Geophysical approach for the detection and evaluation of geothermal energy potential stimulated from geology and tectonics in Cappadocia Region (Central Turkey)

Abstract

Geothermal energy, which is a renewable energy source, can be used to heat buildings or generate electricity and does not contribute to air pollution when used properly, and it is heat continuously produced inside the earth that generates geological phenomena on a planetary scale. Central Anatolia is a triangular region which is limited by North Anatolian Fault Zone (NAFZ) to the north, East Anatolian Fault Zone (EAFZ) to the east, Dead sea FZ and Cyprus FZ to the south. The tectonic structure of the Cappadocia region is composed of NW trending Salt Lake Fault Zone extending approximately 220 km in length, Salanda fault zone extending 140 km, and NE trending Central Anatolian Fault zone more than 700 km in length. There are 82 geothermal regions having 171 sources with low and high temperatures due to the young volcanism and tectonic activities in this region. These geothermal regions caused by fault and fracture zones extending to the mantle parallel to the tectonic zones of the region and are situated on the areas having low Curie, high heat flow values. The Curie point depth, heat flow and geothermal gradient values determined from geophysical data of the region are correlated with tectonics and geothermal potential of the region. While the minimum crustal thickness is 38 km, the maximum crustal thickness is 41 km in Mt. Hasan and Mt. Erciyes. The Curie point depth value is computed as 13.7 km determined from magnetic anomaly data of the region. The geothermal gradient and heat flow values are estimated to be 42.3 °Ckm-1, 88.8 mWm-2, respectively. Geothermal systems and reservoir temperature of geothermal sources should be understood clearly to provide sustainability of the project with respect to the economical conditions. Various geothermometers methods have been used to determine the reservoir temperature in order to estimate the field of usage of the thermal water before the drilling stage because of the high price of the borehole. Silica geothermometers method applied to the SiO2 content of the sources gives the best information about the reservoir temperature. The maximum temperatures and depth to reservoir of the geothermal sources located in the Kayseri region are estimated as 131.8 °C, 1.14 km, respectively, in Kayseri region. It is concluded from these values that the Cappadocia region has very high geothermal potential caused by tectonic activities after the Late Triassic and partial melting of the lower crust. © 2014 Nova Science Publishers, Inc. All rights reserved.