Geological aspects of thermal water occurrences in Hungary

Abstract

In Hungary geothermal resources are in the form of low enthalpy waters within Pliocene - Upper Pannonian reservoirs consisting of sand and sandstone series, and within fractured carbonate rocks mainly of Triassic age. These low temperature reservoirs, maximum water temperature is about 100°C, are presumably heated by conduction and little is known about the nature of the heat source. Geothermal phenomena are controlled primarily by sub-crustal magmatic processes and secondarily by other geologic factors such as tectonics, sedimentation, compaction. Due to a particular crustal structure, the resulting geothermal anomaly accompanied by favorable hydrogeologic conditions, allows an abundance of thermal waters in many parts of the country, particularly in the SE part of the Great Hungarian Plain. For the time being there are more than 450 thermal water wells producing waters warmer than 35°C in Hungary.