HR: 1340h
AN: S33A-1034    [Abstracts]
TI: P-Wave Velocity Structure and Its Tectonics beneath Dabie-Sulu Region
AU: * Xu, J
EM: xujiren1125@yahoo.com.cn
AF: Institute of Geology, Chinese Academy of Geological Science, Baiwanzhuang Road 26, Beijing, 100037, China
AU: zhao, z
EM: zhaozx1010@yahoo.com.cn
AF: Institute of Geology, Chinese Academy of Geological Science, Baiwanzhuang Road 26, Beijing, 100037, China
AU: zhao, z
EM: pete74_1999@hotmail.com
AF: Department of Civil and Environmental Engineering University of Connecticut, 261 Glenbrook Rd., UNIT-2037, Storrs, CT 06269-2037, United States
AB: The 3-D crustal structure of P-wave velocity in the Dabie-Sulu region and the vicinities was studied based on the data obtained by wide-angle seismic reflection and refraction surveys. The results suggest that the high velocity structure zones exist in the upper crust shallower than 20 km beneath the Sulu and Dabie regions. The cause of high velocity zones is attributable to the high pressure metamorphic (HPM) and ultra-high pressure metamorphic (UHPM) terranes with high velocity and density exhuming up to the upper crust and the surface in the Sulu and Dabie orogeny. While, anomalous zones of low velocity reveal in the lower crust near 30 km beneath the Sulu and Dabie regions, respectively. The velocities distributing south of the Qinling mountain are generally greater than those north of the Qinling in the crust deeper than 10 km. The Moho discontinuity is as deep as 38 km beneath the Dabie region, deeper than those in its surroundings obviously. The crustal thickness is about 32-33 km in the Sulu region. The Moho discontinuity beneath the Sulu orogenic region is deeper than those beneath its vicinities a little. The deep Moho discontinuity zone implies the low crustal velocity structure zone in those regions. The low velocity characteristics in the lower crust are probably related to the remnant crustal root of the old mountains due to the orogeny in the Sulu and Dabie regions. So the results in the present analysis suggest that the high or low velocity zones are attributable the orogeny in the Dabie-Sulu region. The high velocity anomaly zones in the upper crust or low velocity anomaly zones in the lower crust beneath the Sulu region are always located northeast of the northern segment of the Tanlu fault, however, the high or low velocity anomaly zones beneath the Dabie region are correspondingly located southwest of the southern segment of the Tanlu fault. Such distribution for the velocity anomalous zones looks to be attributable a left lateral motion along the Tanlu fault. The distribution pattern of velocity anomalous zones may show some evidence for the left strike-slip motion regime of the Tanlu fault.
DE: 1219 Gravity anomalies and Earth structure (0920, 7205, 7240)
DE: 1236 Rheology of the lithosphere and mantle (7218, 8160)
DE: 7270 Tomography (6982, 8180)
DE: 8100 TECTONOPHYSICS
SC: Seismology [S]
MN: 2007 Fall Meeting