Black shale sequence

Peter Zubovic. The coal is overlain by a black shale sequence which, in places, contains abundant pyritized marine fossils. Above the black shale there generally is a gray shale sequence. The thickness of the two units varies from place to place. The total thickness ranges from about 3-50 feet. I do not know the mineralogy of the shale. I suspect that there is a relation between the total thickness of the shale and the vanadium content of the coal. Parts of this area are being mapped at present, and in the near future we expect to have the data necessary to show if this suggested relation is valid. 

The chemical behavior of various minor and trace elements is relatively well characterized for particular redox conditions, and there has been significant effort directed at the development of geochemical proxies for paleo-oxygenation in black shale sequences (see reviews in Calvert and Pedersen, 1993 Arthur and Sageman, 1994 Jones and Manning, 1994 Wignall, 1994 Schieber et u/., 1998a,b). Elements... 

The schematic black shale sequence also can be applied to the upper New Albany Shale of the Illinois Basin, where a facies relationship of the green-gray Hannibal/Saverton Shales with the Grassy Creek has been described by Lineback (26) ... 

Figure 7. Hypothetical black shale sequence. (Reproduced with permission from Ref 14. Copyright 1982, Institute of Gas Technology.)...

A westward or northwestward source for the Ellsworth/upper Antrim, Hannibal-Saverton/upper Grassy Creek, and lower Coldwater/ upper Sunbury is appropriate for the overall geometry of those "upper shale" bodies. It is clear that in the Appalachian Basin great volumes of clastic material came from the east and that some of the black shales in that basin are true distal facies of great influxes of clastic material from the east. Nevertheless, because the authors believe that the hypothetical black shale sequence also applies east of the Cincinnati/Algonquin Arches (in mirror image), some of the black shales in the basin may prove to be more regional in nature and of the "lower shale" (A) type. 

Ettensohn, F. R. and Barron, L. S., Depositional Model for the Devonian-Mississippian Black Shale Sequence of North America A Tectonic-Climatic Approach, in Blackburn, W. H., Compiler, "Black Shale Studies in Kentucky," Final Report, Univ. of Kentucky Research Group (Department of Geology and Kentucky Geological Survey), Lexington, 1980. 

In each of the three areas described above, the black-shale sequence differs in overall aspect from each of the other areas when viewed in outcrops. This difference has led to three sets of stratigraphic nomenclature having been applied to the black Devonian-Mississippian shales. The general distribution of the usages of stratigraphic nomenclature are shown in Figure 2. 

Metalliferous sediments are a common component of modern ocean-floor sedimentary sequences, recording halos of metal dispersion from seafloor hydro-thermal vent systems (Gurvich, 2006). Sulfidic black shales are also commonly present as intercalations in ancient subaqueous volcanic sequences, where each likely represents a significant hiatus in volcanic activity and deposition. These shale horizons form geophysical anomalies (conductors) that are routinely drilled during exploration for volcanogenic massive sulfide (VMS) base metal deposits. 

The mineralized district is restricted by two main strike-slip faults of Kubanan to the east and Posht e Bdam to the west (Fig. la). The host rocks are a thick sequence of Upper Precambrian-Cambrian rhyolite, tuff, alkali granite, syenite, mafic dykes, magnetitite, dolomite, gypsum, limestone, black shale, and sandstone. The Upper Percambrian-Cambrian sequence is overlain unconformably by Mesozoic and... 

Offshore neritic formations in the Paleozoic rock sequence probably include, on faunal and lithologic grounds, the Lower Ordovician Beekmantown dolomites, Middle Ordovician limestones, and Devonian Marcellus and Burket black shales (Table III). The first two are characterized by 0.1-0.4% organic carbons, very low organic nitrogen, and about 20 p.p.m. hydrocarbons but no carbohydrate residues. The Devonian offshore neritic black shales by contrast... 

Thiophene hopanoids. Two C35 thiophene hopanoids are present in the A3 fraction of the bitumens. One of these isomers (XXVI, Figure 19) has been previously identified by Valisolalao et al (7) in black shales. The other isomer (XXVII, Figure 19) has been tentatively identified by Sinninghe Damste et al (6). Because of the lack of a suitable standard for this fraction it was impossible to quantify these compounds as precisely as the previously discussed alkylthiophenes. However, the relative abundance of these hopanoid thiophenes (see experimental section) varies considerably throughout the sequence (Figure 19a). 

Wignall P. B. and Maynard J. R. (1993) The sequence stratigraphy of transgressive black shales. In Source Rocks in a Sequence Stratigraphic Framework, AAPG Studies in Geology 37. American Association of petroleum Geologists, Tulsa, OK, p.35. 

Uranium is low in the list of element abundance, comprising only 0.0027% of the earth s crust (Levinson, 1974). Apart from ore deposits, uranium is most abundant in high silica igneous rocks and in shales, especidly black shales. Reported contents for some common rocks and waters are listed in Table 8.1. Uranium ores are referred to on p. 497ff here it need only be mentioned that most known ore bodies occur within sedimentary rock sequences. 

The H-15D core penetrates the Michigan Formation, Marshall Sandstone, and Coldwater Shale (Fig. 2). The Marshall portion of the core includes a section of medium-coarse sand near its top (23.8 to 35.7 m depth), and a larger section below of interbedded sandstone, siltstone, and shale, including minor sections of black shale. The LP-1 core contains a thicker sand-dominated sequence of Marshall Sandstone (43.3 to KB.6 m depth), and below that, in the lower portion of the core, consists of interbedded sand, silt and clays, that includes the contact with Coldwater Shale (Fig. 2). The cores... 

Wenger, L.M. and Baker, D.R., 1986. Variations in organic geochemistry of anoxic-oxic black shale-carbonate sequences in the Pennsylvanian of the Midcontinent, U.S.A. Org. Geochem., 10 85-92. 

The Beacon rcx ks on Mt. Blackburn, legated close to the confluence of the Van Reeth Glacier with the Scott Glacier north of the LaGorce Mountains, occur at three sites labeled A, B, and C by Doumani and Minshew (1965). At Icxrdity C a sequence of sandstone, conglomerate, and black shale is capped by a layer of massive till about 15 m thick. This till... 

Phosphorites that are richest and thickest and contain the most uranium are the miogeosynclinal type deposited on the outer parts of continental shelves where upwelling of deep marine waters has occurred. These waters were saturated with respect to phosphate and were probably the source of the phosphate in the phosphorites. These phosphorites are commonly present in thick miogeosynclinal sequences, where they are associated with carbonates, black shale, chert, carbonaceous mudstone and minor amounts of mudstone. " The Phosphoria Formation of the western U.S.A. is an example. 

The geology in the project area mostly comprises black to dark grey shale inter-bedded with sandstone and conglomerate of the Cretaceous Saniri Formation (Kim and Hwang 1986). This sedimentary sequence has been intruded by thin to very thick, near-vertical dykes and sills of quartz porphyry. The slope section under consideration is shown in Figure 1(a). 

---