Migrated hydrocarbons in outcrop samples: revised petroleum exploration directions in the Tarim Basin

The application of age-specific biomarker distributions established from mature exploration areas of the Tarim Basin, northwestern China, indicates that most Carboniferous–Permian outcrop samples in the eastern segment of the Southwest Depression, previously believed to have significant petroleum source potential, in fact contain migrated hydrocarbons derived from Cambrian–Lower Ordovician strata. New geochemical results have led to a major revision of petroleum exploration directions in this area.