Study on the Heat Source Mechanism of Sedimentary Hdr by Hydrogeochemistry in the Gonghe Basin, China

Geothermal energy resources are abundant in the Qinghai Gonghe Basin, and helium isotopes indicate that the heat source of the basin's high-temperature geothermal system is crustal heat, with the overlying melt supplying the heat, but the melt genesis is still unclear .The composition of 87Sr/86Sr and δ2H and δ18O confirms that the hot water in the basin is recharged by atmospheric rainfall from the surrounding peaks at an elevation of 3500~5500m. Based on the comparison Compare with the typical mantle source thermal areas such as Yellowstone Park and Yangbajing, we found that the hot spring water of Gonghe Basin is peripheral water, not steam heating water or mantle source water. The Na-K-Mg trilinear map shows that the thermal storage temperature ranges from 140 to 240°C, indicating that the geothermal heating mode of the basin mainly relies on heat conduction, i.e. the deep heat source heats the rocks to form the dry heat rock, and the dry heat rock heats the geothermal water in the shallow area to form the high temperature geothermal system of the basin. Rare gas isotopes indicate that only about 5% of the basin heat comes from the mantle. Geothermal shows good matching with tectonics. The geothermal genesis model in the Gonghe Basin is a rapid uplift of deep rock masses due to high intensity tectonic activity, decompression and high temperature formation of melt.