Study on the resistivity structure and geothermal genesis mechanism of Gudui geothermal field in Tibet, China

The Gudui geothermal field, situated in the Shannan region of Tibet, is classified as a shallow high-temperature hydrothermal field controlled by faults. Geothermal wells in this field can reach temperatures of up to 205 C-degrees at a depth of 230 m, making it the highest recorded temperature for geothermal fields in China at that depth. However, the precise nature of the faults and subsurface structures within the Gudui geothermal field remains poorly understood. Therefore, to gain a deeper understanding of the structure and geothermal genesis mechanism of this field, a total of 361 audio magnetotelluric (AMT) stations were deployed, and the observed data was inverted to establish a large-scale three-dimensional resistivity structure of the study region. The obtained resistivity structure revealed multiple geothermal reservoirs underlying the Gudui geothermal field. Additionally, this structure also provided insights into the dip direction of faults, which serve as channels for water and heat flow. Furthermore, through the analysis of other existing magnetotelluric (MT) data and earthquake distribution, we were able to infer that the deep heat source of the Gudui geothermal field is a high-temperature partial melting body located approximately 5 km below the surface. The high-temperature partial melting body may originate from deep crustal heat flow. Finally, we conducted a brief discussion on the potential existence of other geothermal types in the Gudui region.