Hydrogeological and hydrochemical studies of the salihli geothermal fields

The study area is located in southern rims of the Gediz Graben. Salihli geothermal fields are geographically divided into four main groups; Kurşunlu, Caferbey, Üfürük and Sart geothermal fields. In this study, geothermal and hydrochemical characteristics of thermal waters in the geothermal fields are described. The basement of the study area consists of Menderes Massif rocks, which are formed by highly fractured karstic marbles, granodiorite, gneiss and guartz-schist units are aquifers of the geothermal systems in the study area. Neogene sedimentary units occur in different facies in this area and are called as Acıdere, Göbekli and Asartepe formations overlie the Menderes Massif rocks. These units include poorly cemented clayey levels, have very low perme¬ability as a whole and may locally act as cap rocks for the geothermal systems. Alluvium that extends wide in the region is the most important unit for cold ground water aquifer. Transports of thermal fluids are via faults and fractured zones.Results of environmental isotope analysis show that thermal waters are of meteoric origin. Kurşunlu Spa and Caferbey thermal waters have low tritium and high Cl and EC contents. Therefore thermal waters have long circulation velocity in depth. However, Sart-Çamur Spa thermal waters are also mixed water due to high tritium and low Cl contents.Thermal waters in the study area are oversaturated with respect to carbonate minerals (calcite, dolomite and aragonite). Uranine was pumped into two different reinjection wells. As a result of the tracer tests indicated a geothermal reservoir with quite permeable fractures in the geothermal field.