Electrical Structure of the Crust Beneath the Ordos Block  

作　　者：Zhao Guoze Zhan Yan Wang Lifeng Wang Jijun Tang Ji Chen Xiaobin Xiao Qibin 

机构地区：[1]Institute of Geology, China Earthquake Administration, Beijing 100029, China

出　　处：《Earthquake Research in China》2011年第2期120-134,共15页中国地震研究（英文版）

基　　金：sponsored by Earthquake Research Project for Public Affair(2008419010);the National Natural Science Foundation of China(40374032, 40534023);the Basic Scientific Research Special Program of the Institute of Geology,CEA(DFIGCEA0607117);the Basic Scientific Research Fund of the State Level Institutes for Commonweal (DF-IGCEA-0607-1-17);the National Basic Research Program(2004CB418402),China;the National Key Basic Research Program (95-13-02-02);the Key Program of the Natural Science Foundation of China (40534023)

摘　　要：The Ordos block is a stable tectonic unit since the Cenozoic. Whether low-resistivity layers exist in the middle and lower crust of this kind block is an open question. This work attempts to reveal the entire crustal structure of the block based on interpretation of magnetotelluric data collected along the profile across this region. The result shows that a layered structure characterizes the crust of the Ordos block, with a low-resistivity layer at depth of about 20km, presumably associated with fluids there. In contrast, in the areas of active tectonics on the east and west of the block, there are no such layered electric structures in the crust, and the low-resistivity zones may be related to the decollement zones (or ductile shear zones) in the crust. The difference in electric structure of crust between the Ordos Block and neighboring areas is of significance to analyze the movement and deformation of varied blocks in the continent.The Ordos block is a stable tectonic unit since the Cenozoic. Whether low-resistivity layers exist in the middle and lower crust of this kind block is an open question. This work attempts to reveal the entire crustal structure of the block based on interpretation of magnetotelluric data collected along the profile across this region. The result shows that a layered structure characterizes the crust of the Ordos block, with a low-resistivity layer at depth of about 20km, presumably associated with fluids there. In contrast, in the areas of active tectonics on the east and west of the block, there are no such layered electric structures in the crust, and the low-resistivity zones may be related to the decollement zones （or ductile shear zones） in the crust. The difference in electric structure of crust between the Ordos Block and neighboring areas is of significance to analyze the movement and deformation of varied blocks in the continent.

关 键 词：Ordos block MAGNETOTELLURICS Crustal structure Low-resistivity layer FLUID 

分 类 号：P315.2[天文地球—地震学] TS956[天文地球—固体地球物理学]