| Title | Hydrogeochemical Investigation of Yerköy (Yozgat-Turkey) Geothermal Waters |
|---|---|
| Authors | Yilmaz Turali, E; Simsek, S; Koc, K |
| Year | 2016 |
| Conference | European Geothermal Congress |
| Keywords | Yerköy-Yozgat, Geothermal, Hydrogeochemistry, Geothermometers, Conceptual Model |
| Abstract | Yerköy geothermal area is located in the Central Anatolia of Turkey. Thermal water springs which have been used for spas for many years have temperatures of 41- 45 °C and flow rates of 0.5-2.5 l/s in the area. Geothermal reservoir units are rhyolites, altered granodiorites fractured and faulted zones in the field. Eocene and Oligocene sediments are caprock and overlie unconformably on rhyolites and granodiorites. Quaternary alluvium units overlie unconformably these sediments. Normal slip faults, which are generally NW-SE and NE-SW trending, developed in the region depending on stress tectonics in Neogene and Quaternary. Thermal water springs discharge from the intersection of these faults. Between the years 1992 and 1997, seven shallow wells were drilled ranging from 59 to 262 m with a maximum temperature of 47 °C, in order to the development of spa tourism. For the purpose of investigation of the geothermal potential of the area and development of district heating, two exploration/production wells, YK-2 and YK-3, were drilled ranging from 550 to 750 m, respectively in 2006. The maximum bottom-hole temperatures were measured between 67 and 72°C, respectively in these wells. The thermal waters are alkali sodium chloride type and have high specific electrical conductivities. Hydrothermal alteration minerals, such as chalcedony, quartz, albite, microcline, shows the mineral equilibrium temperature between 60 and 100 °C. According to the isotopic data, thermal waters are meteoric and have a positive δ18O shifts because of water-rock interaction. The low tritium values indicate that thermal waters recharged by precipitation before 1952. As a result of these studies, hydrogeochemical model has been evaluated for hydrothermal system of the area. |