Abstract:
[Objective] This study aims to elucidate the present-day geothermal field, the evolution of geothermal fluids, and the differential heat-control mechanisms of the Kangding–Luhuo, Ganzi–Litang, and Batang geothermal belts in the western Sichuan Plateau. [Methods] we integrated field investigations and hydrochemical data from 55 hot springs and geothermal wells, temperature-logging data from 10 boreholes, geothermal-gradient and terrestrial heat-flow data from two wells, and thermophysical measurements of 43 rock samples, together with regional fault-distribution and deep seismic-velocity data. [Results] The results show that hot springs in the western Sichuan Plateau are mainly distributed in belts along major deep faults, including the Xianshuihe, Ganzi–Litang, and Jinsha River faults. Geothermal gradients range from 17.5 to 59.7 ℃/km, while terrestrial heat flow ranges from 50.8 to 116.2 mW/m
2, with an average of 77.2 mW/m
2, showing an overall pattern of higher values in the southwest and lower values in the northeast. The geothermal fluids are predominantly of the HCO
3-Na type and are mainly recharged by high-altitude meteoric water, with varying degrees of water–rock interaction and cation exchange during deep circulation. SiO
2 geothermometry indicates that reservoir temperatures are mainly concentrated between 100 and 180 ℃, with local values approaching or exceeding 200 ℃. [Conclusion] Overall, the high-temperature geothermal systems in western Sichuan are fault-controlled hydrothermal systems jointly governed by the regional thermal background, deep heat input, heat and fluid transport along major deep faults, and deep circulation of meteoric water. Regional comparison indicates that the Ganzi–Litang geothermal belt is characterized by relatively high terrestrial heat flow and a substantial crustal heat-flow contribution, together with relatively stable fault-controlled fluid transport. The Batang geothermal belt exhibits pronounced deep thermal anomalies and is mainly controlled by strong deep heat input and the coupled effects of the Jinsha River Fault and deeply incised valleys. In contrast, the Kangding–Luhuo geothermal belt has a comparatively lower regional thermal background, although activity of the Xianshuihe Fault and local frictional heating promote the localized accumulation of high-temperature geothermal fluids. Integration of geothermal manifestations and fault distribution suggests that the Ganzi–Litang and Batang geothermal belts have relatively favorable regional exploration potential for high-temperature geothermal resources, whereas the Kangding–Luhuo geothermal belt shows stronger localized potential, particularly at intersections of the main Xianshuihe Fault with subsidiary faults and in areas with concentrated high-temperature geothermal manifestations. [Significance] These results provide a basis for evaluating favorable areas and selecting exploration targets for high-temperature geothermal resources in western Sichuan.