The geochemical characterizations of adsorbed and occluded components of solid bitumen in the Kuangshanliang area of northwestern Sichuan Basin were studied by comparing the results of conventional extraction and mild oxidative degradation. The results indicate that the solid bitumen originated from Sinian-Cambrian ancient oil reservoirs. The main source of the parent material is lowerorder aquatic deposited in a high-sulfur anoxic marine environment. Exposed solid bitumen suffered from severe biodegradation, altering the tricyclic terpane/pentacyclic terpane and (pregnane + homopregnane)/regular sterane ratios as compared to the earlier parent material.

The temporal evolution of hydrocarbons (~500 million barrels oil) and its relationship to the orogenic events of the Longmen Shan Thrust Belt have been extensively debated. The hydrocarbons occur as solid bitumen, as dykes and/or coatings within/along faults/fractures, and as present day oil seeps. Here utilizing organic geochemistry, we demonstrate that all the bitumen exhibit similar organo-gechemical characteristics, and were sourced from the Late Neoproterozoic-Early Cambrian Doushantuo and Qiongzhusi formations. In contrast, the organic geochemistry of the present day oil seeps are distinct from that of the bitumen, and suggest that the source is the Permain This is a revised version with the manuscript Number BLTN16-230 Petroleum generation timing and source in the Northern Longmen Shan Thrust Belt, Southwest China: Implications for multiple oil generation episodes and sources

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