Origin and fate of 4-methyl steroid hydrocarbons. I. Diagenesis of 4-methyl sterenes

Journal Article · Sat Mar 01 04:00:00 EST 1986 · Geochim. Cosmochim. Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(86)90187-0· OSTI ID:6987240

Wolff, G A; Lamb, N A; Maxwell, J R

Treatment of 4-methylcholest-4-ene under mild acid conditions at low temperatures gives chemical evidence for certain features seen in the distributions of sedimentary 4-methyl steroid hydrocarbons, and further indicates that many low temperature diagenetic reactions of steroids are explicable in terms of acid catalyzed rearrangements. Specifically, the results provide: (i) Indirect evidence that the 4-ene skeleton is a key intermediate in the dehydration of 4-methyl stanols in sediments. (ii) An explanation for the distribution of 4-methyl sterenes and A-nor sterenes in the lacustrine Messel shale (Eocene). (iii) An explanation for the presence of 4..beta..-methyl steranes in relatively immature sedimentary rocks, despite the precursor stanols having the 4..cap alpha..-methyl configuration. With increasing maturity in the Paris Basin shales (Lower Toarcian), the less stable 4..beta..-methyl steranes decrease gradually in abundance relative to their 4..cap alpha..-methyl counterparts, at a rate fairly similar to the change in pristane stereochemistry.

• Research Organization: Univ. of Bristol, England
• OSTI ID: 6987240
• Journal Information: Geochim. Cosmochim. Acta; (United States), Journal Name: Geochim. Cosmochim. Acta; (United States) Vol. 50:3; ISSN GCACA
• Country of Publication: United States
• Language: English

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