Deep electrical structure of Qilian to Alxa block in northeastern margin of Qinghai-Tibet Plateau and its geological significance
In order to obtain the deep electrical structure of the Qilian orogenic belt to the Alxa block and to study the deformation characteristics of Qilian orogenic belt and Alax block,a large-scale northeast-tending Magnetotellurics(MT)profile was acquired from Tianzhu,Gansu to Alxa Zuoqi.The deep electrical structure model was obtained,and the 2-D MT data inversion modeling from 48 receiver sites.The result show that the lower crust of the middle of the Qilian-Alxa area is characterized by a low-resistivity deformation belt which suggests that the north-eastward extension of the Qinghai-Tibetan Plateau has reached the northeastern edge of the Qilian-Alxa area.The north Qilian fault zone along the lower crustal low-resistivity belt is a thrust fault with a"ramp-flat"structure and developed secondary faults with propagation propagation northward.The southern margin of the Alxa block moves slowly to the east due to the consumption of strike-slip separation along the fault.In addition,the deep electrical structural characteristics combined with the previous geochronology data show that the Qilian fault belt in the northeast margin of the Tibetan Plateau formed the present basin-mountain tectonic pattern by the sequential way thrust extension deformation of the"ramp-flat"structure,which reflects the deformation characteristics of different stages since the Miocene,and reveals the complex thrust deformation mechanism of the northeast margin of the Tibetan Plateau.
NETL
NSTL
万方数据
