Spatial Variability of the Methane Hydrate Stability Zone’s Upper Boundary Parameters in the Water Column of the Sea of Okhotsk

Abstract

Based on all the available oceanological information (131 286 stations carried out from 1929 to 2020), for the first time for the Sea of Okhotsk, the spatial patterns of the upper boundary distribution parameters of the methane hydrate stability zone (water temperature, salinity, depth of the upper boundary in the water column) are presented and discussed. A model of the methane hydrate stability zone is considered. We revealed that the minimum water temperature and the minimum depth of the upper boundary of the gas hydrate stability zone (less than 1°C and 300–320 m, respectively) in the Sea of Okhotsk are located near the eastern slope of Sakhalin Island. The maximum water temperature and maximum depth of the upper boundary (1.5–1.7°C and 340–350 m, respectively) are characteristic of the area adjacent to the central and northern straits of the Kuril Islands Arc, as well as above the slope of the Kamchatka Peninsula. The salinity at the upper boundary of the methane hydrate stability zone in the Sea of Okhotsk varies within a narrow range from 33.4 to 33.6 psu, which is quite close to the conditions assume for the stability of methane hydrate in seawater. An area where the thermobaric conditions in the water column not favorable for the formation of methane hydrates has been identified.