Some geological and hydrogeochemical characteristics of geothermal fields of Turkey

Abstract

Presently, active hydrothermal areas of Turkey can be divided into three major provinces which correlate particular volcano-tectonic features. These fields are essentially found at western, central and eastern part of the country. There has been no particular geothermal energy fields in the southern part of Turkey since this region is mostly covered by ~2 km thick carbonate sequences and has suffered little recent rifting. The western Turkish geothermal provinces, where horst and graben systems are well developed, have the hottest fluids among others. In this region, normal faults penetrate into the crust and thus the meteoric waters are heated to greater temperatures than in the east where a compressional tectonic regime dominates. In the western Turkish geothermal fields, the fluids have a distinctly higher pH (>7) values than those in the east. This resulted that the Si content of the western Turkish hydrothermal fluids is considerably higher than the others. The geothermal field at Tuzla, situated on the Aegean shore in NW Turkey, has ionic component twice that of conventional seawater. Because of this, the area provides a good opportunity to investigate the interactions between seawater and hot dry rock. Key words: Geothermal fields, seawater, hot dry rock.