| Authors |
Michele SAROLI, Nunzia VOLTATTORNI, Gaspare GIOVINCO, Anna CASALE, Michele LANCIA, Monia PROCESI, Daniele CINTI, Michele DELL'ISOLA |
| Abstract |
The Suio area is part of the peri-Tyrrhenian sector of central Italy, a thermally anomalous area where CO2-pressurized hydrothermal reservoirs develop in a complex geodynamic setting. Thermalism is commonly attributed to the post-orogenic magmatic activity, that occurred from Pliocene to Quaternary in response to an extensional regime. The magmatism of this area occurred between 550,000 and 150,000 years ago. Three eruptive periods have been recognized: the tephrite-phonolite stratovolcanoes, namely High-K series, the explosive eruptions of the Brown Leucitic Tuff (BLT) and the White Trachytic Tuff, and finally, the small explosive eruptions forming two lava domes (Latite) inside the Garigliano caldera close to the eruptive activity. The different geological features (volcanic products belonging to different periods) are reflected into the high chemical variability of local groundwaters. In this area are present several natural springs showing different chemical features. The Suio area shows thermo-mineral springs located in a boundary zone between the NW side of the Roccamonfina Volcanic Complex (RVC) and the Aurunci carbonatic range. The chemical composition of these springs reflects the unique lithology of the aquifer where they are flowing. The relationship between volcanic and carbonate complexes suggests that mineralization is strongly enhanced by acid gas emissions (CO2, H2S) and high temperatures. As a final product, the intense water–rock interaction brings, high mineralized waters that could be divided in two sub-groups according to the amount of solubilized CaCO3 or to the degree of interaction with carbonatic rocks. All Suio thermal waters have a very similar Mg/(Na+K) and Na/K ratio (0.65 and 3, respectively) confirming their circulation into the carbonatic complex, with an enrichment of fluids deriving from RVC. Common geothermometers used in order to evaluate the reservoir equilibrium temperature indicated values ranging from 125° to 150°C. The present acquired data suggest that the area could be a suitable location for direct applications of the geothermal resource. However, other more specific geological-geochemical studies (such as, for instance, isotopic analysis) are in progress in order to improve the understanding of the geothermal potential of the Suio area. Starting from the hydro-geologic model, authors are performing numerical simulations, verifying the conceptual-model and compare simulated results with recollected data. |