The Deep Structure Feature of the Sichuan Basin and Adjacent Orogens |
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| Authors: | XIONG Xiaosong GAO Rui GUO Lianghui WANG Haiyan and JIANG Zhuwei |
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| Institution: | 1 State Key Laboratory of Continental Tectonics and Dynamics, Key Laboratory of Earthprobe and Geodynamics, MLR, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;,1 State Key Laboratory of Continental Tectonics and Dynamics, Key Laboratory of Earthprobe and Geodynamics, MLR, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China,1 State Key Laboratory of Continental Tectonics and Dynamics, Key Laboratory of Earthprobe and Geodynamics, MLR, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;2 School of Geophysics and Information Technology, China University of Geosciences, Beijing 100083, China,1 State Key Laboratory of Continental Tectonics and Dynamics, Key Laboratory of Earthprobe and Geodynamics, MLR, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China and 1 State Key Laboratory of Continental Tectonics and Dynamics, Key Laboratory of Earthprobe and Geodynamics, MLR, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;3 McKay Brook Resources Pty Ltd., Queensland, 4069, Australia |
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| Abstract: | The basin-mountain system in the Sichuan Basin (SCB) reflects the main tectonic activity and the orogenic denudation in this region. The seismic probing work reveals the deep structure of the basin-mountain system. The seismic work was re-sampled to the Moho depth and the sedimentary thickness as well as the P-wave velocity-depth function to analyze the deep structure of the SCB and adjacent orogens. The results show two deposit centers in the SCB: the Deyang area in the west and the Nanchuan area in the east and depression uplift exists in the southwestern part of the SCB; the Moho shallowers gradually from the west to east (ca. 62-36 km deep),the South-North seismic belt (SNSB) is very distinctive: the Moho depth is much shallower (< 50 km)to the east of the SNSB, whereas it is much deeper(>50 km)to the west of the SNSB, suggesting that the SNSB rather than the Longmen Shan tectonic belt is a main Moho transition belt; the topography and the top interface of the basement have the same undulation trend when the sedimentary thickness and the Moho depth have a mirror relationship; the low velocity zone developed in the Kangdian thrust and fold belt and Songpan-Garzê belt implied a soft, weak and thick crust there showing tectonic activity in these areas. |
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| Keywords: | Sichuan basin basin-range contact zone deep structure top interface of basement Moho depth |
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