Выпуск: 8 , Том: 54 , Год издания: 2013

We present results of geochemical studies of organic matter of the Jurassic-Cretaceous deposits in the west of the Yenisei-Khatanga regional trough. The studies were carried out on a representative set of well cores by a complex of modern organic-geochemistry methods (determination of organic-carbon content in rocks, pyrolysis, estimation of the carbon isotope composition in the kerogen of rocks, extraction, liquid and gas-liquid chromatography, and chromato-mass spectrometry). Based on the distribution of biomarkers in the studied bitumens and pyrolysis of rocks, two groups of the samples were recognized: with terrigenous (type III) and marine (type II) organic matter. The terrigenous bitumens are characterized by a low hydrogen index (HI) and a predominance of hydrocarbons C₂₉ among steranes and C₁₉ and C₂₀ among tricyclanes. The marine bitumens, revealed in stratigraphic analogs of the Bazhenovo Formation and in the Malyshevka, Nizhnyaya Kheta, and Shuratovka Formations, show an even distribution of sterane homologues and a predominance of medium-molecular tricyclanes. The Pr/Ph and C₃₅/C₃₄ ratios and the presence of diahopanes testify to the burial of organic matter in suboxidizing sea coast environments. In the Yanov Stan (J₃-K₁), Gol'chikha (J₂-K₁), and, to a lesser extent, Malyshevka (J₂), Nizhnyaya Kheta, and Shuratovka (K₁) Formations, we have recognized widespread stratigraphic levels with marine organic matter of rocks. Its contents and degree of maturity permit these rocks to be considered oil-generating.