Study on hydrochemical characteristics of underground hot water in typical granite thermal storage and hot water development model in Dabie Mountain, Anhui Province

The Dabie Orogenic Belt is rich in geothermal resources, while relevant research is insufficient. To further find out the reserves of geothermal resources and their sources in the Dabie Orogenic Belt, reveal the mechanism of thermal circulations, and conduct quantitative assessments of the recharge sources, temperature of thermal reservoirs and depth of thermal circulations in the research area, on basis of thorough understanding of the geological conditions of the geothermal resources in the Dabie Orogenic Belt, four groups of geothermal water samples and six groups of underground cold water samples were collected in Xifei Geothermal Field for quantitative calculation, so as to test the hydrochemical characteristics and analyse the evolution process of geothermal water. The calculation results show that the geothermal water in Xifei Geothermal Field can be classified into SO4–Na type, and the main anions and cations in it derive from the dissolution of silicate and gypsum minerals. The data of δD and δ18O shows that the geothermal water is mainly recharged by the percolation of meteoric water. The temperature of geothermal reservoirs calculated with quartz and chalcedony geo-thermometers and by simulated multi-mineral equilibrium ranges from 85.05 to 116.31 °C.