| Located in the east part of the East China Sea, the Okinawa trough is one of the areas with possible gas hydrate potentials in the East China Sea. However, little work has been devoted to this problem except for some preliminary surveys and discussions. According to the geological, geophysical and geochemical data from several cruises and various publications and on the basis of an analysis of geological factors which control gas hydrate development as well as much evidence for possible development of gas hydrate in the Okinawa trough, this paper points out that there are probably 4 kinds of hydrate deposit types in the study area, i.e., diagenetic, fault-controlled, diapir-controlled and sliding controlled hydrate deposits. The geological factors which control the development of gas hydrate include tomography, geomorphology, water depth, temperature of sea bottom and sedimentary layers, heat flow, sedimentary sources, sedimentary thickness, source rock, sedimentation rate, structure feature, local structure etc., and the evidence indicating the development of gas hydrate might include BSR, blanking zone, negative polarity of BSR Wave, lower layer-velocity response on seismic migration profile, CH4 anomalies in shallow-surface layer and sea-bottom water shown by geochemical investigation, and temperature-increasing anomalies detected by satellite-based thermal infrared remote sensing. In addition, authigenic minerals such as pyrite and carbonate, gas seepage, and CO2-hydtrates were observed. All these data provide valuable evidence in search for mineral resources of gas hydrate in the Okinawa trough of the East China Sea. The authors hold that the reason for lack of gas hydrates discovery here as compared with other seas is mainly due to the relatively lower exploratory level. |