SEISMOLOGY AND GEOLOGY ›› 2010, Vol. 32 ›› Issue (3): 345-359.DOI: 10.3969/j.issn.0253-4967.2010.03.001

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ELECTRIC STRUCTURE OF THE CRUST BENEATH THE ORDOS FAULT BLOCK

ZHAO Guo-ze, ZHAN Yan, WANG Li-feng, WANG Ji-jun, TANG Ji, CHEN Xiao-bin, XIAO Qi-bin   

  1. Institute of Geology, China Earthquake Administration, Beijing 100029, China
  • Received:2010-08-02 Revised:2010-08-15 Online:2010-09-30 Published:2011-01-14

鄂尔多斯断块地壳电性结构

赵国泽, 詹艳, 王立凤, 王继军, 汤吉, 陈小斌, 肖骑彬   

  1. 中国地震局地质研究所, 北京, 100029
  • 通讯作者: 詹艳,研究员,E-mail:zhanyan66@vip.Sina.com。
  • 作者简介:赵国泽,男,1946年生,研究员,博士生导师,主要从事电磁方法和应用研究,电话:010-62009065,E-mail:zhaogz@ies.ac.cn.
  • 基金资助:
    国家自然科学基金(40374032,40534023);中国地震局地质研究所基本科研业务专项(DF-IGCEA0607117);国家公益性地震行业专项(2008419010);国家重点基础研究发展计划项目(2004CB418402)共同资助

Abstract: The Ordos fault block is a stable block since the Cenozoic time.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 Ordos fault 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 fault block,with a low-resistivity layer at depth of about 20km,presumably associated with fluids there.On contrast,in the areas of active tectonics in the east and west of the fault block,there is no such layered electric structure in crust,while the low-resistivity zones may be related with the detachments(or ductile-shear zones) in crust.The difference in electric structure of crust between the Ordos fault block and neighboring areas is of significance to the analysis of activity and deformation in varied blocks.

Key words: Ordos fault block, magnetotellurics, crustal structure, low-resistivity layer, fluid

摘要: 鄂尔多斯断块作为新生代以来的稳定块体,其中下地壳内是否存在低阻层一直受到关注。基于穿过鄂尔多斯断块大地电磁剖面的观测资料,利用新的数据处理和解释技术,对鄂尔多斯断块的地壳结构进行了整体研究,发现鄂尔多斯断块的地壳具有成层性结构特点,并在约20km深度存在低阻层,推测它是由流体引起的电阻率降低。在断块东、西两侧的构造活动区,其地壳内不存在成层性电性结构,其中的低阻带可能与地壳内的滑脱带(或韧性剪切带)有关。鄂尔多斯断块和周围地区地壳电性结构的不同特点,对于分析不同地块的变形和地震活动性等有一定价值。

关键词: 鄂尔多斯断块, 大地电磁, 地壳结构, 低阻层, 流体

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