Akademik Veri Yönetim Sistemi
JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, cilt.116, ss.215-233, 2002 (SCI-Expanded)
Thermal waters hosted by Menderes metamorphic rocks emerge along fault lineaments in the Simav geothermal area. Thermal springs and drilled wells are located in the Eynal, Citgol and Nasa locations, which are part of the Simav geothermal field. Studies were carried out to obtain the main chemical and physical characteristics of thermal waters. These waters are used for heating of residences and greenhouses and for balneological purposes. Bottom temperatures of the drilled wells reach 163degreesC with total dissolved solids around 2225 mg/kg. Surface temperatures of thermal springs vary between 51degreesC and 90degreesC. All the thermal waters belong to Na-HCO3-SO4 facies. The cold groundwaters are Ca-Mg-HCO3 type. Dissolution of host rock and ion-exchange reactions in the reservoir of the geothermal system shift the Ca-Mg-HCO3 type cold groundwaters to the Na-HCO3-SO4 type thermal waters. Thermal waters are oversaturated at discharge temperatures for aragonite, calcite, quartz, chalcedony, magnesite and dolomite minerals giving rise to a carbonate-rich scale. Gypsum and anhydrite minerals are undersaturated with all of the thermal waters. Boiling during ascent of the thermal fluids produces steam and liquid waters resulting in an increase of the concentrations of the constituents in discharge waters. Steam fraction, y, of the thermal waters of which temperatures are above 100degreesC is between 0.075 and 0.119. Reservoir pH is much lower than pH measured in the liquid phase separated at atmospheric conditions, since the latter experienced heavy loss of acid gases, mainly CO2. Assessment of the various empirical chemical geothermometers and geochemical modelling suggest that reservoir temperatures vary between 175degreesC and 200degreesC. (C) 2002 Elsevier Science B.V. All rights reserved.