Geochemical response of deep geothermal processes in the Litang region, Western Sichuan

摘要

The geochemical characteristics of geothermically heated water can reveal deep geothermal processes, leading to a better understanding of geothermal system genesis and providing guidance for improved development and utilization of such resources. Hydrochemical and hydrogen oxygen isotope analysis of two geothermal field (district) hot springs based on regional geothermal conditions revealed that the thermal water in the Litang region is primarily of the HCO3Na type. The positive correlations found between F-, Li2+, As+, and Cl- indicated a common origin, and the relatively high Na+ and metaboric acid concentrations suggested a relatively long groundwater recharge time and a slow flow rate. The values of delta D and delta O-18 were well distributed along the local meteoric line, indicating a groundwater recharge essentially driven by precipitation. The thermal reservoir temperature (152 degrees C-195 degrees C) and thermal cycle depth (3156-4070 m) were calculated, and the cold water mixing ratio (60%-68%) was obtained using the silica-enthalpy model. Finally, hydrogeochemical pathway simulation was used to analyze the evolution of geothermal water in the region. The results were further supported by the high metasilicate content in the region. Of the geothermal fields in the region, it was found that the Kahui is primarily affected by albite, calcite precipitation, and silicate, while the Gezha field is primarily affected by calcite dissolution, dolomite precipitation, and silicate.