A review of the geothermal system evolution and distribution in the Central Anatolian Crystalline Complex (Türkiye)

Türkiye is located in the Mediterranean sector of the Alpine-Himalayan tectonic belt and is among the foremost seven countries in the world having an abundance of geothermal resources. The Central Anatolian Crystalline Complex (CACC) is one of the most important geothermal regions in Türkiye. This study aims to evaluate the geothermal system of CACC using the geological, structural, and hydrogeochemical properties that were obtained from previous studies. The present study investigated and evaluated the hydrogeochemical and isotopic properties of 762 water samples belonging to 45 different localities from 41 scientific studies. The result shows that CACC has different heat sources and different hydrogeochemical processes. Major element chemistry of the water reveals that the geothermal fluids are mostly of the Ca - Mg - HCO3 , Na - Cl - HCO3 , and Ca-Cl water types. Silica geothermometers suggest that the reservoir temperature ranges from 48 to 180 °C. Based on the δ18O - δD relationship, water samples have a high-altitude meteoric origin. Stable isotopic data indicate that the geothermal fluids are formed by local recharge and deep circulation of meteoric waters.