A complete series of C31-C34 25-norbenzohopanes in the Devonian and Jurassic bitumen sands, NW Sichuan Basin

A complete series of C32-C35 benzohopanes and corresponding C31-C34 25-norbenzohopanes were tentatively identified in Devonian and Jurassic bitumen sands from the northwestern Sichuan Basin in southwestern China. Although other origins cannot be excluded, the relative distributions of C32-C35 benzohopanes and C31-C34 25-norbenzohopanes, along with other biomarker parameters, suggest that the 25-norbenzohopanes formed by demethylation of the corresponding benzohopanes.