Organic Matter in Bottom Sediments of the Shelf Part of the Laptev Sea as an Indicator of Sedimentation (Expedition 2018)

Summary The main idea was to investigate the composition of hydrocarbon (HC) molecular markers, as indicators of the origin of sedimentary material. The object of the study is bottom sediments collected from latitudinal transects stretching along the outer edge of the shelf and the upper continental slope of the Laptev Sea. Sampling was made during the research cruise of FSBI VNIIOkeangeologia in 2018 (R/V Ivan Petrov). The molecular composition of the DOM indicates a significant input of terrigenous components of diagenetic maturity degree to the sediments of the region. Moreover, the input of molecular markers characteristic for the bacterial activity (possibly methanotrophic) is detected in some sediments (n-C16 and n-C18 predominate in composition of the lower molecular weight n-alkanes; the tricyclic terpanes ratio (2(C19+С20)/(C23+С24+C25+С26) < 1). The inflow of the reduced Atlantic waters with the along-slope currents and the processes of bottom and coastal abrasion determine the contribution of the transformed marine DOM to the sediments of continental margin.