| Abstract |
The studied area is located at eastern part of Aksaray province in Central Anatolia. The basement rocks of studied area is Paleozoic aged BozÁaldag formation composed of marble, schist and gneiss. These rock units are overlain uncomfortably by Tertiary to Quaternary aged volcanic rocks of Cappadocian volcanic belt interlayer sediments. The compositions of these units are mainly represented by tuff, ignimbrite, reworked tuff interlayer sediments, basalt lavas, ash fall deposits, pumice and dasite to rhyodasitic lava domes. The study area contains Ziga and Acigˆl (Narkˆy) thermal area, which they have similar geologic environments with in the Cappadocian volcanic belt of the Tertiary to Quaternary age. Existence of surface manifestation like that high regional heat flow, the presence of expanding acidic to weakly acidic hydrothermal alteration surrounding the geothermal area, hot springs which have a temperature of 44-65 oC indicating the important of geothermal possibilities in the area. Initial studies such as field geology, geophysical investigations (gravity-magnetic survey and local electrical resistivity studies); have been completed in the studied area. As well as four gradients well and three shallow production well have been drilled in the study area in 1980's. Reassessment gravity and magnetic studies indicated that four important anomalous exists with respect to geothermal heat source exploration. Magnetotelluric (MT) and Transient-electromagnetic (TEM) methods have been carried out where the anomalous in the study area, for this aim the MT soundings have carried out along the four profiles on 38 points of measurements. Besides MT studies also remote sensing, aerial photo studies, detail geology, surface hydrothermal alteration, water chemistry has been carried out in the studied area. On the basis of the MT measurement low resistivity anomalous are interpreted to be hot, solid and / or partly molten magma bodies which can be considered the heat source of the geothermal system in the study area. It has been found that the average depths of the heat sources are about 5-8 km. A good correlation has been found high gravity - low magnetic, high heat flow and low resistivity body measured with MT exploration in the studied area. On the basis of the MT studies, low resistivity zone exists from the surface to 1500m depth considered with to hydrothermally altered tuff and ignimbrite as a cap rocks, and high resistivity below the low resistivity zone considered with the deep reservoir rocks. On the basis of water chemistry studies show that the hot waters can be classified as Na, Cl, HCO3 and Na, Ca, HCO3, Cl, As and B bearing hot and mineralized water. On the basis of silica and Na/Li geothermometre of the reservoir rocks are 90-153 oC and 135-197 oC respectively. |