| Abstrakt: |
• The BMG and GG are two major graben systems with their geothermal capacities in Western Anatolia. • Although reservoirs look similarity for each graben, the fluid characterization can be change along the grabens, because of different effects. • δ13C isotopes show that the origin of the huge amount CO 2 is marble levels of metamorphic rocks at reservoirs at both graben systems. • Isotopes indicate the origin of SO 4 is mainly gypsum mineral at east part of the BMG, while mantle contribution and oxidation is possible at the GG. The Büyük Menderes Graben (BMG) and the Gediz Graben (GG) are two major graben systems and they have important medium-high temperature geothermal systems, with suitable reservoir temperatures (e.g. 170–276 °C) for electricity production such as Kızıldere (Denizli city), Germencik, Salavatlı, Pamukören (Aydın city) in the BMG and Alaşehir (Manisa city) in the GG. These high temperature geothermal systems are located in a highly fractured zone because of the Aegean Extensional Zone effect. Although the main reservoir rocks retain similar compositions for each graben system, the geothermal fluids chemistry characterization can vary along the BMG and GG as a result of differing variables such as a paleo sea effect, the concentration of non-condensable gases (NCG), as well as mineral effects. The water chemistry results and δ18O-δD isotope values show remarkable differences within the Germencik and Kızıldere systems along the BMG, while the main reservoir rocks are of a similar composition. Chemical, isotope compositions and pH values of thermal waters in Alaşehir differ from those in the BMG geothermal systems. Results for δ13C isotopes indicate that the origin of the large amounts of CO 2 is the marble in metamorphic rocks in the reservoirs in both graben systems. δ34S, δ34S- SO 4 and δ18O-SO 4 values indicate that the origin of SO 4 indicates gypsum and also bacteria effect in the eastern part of the BMG, while different mechanisms such as; oxidation of sulfur, pH, temperature and possible buffer mineral effects on H 2 S dissolution to the west of the BMG and GG display a greater impact. [ABSTRACT FROM AUTHOR] |
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