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Identification and origin of Delta sup 8(14) 5. alpha. - and. Delta. sup 14 5. alpha. -sterenes and related hydrocarbons in an immature bitumen from the Monterey Formation, California

Journal Article · · Geochimica et Cosmochimica Acta; (United States)
 [1]; ;  [2]
  1. Forschungszentrum Juelich GmbH (Germany)
  2. Delft Univ. of Technology (Netherlands)
The aliphatic hydrocarbon fraction of an immature Monterey bitumen contains a high relative abundance of C{sub 27}-C{sub 29} {Delta}{sup 4}, {Delta}{sup 5}, {Delta}{sup 8(14)} 5{alpha}- and {Delta}{sup 14} 5{alpha}-sterenes, each having a very similar carbon number distribution. This is the first report of abundant {Delta}{sup 8(14)} 5{alpha}- and {Delta}{sup 14} 5{alpha}-sterenes in an immature sediment. The {Delta}{sup 4} and {Delta}{sup 5} sterenes appear to originate directly from {Delta}{sup 5} sterols. For the Delta{sup 8(14)} 5{alpha}-sterenes the authors propose an origin from {Delta}{sup 7} 5{alpha}-sterols which may be derived from a microbial transformation of {Delta}{sup 5} sterols. The presence of 5{alpha}- and 5{beta}-steranes in an unusual ratio of ca. 55:45 suggests the formation of a high abundance of 5{beta}-stanols via the known microbial reduction pathway of {Delta}{sup 5} sterols.
OSTI ID:
5094130
Journal Information:
Geochimica et Cosmochimica Acta; (United States), Journal Name: Geochimica et Cosmochimica Acta; (United States) Vol. 56:3; ISSN GCACA; ISSN 0016-7037
Country of Publication:
United States
Language:
English