MOLECULAR TAPHONOMY OF ARTHROPOD AND PLANT CUTICLES FROM THE CARBONIFEROUS OF NORTH-AMERICA - IMPLICATIONS FOR THE ORIGIN OF KEROGEN

Analyses of identifiable organic fossil remains of animals and plants have considerable potential to resolve conflicting models of organic m atter diagenesis and kerogen formation (e.g. selective preservation ve rsus random polymerization). Fossil cuticles of arthropods (scorpion, eurypterid) and plants (cordaite, pteridosperm) from Upper Carbonifero us strata of Lone Star Lake, Kansas, USA and Joggins, Nova Scotia, Can ada were analysed by pyrolysis-gas chromatography/mass spectrometry an d examined by electron microscopy. Recent Pandinus (scorpion) and Arau caria (conifer) provided a basis for comparison. Pyrolysis of Recent d ewaxed scorpion cuticle yielded products derived from chitin and prote ins. These products were absent in the fossil arthropod cuticles, howe ver, which yielded an homologous series of alkanes and alkenes, togeth er with phenolic and other aromatic constituents. Recent dewaxed plant cuticle yielded fatty acids, phenols and carbohydrate-derived compoun ds indicative of cutin polyester and associated lignocellulose. The py rolysates of the fossil plant cuticles, on the other hand, were domina ted by alkane-alkene doublets, with minor phenolic and other benzenoid components. There is no evidence that the preservation of these cutic les as particulate organic matter in kerogen is simply a result of sel ective preservation. Nonetheless, the chemistry and morphology remain characteristic of a particular taxon, thereby eliminating the possibil ity of incorporation of randomly repolymerized materials or the transf er of material between plant and animal residues. The aliphatic moieti es in the fossil cuticles are thought to be the result of polymerizati on of the associated epicuticular, cuticular and/or tissue lipids duri ng diagenesis.