Hydrological Processes of Hot Springs in Mountain Fault Zones Constrained by Geothermal Field: A Case Study in the Chuxiong Basin, <scp>SW</scp> China

ABSTRACT Understanding the genesis of hydrothermal systems necessitates a clear elucidation of both the deep geothermal field and hydrothermal activity. This study examines the formation mechanisms of the hydrothermal system in the Chuxiong Basin, located adjacent to the South Tibet‐West Yunnan, the largest high‐temperature geothermal belt in China. Through an integrated approach combining hydrochemical analyses and geothermal field characterisation, we clarify the hydrological processes that govern deep water–rock interactions and their influence on hydrochemical evolution, thereby uncovering the mechanisms responsible for geothermal formation. The results demonstrate that the hot springs, which are predominantly recharged by precipitation, are characterised by HCO 3 –Na hydrochemical facies. Despite the high regional heat flow (averaging 72.1 mW/m 2 ), Cenozoic and Cretaceous strata within the basin are shallowly buried and exhibit comparatively low temperatures. In contrast, Jurassic and Triassic strata reach considerably higher temperatures owing to their greater burial depth, particularly beneath the central part of the basin where Jurassic deposits exceed 3000 m in thickness. Deep‐seated faults play a critical role in controlling the spatial distribution of heat flow and act as conduits for the ascent of deep hydrothermal fluids. These findings reveal the establishment of a deep groundwater convective circulation system regulated by major fault structures, providing valuable insights for the development of high‐temperature geothermal resources.