Chemical Geothermometry and Fluid-Mineral Equilibria for the ÷mer-Gecek Thermal Waters, Afyon Area, Turkey

Abstract

Thermal waters of the ÷mer-Gecek geothermal field, Turkey, with temperatures ranging from 32 to 92?C vary in chemical composition and total dissolved solid (TDS) contents. They are generally enriched in Na-Cl-HCO3 and suggest deep water circulation. Silica and cation geothermometers applied to the ÷mer-Gecek thermal waters yield reservoir temperatures of 75-155?C. It is concluded that the solubility of silica in most of the waters is controlled by the chalcedony phase. Equilibrium states of the ÷mer-Gecek thermal waters were studied by means of Na-K-Mg triangular diagram, activity diagram and saturation index (SI) diagrams. Most of the spring and low-temperature well waters in the area are classified as shallow or mixed waters which are likely to be equilibrated with calcite, chalcedony and kaolinite at predicted temperature ranges. Temperatures calculated using the chemical geothermometers are in the same range. It was also observed that mineral equilibrium in the ÷mer-Gecek waters is largely controlled by CO2 concentration.