Factors controlling the survival of proteinaceous material in Late Tithonian kerogens (Kashpir Oil Shales, Russia)

Thermochemolysis experiments with tetramethylammonium hydroxide (TMAH), on three Late Jurassic kerogens with contrasting features, confirmed the major role of encapsulation into aliphatic structures for the survival of proteinaceous moieties in kerogens, probably via lipid sulphurisation. It also appeared that (i) some amino acid moieties survived even in the kerogen of a sediment deposited under oxic conditions, although in lower relative abundance compared to the other two kerogens, (ii) the survival of amino acids on geological time scales, within an organic matrix, is probably rather common in kerogens, especially for glycine and alanine, and (iii) thermochemolysis of kerogen sub-units with a lower degree of cross-linking rather than direct thermochemolysis of whole kerogens is recommended to test the presence of amino acid moieties, so as to avoid dilution problems and to increase the accessibility of the TMAH.