GEOCHEMISTRY OF ORGANIC MATTER CENOZOIC SEDIMENTS OF THE INDIGIRO-ZYRYANSKY TROUGH

Using the methods of classical bituminology and gas chromatography-mass spectrometry, organic matter of Cenozoic sediments of the Indigiro-Zyryansky trough was analyzed to study oil source properties of rocks. As appeared the main feature of organic matter was the high yield of bitumoids and their high aliphaticity as the large content of oil fractions, in which high-molecular-weight n-alkanes predominated also some quantity polycyclic aromatic hydrocarbons had been found. Under favorable thermodynamic conditions organic matter of these sediments could generate large quantities of liquid hydrocarbons. However due to the low maturity coefficient (CPI >1), the predominance of asphalt-resin components in the bitumoids composition, and some features of biomarker hydrocarbons distribution, the Cenozoic sediments didn't reach the thermal conditions of the main phase of oil formation. In more submerged parts, deposits of highly paraffinic oils can be found in the sediments of the Elgandinsky Formation. In environmental studies the compositional features of bitumoids as hydrocarbon biomarkers composition from outcrops along the section of Cenozoic sediments can be used to differentiate technogenic hydrocarbon fields (oil pollutions) from natural hydrocarbon anomalies (oil source strata).