thiomolybdate) is quantitative in the overlying euxinic water column and pore water (Barling et al., 2001, Arnold et al., 2004, Neubert et al., 2008).New and existing Mo isotope data from early Cambrian black shales in South China span a range of greater than 3‰, which can only be explained by multi-stage fractionation of Mo isotopes. The ...Prominent maxima in black shale abundance and in black shale/total shale ratio occur at 2.0-1.7 Ga, with less prominent peaks in the Late Neoproterozoic (800-600 Ma) and in the Late Archean (2.7-2.5 Ga). Peaks in chemical index of alteration (CIA) of shales at the same times suggest corresponding warm paleoclimates.The peaks in CIA and black shale abundance are correlated in time at a 94 ...The black shale episodes were dated by biostratigraphic methods and by high‐resolution chemostratigraphy and cyclostratigraphy. Mesozoic black shales are now interpreted as the oceanographic expression of major perturbations of the global carbon cycle and climate. Research into younger (Pliocene to Pleistocene) sedimentary cycles (including ...
Devonian Black Shales Eastern USChattanooga, New Albany, Ohio Shales. The Mid-Late Devonian black shales of the Appalachian, Illinois, and Michigan Basins have long been studied to provide clues to past climates, ocean ventilation, mass extinctions, and general earth history. Common misconceptions about these shales are that they represent ...Early models for Mid-Continent cyclothems placed the black shales in shallow water, with maximum transgression at the fusulinid-bearing zone in the overlying limestone. The most recent model proposed that the black phosphatic shales, which commonly occur between two subtidal carbonates, are widespread and laterally continuous over great ...2.2 Experimental procedure. Shale samples were soaked in two conditions: NaCl solution with sub-critical CO 2 and NaCl solution with super-critical CO 2.The concentration of NaCl solution was 20% (by weight). The pressure of sub-critical and super-critical CO 2 were 7 and 9 MPa, respectively. The temperature for both the two conditions was 40 °C.Black shales have been of increasing interest in recent years due to their oil and gas potential, but also because many are enriched in nonfuel "unconventional" critical elements such as cobalt, chromium, molybdenum, nickel, platinum group elements, rhenium, and vanadium. Critical metals residing in shales presented a challenge to economic ...
Although Lower Silurian black shales within and around the Sichuan Basin have received renewed attention during the past few years because of their potential prospectivity for shale gas, studies associated with shale gas reservoir evaluation are still rare. In this study, eight black shale core samples were collected from a well drilled recently in the Chuandong Thrust Fold Belt, southwestern ...Early Cambrian black shales in the South Qinling (SQL) of China constitute one of the world's most important vanadium- and barium-metallogenic belts. It is controversial on the enrichment mechanics of vanadium (V) and barium (Ba) mineralization. The V and Ba mineralization in the Xichuan area from the northern SQL is mainly hosted by shales and ...…
Reader Q&A - also see RECOMMENDED ARTICLES & FAQs. Black shale is characterized by the enri. Possible cause: Combined with the available data from other deep blocks in the southern Sichuan Basin.
Black shales and massive sulfides represent reduced lithofacies that require isolation from oxic environments to be preserved. This, together with the sedimentary affinity of both lithofacies, can ...The black shales show restricted thickness (up to 29.0 m), and are characterized by overall high ‘black shale' to ‘total shale' ratio (>0.51). Their geochemical characteristics were studied to constrain provenance, palaeoclimate , and tectonic setting of deposition of the Srisailam Formation.Analysis shows that the semi-deep lake subfacies mainly deposit black-dark gray clayey shale. Because the location of well T1 in Puguang area is closer to the lake basin center than well Y1 in Yuanba area during the sedimentary period of J 1 da, the water body is deeper, the sedimentary facies is more stable, and the shale thickness is thicker ...
