Hydrogeochemical characteristics of the thermal and non-thermal waters in the western side of the Sultandag Massif, SW Turkey

Thermal, non-thermal, and mineral waters of different hydrogeochemical properties can be found along the same tectonic region on the western side of the Sultandag Massif in Southwestern Turkey. A total of eight representative water samples were taken from the thermal, non-thermal, and mineral waters in the study area. The waters in the study area are divided into 3 different facies: (i) Ca-Mg-HCO3, (ii) Ca-Mg-HCO3-SO4, and (iii) Ca-Mg-SO4-(HCO3). Major hydrogeochemical processes that control the chemical composition of waters in the region are carbonate and silicate weathering. Thermal and mineral waters in the region have high dissolved ion content due to intense water-rock interaction. The surface temperatures of geothermal waters were found to be between 22.1 and 33.9 degrees C, and reservoir temperatures, which ranged between 30 and 84 degrees C, were calculated according to geothermometer evaluation. The heat source of the thermal waters in the study area is thought to be related to the geothermal gradient. Using the Curie point depth (D-CPD: 17 km) and Curie point depth temperature (T-CPD: 580 degrees C) data, the geothermal gradient and heat flow in the region were determined to be 34.12 degrees C/km and 71.65 mW/m(2), respectively. Based on these data, it is determined that the waters come from a depth of 1.50-2.47 km.