Black shales.

Depositional and diagenetic processes play important roles in controlling the fabric and petrophysical properties of black shales.In this study, an outcrop section of the Wufeng-Longmaxi Shale was studied through sedimentologic facies analysis, petrographic observations (both transmitted- and reflected-light microscopy and scanning electron microscopy), and X-ray diffraction analysis to ...Black shales are of great ecological significance due to the high concentration of heavy metals that are released during weathering. Heavy metals constitute one of the most insidious and dangerous pollutions known to humans (Akpan and others 2002) because they are toxic (e.g. carcinogenic), non-biodegradable, and may enter the global ecobiological cycle (Nurnberg 1984; Lakhan and others 2002).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 ...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 explain their common concurrence in the geologic record. The present study is based on the comparison of Rammelsberg in Germany, Tharsis in …

Molybdenum, Bi, and Te are commonly enriched along with Au, As, and Sb in organic matter and in diagenetic pyrite in black shales (e.g., Large et al. 2007Large et al. , 2011 Gregory et al. 2015 ...The black shales from the Maldeota and Durmala mines, collected a few meters above the Krol-Tal (Pc-C) boundary and occurring in the same stratigraphic horizon, yield 187Re-187Os isochron ages ...Black shale is widely distributed on the northern Yangtze platform, where advanced weathering is present due to the favourable exposure and a humid climate (Ling et al., 2015, 2016). To understand elemental behaviors within the context of catchment-scale weathering, examining vertical weathering profiles is an important approach. ...

Cd in paddy soil was primarily from geogenic source and effected little by anthropogenic source. The concentration as well as mobility and bioavailability of Cd were high in paddy soil in black shales area, which lead to elevated Cd concentration in roots, shoots and grains of rice. As a result, residents in black shales area suffer increased ...

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.Depositional and diagenetic processes play important roles in controlling the fabric and petrophysical properties of black shales.In this study, an outcrop section of the Wufeng-Longmaxi Shale was studied through sedimentologic facies analysis, petrographic observations (both transmitted- and reflected-light microscopy and scanning electron microscopy), and X-ray diffraction analysis to ...Shale, a brownish black to black hard fissile bituminous shale about 350 feet thick. In certain zones, numerous anthraconite concretions occur ranging in size up to three or more feet in diameter. Smaller marcasite concretions from the size of walnuts to a foot across are also present but in less abundance.Black Shale Standard. Equivalent expectations of the gamma-ray log response of black shales can be predicted from core or outcrop samples that have analyses of thorium, uranium, and potassium contents. So, for example, the Marine Sciences Group Black Shale Composite (BSC) described by Quinby-Hunt et al. (1989) is characterized by values of

For black-shale records deposited under locally constant euxinic conditions at non-restricted settings, however, we suggest a ∆ 238 U shale-seawater value of 0.6 ± 0.1 ‰, based on average δ 238 U signatures from the Livello Bonarelli black shales and those in the concomitantly deposited pelagic chalks from Eastbourne, UK. 5. Conclusions

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 ...

A suite of black shales interbedded with thin-bedded cherts occurs at the basal Cambrian in the Northern Tarim Basin (Fig. 2), which is called black rock series in Chinese literature (Li and Gao, 1996a, Li and Gao, 1996b, Li and Gao, 2000).The two studied sections are located at Xiaoerbulake, approximately 60 km away from the Akesu City, and at Sugaitebulake, approximately 50 km away from ...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).Chemical and isotopic signatures for black shales serve as potential proxies for reconstruction of paleoenvironmental conditions. Here we bring Rock‐Eval, major and trace element and Re‐Os isotopic data together to examine the environmental record at the Cambrian‐Ordovician Global Stratotype Section and Point (GSSP) at Green Point in …Mesozoic oceanic anoxic events are determined based on the presence of black shales that are rich in organic carbon. These black shales contain huge amounts of carbon sufficient to source the majority of the petroleum and natural gas (Schlanger & Cita, 1982).Multiple periods of widespread anoxic conditions (Fig. 2) have been recorded in the Mesozoic Era (Schlanger & Jenkyns, 1976).Definition Most modern and ancient aquatic (marine, brackish, and lacustrine) environments were sufficiently oxygenated to permit colonization by numerous benthic, planktic, and …The late Neoproterozoic Lečice black shales and an overlying siliciclastic succession, Bohemian Massif, were deposited in a marine environment on a volcanic arc and provide insights into palaeoenvironmental conditions at the former active margin of northern Gondwana.Field relationships integrated with major/trace element and Mo-Cr-S isotope systematics in two different sections ...

