| Title | Genetic Mechanism and Exploration Target of the Gulu Geothermal Field in Tibet, China |
|---|---|
| Authors | Song ZHANG, Hanping WAN, Weilin HAO, Honglei GAO, Zhihua HU, Jixing CHENG, Rujie WU, Liang SONG, Yu WU |
| Year | 2023 |
| Conference | World Geothermal Congress |
| Keywords | Gulu geothermal field, Genetic mechanism, Exploration target, Tibet |
| Abstract | Gulu geothermal field locates in the north place of Naqu-Nimu geothermal belt, which is the most important geothermal belt in Tibet. There are lots geothermal fields in the belt, including the famous Yangbajing geothermal field. In order to evaluate the geothermal resources, geological, hydrogeological and geophysical works were carried out. The regional residual gravity anomaly shows that there is a low gravity anomaly area in Gulu geothermal field. At the same time, there is a low resistivity anomaly zone, about 5-10 km below the surface. The low resistivity anomaly zone and the regional residual gravity anomaly may indicate that there is partial melt in the deep of the field, which constitutes the main heat source of the Gulu geothermal field. The the S-N striking fracture F4-2 is considered to control the thermal activities due to the fact that most hot spring spots occur along this fracture.The hydrogeological work shows that the hydrochemical type is mainly HCO3-·Cl-Na, salinity is from 2.2 g/L to 2.8 g/L. The content of fluorine in the hot water is more than 10 mg/L, indicating that it experienced deep circulation. According to the SiO2 geothermometer, the highest temperature of the geothermal reservoir in the deep is from 215 °C to 228 °C. There are two types of geothermal reservoirs in the field: banded geothermal reservoir and layered geothermal reservoir. The banded geothermal reservoir is controlled by the fracture F4-2, and located in the fracture F4-2, together with the joints of the hanging wall of F4-2. The sinter and the Quaternary is the cap of the geothermal reservoir. In the exploration area, the fault zone of F4-2 is the target of exploration; but outside the exploration area, the fault on the east side of the Gulu basin should be the paid more attention. |