Informativeness of the pristane/phytane ratio as a genetic index

Journal Article · Tue Sep 01 04:00:00 EDT 1987 · Int. Geol. Rev.; (United States)

DOI:https://doi.org/10.1080/00206818709466206· OSTI ID:7040805

Bylinkin, G P

It has frequently been stated that the pristane/phytane ratio is one of the most important indexes in the genetic comparison of oils one with another and with the disposed organic matter of rocks. These isoprenoid hydrocarbons occur widely in all caustobioliths. The two are very similar in composition and have similar boiling points, so the ratio is least likely to be subject to catagenesis and effects of migration or microbial oxidation, so the ratio obtaining at the time of diagenesis should persist at all transformation stages as far as oil generation. Petrov (1974) showed that phytane and pristane can be formed along with simpler isoprenoids in the decomposition of phytol, which is a basic component of chlorophyll. Bendoraytis et al. (1962) detected phytane and pristane in oils and considered that phytane enters sediments along with chlorophyll and is hydrogenated to hydrophytol, which is converted to hydrocarbons. This may be due either to reduction (phytane) or to oxidation to phytanic acid and subsequent decarboxylation (pristane). It is considered that reducing or oxidizing conditions determine which of the two predominates. Some workers consider that the ratio is < 1 for oils of marine origin related to sapropelic plankton organic matter, while it is > 1 for oils of coastal marine or continental origin. In this review paper, the author concludes that the pristane/phytane ratio does change during maturation of oil, but nevertheless can be used under some conditions as a indicator of source material. 11 references.

• OSTI ID: 7040805
• Journal Information: Int. Geol. Rev.; (United States), Journal Name: Int. Geol. Rev.; (United States) Vol. 29:9; ISSN IGREA
• Country of Publication: United States
• Language: English

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