Crustal Electrical Structure of the Zhaheba Complex Imaged by Magnetotelluric Data and Its Tectonic Implications

Abstract

A Magnetotelluric profile stretching northward from the Wulungu Depression (on the northern margin of the Junggar Basin) to the Dulate arc (crossing the Zhaheba–Aermantai ophiolite belt) was carried out in an attempt to probe the crustal structure and properties of the East Junggar, NW China. Along the profile, the inversion model was used to determine the electrical structure of the crust and uppermost mantle. The results revealed that the crust of the eastern Junggar Basin is composed of the shallow low resistivity layer and underlying high resistivity bodies. There is a crustal detachment in the basement: the upper layer is a Hercynian folded basement and the lower is a Precambrian basement. The Zhaheba complex is characterized by relatively high resistivity, with a thickness of ~5 km, the bottom controlled by the Zhaheba–Aermantai fault. The crust of the Yemaquan arc is composed of the residual continental crust, characterized by stable resistance. The exposed intrusive rocks are characterized by irregular resistors. The crust of the Dulate arc is characterized by relatively low resistivity. The shallow low resistivity layers represent the Zhaheba depression composed of the Devonian-Permian volcanic and sedimentary rocks. The crustal conductive anomalies are related to the magmatism and mechanism of metal deposits in the post-collision period.