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Nouveaux stéroïdes aromatiques fossiles

Abstract : Three novel series of triaromatic steroids have been identified in Paris basin rocks and oils by comparison with synthetic compounds. Those steroids have been used to define a novel maturity index that was used for oil-source rock correlations. Triaromatic steroids bearing methyl groups at position 2 (C21), 3 (C21, C27, C29) or 6 (C21) have been synthesized from pregnenolone, cholesterol or stigmasterol. Molecular structures were confirmed by 200 MHz NMR decoupling or spatial correlation using the nuclear Overhauser effect.

2-Methyl, 3-methyl and 6-methyl triaromatic steroids have been identified in rocks and oils by comparison of their gas chromatography (GC) and mass spectrometry (MS) data with synthetic compounds. They are formed in sedimentary rocks at a late stage of maturity from triaromatic or monoaromatic precursors. 2-Methyl and 3-methyl triaromatic steroids are probably formed from 4-methyl precursors by acid-catalysed methyl migration. Though precursors bearing a carbon function at position 2 or 3 are not excluded.

3 Oils (Dogger, Domerian, Trias) and 13 sedimentary rocks (Toarcian, Hettangian) from the Paris basin have been fractionated by chromatography (CC, TLC, GC, HPLC). Alkanes, Branched/cyclic alkanes, Alkenes, and Aromatic fractions were analysed by gas chromatography-mass spectrometry (GC-SM). Selective detection of steranes have been achieved using metastable transitions. The study of biomarkers in rocks and oils has given insights on palaeoenvironment, thermal maturity and oil migration. Here, a novel maturity index, the methyltriaromatic steroid index (MTSI) has been found useful for rock-rock and rock-oil correlations.
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Contributor : Eric Lichtfouse <>
Submitted on : Thursday, September 20, 2007 - 3:23:22 PM
Last modification on : Saturday, June 6, 2020 - 12:10:45 PM
Long-term archiving on: : Monday, September 24, 2012 - 12:35:44 PM


  • HAL Id : tel-00173767, version 1
  • PRODINRA : 251113



Eric Lichtfouse. Nouveaux stéroïdes aromatiques fossiles. Autre. Université Louis Pasteur - Strasbourg I, 1989. Français. ⟨tel-00173767⟩



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