Genetic Mechanism of Geothermal Anomaly in the Gaoyang Uplift of the Jizhong Depression

Abstract

The Gaoyang uplift is rich in geothermal resources, but there are few studies on the regional geothermal genetic mechanism. A large number of geothermal wells fail in position calculation because of a shortage of basis. By using the methods of P-wave velocity structure imaging and magnetotelluric sounding, it draws the following conclusions: 1) The crustal thickness in the Gaoyang uplift area is relatively thin, about 32 km; 2) The cutting depth of the Gaoyang East fault exceeds 28 km and has reached the bottom of the lower crust. It is a large tensile fault that provides a channel for mantle heat flow into the shallow crust; 3) The Gaoyang uplift and its surrounding depressions form a concave-convex base fluctuation mode, which is conducive to the accumulation of heat flow to the uplift; 4) The deep carbonate thermal reservoir in the Gaoyang uplift is overlaid with Cenozoic sand and mudstone strata, with a thickness of more than 3000 m and low thermal conductivity, which is conducive to the preservation of thermal storage heat. Therefore, the shortening of the heat conduction path caused by regional crustal thinning, convective heat conduction of large faults, concave-convex structure, and thick Cenozoic caprock are the reasons why the heat reservoir temperature in the Gaoyang uplift is higher than that around, which provides a theoretical basis for geothermal development and utilization.