南海东北部及其邻近地区地壳上地幔P波速度结构.pdf

16 4 (();) ol.16 No.4 2009 7 Earth Science Frontiers (China University of Geosciences(Beijing);Peking University) Jul.2009 P 李志伟, 　胥　颐, 　郝天珧, 　徐　亚, 　刘劲松 , 100029 Li Zhiwei, 　Xu Yi, 　Hao Tianyao, 　Xu Ya, 　Liu Jinsong K ey L aboratory of P et rol eum R esources R esearch, I nsti t ute of Geolog y and Geop hy si cs, Ch inese A ca dem y of S ciences , B eij i ng 100029, China Li Zhiwei, Xu Yi, Hao Tianyao, et al.P wave velocity structure in the crust and upper mantle beneath northeastern South China Sea and surrounding regions.Earth Science Frontiers, 200 , 16(4):252-260 Abstract:With the P-wave arrival times from Chinese and ISC stations, we conducted the tomographic inver- sion for the 3D velocity structure in the crust and mantle beneath the northeastern South China Sea (SCS)and surrounding regions by using spherical finite difference technique.We analyzed the tectonic differences and deep geodynamic characteristics based on the tomographic results, which show high velocity anomalies at the uppermost mantle beneath the northeast SCS, and depict the lithospheric mantle extension from South China continent to marginal sea.Because of the low temperature and thick lithosphere beneath the northeast SCS, it seems no magma intruded from mantle, so we inferred that the rift may only occur in the crust rather than extend to the upper mantle, which shows the nature of non-volcanic continental margin.The low velocity a- nomalies at the central sub-basin suggest the uplift of hot materials in the mantle.The high velocities at South China continent and Taiwan region, and the low velocities at Okinawa Trough depict the different tectonics of the crust:the former ones belong to the normal crust of Eurasia continent or thickened crust caused by the col- lision bet