喜马拉雅西北部逆冲带的地壳电性结构(英文)  

ELECTRICAL STRUCTURE ACROSS LESSER AND HIGHER NW HIMALAYA,INDIA

作　　者：K. VEERASWAMY K. K. ABDUL AZEEZ SHARANA BASAVA G. DHANUNJAY NAIDU T. HARINARAYANA 

机构地区：[1]National Geophysical Research Institute, Uppal Road, Hyderabad - 500 007, India (Council of Scientific and Industrial Research)

出　　处：《地球物理学报》2010年第3期576-584,共9页Chinese Journal of Geophysics

基　　金：funding support from Ministry of Non-conventional Renewable Energy, New Delhi

摘　　要：印度板块北部地形起伏较大的喜马拉雅山地区由几个构造互异的地质单元组成,依地形高、低把喜马拉雅碰撞带分成低喜马拉雅和高喜马拉雅.为了研究与主要逆冲带(含主缝合带MCT和主边界带MBT)有关的地壳电性结构,沿Rohtangpass(海拔4000 m)到Mandi(海拔400 m)剖面进行了MT探测.通过对16个测点观测资料的分析和考虑地形的二维反演,获得了沿剖面的二维电性结构.电性结构显示,在Chail和主逆冲边界带下方,东西走向的缝合带突然转向北.在下喜马拉雅的Rampur区段的元古代基底为范围较大的高阻体,而浅部地壳被逆冲带分成向北倾的电导性块体和电阻性块体.Chail逆冲带东侧低喜马拉雅Rampur区段的推挤和它西侧的基底脊柱体导致主边界带及相关的逆冲带(Kangra拐角)向北转弯,Kangra拐角处的应力可能是由于西侧基底脊柱体进入到Kangra区引起的.The Himalayas - worlds well known topographic feature in the northern part of Indian plate which is subdivided into several contras＇ting geological units separated by major tectonic contacts. Lesser and Higher Himalayas form major litho-tectonic units of Himalayan collision belt. The paper presents the electrical conductivity structure from MT investigations carried out in the NS direction across the above major thrust zones （MCT and MBT） lying in between Bilaspur and Rohtangpass situated at elevations of 400 m and 4000 m respectively. The data acquired from 16 MT soundings are analysed and inverted to obtain resistivity models using 2D inversion approach. As the area is characterised with topographic undulations, corresponding elevation values are also included in 2D inversion modelling. The results bring out conductivity regions under the Chail and main boundary thrust belts where E-W oriented MCT suddenly takes northward trend. A large resistive block characterizing the Proterozoic basement of the Rampur window in the Lower Himalayas has been delineated in the resistivity model in addition to shallow north dipping conductive and resistive blocks separated by thrust belts. The close proximity of the Rampur window of the Lesser Himalaya on the eastern side of the Chail thrust region and the basement ridges on the western side of the Chail thrust region would have contributed to the northward turn of MBT and associated thrust belts （Kangra reentrant）. The stresses for the reentrant could have been due to the basement ridges entering into the Kangra region.

关 键 词：喜马拉雅西北部 逆冲带 电导性结构 大地电磁 

分 类 号：P631[天文地球—地质矿产勘探] P541[天文地球—地质学]