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Publication . Article . 1987

Petrology of the Desmoinesian Excello Black Shale of the Midcontinent Region of the United States

Omer Isik Ece;
Published: 01 Jan 1987 Journal: Clays and Clay Minerals, volume 35, pages 262-270 (issn: 0009-8604, Copyright policy )
Publisher: Springer Science and Business Media LLC
The Excello Shale is one of the best exposed and most laterally continuous of the Pennsylvanian cyclothemic black shales in the midcontinent region of the United States. Its petrology and paleoenvi-ronmental significance were studied to understand the nature of cyclic black shales in general and how they relate to the habitat of hydrocarbon source beds. The Excello is thinly laminated, fissile where weathered, and rich in organic matter and phosphate nodules; it is 90–120 cm thick. Its thin laminations, fine particle size, and high total organic carbon (TOC) content suggest that it was deposited in a quiet water environment of an epeiric sea having anaerobic bottom water. The Excello Shale consists of two lithofacies: non-bioturbated black shale and bioturbated yellow-brown shale. Petrographic studies show that the black shale contains wavy to straight laminations and that the yellow-brown shale contains discontinuous and random laminae and mottled stratification. The close association of organic matter and phosphate-controlled nodule morphology (spherical, elongated, bladed, and platy) appear to be related to progressive decreases in nutrient supply of the sea water from the ancient ocean (Panthalassa).
Subjects by Vocabulary

Microsoft Academic Graph classification: Total organic carbon Organic matter chemistry.chemical_classification chemistry Petrology Oil shale Stratification (water) Geology Petrography Pennsylvanian Bottom water Water environment


Earth and Planetary Sciences (miscellaneous), Geochemistry and Petrology, Soil Science, Water Science and Technology

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Article . 1987
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