Hydrogeochemical and environmental isotopes study of the northeastern Algerian thermal waters

Thermal waters from northeastern Algeria have been investigated for their hydrochemical and isotopic characteristics to identify the geothermal processes that have produced these waters. Fifteen samples were collected from cold and hot springs. The data obtained from sampling period indicate a high level of mineralization (a TDS of up to 6657 mg/L) of thermal waters with three dominant water types (Ca–SO₄, Ca–HCO₃, Na–Cl). The chemical geothermometers applied to thermal waters show that the study area is influenced in part through dilution by the infiltration of surface waters. The isotopic contents of hot springs vary from − 8.26 to − 6.83‰ for δ¹⁸O and from − 55.23‰ to − 42.01‰ for δ2H. These results reveal a meteoric origin of thermal waters infiltrated at major faults and heated by deep flow before being discharged to the surface by fractures.