Less abundant elements Mo, Sb, Zn, and Se have median ranges of 10 to 100 ppm, and Ag, Bi, Te, Cd, and Au have median ranges of 0.01 to 10 ppm. Our dataset reveals three main groups of trace elements that are incorporated into pyrite in different ways. Group 1 elements (As, Ni, Co, Sb, Se, and Mo) are contained uniformly throughout the pyrite ...The lower Toarcian black shale and mudstone succession of the Anya section in the northeastern Ordos Basin records a climatically controlled evolution of the lacustrine system during the negative carbon isotope excursion (NCIE) of the Toarcian oceanic anoxic event (T-OAE; ca. 183 Ma). In the Anya section, petrography integrated with climate ...May 30, 2006 · The Lower Cambrian black shale sequence of the Niutitang Formation in the Yangtze Platform, South China, hosts an extreme metal-enriched sulfide ore bed that shows >10,000 times enrichment in Mo, Ni, Se, Re, Os, As, Hg, and Sb and >1,000 times enrichment in Ag, Au, Pt, and Pd, when compared to average upper continental crust. We report in this paper trace- and rare-earth-element concentrations ...
Upon oxidative weathering of black shale in surface envir A dark, thinly laminated carbonaceous shale, exceptionally rich in organic matter (5% or more carbon content) and sulfide (esp. iron sulfide, usually pyrite ), and often containing …Black shales do not differ significantly in terms of mineralogical composition compared to ordinary shales. Nevertheless, the deposition in anoxic or oxygen-depleted environments has some effect on the relative amount of minerals. Pyrite content especially varies largely across black shale successions and is commonly high in marine shales. The black shale sequence of the Dingtai profile hateristics of black shales deposited in thos Dec 15, 2022 · First, that black shale deposition was the result of basin-wide anoxic conditions (Murphy et al., 2000; Chen and Sharma, 2016; Bingham-Koslowski et al., 2016). According to this explanation, black shale deposition should be isochronous and the relationship between black shales and gray shales should be abrupt vertical contacts. The black graptolitic shales of the lower part of the Lungmachi Formation, which span the Ordovician and Silurian boundary and may extend into lower Telychian in some localities, lie conformably on the Kuanyinchiao Beds, or disconformably on the Wufeng Formation or overlying strata of earlier age (Fan et al., 2011). The Chang 7 black shale in the Upper Triassic Yanchang Formati The black shales below and above show relatively lower Fe T /Al ratios, reflecting the same range as sediments from the Black Sea, which is the largest modern anoxic ocean basin (Severmann et al., 2008). Table 1. TOC (total organic carbon) concentrations of black shales are Black shales are known to be geogenic sourceAge: Middle Ordovician Period Distribution: West-central Arkansa The black shales parent rocks have elevated Cd concentration and act as a source of Cd. The liberated Cd from black shales outcrop temporarily accumulated in the acidized surrounding soil and could arise potential adverse impacts on environment due to rainfall. Although high concentration of Cd was not detected in stream water, Cd concentrated ...Biomarkers in the black shale change regularly, and have an obvious "inflection point" at the depth of 2753-2777 m in the Chang 7 3 Sub-member, indicating that the input of terrigenous organic matter increased. However, there is a negative drift about 2% of organic carbon isotopic composition near the "inflection point", which is in ... Shale forms from the pressure of layers of sediment comp Early models for Mid-Continent cyclothems placed the black shales in shallow water, with maximum transgression at the fusulinid-bearing zone in the overlying limestone. The most recent model proposed that the black phosphatic shales, which commonly occur between two subtidal carbonates, are widespread and laterally continuous over great ...Black shales are mixtures of terrigenous, biogenous, and hydrogenous sediment in which organic matter constitutes at least 0.5% of the material. Shales are the end product of the processes that ... China's most successful horizon for shale-gas [Stanford University. High-pressure methane sorption isoA ∼20 m thick unit of dolomitic, pyritic, and finely laminated or Black shale is an important host for redox-sensitive metals, such as Mo, Ni, V, U, Re, and a number of other metals including Cu, Pb, Zn, Au, Ag, Hg, Sb, etc. in various geological periods and settings (Holland 1979; Coveney et al. 1992; Pasava 1993).Metal-enriched black shale of Early Cambrian age occurs over several thousands of kilometers throughout the Yangtze Platform in South China.