Characteristics of geothermal resources in Wentang Gorge anticline of Chongqing

The Wentang Gorge anticline is one of the anticlines in the broom-shaped dome pleats of Huaying Mountain, with abundant geothermal water resources of natural hot springs and artificial hot springs. Through statistics and analysis of the water quantity, water quality and aquifers of geothermal drillings on both sides of the anticline, the authors have identified that its main thermal storage aquifers are Member 2 and Member 4 of Jialingjiang Formation, and its secondary thermal storage aquifers are Member 1 and Member 3 of Jialingjiang Formation. The main hydrochemical type is sulfate type, but the conditions in the two wings of the anticline are different. The equivalent concentration ratio of magnesium to calcium ions is less than 1, which indicates that the chemical composition of the geothermal water is mainly from limestone aquifer. The water quality and quantity were controlled by the geological structure. The Wentang Gorge anticline has the characteristic of layered structure which includes thermal reservoir cap rocks, thermal reservoir and lower thermal reservoir insulation and confining bed, and the thermal storage temperatures for the two wings of the anticline are similar. The thermal storage temperature is between 26.42 ℃ and 51.7 ℃ at 1 700-2 000 m depth according to the geophysical logging data, with an increasing trend from north to south. This research would provide some references and guide for further exploration and exploitation of thermal water resources in Wentang Gorge.