Geochemistry of the alginite and amorphous organic matter from type II-S kerogens

Organic Geochemistry
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Abstract

Maceral fractions of the Type II-S kerogens from the Monterey Formation (Miocene. California. U.S.A.) and Duwi Formation (Campanian/Maastrichtian, Egypt) were separated by density gradient centrifugation. The Monterey Fm. kerogen sample was comprised chiefly of light red-fluorescing amorphous organic matter (AOM), the flash pyrolyzate of which was characterized by a predominance of alkylbenzenes, alkylthiophenes and alkylpyrroles. In contrast, the pyrolyzates of its alginite concentrate showed a highly aliphatic character, typical of this maceral, with the series of n-alkenes and n-alkanes (C6- C26) predominating. The pyrolyzate of the dominant light brown-fluorescing AOM of the Duwi Fm. kerogen had a relatively high concentration of alkylbenzenes and alkylthiophenes, while its elginite concentrate showed a more aliphatic character upon pyrolysis. There was a marked enrichment of thiophenic sulfur in the light-colored AOM of both samples (and also pyrrolic nitrogen in the case of the Monterey) relative to the alginite. The results support a bacterially-mediated, degradative origin for Type II-S amorphous organic matter, with algal remains as the primary source of the kerogen.
Publication type Article
Publication Subtype Journal Article
Title Geochemistry of the alginite and amorphous organic matter from type II-S kerogens
Series title Organic Geochemistry
DOI 10.1016/0146-6380(96)00048-4
Volume 24
Issue 5
Year Published 1996
Language English
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Organic Geochemistry
First page 495
Last page 509
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