Study On Electrical Structure Of Middle Section And Lithosphere In Gangdise

Since the formation of the Qinghai-Tibet Plateau, from the south to the north to form the Himalayan terrane,Brahmaputra suture zone,Lhasa - Gangdise terrane, Ban Gong - Nujiang suture zone, Qiangtang terrane and other geological units and boundaries. The collision between the Indian plate and the two plates of the Asia-Europe plate is of great importance for the formation of the suture zone and the evolution of the terrane. In this paper, relying on the project "Gangdese earth magneto-profile survey and lithosphere electrical structure research", select the main research area for the Yarlung Zangbojiang suture north, Bang Gong - Nujiang suture south of Gangdise terrane. The geomagnetic sounding section of the Yarlung Zangbojiang suture zone and the Bangong-Nujiang suture zone was designed. The advanced geomagnetic data of the collected geomagnetic data were used to analyze the two-dimensional deviation of the data points, the magnetic induction vector and the phase tensor decomposition. After the process, two-dimensional inversion and three-dimensional inversion are carried out in the region, and the deep electrical.structure model of the Gangdese terrane is obtained.The model shows that the whole section has the characteristics of "horizontal block, longitudinal stratification". The electrical structure of the study area is divided into three electrical layers from shallow to deep: the first layer is mainly composed of discontinuous high resistivity, and the average buried depth is about 20km-30km. The middle and lower crust of the second layer began to exist in the Yarlung Zangbojiang suture zone, and the thickness of the north and north gradually increased, and the high conductor on the south side of the Bangong-Nujiang suture zone extended to the upper mantle. The lower crust and upper mantle are mainly high resistivity. According to the electrical structure model of the electrical gradient zone and the characteristics of high conductivity layer, combined with geological data division of geological units.The deep structural features of the Himalayan terrane, Gangdise terrane and Qiangtang terrane are analyzed and illustrated by the characteristics of the electrical structural model. The results of the three-dimensional inversion of the 500-line and the profile are concluded: the electrical structure of the east-west side of the Bangong-Nujiang suture zone is consistent, indicating that the Gangdese terrane, the high-resistivity and the high- To the connectivity.The high resistance layer of the upper crust of Gangdise may be the performance of large-scale shallow igneous rocks in Gangdise, which is related to the large-scale magmatic movement in the early stage. In the presence of the gangue-Nujiang suture zone along the depths of the deep high-resistance, speculation may occur in the event of magma after the cooling effect of the formation of large-scale rock. There is a continuous high conductivity layer in the high resistivity, which may be the result of the interaction of the water and the melt.