Hydrogeochemical characteristics and trace element of geothermal systems in Central Anatolia, Turkey

Abstract

Located on the Alpine–Himalayan orogenic belt, Turkey has an outstanding geothermal potential due to geothermal systems developed by young tectonic and volcanic activity. In particular, Central Anatolia is Turkey's geopolitical region with the second-greatest potential in terms of geothermal resources. In a contribution to hydrogeochemical studies performed in a limited part of Central Anatolia, we designed a study to determine the hydrogeological and hydrogeochemical properties of the geothermal fields located in provinces within the region's Konya Plain Project (KOP)-Aksaray, Karaman, Kırıkkale, Kırşehir, Konya, Niğde, Nevşehir and Yozgat-which collectively occupy 12.2% of Turkey's total area and contain 39 geothermal fields. In the study area, geothermal fluids are used for tourism, greenhouse cultivation, city heating and industrial purposes, and the outlet temperatures of thermal waters were recorded to range from 21.0 to 105.5 °C. In the study area, there are four different water types as (i) CaMgHCO3, CaHCO3, (ii) CaNaHCO3Cl, (iii) NaCaClSO4 and (iv) NaCl and reservoir rocks were generally Palaeozoic metamorphic (i.e. marble) and/or igneous (i.e. granodiorite, granite and rhyolites). Chemical geothermometers (i.e. cation and silica) were used to determine the reservoir temperature of the geothermal waters.