engleski

Upwelling time of thermal waters inferred using radionuclides: the case study of the Euganean Geothermal Field (Veneto - NE Italy)

The Euganean thermal waters (65-86°C) constituting the homonymous thermal field (Euganean Geothermal Field ; Veneto region ; NE Italy) are investigated in this work to constraint the time scales of their upwelling based on Ra and Rn isotopes. Two groups of samples can be distinguished on the base of the 223Ra/226Ra and goethite saturation index. The thermal waters in the northern part of the thermal field are characterized are characterized by goethite S.I. <1.6 and 223Ra/226Ra<0.046 that were interpreted as the result of quick rise to the surface (maximum 3 days) through large fractures. The thermal waters in the central and southern parts of the thermal field are clearly saturated in goethite (S.I.>1.6) and in general characterized by 223Ra/226Ragreater than equilibrium value (0.046). This result was interpreted as connected to a slower rising path through a finely fractured aquifer yielding an enhanced water/rock interactions.

radium isotope ; groundwater age ; thermal water ; Euganean Geothermal Field

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