[MIS32-P06] Characteristics of methane hydrate fields in the southwestern margin of the Yamato Basin, southern Japan Sea
Keywords:shallow-type methane hydrate, Yamato Basin, Japan Sea
Geothermal gradient was measured at the southwestern slope of the basin as 71.33 mK/m and base of gas hydrate stability was estimated to be 138.6 mbsf. Several huge gas chimneys, hundreds of meters in width, were found in the northwestern slope of the Oki Ridge. Carbonate concretions just below the seafloor and shallow (<2.4 m) sulfate-methane interface (SMI) depths around the gas chimneys indicate high methane flux and strongly suggest large volumes of methane hydrate in the gas chimneys.