DISCUSSION

Gas hydrates may exist in the Dongsha Islands area of the northern SCS based on the analyses of seismic，logging and geothermal data.Bottom simulating reflectors（BSRs）and amplitude blanking zone are revealed on seismic profiles.High-velocity intervals and velocity reverse are distinguished from sonic logging curve.The BSR depth is consistent with the thickness of GHSZ from geothermal data at site 1144and the average geothermal gradient data of the northern margin of the SCS.Bedding planes are usually parallel to the seafloor on the north margin of the SCS，so it is difficult to recognize BSR.However，blanking zones provide important information for the recognition of gas hydrates.The BSR at ODP site 1144and 1148are both deep，at 654m and 475m below the seafloor respectively.The top of amplitude blanking zone at these sites may be related with that of gas hydrates-bearing strata in the region adjacent to site 1144，at about 450meters below the seafloor.Research relating to gas hydrates in the Dongsha Islands area is preliminary and further processing and analysis is under way.Ongoing researches on BSRs at other sea regions［16］are useful for the recognition of BSRs in South China Sea.(https://www.daowen.com)