PETROLEUM GEOCHEMISTRY OF THE TALIMU BASIN

The Talimu Basin in China consists of a Paleozoic platform and a Meso- Cenozoic land block series. On the basis of sedimentological and tecto nic studies of the Talimu Basin, it is proposed in this paper that two different kinds of oil-generating sub-basins and source beds are pres ent, and responsible for the formation and accumulation of both marine and nonmarine hydrocarbons. A preliminary evaluation for different so urce beds within the basin has been carried out using the disciplines of sedimentology, lithofacies-paleogeography and organic geochemistry. We distinguish various depositional settings, with different oxidatio n and/or reduction features, by showing systematic differences in rela tive molecular distributions. These include characteristic facies-rela ted biomarkers, such as tricyclic terpanes, pregnanes, fluorenes, dibe nzofurans and dibenzothiophenes. Types of organic matter in source roc ks are revealed by the presence/absence of land plant-derived biomarke rs, including pimarane, abietane, dehydroabietane, fluoranthenes, chry senes and perylenes. Kerogens, from black mudstones of the Saergan For mation and the Yingan Formation at the northwestern margin of the basi n, have been selected for detailed examination of their hydrocarbon po tential. Favorable regions for hydrocarbon prospecting in the basin ar e also discussed.