Kestanbol geothermal field is located in northwestern Turkey and is one of the highest temperature geothermal fields in the Biga Peninsula. In this study, one geothermal well, two geothermal springs, and two cold springs were monitored for one year in Kestanbol geothermal field to determine hydrogeochemical and isotopic characteristics. Additionally, any possible relationship between seismic activity and variations in the hydrochemistry of geothermal water was investigated. The Kestanbol geothermal field is controlled mainly by the right-lateral strike-slip Kaplıca fault with normal components. The distribution of the geothermal waters is roughly parallel to the fault. | Turkish Journal of Earth Sciences Turkish J Earth Sci 2021 30 1112-1133 http earth TÜBİTAK Research Article doi yer-2105-15 Hydrogeochemical and isotopic monitoring of the Kestanbol geothermal field Northwestern Turkey and its relationship with seismic activity 1 2 3 Deniz ŞANLIYÜKSEL YÜCEL Süha ÖZDEN Harika MARMARA 1 Department of Mining Engineering Faculty of Engineering Çanakkale Onsekiz Mart University Çanakkale Turkey 2 Department of Geological Engineering Faculty of Engineering Çanakkale Onsekiz Mart University Çanakkale Turkey 3 Department of Geological Engineering School of Graduate Studies Çanakkale Onsekiz Mart University Çanakkale Turkey Received Accepted Published Online Final Version Abstract Kestanbol geothermal field is located in northwestern Turkey and is one of the highest temperature geothermal fields in the Biga Peninsula. In this study one geothermal well two geothermal springs and two cold springs were monitored for one year in Kestanbol geothermal field to determine hydrogeochemical and isotopic characteristics. Additionally any possible relationship between seismic activity and variations in the hydrochemistry of geothermal water was investigated. The Kestanbol geothermal field is controlled mainly by the right-lateral strike-slip Kaplıca fault with normal components. The distribution of the geothermal waters is roughly parallel to the fault. The temperature electrical conductivity salinity and pH value of the geothermal waters were within the range of to C 30300 to 35700 μS cm to and to respectively. The temperature interval was from to C for cold waters. The hydrochemical facies of the geothermal waters were Na-Cl type and the cold waters were Ca-HCO3-Cl type. The high concentrations of As Ba Fe Li and Mn in geothermal waters were mainly derived from prolonged water-rock interactions under high-temperature conditions. The δ18O and δ2H
