| Abstract |
Geothermal uses in Korea have been primarily and traditionally provided in public baths, which are recently the most economic way. In Korea no geothermal energy has been yet utilized for electric power generation, nor will such plans be made in the near future. KIGAM (Korea Institute of Geology, Mining & Materials) not only plays a major role in geothermal investigations and research, but also is currently the unique governmental institute to continue geothermal studies and hot spring assessments. From 1992 to 1998, KIGAM conducted the analysis of U, Th, and K, mainly in granites and partially in sedimentary rocks from more than 200 outcrops, and measured about 149 thermal conductivities from fresh outcrops and drilling cores. Additionally, continuous temperature logs have been taken from over 350 boreholes nationwide (depth ranges from 150 to 1,500 meters). Heat flow rates can be estimated from the thermal gradients of the temperature logs and the neighboring heat production rates. The geothermal resources in Korea are mainly distributed in areas of granitic rocks, and the granite contribution is the major source of geothermal phenomena. The temperature measurements and isotopic analyses mentioned above are focused in these granitic areas, and its average value is somewhat higher than the average in nation-wide geothermal properties. Heat production rates in granites generally do not coincide with high geothermal potential areas. The high geothermal gradients, however, indicate the high geothermal potentials, and are mainly dependent on the local convective ground waters. Geological evidence shows that the geothermal waters in Korea should be considered as local convective ground waters without direct conduction of volcanism and tectonism. The deeply circulated ground waters in granites show higher temperatures near the surface, especially along and near the fracturesósuch as extention faultsóthan those showing normal geothermal gradients. |