Black shales are widespread at the Precambrian/Cambrian transition and document a global ocean anoxic event, which is part of major environmental and biological changes, such as plate tectonic reconfiguration, mass extinction, and accelerated diversification of metazoans (Kimura and Watanabe, 2001, Steiner et al., 2001).The …Permian black shales from the lower Ecca Group of the southern main Karoo Basin (MKB) have a total organic carbon (TOC) of up to ~5 wt% and have been considered primary targets for a potential ...The Xiaotan section, situated on the southwestern Yangtze Platform, South China, contains an unusually expanded sedimentary record, spanning the upper Neoproterozoic to the Cambrian and representing more than 40 My of marine sedimentation.Three distinct black shale units of the Shiyantou and Yuanshan formations were analysed for redox-sensitive trace elements and iron speciation, in order to ...Pb–Pb dating of black shales and the sulfide ore bed from the Niutitang Formation yielded ages of 531 ± 24 Myr and 521 ± 54 Myr, respectively (Jiang et al., 2006). Jiang et al. (2009) reported a U–Pb zircon age of 532.3 ± 0.7 Myr for an ash bed a few meters below the polymetallic Ni–Mo–PGE ore layer in the Zhongnancun section ...Several outcrops of black shales from the Triassic turbidite sequences of the Semanggol and Semantan formations have been described and logged (Table 1 & Fig. 3). Black shales in the Semanggol Formation occur as thin-to medium-bedded, finely-laminated dark grey to grey shales up to 15 m thick (Fig. 4 A-D). On the other hand, black shales of ...Some shales are rich in unoxidized carbon. These are known as black shales, and some of them may also contain heavy metals like uranium, vanadium, zinc, …

Black shale is commonly deposited in anoxic environments and hosts abundant organic matter, sulfides, and a variety of hazardous elements (Mao et al. 2002;Lehmann et al. 2007), resulting in its ...

Time equivalent black shales are suggested to be coeval with black shales found in the Western Tethys and Atlantic Ocean (Herrle et al., 2004). Calcareous nannofossil analyses and carbon isotopes indicate higher surface water productivity (mesotrophic), warmer surface water, and higher sea-level during the formation of the NN4 black shales.Chemical and isotopic signatures for black shales serve as potential proxies for reconstruction of paleoenvironmental conditions. Here we bring Rock‐Eval, major and trace element and Re‐Os isotopic data together to examine the environmental record at the Cambrian‐Ordovician Global Stratotype Section and Point (GSSP) at Green Point in western Newfoundland, Canada. The Green Point shales ...The enrichments in Te, Mo and Co in the black shale bear comparison with the enrichments found in the ferromanganese seafloor deposits, although the black shales have less extreme enrichments. Ferromanganese crusts and black shales represent oxidising and reducing depositional conditions respectively, with alternate mechanisms enriching the ...Dec 1, 2021 · An indicative classification of black shales can be compiled based on the literature that refers to the degree of commodity metal accumulation (Table 1).Vine and Tourtelot (1970) set the threshold of metalliferous black shales’ (MBS) definition above the 90th percentile of a metal concentration in given dataset, whereas the final classification depends on the frequency (percentage) of ... 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 ...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 ... A shale is a sedimentary rock that is composed of small (mostly less than 0.1 mm) particles dominated by phyllosilicate (clay) minerals and containing subordinate amounts of …The black shales in this part of the Appalachian Basin are relatively immature (R o ∼0.5%) Rimmer et al., 1993, Curtis and Faure, 1997. There is little reason for concern about interpretation problems associated with the loss of carbon that accompanies thermal maturity (as discussed by Raiswell and Berner, 1987), thus S/C ratios may be …Black shales deposited in transitional environments such as tidal and deltaic environments have high terrigenous OM input. The pore structure characteristics of bulk OM in these transitional shales should have intermediate values between oil-prone OM (Fig. 19) in shales and terrigenous OM in coals at a specific maturity. Therefore, the ...

Lacustrine black shales are widely developed within the Late Cretaceous Nenjiang Formation (k 2 n) of the Songliao Basin. These black shales provide an ideal natural laboratory for reconstructing the paleoclimate and paleoenvironment during the Late Cretaceous in Northeast China and have great significance in the exploration for potential oil and gas resources.

The Carboniferous (Namurian) Clare Shale Formation (Shannon Group) consists of finely laminated, pyritic, deep marine black shales, deposited 326.5-318.5 Ma (Menning et al., 2006; Wignall and Best, 2000).The black shale sequence is up to 180 m thick at surface, (Tanner et al., 2011), with a maximum observed thickness of 280 m in the 'Doonbeg No 1' drill hole, Co Clare (Goodhue and ...

