Hydrogeochemistry, environmental isotopes and the origin of the Hamamayagi-Ladik thermal spring (Samsun, Turkey)

Hamamayagi thermal spring (HTS) is located along the North Anatolian Fault Zone. The thermal spring has a temperature of 36°C, with total dissolved solids ranging from 485.6 to 508.5 mg/L. Hard, brittle, and gray limestones Permian aged are the reservoir rocks of the HTS. δ¹⁸O–δ²H isotope ratios clearly indicate a meteoric origin for the waters. The δ³⁴S value of sulfate in the thermal water is nearly 4.1‰ and implies a diagenetic environment characterized by reduced sulfur compounds. The δ¹³C ratio for dissolved inorganic carbonate in the HTS lies between −1.78 and −1.62‰, showing that it originates from the dissolution of fresh-water carbonates. Quartz geothermometry suggests a reservoir temperature of 52–85°C for the Hamamayagi geothermal field, but chalcedony geothermometers suggest reservoir temperatures between 30 and 53°C.