Distribution of permafrost and gas hydrates in relation to intensive gas emission in the central part of the Laptev Sea (Russian Arctic)

Abstract

This article describes the results of a comprehensive analysis of the causes of intensive gas emission over a large zone (ca. 80 × 220 km) of the Central Laptev shelf area. The upper parts of 28 sections of common depth point (CDP) seismic lines acquired by the JSC MAGE, covering a total length of 5930 km over an area of 55,000 km2, were interpreted and 519 anomalous objects potentially connected with gas saturation were revealed. For the first time, the boundary between frozen and thawed sediments was defined in the Laptev Sea. The absence of subsea permafrost and gas hydrates in the intensive gas seepage zone was determined. The connection between gas seeps and deep-seated faults identified in seismic sections was substantiated. This study demonstrated that seismotectonic factors caused a large spatial window of long-term Earth degassing with direct intensive migration of deep thermogenic gas to the hydrosphere through a system of faults. A zone of potential gas hydrate distribution was observed on the continental slope.