| Abstract |
The study area is located in southern rims of the Gediz Graben in Western Anatolia region in Turkey. In this study, geothermal and hydrochemical characteristics of thermal waters in the Salihli geothermal fields are described. Thesegeothermal fields are geographically divided into four main groups; Kursunlu, Caferbey, Ufuruk and Sart-Çamur geothermal fields. In the study area, the thermal waters have outlet temperatures between 30-55°C in springs and from 51°C to 155°C in wells. However, their discharges are between 2-80 l/s from springs or wells. According to IAH (International Association of Hydrogeologists), chemical classifications, waters in the study area reflect the water types of Na-HCO3, Ca-Mg-HCO3, Ca-Na-HCO3 and Ca-Mg-SO4 in Kursunlu, Caferbey, Sart-Çamur and Ufuruk, respectively. Cold waters are mainly dominated by the HCO3 and SO4 anions and Na, Ca and Mg cations. Kursunlu geothermal field is one of the most important geothermal areas in the Gediz Graben on the basis of location and potential. It has a shallow reservoir about 250m deep and contains hot springs and wells. Approximately, 5900 residences in Salihli town have been heated by using the production wells in this field. Understanding of the behavior of re-injected waters in the subsurface, tracer tests were performed inKursunlu geothermal fields. Na-fluorescein was pumped into two different re-injection wells. Results of tracer tests showed that water injected from the re-injection wells flowed through the shallow aquifer velocities varied between 2.14 and 17.96 m/h and the peak arrival times varied between 13 and 97 hours. Therefore, the tracer tests indicated a geothermal reservoir with quite permeable fractures in the geothermal field and may be caused cooling in the production wells. Results of environmental isotope and chemical analysis show that thermal waters are of meteoric origin and major hydrogeochemical processes are the water-rock interactions under high temperature conditions. According to silica geothermometers, reservoir temperatures vary between 90ºC to 200ºC. Cation geothermometers give also temperatures ranging from 190 to 300ºC. Thermal waters in the study area are oversaturated with respect to carbonate minerals (calcite, dolomite and aragonite). These are likely to cause scaling problems during the production and utilization of thermal water. |