Development of the Yinchuan Basin:Deep seismic reflection profile revealed the linkages between shallow geology and deep structures
Huang Xingfu1, Feng Shaoying2, Gao Rui1, Li Wenhui1
1. State Key Laboratory of Continental Tectonics and Dynamics, Key Laboratory of Earthprobe and Dynamics, MLR, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037;
2. Geophysical Exploration of China Earthquake Administration, Zhengzhou 450002
The NW trending deep seismic reflection profile across the Yinchuan Basin precisely revealed the boundary faults and crust structures of the Yinchuan Basin. It has great significances for understanding development of the Yinchuan Basin. Helanshan eastern piedmont fault as the western margin fault of Yinchuan Basin is a gentle dipping listric fault which extends downward to the boundary of upper crust and low crust. While, Huanghe fault of the eastern boundary fault is a deep fracture which cuts through the whole crust. The shallow structure of Yinchuan Basin indicates a listric faults controlled Cenozoic depression reveled by the deep seismic reflection profile. The dramatic characteristics of the low crust are the nearly flatten Moho which have a great contrast with the traditional cognition of uplift Moho under basin and the 2~3.2 km thickness of layered reflections. According to previous studies of layered reflections, we inferred that the layered reflections consist of mafic magma result from the mantle magma underplating. We proposed that the layered reflections under the low crust counteract the crust thinning effect which ultimately lead to the nearly flatten Moho under sedimentary basin.