Black shales
Age: Middle Ordovician Period Distribution: West-central Arkansas, Ouachita Mountains; southern Oklahoma Geology: The Womble Formation is mostly black shale with thin layers of limestone, silty sandstone, and some chert. Some green shales are interbedded with the black shales, but less so than in the Mazarn Shale. Cleavage, at an angle to bedding, frequently displays ribboned cleavage surfaces.Jan 30, 2018 · The black shales in the Qusseir area (Duwi Formation, Campanian–Maastrichtian) were deposited in an anoxic marine environment, and are remarkably high in their enrichment of redox-sensitive and sulfide-forming trace metals. Measurements of Mn, U, V, and Mo reveal that the studied black shales deposited under shallow anoxic-sulfidic conditions.
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Two black shale areas, the Dongping and the Yanxi areas of the county, were selected for this study (Fig. 1). The black shales of both areas are organic-rich carbonaceous shales that host vanadium ores in Dongping area and uranium ores in Yanxi area. Soils developed on the black shales are typically yellowish.The Fe enrichment of Nkporo shale is relatively similar to Oshosun Gery and Black Shales (Ajayi et al. 2006) but the K and Na enrichments vary in the shale samples. The Fe mean value of Ekenkpon Shale is slightly higher than Nkporo Shale, while the K and Na mean values are relatively similar (Table 5 and Fig. 6 ).The black-shale intervals lack bioturbation and feature mm-thick sub-layers of varying dark-grey and sometimes grey-green colour (in web version). Occasionally, small 1-2 cm thick limestone layers are intercalated (e.g., in couplet 2). The prominent black-shale intervals in couplets 7 and 9 lack limy sub-layers.The black shales of the Río Mayer Formation contain information that corresponds to the entire Lower Cretaceous of the Austral Basin. During this period, major tectonic changes occurred at the southern hemisphere, including the break-up of Gondwana and the initial opening of the Weddell Sea and the Atlantic Ocean ( i.e., Dalziel et al., 1974 ...The Mamfe basin hosting the studied shales lies on basement rocks of the Precambrian age constituting of granite, syenites, gneisses, and mica-schists [12], [59].The sedimentary cover is mainly composed of variable black shales [6], [23].The shales are dark grey to black in colour deposited in a shallow lacustrine, oxygenated depositional …The black shale mineral composition is mainly composed of calcite, apatite, quartz, pyrite and clay minerals. The average values of Cu, Ni, Zn, Cr, V, As and Se and the ratios Rb/Sr and Cr/Ni in ...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 ...Of the two black-shale sequences in the basin, the upper is the Devonian and Mississippian shales, which have attracted interest as a source of uranium, oil and gas, and pyrolytic oil. These studies have provided the necessary framework for resource evaluations and for geochemical characterizations, including analysis of the chemical structure ...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 ...Weathered black shales and cherts show significant loss of Cr, and heavier Cr isotopes are released to weathering fluids, with isotope fractionations ranging up to 0.31‰. However, some weathered shales show enrichment of Cr with heavy isotopes, suggesting re-sequestration of mobilized Cr(VI) near redox-active zones (water table and …In order to reconcile these conflicting results, four black shale samples, each between 10 and 20 cm long, were collected over a depth range of 98.3–141.25 m in ABDP core #3 (Hardey Formation) and five samples of black shale, each between 10 and 15 cm long, were collected over a range of depth of 85.2–267.81 m in ABDP core #6 (Table 1). 2.2Aug 1, 2021 · Two immature black shales from the Mesoproterozoic Xiamaling Formation, Xiajiagou outcrop, Zhangjiakou, Hebei Province, China, two immature black shales from the Cambrian Alum Shale Formation, Degerhamn, Öland island, Sweden, and a carboniferous low rank coal with VR o of 0.56% (sample ID ZJJ-C4) were collected for this study (Table 1). Aug 22, 2023 · Shales that are rich in organic matter (>5%) are known as black shales. Black color is given to these rocks by organic matter. Organic matter should be decomposed in normal conditions by bacteria, but high productivity, rapid deposition and burial or lack of oxygen may preserve it. Pyrite is a common sulfide USGS Numbered Series. Larger Work Title. Uranium in carbonaceous rocks. Google Analytic Metrics. Metrics page. Additional publication details. Part or all of this report is presented in Portable Document Format (PDF). For best results viewing and printing PDF documents, it is recommended that you download the documents to your computer and open ...Black shale is a dark-colored mudrock containing organic matter that may have generated hydrocarbons in the subsurface or that may yield hydrocarbons by pyrolysis. Many black shale units are enriched in metals severalfold above expected amounts in ordinary shale.Black shales were deposited in the continental margin rifts when the North China Craton underwent regional extension and break-up events during Mesoproterozoic era. The rock series, composed of clastic rocks, carbonate rocks, and minor volcanic rocks, are rich in gold, and become the source for gold mineralization.The widespread, yet under-utilized, unfossiliferous Devonian black shales may hold the key to test this hypothesis by filling temporal and spatial gaps in the global path of afforestation and ...At Dotternhausen (Fig. 5), oil shales near the base of Member II (e.g., the Koblenzer, Hainzen, and Fleins) have greater values of ε 205 Tl than the black shales (i.e., the Tafelfleins and Seegrasschiefer) of Member I, which suggests the global expansion of oxygen-minimum zones and anoxic water masses in the marine realm (Them et al., 2018).Dec 31, 2020 ... Composition, stratigraphic and structural position of Jurassic-Lower Cretaceous radiolarian-rich siliceous rocks and black shales are ...
