YANG WenCai,
JIN Sheng,
ZHANG LuoLei et al
.2020.The three-dimensional resistivity structures of the lithosphere beneath the Qinghai-Tibet Plateau Chinese Journal of Geophysics(in Chinese),63(3): 817-827,doi: 10.6038/cjg2020N0197
The three-dimensional resistivity structures of the lithosphere beneath the Qinghai-Tibet Plateau
YANG WenCai1,2, JIN Sheng2, ZHANG LuoLei3, QU Chen4, HU XiangYun5, WEI WenBo2, YU ChangQing4, YU Peng3
1. School of Earth Sciences, Zhejiang University, Hangzhou 310027, China; 2. School of Geophysics and Information Technology, China University of Geosciences(Beijing), Beijing 100083, China; 3. State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China; 4. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China; 5. Institute of Geophysics&Geomatics, China University of Geosciences(Wuhan), Wuhan 430074, China
Abstract：After multi-team researches in relays, our magnetotelluric investigations have covered most of area of Qinghai-Tibet Plateau, providing a reliable foundation for the study of three-dimensional lithosphere resistivity imaging. A reliable three-dimensional resistivity image set of the Qinghai-Tibet Plateau is obtained by fine assimilation, fusion, processing and inversion of the magnetotelluric data. The imaging area is 28°N-35°N and 80°E-104°E. The mesh size used in the three-dimensional inversion is 20 km by 20 km, the vertical direction is divided into 26 layers with the unequal spacing down to 200 km. The results show that the current lithospheric resistivity anomalies in the Qinghai-Tibet Plateau mainly reflects the thermal fluid movement caused by the subduction of the Indian craton to the Eurasian Plate. In the lithosphere mantle, the Zayu block, the Himalaya block and the eastern part of the Lhasa block are linked to a unified high resistivity anomaly, which reflects the Indian craton subduction to the northeast. The low resistance zone in the eastern Qinghai-Tibet Plateau expands downwards along the 100°E, reflecting the trend of the Jinsha River fault zone cutting through the lithosphere. The disturbance patterns of mantle resistivity clearly show that the splicing format of terranes in the east and west parts of the Qinghai-Tibet Plateau is different. In the western part of the Qinghai-Tibet Plateau, the terranes of Qiangtang, Lhasa and Himalaya are combined along direction from north to south. In the eastern part of the Qinghai-Tibet Plateau, Qiangtang-Lhasa, Zayu, Indochina, Yaan and Yangtze terranes are combined along direction from west to east. The combination of the west terranes has occurred first, and a wide range of deformation structures have been formed in the crust, including orthogonal detachment bands and rift systems. In the east part, the terranes have been combining afterwards, extensive deformation is being caused in the crust, including the non-orthogonal disassembly belts and the pressure-rotational tectonic systems. From the distribution pattern of the high-to-low resistance zones we see that the geological processes going on the east Qinghai-Tibet Plateau has a deep mantle roots, which will further develope in the future.
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