| Abstract |
Turkey has high potential for the explotation of geothermal energy. The thermal waters in Turkey are distrıbuted along the North Anatolian Fault Zone (NAFZ), East Anatolian Fault Zone and in Western Anatolia intensively. The Thermal waters in western Anatolia are situated in the rift zones of the Gediz, the Küçük Menderes and the Büyük Menderes within the Menderes Massif. The thermal waters of Kızıldere are one of the three high entalpy and temperature thermal waters in the rift zone of the Büyük Menderes. The other two are Salavatlı and Germencik in the same rift zone. The thermal waters of Kızıldere are associated with NE-SW and NW-SE oriented faults, representing a compressional event that followed extensional formation of the rift zone. In the thermal field of Kızıldere, the basement is comprised by Paleozoic metamorphic rocks that consist of gneiss, schist, and Iğdecik formation alternating with quartzites, mica schists, and marbles. The basement rocks are overlain by Pliocene sediments of fluvial and lacustrine characters which consist of (i) the 200 m thick Kızılburun formation, (ii) the Sazak formation with a thickness ranging from 100 to 250 m, (iii) the Kolonkaya formation ranging in thickness from 350 to 500 m, and (iv) the 500 m thick Tosunlar formation. At the surface, the thermal field of Kızıldere is recognized by a distinct color change in the rocks. The rocks are intensively altered through fluid-rock interaction, and marked by silicic, carbonatized and hematitized alteration zones. The thermal waters of Kızıldere are of meteoric origin. In the area, Groundwaters of meteoric origin percolated into the fault zones to a depth of up to 5 km in secondary rocks, in this case the Sazak and İğdecik formations. These rocks are present as a reaction zone in the roof area of a magma chamber , situated at a probable depth of 2-4 km. Here, the meteoric waters are heated by the cooling magma and subsequently ascend to the surface of their low densities caused by convection calls. In the thermal field of Kızıldere, the Sazak formation, comprising limestones, marls, and siltsones, is a good first reservoir of the thermal wa ters due to primary permeabiliy. Therefore, it can be considered the first (shallow) reservoir at a depth of 400 m. The reservoir temperatues range from 148 to 198 C. The İğdecik formation, comprising quartzites, mica schists and marbles, constitutes the second (deep) reservoir of the thermal waters at a depth up to 2500 m due to secondary permeability caused by faults and joints. The reservoir temperatures are up to 240 C. The spacial development of the reservoir characteristic is understood as unfavorable pre-conditions for a reinjection. It seems to depict, that total inorganic carbon in cooler margins of this geothermal system increases clearly. Furthermore, it is intelligibly, because the solubility of CO2 rises with decreasing temperature. The acidification of pH value in the margins of the system effectuates a clearly increase of saturation concentration of Ca2+, as long as the reservoir water could be saturated with calcite before. These facts create problems for a reinjection clearly. During silica scalings in reinjection system main problems constitute, carbonate scalings ocur in the reinjection reservoir clearly which brings the prosess to a standstill for a short term. An approach of the ınjection point to the production zone may reduces this main problem indeed, but it is to a |