| Abstract:The Tianshui area is located in the southeast of Gansu Province. It is rich in geothermal resources and is a favorable prospective area for geothermal exploration in Gansu Province. As a critical parameter characterizing the thermal state, terrestrial heat flow is the most fundamental data for evaluating geothermal resources in a given area. However, relevant research in the Tianshui region is relatively weak, and there is a scarcity of heat flow data, making it difficult to characterize the regional geothermal field in this area. To address this deficiency, this study measured the thermal properties of different rock types in the Tianshui area. By combining the existing data on Moho temperature and depth, as well as the corresponding crustal stratification in the region, new heat flow values were calculated, and a terrestrial heat flow contour map was generated. Based on these results, the spatial distribution characteristics of terrestrial heat flow and the mechainisms behind thermal anomalies were discussed. The study revealed that the heat flow in Tianshui area exhibits a spatial distribution trend of "high in the southwest and low in the northeast". The mechanism for thermal anomalies in the central and southern regions is hypothesized to be related to the upwelling of high-temperature materials due to the uplift of the asthenosphere and basal subduction in this region. These thermal materials form a low-velocity, high-conductivity layer in the shallow crust, which acts as a heat source, leading to the formation of thermal anomalies at the surface.The mechanism for thermal anomalies in the western region is speculated to be caused by the weak material flow from the Qinghai-Tibet Plateau that passes through the middle to lower crust of the Qinling Mountains and reaches the western Tianshui area, inducing thermal anomalies in this region.Additionally, the spatial distribution of faults in the study area shows a notable correlation with areas of high geothermal flux and hot spring outcrops. The deep fault zone along the northern margin of the western Qinling Mountains serves as a primary thermal conduction pathway, facilitating the transfer of deep heat materials and heat to the shallow crust. Furthermore, relative shear movements between blocks may also generate additional heat. |
