Geochemical Anomalies of Hydrocarbon Gases in Bottom Sediments of Geostructures of the Laptev–Siberian Sea Transition Zone of the East Arctic Shelf

The data of gas-geochemical studies of bottom sediments of the Laptev—Siberian Sea transition zone are presented. The established isotope–geochemical parameters indicate the domination of epigenetic hydrocarbon gases of various gas sources in the sediments. Methane concentrations up to 8.3047 cm 3 /kg and the sum of homologues up to 0.0260 cm 3 /kg indicate the formation of hydrocarbon anomalies exceeding the anomaly criteria for Arctic shelf sediments by a factor of 166 and 26. The main geological factors for the formation and distribution of anomalies in the bottom sediments of the Laptev–Siberian Sea transition zone are the high gas content of the underlying sediments and gas sources, the fold and fault tectonics, the geostructural position, the seismic activity, and the depth of occurrence of hydrocarbon gas sources.