HR: 10:50h
AN: S42A-03    [Abstracts]
TI: The Crust and upper mantle structure beneath Yunnan from joint inversion of receiver functions and Rayleigh wave dispersion data
AU: * Li, Y
EM: lyhgeomag@sina.com
AF: Institute of Geophysics, China Earthquake Administration, No.5 Minzuxueyuan Nanlu, Haidian District, Beijing, 100081, China
AU: Wu, Q
EM: wuqj@cea-igp.ac.cn
AF: Institute of Geophysics, China Earthquake Administration, No.5 Minzuxueyuan Nanlu, Haidian District, Beijing, 100081, China
AU: Zeng, R
EM: zengrs@cea-igp.ac.cn
AF: Institute of Geophysics, China Earthquake Administration, No.5 Minzuxueyuan Nanlu, Haidian District, Beijing, 100081, China
AU: Wang, B
EM: wangbs@seis.ac.cn
AF: Institute of Geophysics, China Earthquake Administration, No.5 Minzuxueyuan Nanlu, Haidian District, Beijing, 100081, China
AB: We apply joint inversion of receiver function and Rayleigh wave dispersion (phase and group) velocities data to estimate a shear-wave velocity structure for the Yunnan and its adjacent region. Our joint inversion models indicate strong lateral variations in crustal thickness in this area, which is gradually increase from 32 km in SE to 56km in NW of Yunnan. The gradual change in crustal thickness matches with the gradual topography change over this region. Our models also show a uniform crust upper mantle S velocity structure across the region, with a 8 ~ 22 km thick upper crust (Vs <3.4 ~ 3.5 km/s), overlying a gradational middle to lower crust with shear wave velocities up to 3.5 ~ 4.1 km/s at Moho depth. The thickness of middle to lower crust is correlated with the Moho depth beneath the seismic stations. We see evidence of crustal flow in middle to lower crust beneath the Yunnan region, especially in the western Yunnan. It is possible that the thick crust in this study area is mainly caused by a more ductile flow in the middle to lower crust. The upper mantle S velocities (Sn) vary from 4.15 to 4.75 km/s across the Yunnan and its adjacent region. The Sn velocities are slightly higher beneath the southern Yangtze block and Southeast Yunnan fold belt than the other block. This low Sn velocity and LVZ in middle to lower crust beneath western Yunnan and Panxi rift may imply that there has been thermal disturbance to the uppermost mantle away from deep structures in this region.
DE: 1734 Seismology
DE: 1744 Tectonophysics
SC: Seismology [S]
MN: 2007 Fall Meeting