A PROFILE STUDY OF GRAVITATIVE-MAGNETIC AND SEISMIC COMPREHENSIVE SURVEY IN THE EAST CHINA SEA
GAO De-Zhang ZHAO Jin-Hai BO Yu-Ling Tang Jian WANG Shun-Jie Institute of Shanghai Offshore Petroleum Branch, SINOPEC, Shanghai 200120, China
We apply the comprehensive inversion and interpretation method of gravitative, magnetic and seismic data for crustal structure to the study of lithospheric structure beneath the East China Sea. This study is based on a gravitative-magnetic and seismic survey profile which extends from the East China Sea shelf to the Phillipine basin. As result we make geortransect map of the lithospheric structure for this area. The map shows that the Jilong depression (near Taiwan) is a Mesozoic-Cenozoic sedimentary basin where the sediment is 14km thick. The Okinawa trough basin is of the back arc extentional graben type with crustal thickness of merely 14.5km. The Phillipine plate under thrusts dives toward the Eurasia plate in NWW direction, resulting in steep Moho interface and formation and development of the Okinawa trough, where the lithosphere is about 80km thick. But at other positions on the profile, the lithospheric thickness varies. For instance it is 53km at the site 370km and more than 100km at the site from 450km to 540km on the profile.