Genetic mechanism of geothermal systems in western Mufushan based on multi-source data

The Mufushan area, located at the junction of Hunan, Hubei, and Jiangxi provinces, hosts seven identified geothermal anomaly zones, indicating significant potential for geothermal resource development. However, the genetic mechanism of geothermal formation in this region remains insufficiently understood, limiting further exploration and sustainable utilization. By integrating multi-source datasets including geothermal field measurements, geophysical surveys, drilling data, hydrogeochemical analyses, and isotope tracing, this study investigates the formation conditions and genetic mechanism of geothermal resources in the Changtan area of the western Mufushan. The results demonstrate that the spatial distributions of subsurface temperature and geothermal gradient are significantly controlled by fault structures, while vertical variations in temperature indicate that geothermal anomalies are mainly governed by thermal convection. The granitic rock mass is classified as a medium- to high-heat-producing rock, providing a stable basal heat source for geothermal development in the region. The V-shaped structural zone is characterized by well-developed fractures, high porosity, and strong permeability, offering favorable conditions for groundwater storage and hydrothermal exchange. Hydrogeochemical and isotopic evidence indicates that geothermal water has undergone deep circulation and is mainly recharged by atmospheric precipitation from high-elevation areas of Mufushan. Based on these findings, a genetic model is proposed: under the control of major faults (F1 and F2), meteoric water infiltrates through weathered fractures, converges and migrates downward along the fault zones. It is subsequently heated by deep convective circulation and radioactive heat, then ascends through highly permeable structural zones to form confined geothermal water reservoirs. This study provides valuable insights into geothermal geological research of the Mufushan area and offers guidance for future exploration and development. <sec><label/><title/><fig id="F1"><alternatives><graphic specific-use="print" href="./online/1000-2618-2025-42-6-641-F001.jpg" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="./online/1000-2618-2025-42-6-641-F001.jpg"/><graphic specific-use="online" href="./online/1000-2618-2025-42-6-641-F001c.jpg" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="./online/1000-2618-2025-42-6-641-F001c.jpg"/></alternatives></fig></sec>