Geological aspects of the formation and distribution of gas anomalies in bottom sediments of the New Siberian sedimentary basin and adjacent geostructures of the East Siberian Sea

In bottom sediments of the New Siberian sedimentary basin and adjacent geostructures of the East Siberian Sea, we identified SN4, as well as its limit and unsaturated homologues (up to and including C (sub 5) H (sub 12) ), CO (sub 2) , CO, H (sub 2) , He, H (sub 2) S, O (sub 2) , N (sub 2) , and Ar. Isotope-gas-geochemical parameters delta (super 13) C CO (sub 2) , CN (sub 4) and C (sub 2) N (sub 6) , of the molecular mass of hydrocarbon fraction and genetic coefficients indicate the presence of both syngenetic and epigenetic gases of various gas sources in sediments, including recent sediments, peatlands, coal-bearing and gas-bearing formations, solid bitumen, igneous formations, accumulations of gas hydrates and prognostic condensate-gas, condensate, oil-and-gas and gas-and-oil reservoirs. Concentrations of CO (sub 2) and CO reach 29.25 and 0.06 cm (super 3) /kg, CH (sub 4) and the sum of its homologues - 5.93 and 0.031, N (sub 2) and He - 0.78 and 0.318, H (sub 2) S - 0.092 cm (super 3) /kg; this indicates that gas-geochemical anomalies, exceeding the anomaly criteria by 6-124 times, form in bottom sediments. The formation and distribution of abnormal concentrations of natural gases depend on the complex influence of gas-controlling factors - geological structure, fold and fault tectonics, magmatism, coal-oil-gas content, bituminous content, organic saturation, lithological composition, water-physical and reservoir properties of sediments, hydrogeological, geocryological and other conditions for accumulation of natural gases or their degassing.