Molecular characterization of fossil organic matter in Glyptostrobus europaeus remains from the Orawa basin (Poland): comparison of pyrolytic techniques

Abstract

Pyrolytic methods (standard Curie-point pyrolysis and pyrolysis in the presence of tetramethylammonium hydroxide (TMAH), followed by gas chromatography–mass spectrometry, were used to analyze the organic composition of Glyptostrobus (Taxodiaceae) remains from the Miocene deposits of Lipnica Mala (Poland), consisting of branches with their leaves. The pyrolytic analysis revealed a series of aromatic compounds with a large proportion of guaiacyl-type lignin markers (including intact C3-methoxyphenols), and small quantities of polycyclic aromatic hydrocarbons. The alkyl compounds included fatty acid series where the C14–C18 homologues dominated as well as additional amounts of alkanes and alkenes (maximum ca. C21). The results suggest that lignin as well as protective epicuticular lipid polymers (including cutin and other long chain-based polyalkyl structures) selectively show the greatest degree of molecular preservation in the Glyptostrobus remains. The comparison between pyrolytic methods shows that the lignin-derived aromatic assemblages predominate in the chromatograms after conventional pyrolysis whereas thermochemolysis with TMAH leads to an “aliphatic enhancement”. This latter technique was found to be the best for analysis of the lipid signature in fossil samples with condensed polymethylene networks.