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Organic geochemistry and organic petrography

Journal Article · · U.S. Geol. Surv., Prof. Pap.; (United States)
OSTI ID:5261663

The Vermillion Creek coals and shales contain dominantly humic organic matter originating from woody plant tissues except for one shale unit above the coals, which contains hydrogen-rich kerogen that is mostly remains of filamentous algae, of likely lacustrine origin. The coals have two unusual features - very low inertinite content and high sulfur content compared to mined western coals. However, neither of these features points to the limnic setting reported for the Vermillion Creek sequence. The vitrinite reflectance of Vermillion Creek shales is markedly lower than that of the coals and is inversely proportional to the H/C ratio of the shales. Rock-Eval pyrolysis results, analyses of H, C, and N, petrographic observations, isotope composition of organic carbon, and amounts and compositions of the CHCl/sub 3/-extractable organic matter all suggest mixtures of two types of organic matter in the Vermillion Creek coals and clay shales: (1) isotopically heavy, hydrogen-deficient, terrestrial organic matter, as was found in the coals, and (2) isotopically light, hydrogen-rich organic matter similar to that found in one of the clay-shale samples. The different compositions of the Vermillion Creek coal, the unnamed Williams Fork Formation coals, and coals from the Middle Pennsylvanian Marmaton and Cherokee Groups are apparently caused by differences in original plant composition, alteration of organic matter related to different pH conditions of the peat swamps, and slightly different organic maturation levels.

OSTI ID:
5261663
Journal Information:
U.S. Geol. Surv., Prof. Pap.; (United States), Journal Name: U.S. Geol. Surv., Prof. Pap.; (United States) Vol. 75:1314-H; ISSN XGPPA
Country of Publication:
United States
Language:
English