[S21-P] Poster

[S21-P-09] Upper Mantle and Crustal Structure of Sino-Korean and Yangtze Block from Onshore-Offshore Wide-angle seismic surveys

^○Lihua Liu, Tianyao Hao, Chuanchuan Lyu, Qingyu You, Ya Xu (Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China)

By combination with other geophysical data, setting active source onshore-offshore wide-angle seismic survey lines in the Bohai Sea, Shandong peninsula and the south Yellow Sea can help us reveal the deep structure of Sino-Korean and Yangtze block, determine the block boundary, obtain the tectonic structure characteristics of the conjuncture of the blocks. In 2010 and 2011 onshore-offshore surveys along two lines in the Bohai area were carried out, these two lines revealed the P-wave velocity (Vp) structure of upper mantle and crust of Sino-Korean. In 2013, another line was carried out, which started from the Bohai Sea area and ended in the south Yellow Sea. By using first arrival tomography and ray-tracing modeling method, we got the Vp structure from Sino-Korean block to Yangtze block. Considering these three lines together, we found that the block boundary is marked by great deep fault zone, the Vp structure is very different from each other on the two sides of the fault zone. The north of Muping-Jimo fault zone belong to Sino-Korean block, where there is no large-scale undulance of Moho. The south of Qingdao-Wulian-Rongcheng fault zone belong to Yangtze block, the thickness of crust is about 32km and the lateral velocity changes smaller than Sino-Korean block. The areas between these two fault zones belong to the suture zone of these two blocks, where the structure is much more complicated. We can find that there is a large scale high velocity zone in the upper crust beneath the Qianliyan uplift and a large scale low velocity zone in the middle crust beneath the Sulu orogenic belt, and the Moho depth increasing from south to north in step plunging, which suggests the process of combination of Sino-Korean and Yangtze block.