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Geochemistry of the Alginite and Amorphous Organic Matter from Type II-S Kerogens
Department of Earth and Environmental Studies Faculty Scholarship and Creative Works
  • B. Artur Stankiewicz, Southern Illinois University
  • Michael Kruge, Montclair State University
  • Maria Mastalerz, University of Bristol
  • Gary L. Salmon, Indiana University Bloomington
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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.

Citation Information
B. Artur Stankiewicz, Michael Kruge, Maria Mastalerz and Gary L. Salmon. "Geochemistry of the Alginite and Amorphous Organic Matter from Type II-S Kerogens" (1996)
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