Chemical and isotopic characteristics and origins of thermal springs in the Jiangcang Basin, China

Abstract

Thermal springs in the Jiangcang Basin occur in a typical geothermal zone along the northeastern edge of the Qinghai-Tibet Plateau in the northern Qilian orogenic belt. The thermal spring water (TSW) in this region can be divided into three groups on the basis of temperature and salinity, but the origin and recharge-discharge mechanism of the geothermal fluid remain unclear. The chemical and isotopic characteristics of these thermal springs were studied, and the genesis of the thermal system hosted by deep-seated faults was assessed. The results indicate that the springs in this region are of meteoric origin and heated via deep circulation through well-developed faults. The TSW in the Datong River washland and in the southern part of the basin are derived from carbonate rocks recharged from Datong Mountain, whereas the TSW in the northern part of the basin originates from silicates recharged from Tuolai Mountain. Differences in the circulation depth, flow pathway, residence time, and mixing relationship with cold water lead to different TWS characteristics. The results are used to establish a conceptual model of the origins and circulation of the Jiangcang thermal springs. These findings provide a geological and scientific basis for the development and use of geothermal resources in the northeastern Qinghai-Tibet Plateau.