首页|Imaging the Western Boundary of the Sichuan Craton from Multiple Geophysical Observations

Imaging the Western Boundary of the Sichuan Craton from Multiple Geophysical Observations

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The boundary between cratonic and orogenic lithospheres is a significant seismogenic zones marked by intense lithospheric deformation.The Sichuan Craton(SCC),as a key tectonic block bordering eastern Tibetan Plateau,resists the eastward escape of plateau's crustal materials,resulting in the uplift of the Songpan-Ganzi Block(SGB)and crustal deformation of the Longmenshan tectonic belt(LMTB).To elucidate the compressional structures and deformational modes of the LMTB and SCC,it is essential to accurately determine the location and geometry of the SCC'western boundary.To investigate this issue,the lithospheric properties of the obducted SGB,underthrusting SCC,and LMTB were analyzed using various geophysical data,including seismic reflection profiles,magnetotel-lurics,aeromagnetics,gravity,and seismic tomography.The SGB crust is characterized by low magne-tism,seismic velocity,resistivity and Bouguer gravity,whereas the SCC crust exhibits non-uniform high magnetism,seismic velocity,resistivity and Bouguer gravity.The LMTB,as the boundary between the SGB and SCC,exhibits geophysical characteristics similar to those of the SCC in the southern and central segments.The integration of these geophysical observations indicate that the SCC's western boundary is situated west of the Wenchuan-Maoxian fault zone in the southern and central segments,exhibiting distinct westward wedging and underthrusting.However,this boundary aligns with the Yingxiu-Beichuan fault in the northern segment,without significant underthrusting.The irregular ge-ometry of the SCC's western boundary further elucidates the variation in structural deformation along the LMTB.By comparing crustal thickness and lithospheric strength between the SGB and SCC,this study posits that the differing crustal strength between tectonic blocks may control the irregular geometry of the SCC's western boundary.

Sichuan CratonLongmenshan tectonic beltgeophysical imaginglithospheric struc-turetectonic wedginggeophysicsstructural geology

Qihang Yin、Xi Xu、Xiaodong Yang、Xuhua Shi、Lei Wu、Andrew V.Zuza、Liu Yang、Hefeng Tian、Yuanhai Shu、Shufeng Yang

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School of Earth Sciences,Zhejiang University,Hangzhou 310058,China

China Aero Geophysical Survey and Remote Sensing Center for Natural Resources,China Geological Survey,Beijing 100083,China

SINOPEC Key Laboratory of Geophysics,Nanjing 211103,China

Key Laboratory of Ocean and Marginal Sea Geology,South China Sea Institute of Oceanology,Innovation Academy of South China Sea Ecology and Environmental Engineering,Chinese Academy of Sciences,Guangzhou 511458,China

Nevada Bureau of Mines and Geology,University of Nevada,Reno,Nevada 89557,USA

School of Mechanical and Electrical Engineering,Hubei Open University,Wuhan 430074,China

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2024

10.1007/s12583-023-1974-z

地球科学学刊(英文版)
中国地质大学

地球科学学刊(英文版)

CSTPCD
影响因子：0.724
ISSN：1674-487X
年,卷(期)：2024.35(6)