In the secondary metamorphic rocks and fault fracture zones of Kuanping Group in this area, fractures are developed and connectivity is good. These faults with good connectivity provide a medium for precipitation infiltration and confluence with deep faults. In addition, the cracks in the loess of the secondary thrust fault of the piedmont fault are also well developed, and the precipitation can penetrate into the deep fault. Because precipitation seeps into loess, it is easy to take away some chemical elements, which has certain influence on the composition and content of chemical elements in hot springs.
The thermal anomaly area in this area is closely related to the structural distribution, and five faults (including hidden faults) are densely distributed in the thermal anomaly area.
Fracture), the abnormal center is the intersection of piedmont fault and concealed fault, that is, the hot spring exposure. Moreover, the current activity of active faults also affects the temperature of hot springs. At present, the piedmont fault activity in the northern slope of Qinling Mountains is stronger than that in the northern platform of Weihe Basin, and the heat source conduction is active, so the hot spring temperature in this area is higher than that in the northern platform of Weihe Basin. Geothermal energy is more obvious at the intersection of active faults.
The water source of hot springs in this area is atmospheric precipitation, and the recharge area is mainly Kuanping Group south of piedmont fault. Because of the large recharge area and abundant precipitation, there is plenty of water.
It usually takes several years for atmospheric precipitation to penetrate deep faults through cracks and then further penetrate into deep water circulation. During this period, the fault zone provides a large enough energy and material exchange surface for the deep atmospheric precipitation, so that it can fully interact with the surrounding rock, thus increasing the temperature and obtaining the corresponding chemical composition.
Rock fracture is the strongest at the intersection of faults, and the degree of fracture development is high, which provides a good channel for the overflow of hot water.
Structural control of hot springs
Except precipitation, the formation conditions of Tangyu Hot Springs are almost all controlled by structure. Atmospheric precipitation seeps along the fault with good connectivity, flows into the deep fault, and penetrates deeper. In the process of infiltration, the salinity and temperature of water will change. After the water penetrates into the deep fault to a certain depth, it has enough time and energy, and the material exchange surface carries out chemical reaction and heat exchange with the surrounding rock, so that the water can obtain higher salinity and temperature. After the above process, underground hot water finally rises to the surface, forming hot springs. The exposure of this hot spring depends on the thermal anomaly and the vertical overlap between the active fault and the low terrain intersection zone.