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A PRELIMINARY STUDY OF GAS HYDRATES IN DONGSHA REGION NORTH OF SOUTH CHINA SEA
SONG Haibin1，2 GENG Jianhua2 WONG How-Kin3 ZHANG Wensheng4 FANG Yinxia5 HAO Tianyao1 JIANG Weiwei1
（1.Institute of Geology and Geophysics，CAS，Beijing，100029，China；2.Key Lab of Marine Geology，Tongji University，Shanghai 200092，China；3.Institute of Biogeochemistry and Marine Chemistry，Hamburg University，D-20146，Germany；4.Institute of Computational Mathematics and Scientific/Engineering Computing，CAS，Beijing 100080，China；5.Key Lab of Submarine Geosciences，SOA，Hangzhou，310012，China）
Abstract：By using seismic，sonic logging and geothermal data the distribution characteristics of gas hydrates in Dongsha region north of South China Sea are studied.Bottom simulating reflectors（BSR）and amplitude blanking zone are discovered in seismic profiles.And high-velocity interval and velocity reverse are distinguished in sonic logging curve.The BSR depth is compared with thickness of gas hydrates stability zone from thermal gradient data.The depth of BSR depth is in agreement with that obtained at at ODP site 1144and 1148，which are 654and 475meters below sea floor，respectively.The top of amplitude blanking zone may be related with that of gas hydrates-bearing strata in adjacent region of ODP site 1144which is about 450meters below sea floor.
Key words：Gas hydrates；North of South China Sea；Bottom-simulating reflectors；Amplitude blanking zone；Sonic logging；Temperature-pressure condition