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 ...We target the Alum Shale in Sweden, which represents a relatively continuous sedimentary succession of black shales deposited across this time interval. These organic-rich shales allow us to apply proxies that more directly characterize both local and global redox conditions in the later Cambrian ocean: iron speciation, trace metal abundances ...Black shales may serve as an important source of metals such as Co, Ni, or As, largely due to anoxic to euxinic conditions in association with high concentrations of sulfur leading to efficient scavenging and transport of metals from seawater into the seafloor sediment. We report on an unusual type of Au mineralization newly discovered in …The Taiyuan formation, which consists of black shale, coal, limestone and sandstone, was deposited in this environment during the early Permian, with a thickness ranging from 30 to 175 m. Second, the collision between the North China plate and the Siberia plate caused large-scale tectonic movement and a marine regression from north to south.Jun 1, 2023 · The Global Geochemical Database for Critical Metals in Black Shales (CMIBS) contains new geochemical data compilations for fine-grained sedimentary rocks in which each geologic material sample has one best value determination for each analyzed species, greatly improving speed and efficiency of use (Granitto and others, 2013). The black shales developed in the Chang 7 Member of the Yanchang Formation in the Ordos Basin are considered the most important hydrocarbon source rocks in Central China. The shales are deposited by frequent volcanic activities and preserved by extremely rich volcanic ash layers, making them an excellent example when investigating the influence ...Black shale is commonly deposited in anoxic environments and hosts abundant organic matter, sulfides, and a variety of hazardous elements (Mao et al. 2002;Lehmann et al. 2007), resulting in its ...'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 ...Colour: Black, Grey Group: Clastic Sedimentary Rock Texture: Clastic; Very fine-grained (< 0.004 mm) Silty shale . Clay shale . Sandy shale Mineralogical …

Black Shale Standard. Equivalent expectations of the gamma-ray log response of black shales can be predicted from core or outcrop samples that have analyses of thorium, uranium, and potassium contents. So, for example, the Marine Sciences Group Black Shale Composite (BSC) described by Quinby-Hunt et al. (1989) is characterized by values ofThe Datangpo Formation can be sub-divided into four lithostratigraphic members from bottom to top (Fig. 2): (1) Member I is a succession of black manganiferous shale and Mn carbonates (Mn contents distinguish manganiferous shales with Mn < 10 % from Mn carbonates with Mn > 10 %); (2) Member II is composed mainly of black carbonaceous shale; (3 ...shale definition: 1. a type of soft, grey rock, usually formed from clay that has become hard, that breaks easily…. Learn more.U.S. Department of Energy Office of Scientific and Technical Information. Search terms: Advanced search options. ...Instagram:https://instagram. great weekend gifneeds of communitysilver berry fruit20 day forecast las vegas strip The dark shales in the Dongyuemiao member can be grouped into four general categories: shore, shallow, semi-deep, and deep lacustrine shales.Stow et al. (2001) stated that black shales are fine-grained sediments or sedimentary rocks with total organic carbon (TOC) content of >1%. It has been proposed that black shale was closely related to OM-rich shale, but it was formed under dysoxic or anoxic conditions, and does not always have high TOC contents (Kemp, 1991; Wignall … ciao gifhow far is kansas from arkansas The Exshaw black shales have increasing maturity levels from east to west in the Western Canada Sedimentary Basin. Large sulfur isotope fractionations (-15‰ to 65‰) between original seawater sulfate and pyrite is best explained by microbial sulfate reduction during deposition and early diagenesis rather than thermochemical sulfate ... anderson window crank replacement Black shales of the ca. 1.73 Ga Wollogorang Formation previously yielded an erroneously young Re-Os date of 1359 ± 150 Ma, likely due to post-depositional hydrothermal alteration at ca. 1640 Ma. Higher δ 238 U is observed in samples closer to the base of the black shale unit where the greatest extent of open-system Re-Os behavior was observed.The paleodepositional environments related to Ediacaran black shales from the Série Negra succession in Ossa-Morena tectonostratigraphic zone were investigated using their geochemical composition to identify the sedimentary sources and depositional conditions. Their potential for assisting the genesis of metal deposits was also discussed. The sedimentary sources of the black shales are ...Black shale source rocks can also host oil and gas forming unconventional reservoirs. Therefore, a distinctly light Li isotopic composition of pore fluids, suggesting influx of hydrocarbon-sourced Li, may be useful in identifying productive intervals of a shale. We studied several well-known hydrocarbon source rocks to compare the Li isotopic ...