Chemical And Isotopic Characterization Of The Thermal Fluids Emerging From Nestos River Delta Basin in North Greece

In this work we study the isotopic and hydrochemical properties of waters emerging from Nestos river delta basin (Erasmio, Eratio and Myrodato), which is forming the continental margin of the broader graben type basin of Prinos that includes the Nestos delta and the offshore extension between Thassos island and the main land around Kavala bay. Our scope is the identification of the procedures that are related to the waters composition as well as their origin. Some of our samples are characterized by low Cl¯ which excludes the marine contribution while the others present high Cl¯ and Br¯ which indicated marine participation. In addition, the low values of B and Li+ show that these elements derive from seawater, which is more or less diluted by fresh water with no water-rock interaction. This assumption is, also, confirmed by the δ18O and δ34S isotopic values. Finally, we use isotopic geothermometers for the evaluation of reservoir temperature and we conclude to the existence deep geothermal field of low to middle enthalpy, with the exception of one sample which has middle to high enthalpy.