applied sciences Article Understanding the Origin and Mixing of Deep Fluids in Shallow Aquifers and Possible Implications for Crustal Deformation Studies: San Vittorino Plain, Central Apennines Marino Domenico Barberio 1 , Francesca Gori 1 , Maurizio Barbieri 1 , Tiziano Boschetti 2 , Antonio Caracausi 3 , Giovanni Luca Cardello 4 and Marco Petitta 1,* 1 Earth Sciences Department, Sapienza University of Rome, 00185 Rome, Italy;
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[email protected]; Tel.: +39-064991-4834 Abstract: Expanding knowledge about the origin and mixing of deep fluids and the water–rock–gas interactions in aquifer systems can represent an improvement in the comprehension of crustal defor- mation processes. An analysis of the deep and meteoric fluid contributions to a regional groundwater circulation model in an active seismic area has been carried out. We performed two hydrogeochemical screenings of 15 springs in the San Vittorino Plain (central Italy). Furthermore, we updated the San Vittorino Plain structural setting with a new geological map and cross-sections, highlighting how and Citation: Barberio, M.D.; Gori, F.; where the aquifers are intersected by faults. The application of Na-Li geothermometers, coupled with Barbieri, M.; Boschetti, T.; Caracausi, trace element and gas analyses, agrees in attributing the highest temperatures (>150 ◦C), the greatest A.; Cardello, G.L.; Petitta, M.