Research on relationship between the deep structure and geothermal resource distribution in the Northeastern Tibetan Plateau

Large number of geothermal fields are distributed on the margin and inside of the Tibetan Plateau, such as Gonghe-Guide geothermal field, Zhangye geothermal field, Tianshui geothermal field and Tengchong geothermal field. All these geothermal fields are basically characterized by zonal distribution along the Tibetan Plateau and systematically controlled by its tectonic activities. The analysis on multiple geothermal fields shows that they all have a deep heat source with vertical upward heating conduction through favorable channels from deep faults to their secondary faults. It is revealed that several channel flows exist under the deep Tibetan Plateau and are remarkably shown in geophysical data like the seismic tomographic imaging and teleseismic P-wave travel time tomography. It has also been verified by petrologic evidence that the low-velocity and high conductive layer beneath the crust of the Mid-Northern Tibetan Plateau is a partial melting layer. In view of geothermal fields distributed along the channel flow and combined with other research results, it is believed that the channel flows not only act as heating resources, but also form significant abnormal zones of terrestrial heat flow. In the area of channel flows, crust is thinned, structural activities are intensified, which enables heat to be easily transferred upward. According to comprehensive analysis, the relationship model of geothermal distribution and channel flow, and the geothermal field model related to channel flow are preliminarily established. It is believed that geothermal fields distributed in the northeast margin of the Tibetan Plateau are controlled by the channel flow in the deep crust. Through the analysis of the prospect of geothermal resources in this area, it is suggested that the Tianshui area in Gansu Province is located at the intersection of channel flows, and has great potential for prospecting of geothermal resources.