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. Some black shale units have served as host rocks for syngenetic metal deposits.Black …

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, …

The presence of thick (∼. 200 m) carbonaceous shales of Cretaceous age in the deep waters of the eastern Equatorial Atlantic was first revealed by drilling at DSDP sites 367 and 368 near the Cape Verde Islands.. More recent seismic investigations show that black shales are widely distributed in this region. In the Gambia Basin they are …

Black shales host a discontinuous sulphide- and phosphate-rich stratiform body ranging from less than 1-cm to 2-m in thickness, that can be traced over the entire 1600 km paleocoastline of the Yangtze craton. ... (0.906 to 0.941) indicate marginally reducing conditions of sedimentation of barren and mineralized black shales. …

Platinum group elements (PGEs) occur mainly in basic–ultrabasic igneous rocks and are concentrated by the differentiation and crystallization of magma. Thin polymetallic layers including Ni, Mo, V, PGEs, and rare-earth elements are widely developed in lower Cambrian black shales in southern China. The PGE contents in such layers …

The mid-Tournaisian Event, also called the Lower Alum Shale Event (LASE), was a global anoxic event that occurred ca. 355 Ma ago. This event is connected to drastic facies changes from pelagic carbonate sedimentation to widespread black organic-rich siliceous shales and radiolarites in many parts of the world.

Depositional processes involve a range of relationships among such factors as organic productivity, clastic sedimentation rate, and the intensity of oxidation by which organic …

The high sedimentation rate of the Stoer Group, ... The black shales have a wide range of Mo contents, with maximum and mean contents of 232 p.p.m. (Figs 1 and 2) ...

Depending on depositional environment, shales may contain sufficient quantities of organic matter to be classified as black shales (Arthur and Sageman, 1994, Tourtelot, ... lithologic composition, sedimentation rate, duration of anoxia, redox conditions, and degree of thermal maturation of the shales (Lüning and Kolonic, 2003).

velopment of sedimentary environments where black shales may be deposited. The nature of the black shales that are deposited, i.e. lithology and type of …

Three main styles of sedimentation occurred within these formations: (1) laminates in a dominantly carbonate rock with thin recurrent interlayers of black shales; (2) alternating layers of marls and limestones, both containing interlayers of black shales and with occasional laminations in the limestones; and (3)more »

The Cenomanian–Turonian Oceanic Anoxic Event (OAE-2) is generally identified in basinal and restricted environments appropriate for the deposition of black shales, commonly used as the main criteria of this global event. Despite, it would not always be easy to identify with certitude this event in shallower and more open depositional …

The lacustrine black shales in the Chang7 Member from the Upper Triassic Yanchang Formation of the Ordos Basin in Central China are considered one of the most important hydrocarbon source rocks. However, the mechanism of organic accumulation in the black shales remains controversial. To resolve the controversy, with the former …

Black shale, the subject of this article, is a dark-colored muddy sedimentary rock that is substantially enriched in organic matter. Depending on the grade of thermal …

Black shales provides the first comprehensive synthesis of the diverse research regarding the origin of petroleum source rocks. The book offers in-depth reviews from the fields sedimentology, palaeoecology, and geochemistry, and particularly focuses on the influence of palaeo-oxygen levels. Current debates--including the one over the influence of …

Black shales often are metalliferous and may host or are associated with economically important ore deposits, ... Another indication for low sedimentation rates in the deep ocean basins is the presence of a layer extremely enriched in Mn at greater paleodepths off the NW Australian margin (ODP Site 766; Thurow et al., 1992), ...

Sedimentological evidence suggests that the Tethyan black shales generally contain little terrigenous admixture. 2) Furthermore, the Bonarelli black shale was deposited in a pelagic setting with an estimated mean sedimentation rate of as low as 1 to 3 mm kyr −1, suggesting only a minor contribution of allochthonous material. 51,62) The ...

The black shale depositional processes most commonly involved are pelagic settling, hemipelagic sedimentation and turbidity currents. Debris flows and slides are also noted in some cases, and hyperpycnal flood events seem likely to have influenced others.

Four black shale samples have TOC contents between 7.9% and 11.4% (Fig. 2b), while those of the other 19 black shales from well YK1 exceed 12%. The TOC contents of the studied black shale samples range between 12.1% and 29.9%, with an average of 18.2% (Table 1). In spite of the fact that the TOC is an important criterion for source. …

The Alum Shale Formation is a metal-rich black shale, deposited on the Baltoscandian platform between Middle Cambrian and Early Ordovician. These black shales may be of particular economic interest for their relatively high uranium content (100–300 ppm) and their wide distribution from Norway to Estonia.Scandinavian Alum …

The limestone sedimentation is interrupted by a 10- to 20-cm-thick black shale interval interpreted as equivalent of the Hangenberg Black Shales (Perri and Spalletta 2000). The irregular shape of the black shale level was …

The stratum is composed of mudstones, carbonaceous shales, oil shales, siltstones, fine sandstones and volcanic tuff intervals, with the Zhangjiatan oil shales distributed in the Chang 7–3 interval and characterized by high gamma-ray (GR) and low density (DEN) logging signatures (Fig. 1 b). 3. Samples and analytical methods

The laminated black shales which constitute most of the black-shale sequence are broken by two major sequences of interbedded greenish-gray, clayey shales which contain bioturbation and pyritized micromorph invertebrates. ... clastic, evaporite, and organic-rich sedimentation, fluctuating sea-level and bottom water oxygenated, and oceanic ...

It was shown that the contents of Ni, Mo, and Co in the siliceous clay black shale rocks of the normal sections of the Bazhenov Formation are several times higher than the global mean contents of these elements in black shales. These rocks have the highest contents of pyrite and organic carbon and show evidence for strongly reducing formation …

The main factors that control metal enrichment in black shales are sedimentation rate, OM type and content, metal source and depositional environment (Leventhal 1991; Orberger et al. 2003a, b). Relatively deeper depositional environments can favour a stagnant euxinic layer for OM depositions which is further enhanced by low …

The Olentangy Shale consists of gray shales, with minor lenses or thin layers of limestones in the lower part of the unit, and interbedded thin black shales in the upper part of the unit (Stauffer, 1938).Thin black shales at the upper contact have sharp basal contacts and diffuse upper contacts due to bioturbation originating in the overlying …

Phanerozoic black shales. Black shales may be deposited during most stages of the Wilson Cycle, but the depositional environment and partly also the type of black shale (Fig. 2) depend, for each basin, on the Wilson Cycle stage. Simi-larly, black shales were deposited throughout the Phanero-zoic, but periods of relatively widespread …

ITCZ controls on Late Cretaceous black shale sedimentation in the tropical Atlantic Ocean - Hofmann - 2011 - Paleoceanography - Wiley Online Library Paleoceanography Regular …

Black shales and massive sulfides represent reduced lithofacies that require isolation from oxic environments to be preserved. ... and Draa Sfar were in the range 7–13, 8–14, and 19–27 cm/ka, respectively. Continuous sedimentation of black shale favored the isolation of the massive sulfides and organic material from bottom waters and ...

The presence of lamination on sedimentary rocks is a distinct characteristic, particularly in shales. They are distinct due to the contrast between successive layers with regard to grain size, composition, color, and sedimentary structures, such as graded beds. Typically, the degree of lamination is controlled by the sedimentation rate and flow …