Geothermal resources in the carbonate aquifers of the Friuli Venezia giulia coastal area: preliminary conceptual model

Conclusions. The thermal waters hosted in the Mesozoic carbonatic platform of the Friuli Venezia Giulia coastal area have the nature of ancient, diagenetically modified seawater. Srisotopes indicate that the deep saline reservoir might represent remnants of seawater entrapped in the Cretaceous carbonate strata during the late Oligocene - Miocene sea transgression which followed the uplift of some portions of the carbonatic units during upper Eocene. The carbonatic aquifer has a complex geometry, is confined and interested by important fault systems which allow the development of hydrothermal cells and some local mixing with the shallower freshwater aquifers. The data indicate that the waters outflowing at Monfalcone and sampled by the deep wells of Grado-1 and Lignano likely fed by the same regional saline reservoir, which underwent interactions with more superficial aquifers at different extent in the different sites.