New findings on Gas hydrates in the Sea of Okhotsk during the CHAOS-II expedition

Abstract

Many active gas and fluid venting sites at the seafloor and large-scale methane releases into the water column have been detected in the Sea of Okhotsk, where several gas hydrate deposits have been found. The area of focused fluid venting on the NE continental margin off Sakhalin Island, the Sea of Okhotsk was investigated during the CHAOS-II (hydro-Carbon Hydrate Accumulations in the Okhotsk Sea) expedition onboard of RV \\'Akademik Lavrentyev\\' in the period of 20 May to 10 June 2005. The International Research Project CHAOS-II (Russian-Korean-Japanese) aimed at the study of gas hydrate formation processes associated with the fluid venting in the Sea of Okhotsk. A total of 270 gss flares were newly compiled by hydroacoustic survey. Several new gas hydrate accumulations were discovered during the cruise. Hydrate-associated structures have been named as KOPRI, VNIIOkeangeologia, POI and KIT (the names of cruise participant institutes). Some of hydrate-bearing cores contain big amount of gas hydrates: massive gas hydrate layers (up to 35 cm thick) were recovered. The shallowest submarine gas hydrate accumulations in the world (at the depth less then 400 m) were discovered during the cruise.