Abstract:
The Tianshui area is located in the southeastern part of Gansu Province, with an average heat flow of 70.8 mW/m2, which is higher than the average heat flow value in mainland China. Currently, six hydrothermal geothermal fields have been discovered in this area, indicating promising prospects for geothermal exploration. However, the research foundation of geothermal resources in the Tianshui area remains relatively weak, lacking comprehensive studies and evaluations of its geological background, geothermal field characteristics, and the genesis model of the thermal regime. Based on extensive survey data and previous research, this study delineates the heat flow and geothermal gradient distribution patterns in the Tianshui area for the first time. The results show that the heat flow and geothermal gradient exhibit an overall characteristic of "higher in the southwest and lower in the northeast". The distribution of the present geothermal field is mainly controlled by fault structures, and the fluctuation of the basement also plays a role. The distribution of geothermal fields (hot springs) is fault-controlled, mostly occurring at the intersections of active fault zones. The primary heat source mechanism is deep circulation heating, where the well-developed fault structures facilitate heat and fluid transport. The thermal reservoir lithology is dominated by granite and metamorphic rocks, overlain by Neogene and Quaternary sedimentary sequences. Atmospheric precipitation is the main source of geothermal water supply. This study provides an overview of the current status of geothermal research in the Tianshui area, summarizes the existing problems and limitations, and proposes suggestions for future research directions. The findings can serve as a valuable reference for subsequent geothermal research and exploration activities in the Tianshui region.