Smithsonian National Museum of Natural History Washington, DC, United States. Details. Title: Black shale; Location Created: Locality Key: Triassic ...Black shale. This page is currently not sponsored. Click here to sponsor this page. A shale with at least 1% carbonaceous material indicating a reducing environment. 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 ...Identification of black shale-hosted critical element deposits in the U.S. (initial focus on the Heath Formation metalliferous oil shales in Montana); and; Evaluation of processes that form metal-enriched black shale deposits. Return to Mineral Resources Program | Geology, Geophysics, and Geochemistry Science CenterMar 18, 2022 ... The black color is possibly introduced in these shales because of organic matter incorporated in the sediments. Hence, these shales tentatively ...
Metallic minerals in black shale. In order to analyze the types of metallic minerals present in the lower Cambrian black shale, minerals from samples in the Xa1 and Xb1 wells have been preliminarily identified. The main sulfur-bearing mineral is pyrite that forms clumps and bands (Fig. 3).The black shale or coal shale is included in the Guryongsan Formation in the Dukpyungri and Iwonri areas (Lee et al., 1980). METHODS Sampling of rocks and soils was carried out in the 11 study areas. Most rock samples were taken from available outcrops of black shales and slates in the Guryongsan and Changri Formations, and a number of ...…
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Black shales, which are rich in organic matter, are important for the natural fuel-resource economy of the world. Most shales contain 1 % or more organic carbon; 2-10 % is a common range. A few shales contain more than 20 % organic carbon [1]. Source rock potential of the oil-producing rocks of marineJun 16, 2004 · Black shales occur in a pivotal part of the classic Kansas cyclothem originally described by Moore (1936) and designated the core shale by Heckel (1977).The terminology differentiates this shale from other shales in the cyclothem, particularly the thicker nonmarine shales that separate the marine bundles of units that compose the majority of the cyclothems.
The HI values in most Kroh black shale samples are below 1 mg HC/g TOC (see Table S1). This result implies that the OM in the Kroh black shale samples can be categorized as predominantly a weak version of Type III kerogen (see Fig. 8), representing terrestrial and derived from the lignin of vascular plants (Vandenbroucke and Largeau, 2007).In black shales of the Touirist Formation diahopane/hopane ratios conspicuously increase with core depth (Table 3); however, maturity can be excluded as a major control of the observed distribution, since all samples exhibit similar R c values (∼0.5-0.6; Table 4).
Because black shales of this formation represent an important sourc The 250-300-m-thick Carajás Formation in the Carajás mineral province, northern Brazil, consists of banded iron formation (including giant high-grade iron-ore deposits) and minor black shale, overlying a thick pile (2-3 km) of about 2.75-Ga-old metabasalt.Carbonaceous shale with pyrite- and locally pyrrhotite-rich patches from drillcore of the Serra Sul exploration project has up to 29 ... Black shale and coal Clarke values are the average trace elementStanford University. High-pressure methane sorption isotherms wer Jun 22, 2022 · China’s most successful horizon for shale-gas exploration and development is the Upper Ordovician Wufeng Formation through the Lower Silurian Longmaxi Formation in its Upper Yangtze Region. In this study, the Wufeng–Longmaxi Formation black shales in the Upper Yangtze Region are analysed to determine their microstructural characteristics, total organic carbon (TOC) content, and well log ... 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 ... The black shale mineral composition is ma The organic-rich black shale in the Yangtze area is mainly developed in the Upper Ordovician Wufeng Formation (O 3 w) and the Lower Silurian Longmaxi Formation (S 1 l) (Chen et al., 2004, 2015b; Fan et al., 2011) (Fig. 1 C). The sediments of the O 3 w are dominated by organic-rich black shale with a thickness of generally less than 10 m (Fig. 1, Fig. 2), which is easily distinguished from the ...Black shale is a dark-colored sedimentary rock that is widely deposited around the world. Ore is substantially enriched in organic matter. Depending on the level of the thermal maturity, black ores are divided to oil shale, bituminous shale, sapropel. As sources of petroleum and natural gas given ores are exploited worldwide. Quite often black ... Sequences of black shales, present in the subducting sediment The black shale in the Lower Cambrian Niutitang FoSeveral outcrops of black shales from the Triassic We suggest that deposition of black shales represented a major sink for atmospheric carbon. Sequence stratigraphy reveals that widespread black shale deposition occurred in transgressions, whereas regressions are characterized by deposition of bioturbated facies, allowing changes in lithofacies and deep-water redox conditions to be related to ...The amount of organic carbon in the Devonian shale sequence rantes from less than 0.5% to nearly 20%. The average organic carbon content for the black shales having a color value of N 1-N 3 is about 4% by weight. Those shales lighter in color than N 3 have an average of about 0.8% organic carbon. The lower part is organic-rich black shale, comp Fragments below exposure of fissile Marcellus black shale at Marcellus, N.Y. The Marcellus consists predominantly of black shale and a few limestone beds and concentrations of iron pyrite (Fe S 2) and siderite (FeCO 3). Like most shales, it tends to split easily along the bedding plane, a property known as fissility.The black shale mineral composition is mainly composed of calcite, apatite, quartz, pyrite and clay minerals. The average values of Cu, Ni, Zn, Cr, V, As and Se and the ratios Rb/Sr and Cr/Ni in ... Geochemical and petrographic analysis of an interval of b[Black shales are widespread at the Precambrian/CaBlack shale is commonly deposited in anoxic env When black shales are weighted by preserved thickness, a time series (Isley and Abbott, 1999) shows three peaks in the Paleoproterozoic (i.e. ∼2.0, 1.85, and 1.7 Ga), with small peaks at 600 Ma and 1.45 Ga, ̄ and a maximum near the Archean/Proterozoic boundary between 2.7 and 2.5 Ga (Fig. 2).Plotted as a time series weighted by errors in ages and by the ratio of black shale to total shale ...