Abstract: Solid bitumen from the Northeastern Sichuan Basin is investigated by the present authors using selective chemical degradation combined with various organic geochemical analyses. Biomarker parameters and bitumen reflectivity indicate that the solid bitumen has experienced a relatively high thermal maturity. The facts that C₁₆ and C₁₈ fatty acids are the predominant biomarkers released by chemical degradation and fatty acids are of remarkable even-odd predominance suggest that the precursor of the solid bitumen may mainly derived from bacteria and algae input. The products of chemical degradation also contain some n-alkanes, steranoids and terpenoids. Comparison reveals that they possibly have same source as the corresponding components in the extracts of solid bitumen, but display a relatively lower thermal maturity than the latter. Carbon isotopic compositions of the individual compounds suggest that the precursor of the solid bitumen was mainly formed in a half deep water-deep water environment, and hydrogen isotopic composition indicates a possibly D-enriched marine environment.

Key words: solid bitumen, selective chemical degradation, biomarker, carbon isotope, hydrogen isotope