A Geochemical Approach to the Origin of Geothermal and Mineral Waters Southwest of Uludag Mountain (Bursa)

In this study, hydrogeochemical characteristics and the origin of geothermal springs and mineral waters southwest of Uludag (Bursa) Mountain were investigated. Temperatures of thermal waters are 37-64.5 degrees C and those of mineral waters range from 15.6 to 22.5 degrees C. Total dissolved solid (TDS) content of waters is in the range of 451 to 2026 mg/l. The pH of mineral waters (6.2 - 6.7) is much more acidic than thermal waters (7.1 - 7.3). Thermal waters are represented by Na-Ca-HCO3 facies type, while mineral waters are Mg-Na-Ca-HCO3 type. Tritium measured in the Bursa mineral waters is 0.34 to 5.96 TU. Thermal waters (0.34 to 1.95 TU) have lower tritium content than mineral waters (1.57 to 5.46 T). These results indicate that most of studied fluids are regarded as modern waters. delta O-18 of samples is -11.08 to -7.97 parts per thousand (VSMOW) and delta D values are in the range of -73.81 to -57.64 parts per thousand (VSMOW). Stable isotope compositions of Bursa mineral water are located between Global and Mediterranean Water Lines, indicating meteoric origin. delta C-13 values measured in dissolved inorganic carbon (HCO3) are between -15.3 and +10.12 parts per thousand (VPDB). Carbon isotope compositions of thermal waters are about 15 parts per thousand lower than those of mineral waters, implying that carbon in thermal springs is derived from an organic source. Carbon in mineral waters originates from marine limestones. Using the deuterium-altitude relationship, the recharge zone for Bursa mineral waters was at 1180-2300 m.