Geochemistry of Organic Matter in Permian Deposits in the Northeast of Korotaihinsky Depression

The article presents results of geochemical studies of Permian deposits in the northeastern part of Korotaihinsky depression. We show the distribution of organic carbon and bitumen in various lithological varieties of rocks. The smallest (0.04-0.7 %) concentrations of organic carbon are confined to the limestone and sandy-silty varieties; the maximum ones are set in the mudstone, carbonaceous mudstones (1.0-1.7 %) and coal (26 %). Deposits of Late Permian age are characterized by a high content of bitumen (0,018-0,293 %). The distribution of n-alkanes and isoprenoids in the hydrocarbon fraction of bitumen shows a significant proportion of sapropel organic matter with a small contribution of humic compounds. Permian bitumen is mixed – autochthonous with a dash of allochthonous hydrocarbons. Results of pyrolytic studies show low residual generating potential of rocks (HI < 65 mgHC/g Corg), due to the composition of organic matter and its catagenetic transformation.