The electrical conductivity structure of the Tarim basin in NW China as revealed by three-dimensional magnetotelluric inversion

Abstract

The Tarim basin, located in northwestern China, is the largest inland basin with oil, gas, and mineral resources in China. To study the deep structure of the Tarim basin, we conducted a magnetotelluric (MT) survey of the entire basin using 756 datasets to build a three-dimensional (3-D) electrical conductivity model. Based on the initial 3-D model, which was derived from a two-dimensional (2-D) minimum support gradient (MSG) inversion, the electrical conductivity structure of the Tarim basin was imaged by a 3-D MT regularized inversion using the contracting integral equation method (CIE) and quasi-Newton optimization. Based on simulation results, a thick resistive anomaly exists near the center of the Tarim basin, which suggests that the basin has the properties of a cratonic basin. The basin is also surrounded by resistive lithosphere faults, which indicates that it has the properties of a fault basin. The crystalline basement of the Tarim basin is divided into a resistive craton basement, high resistance basalt basement, and conductive crevice water metamorphic basement based on the shallow resistivity structure. In addition, the lithospheric thickness was estimated using the deeper resistive structure.