Abstract

The metamorphic units belonging to Menderes Massif occur in the area as basement rocks. These rocks are predominantly formed during Paleozoic. At the top of these rock units, there are some Miocene and Paleocene aged sedimentary rocks, which are covered by Quaternary aged alluviums. The Menderes block (often described as Menderes Massif was elevated due to compressional tectonic forces from south and north side of the block. On the other hand, there have been some active en echelon faults on both sides of the massif. These fault system gave rise to the occurrence of several horst and graben system in the area. The Hıdırbeyli geothermal area is found at the western side of Menderes graben, between Bozköy and Ömerbeyli thermal areas. All these thermal spots were developed on the East-west oriented fault belt. At the Germencik-Ömerbeyli geothermal area, there have been 9 research-drilling holes made by the MTA (Mineral Research and Exploration General Directorate of Turkey) and these resulted in high temperature and discharge water. As a result of these findings, the investigations were concentrated to the Hıdırbeyli area, in where two drilling holes (HB-1 and HB-2) were made to find geothermal steam and waters (if any) in the area. The drillings revealed that there has been some steam plus water. The produced steam from these wells are colorless, odorless and some cloudy.  The steam and waters of HB-1 have 5197.47 mg/l minerals, and it has been classified as boric-silisic sodium-bicarbonate waters. On the other hand, the steam and waters of HB-2 can be classified as boric-silisic-cloric sodium-bicarbonate waters with 4745.4 mg/l mineral components. HB-1 and HB-2 are the first deep-wells in the region and the steam and waters of these wells can be used for electricity generation and heating of nearby settlements with 142^oC and 120.5^oC average water temperatures; the sum of discharge of these two wells is 274 l/s.

Key words: Menderes graben, source of thermal water, hydro-geochemistry, Hıdırbeyli, Turkey.