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Controls on porphyrin concentrations of Pennsylvanian organic-rich shales, Western U.S.A.

Energy & Fuels

By:
and

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Abstract

Organic-rich black shales of Middle Pennsylvanian (Desmoinesian) age occur over much of the central U.S. and as far west as the northern Denver and southeastern Powder River basins. Total organic carbon contents (Corg) are commonly greater than 10 wt %. Porphyrin concentrations (vanadyl + nickel) are as high as 40000 ppm relative to extractable bitumen. In bulk, the organic matter contained in the shales is mostly type II and III (Rock-Eval hydrogen indexes 200-400 mg of hydrocarbons/g of Corg). The finding of high porphyrin concentrations in type III organic matter is unusual but can be explained by a depositional model wherein high preservation of primary organic production (water column photosynthesis) is combined with substantial input of allochthonous organic matter. The allochthonous organic matter (low porphyrin concentration) may come from erosion during advance of the sea across the area or from fluvial transport from shore.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Controls on porphyrin concentrations of Pennsylvanian organic-rich shales, Western U.S.A.
Series title:
Energy & Fuels
Volume
4
Issue:
6
Year Published:
1990
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Energy & Fuels
First page:
644
Last page:
646
Number of Pages:
3