Hydrochemical characteristics and genesis model of Yaoshuitan geothermal field in Huangzhong District, Xining City

Abstract

Abstract The Yaoshuitan geothermal field in Huangzhong District, Xining City, Qinghai Province, is located at the southern edge of the Xining Basin. The geothermal resources in this area belong to the uplifted mountain and limestone type, which are entirely different from the geothermal resource’s characteristics in the northern part of the Xining Basin. Studying its formation mechanism is of significant importance for guiding the search for geothermal resources in limestone regions. The results indicated that: (1) The study area is characterized as a small-scale, low-to-medium temperature geothermal field. Groundwater from wells YST1 and YST2 was measured at 41 °C, and the hydrochemical composition was classified as the HCO3-Ca·Mg type. (2) The geothermal water is primarily replenished by atmospheric precipitation from the southern Laji Mountains at elevations ranging from 3619.52 to 3797.52 m. The temperature of the thermal reservoir ranges from 56.52 to 67.34 °C. (3) The genesis model is as follows: The heat source is derived from heat flow in the lower crust and upper mantle. Due to the unique geological conditions of the region, no effective cap rock is present in the Yaoshuitan geothermal field. The thermal reservoir is primarily composed of carbonate rocks of the Kesuer Formation within the Jixian System.