Hydrogeochemical Characteristics and Genesis Analysis of High‐Salinity Geothermal Water in the Haihu New District, Xining City

The abundant geothermal resources of the Haihu New District of Xining City are significantly constrained in their development and utilization, as the geothermal water is characterized by high salinity. This study aimed to investigate the hydrogeochemical characteristics and genesis of geothermal water in the Haihu New District by analyzing water chemistry data from five geothermal wells using traditional hydrogeochemical methods, statistical analysis, isotope analysis, and geochemical simulations. The findings revealed the chemical characteristics of the geothermal water and identified its recharge sources, elevation, circulation depth, and reservoir temperature. Representative reaction pathways were selected to simulate water–rock interactions along the geothermal water flow path based on the genetic model of geothermal water and the analysis of rock mineral compositions. This study examined the dissolution and precipitation characteristics of rock minerals, elucidating the chemical genesis of geothermal water in the district. The results showed that (1) the analyzed geothermal waters reveal a significant salinity level and a mildly alkaline nature, with Na + as the dominant cation and SO 4 2− and Cl − as the dominant anions. For this reason, these waters can be classified as Na‐SO₄•Cl waters. (2) The geothermal system in the study area was classified as medium to low temperature. Atmospheric precipitation infiltrates from the Laji and Laoye mountains, with recharge elevations ranging from 2910 to 2980 m. The reservoir temperature is estimated to range from 52.40°C to 70.45°C, with circulation depths between 1000 and 1600 m. (3) The primary sources of Na + and Cl − in the geothermal water are halite dissolution and cation exchange, while SO 4 2− primarily originates from gypsum dissolution, with additional influence from H 2 S oxidation and the common ion effect. This study provides a comprehensive understanding of the hydrogeochemical characteristics and genesis mechanisms of the geothermal system in the Haihu New District, offering critical insights for the effective and sustainable development of geothermal resources in the region.