Geothermal fluid characteristics and evolution process in Western Sichuan

The characteristics and evolution law of groundwater can reveal the deep geothermal process, which is of great significance to the development and utilization of groundwater resources. There are abundant geothermal water resources in Western Sichuan, but the degree of research is low. 24 hot springs in two geothermal fields in Batang and Litang areas were selected for hydrochemical analysis and hydrogen and oxygen isotope analysis. Besides, the temperature of thermal reservoir is calculated and the upflow cooling process of hot springs is analyzed. Finally, the water-rock interaction of hot springs in underground is simulated.The results show that most of the hydrochemical types of underground hot water in Batang and Litang areas in Western Sichuan are HCO3-Na type, and there are very few groundwater of HCO3-SO4-Na type in Litang area.Ion variation in Batang area is mainly affected by water-rock interaction, and there is a good positive correlation between Na + and B and Cl in Litang area, indicating that they have the same material source.The content of Na+ and metaboric acid is relatively high, which indicates that the groundwater runoff in the two areas is relatively long and the flow velocity is slow, and the content of metasilicic acid is relatively high also confirms this situation.Hydrogen and oxygen isotopes are basically near the atmospheric precipitation line, indicating that groundwater recharge is basically precipitation.The geochemical temperature scales were used to calculate the thermal storage temperatures of Batang (88 ~ 199Ž) and Litang (96 ~ 154Ž).The chemical composition of hot spring water in Batang area is mainly affected by the dissolution of albite and calcite and the precipitation of silicate. By studying the characteristics and evolution process of groundwater hot water in Western Sichuan, this paper provides guidance for the sustainable development and utilization of groundwater in this area