Hydrogeochemistry and reservoir characterization of the Konya geothermal fields, Central Anatolia/Turkey

A conceptual model with water samples from ten geothermal fields (İsmil, Ilgın (Çavuşcugöl), Tuzlukçu-Akşehir, Seydişehir and Kavakköy, Hüyük, Ereğli-Akhüyük, Kadınhanı, Cihanbeyli, Karapınar and Beyşehir) in the province of Konya defined the geothermal system. Carbonates, quartzite and marbles of Paleozoic metamorphics are the reservoir rocks and the heating sources are igneous rock intrusions and geothermal gradient. The variable thermal water (CaMgHCO3, CaSO4, NaSO4, CaHCO3, CaNaHCO3, NaCl and CaNaClHCO3) had EC and temperature between 177.8 and 56,100 μS/cm and between 18.3 and 44 °C, respectively. Ca2+ in geothermal fluids are associated with marble and carbonate rocks and the high chloride shows direct connection with deep geothermal system, and prolonged contact with evaporite rocks. Sulphate originates from dissolution of and oxidation of sulphate and sulphur-bearing minerals. The high As, B, F and Mn concentration in some thermal water samples were determined as 85 μg/l, 148.56 mg/l, 3.01 mg/l and 208.13 mg/l, respectively. Reservoir temperatures computed by Na/K geothermometers were between 85.37–158.89 °C for Akşehir thermal waters and 58.78–90.45 °C for Ereğli thermal waters. The maximum reservoir temperature of other geothermal waters was 75 °C by the silica geothermometers.