GAS GEOCHEMICAL ANOMALIES OF HYDROCARBON GASES IN BOTTOM SEDIMENTS OF ADJACENT WATER AREAS OF THE EASTERN PART OF THE KAMCHATKA PENINSULA

New data on the composition and concentrations of hydrocarbon gases in the upper horizons of bottom sediments of Avacha Bay and the adjacent sector of the Pacific Ocean are presented. The established concentrations of methane and the sums of its homologues are characterized by high variability – 0.0003–120.9385 and 0.00005–0.00753 cm³/kg and the formation of gas anomalies in the sediments of the shallow shelf (Avacha Bay, Russkaya Bay, Vilyuchinskaya Bay and Listvennichnaya Bay), the outer shelf and the continental slope at sea depths and sampling of 14–800 m and 3–50 cm. The data on the isotopic composition of carbon δ¹³C–CH₄ from −78.1 to −33.4‰ and δ¹³C–CO₂ from −19.8 to −11.1‰ indicate the formation of natural gases of various polygenetic (mixed) genesis in the bottom sediments of the region and, with a high degree of probability, their significant influx from the underlying sediments.