Geothermal geological characteristics and genesis of hot water in the central mountain area of Shandong Province

There are hot water resources distributed in Laiwu Depression, Dongping Uplift and Xinfushan Uplift of the fifth grade structural unit in the central mountain area of Shandong Province.It is found that the burial depth of hot water, the type of thermal reservoir and the genetic mechanism are varied in different structural positions.Based on the temperature measurement data of typical geothermal wells, the hydrochemical composition and isotope comparative analysis of hot water with other types of water, the authors studied and calculated the geothermal geological characteristics, hot water genesis and thermal storage temperature value.The results show that the precipitation is the source of hot water supply.The chemical types of the hot water in this area are SO₄-Na·Ca and SO₄·R-Na·Ca(R standing for Cl or HCO₃), with low δ ¹⁸O and δ D values compared with other waters.The calculated temperature value of each heat storage is lower than 100℃, suggesting a medium low temperature heat storage.The hot water is immature water, which indicates that the water rock interaction of geothermal water has not reached the ion equilibrium state, the dissolution is still in progress, or the hot water is mixed by exogenous cold water.The Lengjiazhuang geothermal system in the basin belongs to the heat conduction type, and the Anjiazhuang and Qiaogou geothermal systems in the basin margin uplifts belong to the thermal convection type.The research results provide a theoretical basis for the development of geothermal water resources in the central mountain area of Shandong Province.