Basin-Mountain Coupling Relationship In The Northeastern Tibetan Plateau: Evidence From The Thermal History of Hot Dry Rocks In The Gonghe Basin

The Gonghe basin is located within the interjunction of the Qinling, Qilian, and Kunlun orogenic belts, records complex tectonic, magmatic, metamorphic and sedimentary events, and is an ideal area for studying basin-mountain coupling process and tectono-thermal evolution in the northern part of the Tibetan Plateau. In recent years, the discovery of high-temperature hot dry rocks (HDR) in Gonghe basin makes this area a strategic base of new geothermal resources. In order to study the thermal history processes and heat source mechanisms of HDR in the Gonghe basin, we carried out systematic low-temperature thermal chronology study using deep drilling cores and outcrop samples from the northeastern part of the basin, and combined the results of petrology, zircon U-Pb geochronology, mineral thermobarometer and obtained the tectonic-thermal evolutionary history of the basin during Mesozoic-Cenozoic. The thermochronology results of deep drilling core samples record rapid heating process and slow heating process from the middle Miocene to present, which may be the main reason for the formation of high temperature hot dry rocks in the Gonghe basin. The Indosinian granites in the deep of the Gonghe basin and outcrops have experienced obvious thermal events during the Middle Miocene-Late Miocene (15 Ma~5 Ma), and show completely different thermal history, with cooling uplift in the outcrop area and heating in the deep of the basin. The thermal history of HDR suggest that the heating process is related to basin development process. Combined with the tectonic events around the Gonghe basin, the tectonic thermal events of HDR experienced responded to the stronger tectonic activities in the northeastern margin of the Tibetan Plateau and related to the NE-direction expansion and deformation of the Tibetan Plateau during this period. The heat source mechanism of hot dry rocks in the Gonghe Basin is related to mantle upwelling, which resulted in the middle and lower crust partial melt bodies. They constitute the regional and local heat source of HDR and formed a short-path and multi-source heating model.