摘要
内蒙古额济纳旗东北部雅干断裂带的空间展布及深部构造特征一直存在争议。本文按照“由已知到未知”的研究思路,在研究区内完成5条大地电磁测深剖面,首先对研究区内西侧大地电磁剖面MT01的电性结构特征与剖面区段内所出露的雅干断裂带地质构造信息之间的关系进行了深入分析,确定了雅干断裂带的电性特征表现为“北倾+大倾角+大深度”的电阻率梯级带,并以此作为特征标志,结合区内东侧覆盖区内4条MT剖面(MT02~MT05)反演解释结果,识别出各剖面区段内雅干断裂带的深部位置及构造特征。同时,采用阻抗张量分解技术获得了各条MT剖面的电性主轴方向,结合二维反演解释结果确定了雅干断裂带空间走向。结果表明,研究区内雅干断裂带在浅地表处总体走向为近EW向(深部为NE45°),平均宽度约6.8 km,是一条由西向东且逐渐向北弧形偏转的逆断层,断层倾向总体向北,断层倾角60°~67°,断层深度约20 km。本文所获得的深部电性结构模型有效地揭示了研究区内深部构造特征,对于区域构造演化研究具有一定的参考意义。
There exists a continued debate concerning the spatial distribution and deep structural characteristics of the Yagan fault zone in northeastern Ejina Banner,Inner Mongolia.Adhering to the known-to-unknown research approach,this study completed five magnetotelluric sounding(MT)profiles.First,it delved into the relationship between the electrical structure characteristics of a MT profile(MT01)on the west side of the study area and the geological structure information of the Yagan fault zone within the profile.In terms of electrical characteristics,the Yagan fault zone was determined as a resistivity gradient zone characterized by northward dip,high dip angles,and deep depths.Based on these characteristics,and combined with the inversion interpretation results of four MT profiles(MT02~MT05)on the east side,this study identified the deep positions and structural characteristics of the Yagan fault zone within all the MT profiles.Moreover,it determined the major electrical directions of all the MT profiles using the impedance tensor decomposition technique,and the spatial trend of the Yagan fault zone based on the two-dimensional inversion interpretation results.As revealed by the results,the Yagan fault zone within the study area exhibits an overall nearly EW strike at the shallow surface and a strike of NE45°in the deep part,with an average width of approximately 6.8 km.It is a reverse fault with a gradual arc deflection to the north from west to east,manifesting a generally northward dip direction,dip angles ranging from 60°to 67°,and a fault depth of about 20 km.The obtained deep electrical structure model effectively reveals the deep structural characteristics of the study area.providing certain reference significance for the study of regional tectonic evolution.
作者
王文杰
陈磊
雷聪聪
石晓峰
杨彪
王文宝
孙大鹏
徐浩清
WANG Wen-Jie;CHEN Lei;LEI Cong-Cong;SHI Xiao-Feng;YANG Biao;WANG Wen-Bao;SUN Da-Peng;XU Hao-Qing(Hohhot General Survey of Natural Resources Center,China Geological Survey,Hohhot 010200,China;Chinese Academy of Geological Sciences,Beijing 100083,China)
出处
《物探与化探》
CAS
2024年第3期640-650,共11页
Geophysical and Geochemical Exploration
基金
中国地质调查局项目“内蒙古自治区额济纳旗辉森乌拉等三幅1∶5万区域地质调查”(DD20230252)。
关键词
额济纳旗
雅干断裂带
大地电磁测深
电性结构特征
Ejina Banner
Yagan fault zone
magnetotelluric sounding(MT)
electrical structure characteristics
