Results of a Geochemical Study of Core Samples from Petroleum Source Rock Deposits of Cretaceous and Jurassic Age in the Southwestern Part of the Yenisei–Khatanga Regional Trough

This paper presents the results of a comprehensive geochemical investigation of core material, extracted bitumens, and gas condensates from the southwestern part of the Yenisei–Khatanga Regional Trough (Arctic region). The study aimed to evaluate the petroleum source potential of the investigated stratigraphic units, determine the type and thermal maturity of organic matter, and clarify its genetic relationships with hydrocarbons. The research was carried out using total organic carbon (TOC) determination, programmed pyrolysis (Rock-Eval analogue) with analysis of the S1 and S2 parameters, solvent extraction of bitumens, and biomarker analysis by gas chromatography–mass spectrometry (GC–MS). The obtained data revealed a wide range of TOC values and significant lithological and geochemical heterogeneity within the studied section. In several samples, elevated S1 values combined with low residual generative potential (S2) were identified, which is interpreted as evidence of advanced thermal transformation of organic matter and the presence of migrated hydrocarbons in certain intervals. Biomarker investigations enabled differentiation of genetic types of organic matter and revealed variations in depositional environments. The results refine current understanding of the petroleum source characteristics of the studied formations and may be applied in the interpretation of hydrocarbon genesis and in further petroleum geological investigations of the region.