Geochemical constraints for the origin of thermal waters from western Turkey

Published

Journal Article

The combined chemical composition, B and Sr isotopes, and the basic geologic setting of geothermal systems from the Menderes Massif in western Turkey have been investigated to evaluate the origin of the dissolved constituents and mechanisms of water-rock interaction. Four types of thermal water are present: (1) a Na-Cl of marine origin; (2) a Na-HCO 3 type with high CO 2 content that is associated with metamorphic rocks of the Menderes Massif; (3) a Na-SO 4 type that is also associated with metamorphic rocks of the Menderes Massif with H 2 S addition; and (4) a Ca-Mg-HCO 3 -S0 4 type that results from interactions with carbonate rocks at shallow depths. The Na-Cl waters are further subdivided based on Br/Cl ratios. Water from the Cumali Seferihisar and Bodrum Karaada systems are deep circulated seawater (Br/Cl = sea water) whereas water from Çanakkale-Tuzla (Br/Cl < sea water) are from dissolution of Messinian evaporites. Good correlations between different dissolved salts and temperature indicate that the chemical composition of the thermal waters from non-marine geothermal systems is controlled by: (1) temperature dependent water-rock interactions; (2) intensification of reactions due to high dissolved CO 2 and possibly HCl gasses; and (3) mixing with overlying cold groundwater. All of the thermal water is enriched in B. The B isotopic composition (δ 11 B = 2.3‰ to 18.7‰; n = 6) can indicate either leaching of B from the rocks, or B(OH) 3 degassing flux from deep sources. The large ranges in B concentrations in different rock types as well as in thermal waters from different systems suggest the water-rock mechanism. 87 Sr/ 86 Sr ratios of the thermal water are used to differentiate between solutes that have interacted with metamorphic rocks ( 87 Sr/ 86 Sr ratio as high as 0.719479) and carbonate rocks (low 87 Sr/ 86 Sr ratio of 0.707864). © 2002 Elsevier Science Ltd. All rights reserved.

Full Text

Duke Authors

Cited Authors

  • Vengosh, A; Helvaci, C; Karamanderesi, IH

Published Date

  • March 11, 2002

Published In

Volume / Issue

  • 17 / 3

Start / End Page

  • 163 - 183

International Standard Serial Number (ISSN)

  • 0883-2927

Digital Object Identifier (DOI)

  • 10.1016/S0883-2927(01)00062-2

Citation Source

  • Scopus