Geochemistry of Hydrocarbons-Biomarkers and Carbon Isotopes of Organic Matter in the Domanik Deposits of the Timan–Pechora Basin.

Abstract—It has been established that the average values of some hydrocarbons biomarker coefficients of bitumens from the Domanik deposits and oils from the Domanik–Tournaisian complex coincide. These are the proportions of C₂₇–C₂₉ steranes, tri-/pentacyclanes ratio, and coefficients 2 × С₁₇/С₁₆ + С₁₈ and 2 × С₂₇/С₂₆ + С₂₈ calculated from n-alkane composition. Such indicators as the Pr/Ph, (Pr + Ph)/(n‑C₁₇ + n‑C₁₈), dia-/reg-steranes, and the sterane/hopane ratios in oils are slightly lower than in the bitumen. The average values of δ¹³C in asphaltene, resin, aromatic hydrocarbons, and aliphatic hydrocarbons fractions from oils of the Domanik genotype and in the studied bitumens are similar. The carbon isotope composition of asphaltenes in oils is depleted in ¹³С compared to those of resins and aromatic hydrocarbons, and vice versa in bitumens. A heterogeneous composition of the bacterial flora in the sediments of the Domanik Sea is suggested. In some places, species with high concentrations of diplopterol or hexafunctional bacteriohopanes likely dominated over bacteriohopantetrol. [ABSTRACT FROM AUTHOR]