Carbon isotope composition in the Early Palaeozoic crude oil, natural bitumens and kerogeneous rocks of the Baltic region

The Baltic region is of interest to organic geochemists because of the occurrence of crude oil accumulations, natural bitumen shows and oil shale deposits. For elucidating possible correlation between them, a suite of four crude oils, eight natural bitumens and three kerogeneous rocks was examined for organic carbon isotope composition. δ13 C values for the studied crude oils and natural bitumens are similar and on an average -30.0 ‰ inherent in the Cambrian organic matter. In the series: oil → maltha → asphalt → asphaltite the value of δ13 C increases gradually showing the genetical relationship between the members of the series. No correlation by the carbon isotope composition between crude oils and natural bitumens, and organic matter of any studied kerogeneous rock is observed.