Hydrochemical Interpretation of Kangding Geothermal System Formation Mechanism, Sichuan, China

To better understand the hydrothermal heterogeneity of the Kangding geothermal system in western Sichuan, this study conducts a comparative analysis of three representative hydrothermal zones: Yulingong, Zhonggu-Reshuitang, and Erdaoqiao. By integrating hydrogeochemistry, application of isotopes, and geothermometry, this study systematically elucidates the formation mechanisms of geothermal waters and the genetic model of the Kangding geothermal system. The results reveal distinct hydrochemical types among the three areas: The geothermal waters exhibit distinct hydrochemical facies, with Zhonggu-Reshuitang being HCO3–Na type, Erdaoqiao as HCO3–Ca·Mg type, and Yulingong showing mixed types including HCO3–Na, Cl–Na, and HCO3·Cl–Na. The geothermal waters of Yulingong and Zhonggu-Reshuitang exhibit clear signals of deep magmatic fluid input, deeper circulation pathways, and higher reservoir temperatures, whereas the involvement of magmatic components in the Erdaoqiao hot springs remains uncertain. Consequently, the Zhonggu-Reshuitang and Yulingong hot springs are interpreted to originate from the mixing of parent geothermal fluids containing magmatic components with shallow cold water. This comparative study sheds light on the relationship between geothermal reservoir types and system evolution, and provides a scientific basis for the rational development and efficient management of regional geothermal resources.