Geothermal field of the Grodno region of the Republic of Belarus

Abstract

The geothermal field of the platform cover within the Grodno region is considered. The cover rests on a crystalline basement of Precambrian rocks. Temperature distribution maps for depths of 100; 200 and 300 m below ground level were compiled based on thermograms recorded in boreholes and were supplemented by the heat flow map. These reveal geothermal anomalies both of temperature and heat flow density distribution within the region. The temperature in the region monotonously increases with depth, while preserving the general features of the thermal field. The anomalies identified on the 100 m map persist for depths of 200 and 300 m. The main role in the formation of temperature anomalies is played by near-surface factors, such as groundwater circulation, and the influence of paleoclimatic changes on the Earth’s surface in the past. A low heat flow (< 30 mW/m 2 ) in the eastern part of the region gradually increases up to 50 mW/m 2 in the vicinity of Grodno. Its areal variation relates to the distribution of granitoid and blastomylonite rocks in the crystalline basement. Increased heat flow is typical of silicic rock massifs with elevated concentrations of long-living radioactive isotopes of uranium, thorium and potassium. Their decay creates an additional radiogenic component of heat flow.