| 代县盆地可控音频大地电磁浅层电性结构探测 |
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| 引用本文： | 王立凤,陈小斌,赵国泽,詹艳,汤吉.代县盆地可控音频大地电磁浅层电性结构探测[J].地震地质,2011(4):928-937. |
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| 作者姓名： | 王立凤 陈小斌 赵国泽 詹艳 汤吉 |
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| 作者单位： | 中国地震局地质研究所 |
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| 基金项目： | 地震行业科研专项“中国地震活动断层探察-华北构造区”(200908001)资助 |
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| 摘 要： | 为研究代县盆地及其断裂的空间展布以及深部的延展情况,东南跨过五台山北麓断裂带,西北至恒山山前黄土丘陵区,布置了一条NW向穿过代县盆地的可控音频大地电磁(CSAMT)测深剖面,全长12.55km.共完成可控源音频大地电磁测点246个,观测频率为8533.333 ～1.333333Hz.视电阻率、相位曲线具有明显的分段特征...
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| 关 键 词： | 可控音频大地电磁 电性结构 断裂 代县盆地 |
CSAMT EXPLORATION TO SHALLOW ELECTRIC STRUCTURE BENEATH THE DAIXIAN BASIN |
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| G Li-fengCHEN,iao-O Guo-zeZHAN,anTANG Ji.CSAMT EXPLORATION TO SHALLOW ELECTRIC STRUCTURE BENEATH THE DAIXIAN BASIN[J].Seismology and Geology,2011(4):928-937. |
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| Authors: | G Li-fengCHEN iao-O Guo-zeZHAN anTANG Ji |
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| Institution: | (Insitute of Geology,China Earthquake Administration,Beijing100029,China) |
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| Abstract: | The Daixian Basin,a typical asymmetric half-graben basin,lies in the northern Shanxi Fault zone.It is bounded by the northeast trending Wutaishan northern piedmont fault zone and Hengshan southern piedmont fault zone.To investigate the shallow electric structures beneath this basin and the boundary faults,a CSAMT profile was applied which runs northwesterly through the basin.CSAMT data were recorded at 246 locations along the 12.55km-long profile.At each location data were recorded from 8533.333 to 1.333333Hz and processed to give estimates of apparent resistivity and phase.The profile is through the Wutaishan Fault in the southeast and arrives at the Hengshan piedmont loess hilly region in the northwest.Some data are of low signal-to-noise ratio due to ractive noises from power lines,pipelines,railways,highways and power substations.But useful data can be acquired 200meters away from the interference sources.The curves of apparent resistivity and phase have an obvious segmentation character.The shape of the curve of each section is consistent to the adjacent section and the segmentation shows good correlation with geomorphologic features.NLCG inversion was performed on the CSAMT data along this profile to reveal the electric structure within the depth of 1km from the surface in the basin.The result shows that the Wutaishan northern piedmont fault zone consists of a set of north-dipping normal faults which decline down stepwise,verging toward the Daixian Basin.Because the CSAMT profile does not run through the whole Hengshan southern piedmont fault zone,only partial features of it are revealed,i.e.the southeast-dipping high-resistivity foot wall bedrock and low-resistivity hanging wall alluvial deposits are underlain by thin-bed low-resistivity flood deposits.Besides,it is found that the Daixian Basin is laterally inhomogeneous,corresponding to its topography,where the tilting alluvial-flood plain is underlain by low-resistivity layer and the resistivity below the alluvial plain is slightly higher.The application of CSAMT to the Daixian Basin indicates that this method can be used to determine the location,dip and size of faults,and provide reliable basic data for survey of active faults. |
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| Keywords: | controlled source audio-frequency magnetotellurics(CSAMT) electric structure fault Daixian Basin |
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