Abstract
A novel sterane, 27-nor-24-methyl-5α-cholestane, has been identified in sedimentary hydrocarbon mixtures by coinjection with an authentic standard. The C27 sterane occurs in silica-rich sediments from the Monterey Formation, USA, the Onnagawa Formation, Japan, and the Menilite Shale, Poland, and in bituminous marls from the Vena del Gesso basin, Italy. The compound seems to be biosynthetically related to 24-norcholestanes which co-occurs in sometimes relatively high amounts. The 13C-content of the sterane in the Monterey Formation indicates an algal source similar to other steranes present in this sediment. A diatom or a dinoflagellate source is suggested for this compound.