Geochemical Typing of Organic Matter in the Bottom Sediments Based on Molecular Composition of Saturated Aliphatic Hydrocarbons
The paper presents approaches to the typing of organic matter (OM) from the bottom sediments based on molecular indicators and statistical analysis. Based on the results of the analysis of molecular composition and concentration of saturated hydrocarbons (n-alkanes) in thawed and permafrost deposits from the Buor-Khaya Bay (Laptev Sea), specific types of n-alkane composition were identified. Principal component analysis allowed to identify five types of molecular spectra that differ in origin, degree of bacterial transformation, and concentration of n-alkanes. It was found that at a relatively small distance (10 km) from the continent, the composition and concentration of n-alkanes change drastically, which is explained by the spatial dynamics of OM fluxes in the conditions of Late Quaternary epicontinental morpholithogenesis of the Laptev Sea. A contribution of coastal vegetation and aquatic components away from the continent increases markedly along with the overall increase in n-alkanes concentration, while deposits from coastal shallow waters differ in dominance of terrigenous homologues and general decrease of n-alkane concentration. The influence of cryogenesis on the molecular composition of hydrocarbons in the studied deposits was not revealed.