Hydrothermal alteration at the San Vito area of the Campi Flegrei geothermal system in Italy: mineral review and geochemical modeling

The Campi Flegrei geothermal system sets in one of the most famous and hazardousvolcanic caldera in the world. The geothermal dynamics is suspected to have a crucial role in themonitored unrest phases and in the eruption triggering as well. Numerical models in the literaturedo not properly consider the geochemical effects of fluid-rock interaction into the hydrothermalcirculation and this gap limits the wholly understanding of the dynamics. This paper focuses onfluid-rock interaction effects at the Campi Flegrei and presents relevant information requested forreactive transport simulations. In particular, we provide: (1) an extensive review of available data andnew petrographic analyses of the San Vito cores rearranged in a conceptual model useful to definerepresentative geochemical and petrophysical parameters of rock formations suitable for numericalsimulations and (2) the implemented thermodynamic and kinetic data set calibrated for the San Vito1 well area, central in the geothermal reservoir. A preliminary 0D-geochemical model, performedwith a different contribution of CO2 at high (165 oC) and low (85 oC) temperatures, firstly allowsreproducing the hydrothermal reactions over time of the Campanian Ignimbrite formation, the mostimportant deposits in the case study area.