Geochemical characterization of the Biga Peninsula thermal waters (NW Turkey)

Abstract

Thermal water chemistry from the Biga Peninsula (NW Turkey) was investigated in order to discriminate among hydrochemical facies, and isotopic groups and identify the major geochemical processes. A systematic hydrogeochemical survey was carried out, incorporating new data as well as results from the previous studies. Results were used to further develop hydrogeological and geochemical models. Thermal water compositions were classified into four groups and the processes affecting evolution of water compositions were interpreted. Types 1, 2 and 3 are representatives of water corresponding to sulfate dominant fluids (mainly NaSO 4 -type), chloride dominant fluids (mainly NaCl-type), and bicarbonate dominant fluids (Na-or CaHCO 3 -type), respectively. Group 4 comprises the fluids with compositions that are not dominated by any distinctive anion. Groundwater infiltrates and circulates through the marbles of the Paleozoic basement. The isotopic composition of thermal waters revealed that deep infiltration of meteoric water took place in periods of changed climatic conditions.

Hydrochemical and Isotopic Composition of Tuzla Geothermal Field (Canakkale-Turkey) and its Environmental Impacts

“…The cation geothermometers applied to water samples 13 and 23 for June 2004 include Na-K, K-Mg (Giggenbach, 1988) and Na-K-Ca (Fournier and Trusedell, 1973). The results of geothermometer applications (Table 1) indicate some estimations for subsurface reservoir temperature that range from 182.4 • C to 232.59 • C. These results also are consistent with previous results calculated by Mutlu and Gulec, 1998;Tarcan, 2005, andYalcin, 2007. Temperatures of up to 145 • C were observed at 50-m depth in some of wells in the TGF.…”

“…The isotopic values of Kestanbol (10 km north of Tuzla) and Tuzla have similar salinity values to Nysiros brine shown in Figure 12. Yalcin (2007) gives the most probable explanation for the origin of discharging brine in Tuzla and Kestanbol areas as deep-seated hot fossil seawater resulting from dilution and cooling during uprising by infiltrating meteoric water. Accordingly, the Br/Cl ratio of the Tuzla brine is rather lower than that of the recent seawater (Mützenberg et al, 1992).…”

“…Accordingly, the Br/Cl ratio of the Tuzla brine is rather lower than that of the recent seawater (Mützenberg et al, 1992). Furthermore, Yalcin (2007) points out that Tuzla geothermal brine is stretched to the values of Nysiros brine by dilution of deep-seated hot brine. This explanation is shown in Figure 12 by the dashed line.…”

“…According to previous studies, Tuzla geothermal brine originates from the dissolution of marine evaporates and is formed by chemical alteration (dissolution of halite, dolomitization, reduction of sulphate, precipitation of anhydrite, digenetic reactions of silicates, Ca and Na ion exchange and reactions with organic matter), which generates the higher mineralization. Alternate models for the origin of the TGF include derivation from relics of evaporated seawater trapped in sediments (Balderer, 1997;Mützenberg, 1997), dissolution of Messinian evaporites (Vengosh et al, 2002) and trapped relict seawater within pore spaces in rocks (Yalcin, 2007). Mutlu and Güleç, 1998, * * * Calculated by Yalcin, 2007).…”

“…Alternate models for the origin of the TGF include derivation from relics of evaporated seawater trapped in sediments (Balderer, 1997;Mützenberg, 1997), dissolution of Messinian evaporites (Vengosh et al, 2002) and trapped relict seawater within pore spaces in rocks (Yalcin, 2007). Mutlu and Güleç, 1998, * * * Calculated by Yalcin, 2007).…”