DISTRIBUTION OF HYDROCARBON BIOMARKERS WITH DEPTH IN MARINE SEDIMENTS IN THE AREA OF THE LINEAR DEPRESSION OF THE WEST KARA STAGE

Studies of molecular and hydrocarbon composition in marine sediments provide important information on sedimentary organic matter (OM). In this work, the distribution of hydrocarbons and molecular markers along the depth of the sedimentary cover in the region of the linear depression of the West Kara stage was studied. For this, two sediment columns were sampled during the 89th cruise of the R/V “Akademik Mstislav Keldysh”: at station 7444 and at background station 7441. The distribution of n-alkanes was measured by GC-MS analysis and the peculiarities of distribution of the sediment OM in marine sediments of biomarker indices with sediment depth were determined. It was shown that higher terrestrial vegetation was the dominant source to the sediment OM of marine sediments at stations 7444 and 7441. The OM had low maturity as shown by the values of the Ts/(Ts+Tm) ratio. According to the values of H31–S/H31–(S+R) and NAR indices, a small constant inflow of petrogenic hydrocarbons was observed in the study area, while at the background station 7441 the inflow was much less. Based on the distribution of CPI25–33, TAR and NAR indices, the presence of hydrocarbons of anthropogenic origin in the near-surface layers of 0–15 cm sediment at the background station 7441 was assumed.