Hydrogeological and hydrochemical studies of the Kaman-Savcili-Büyükoba (Kirsehir) geothermal area, Turkey

The Savcili-Büyükoba (Kirsehir) geothermal area is located in Central Anatolia, about 150 km southeast of Ankara and 5 km north of the Hirfanli Dam. The Savcili-Büyükoba geothermal area is controlled mainly by NE-SW and NW-SE faults. Thermal waters emerge at the intersection of faults. The temperature of the thermal waters in the field varies from 30.0 to 34.6 °C and the electrical conductivity ranges from 513 to 565 μS/cm. The hydrochemical facies of the thermal waters are of the Na-Cl type and those of cold waters are of the Ca-HCO3 type with respect to the ion concentrations. The thermal waters of the study area plot along the Local Meteoric Water Line (LMWL), and this suggests that the geothermal waters are of a meteoric origin. The low tritium concentrations of the thermal waters show that the thermal aquifer of the Savcili-Büyükoba geothermal area is recharged by groundwater that has a relatively long residence time, which indicates a deep groundwater circulation system. The temperature of the reservoir was calculated to be 68-74 °C using silica geothermometry.