Occurrence of (20R)- and (20S)-. Delta. sup 8(14) and. Delta. sup 14 5. alpha. (H)-sterenes and the origin of 5. alpha. (H),14. beta. (H),17. beta. (H)-steranes in an immature sediment

Journal Article · Tue Aug 01 00:00:00 EDT 1989 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(89)90320-7· OSTI ID:7273139

Peakman, T M ^[1]; Ten Haven, H L; De Leeuw, J W ^[2]; Rechka, J R; Maxwell, J R ^[3]

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1. Univ. of Bristol (England) Delft Univ. of Technology (Netherlands)
2. Delft Univ. of Technology (Netherlands) Institute of Petroleum and Organic Geochemistry, Julich (West Germany)
3. Univ. of Bristol (England)

Series of (20R)- and (20S)-{Delta}{sup 8(14)} and {Delta}{sup 14} 5{alpha}(H)-sterenes have been identified in an immature marl from a hypersaline deposit (northern Apennines, Italy) by co-injection studies with authentic compounds. These alkenes co-occur with {Delta}{sup 13(17)} 5{alpha}(H)-spirosterenes and transient (20R)- and (20S)-{Delta}{sup 14} 5{alpha}(H),17{beta}(H)-sterenes. The source of these isomeric steroid alkenes is probably {Delta}{sup 7} (and {Delta}{sup 8(14)}) 5{alpha}(H)-sterols via ({Delta}{sup 2,7}), {Delta}{sup 2,14} 5{alpha}(H)-steradienes. Reduction processes in the sediment, via the {Delta}{sup 14} 5{alpha}(H),17{beta}(H)-sterenes, can give rise to the C-20 isomeric 5{alpha}(H),14{beta}(H),17{beta}(H)-steranes present in anomalously high relative abundances from a thermal maturity viewpoint. This diagenetic pathway is supported by laboratory rearrangement/hydrogenation experiments of 5{alpha}(H)-cholest-7-ene and from considerations of carbon number distributions of various steroid hydrocarbons in the sediment extract.

• OSTI ID: 7273139
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Vol. 53:8; ISSN 0016-7037
• Country of Publication: United States
• Language: English

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