APPLICATION OF COMPREHENSIVE GEOPHYSICAL PROSPECTING IN DEEP BRINE POTASSIUM DEPOSIT EXPLORATION IN SALT LAKE OF QAIDAM BASIN

Qaidam Basin in Qinghai Province is a well-known potash fertilizer production base as well as major producer of salt minerals in China. The previous exploration mainly focused on the Quaternary shallow salt minerals, while the work on the Quaternary deep part and Paleogene-Neogene brine potash deposit was not enough, and the situation of resources is still unknown. Due to the high salinity of shallow brine in salt lake area, the resistivity method will have a serious low resistance shielding effect, thus affecting its detection depth and causing great limitations for application of geophysical methods. To find out the deep brine potassium mineral resources in the area, the transient electromagnetic method (TEM) with high sensitivity to low resistance, strong signal intensity and high vertical-lateral resolution, combined with the magnetotelluric sounding (MT) with large exploration depth, is used to explore the deep brine potassium deposit. The exploration results identify the relatively low resistivity anomaly area, and the detection results are reliable through later drilling verification, indicating that the geophysical methods of TEM and MT are effective in exploration of deep brine potassium deposit in salt lake areas, which reveals good prospects of the two methods in exploration of deep potassium resources in salt lake areas.