Isotope and hydrochemical assessment of the Samothraki Island geothermal area, Greece

Thermal and cold water samples were collected from the island of Samothraki, in the northern part of the Aegean Sea. Isotopic (δD, δ18O, δ34SSO4, δ34SS2−, δ18OSO4) and chemical analyses (major ions, Br, B, Li, SiO2) were performed in most of them. The study of ionic and isotopic contents shows that, the thermal waters of Samothraki Island are mainly locally fed groundwater that changes, chemically and isotopically, during its circulation within a major fracture zone reaching great depths. More specifically, the evaluation of the entire dataset indicates that water–rock reactions and mixing with brines are the principal sources of the isotopic and salinity fingerprint of these waters. otopic [δ18O (SO42 −–H2O)] and chemical geothermometers applied on the waters of the thermal springs, suggest the probable existence of a geothermal reservoir of high enthalpy. The temperature attributed to this deep geothermal field is higher than 220 °C.