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GEOCHEMICAL CHARACTERISTICS OF ORGANIC MATTER IN THE LOWER CRETACEOUS DEPOSITS WITHIN THE DERYABINSKAYA AREA IN THE WESTERN YENISEI-KHATANGA REGIONAL TROUGH

A. P. Rodchenko

A.A.Trofimuk Institute of Petroleum Geology and Geophysics SB RAS, Novosibirsk, Russia

The paper presents the results of geochemical studies of Lower Cretaceous deposits, including transitional layers from the Upper Jurassic, it is aimed at their evaluation as a possible source of petroleum hydrocarbons. The rocks of transitional layers between the Golchikha and Shuratov Formations have relatively high Сorg contents (1.3–3.7% per rock), type II and II/III kerogen prone to generation of liquid hydrocarbons, and catagenetic maturity corresponding to the beginning of the main zone of oil window (the beginning of the MK1 2 gradation). Biomarkers in aliphatic fractions of bitumoids indicate predominantly aquatic sources of matter – phytoplankton and bacterial communities, and suboxidizing conditions of accumulation and burial of initial organic matter of rocks. In the overlying mudstones of the Shuratov Formation the content of organic matter is below or at the level of bulk earth values (<0.9% per rock), kerogen corresponds to type III, formed mainly due to higher terrestrial vegetation and capable of generating gaseous hydrocarbons, catagenesis of organic matter corresponds to maturity stages from MK1 1 to MK1 2.

Keywords: organic matter, isotope composition of carbon, biomarkers, Lower Cretaceous, Shuratov Formation, Deryabinskaya area, Yenisei-Khatanga trough.

DOI 10.20403/2078-0575-2024-1-32-44

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