Low entalpy geothermal suitability of North Sardinia (Italy)

Heat flow density over Sardinia is relatively high. Tertiary geodynamics and radiogenic heating from the Variscan batholith are the possible concurrent causes. Major anomalies were thought confined to the Tertiary basins, where 180 mW/m2 are reported. New data ascertain that the occurrence of the hottest thermal springs does not mirror these basins, as they pour out from Variscan granites. Hence the high thermal flow from the basins can result from basin-wide heat redistribution by hot "granite" water flowing laterally in shallow aquifers. This scenario is particularly favourable for low-medium enthalpy fluids exploitation as well as for geoexchange.