Distribution and Aggregation Mechanism of Geothermal Energy in Gonghe Basin

Gonghe Basin of Qinghai Province, which locates in northern Tibetan Plateau, is a faulted basin formed since mesozoic era. Around the basin is controlled by large active faults; inside the basin is the accumulation of large thickness of Quaternary and Neogene strata, the exposed thickness is up to 900-1440m, and the substrate is formed by Indosinian granite. Exploration results display that the value of heat flow is high inside the basin. Besides, the basement granite geothermal gradient is greater than 5℃, thermal anomaly is obvious. According to the broad band seismic observation data on the Qinghai-Tibet Plateau, there is a 150km low-velocity zone on the east Kunlun orogen where Gonghe Basin lies in. It is associated with the mantle plume in deep mantle of the Bayan Har orogen, which is characterized by huge low-velocity abnormity. The low-velocity zone extends to the earth crust and forms an abnormal area of heat flux at different parts with 1-40km below the earth's surface in Gonghe Basin and its surroundings, accounting for the forming of geothermal energy based on abundant hot-dry rocks and geothermal water in shallow part of the basin. It is significant not only for the city's heating system but also for electricity generation.