FINITE-DIFFERENCE TOMOGRAPHY OF UPPER CRUSTAL STRUCTURE IN DABIESHAN OROGENIC BELT
WANG CHUN-YONG; ZHANG XIAN-KANG; DING ZHI-FENG; RUAN HONG; DENG HONG-ZHAO (Institute of Geophysics, State Seismological Bureau, Beijing 100081, China)(Geophysical Prospecting Center, State Ceismological Bureau,Zhengzhou 450003, China)
The finite-difference inversion method is used to the tomography of travel time of the first arrival in upper crust on the deep seismic sounding profile across the Dabieshan orogenic belt. The lateral inhomogeneous structure of upper crust shows that although the ecologite rocks were discoveried in the south-Dabie ultra-high pressure (UHP) metamorphic belt, the basement above the depth of 3km has the normal velocity of the crystalline basement in the continental crust (6.00km / s). The normal velocity is retained in the whole upper crust of the north-Dabie area. However,there is a relative high velocity anomaly region beneath the depth 3km in the UHP area, which may related to the medium with high-content UHP rock, and the significant difference betWeen the north-Debie and south-Dabie exists in upper crust at least. Therefore, the Shuihuo-Wuhe fault, the boundary between the north and south-Debie, may be the major tectonic boundary inside the Debieshan orogenic belt.