GNGTS 2013 - Atti del 32° Convegno Nazionale

waters have been found mainly in the area of Contursi Terme, along the tectonic lines of the Sele Valley; • A deep and probably slow circulation of hypothermal and thermal waters belong to Contursi Bagni circuit. These waters are recharged in/by carbonate massive outcrops in the area (Mt. Polveracchio, Mt. Marzano), infiltrate and reach the Mesozoic carbonatic and dolomitic deep complex (from -1000 to -3000 m). The waters, that become hot (50-70°C) for the normal geothermal gradient existing (30°C/km), are enriched in CO 2 , acquire their salt concentration and go back along the main tectonic discontinuities in the emerging area of Contursi Bagni. These waters have an intensive interaction with carbonate rocks (limestone and dolomite) and evaporite deposits (anhydrite and gypsum), as consequence have a high salinity (electrical conductivity up to 7000 mS/cm) and a Na (Ca-Mg)-HCO 3 (Cl) e Na (Ca)-Cl (HCO 3 ) chemistry. These waters have high CO 2 concentration (up to 450 cc/l), acid pH, important concentration of Na, Cl, K, Mg and SO 4 , are enriched in minor and trace elements (i.e. the thermal indicators, such as Li, B, As and Rb). Some thermal water during the ascent is mixed with cold water less saline and showing a geochemical composition between hot and cold water: they belong to the group of hypothermal water of Contursi Bagni area. We selected and tentatively applied the SO 4 /F 2 geothermometer, that indicated a realistic deep temperature estimate of about 50-60°C. This results is in accord with the normal geothermal gradient (30°C/km) estimated for Contursi Terme area (Cataldi et al. , 1995), leaving assume that the thermal waters reach depths of 2-3 km. References Calcara M., Guerra I., Moretti A., Pizzino L., Quattrocchi F.; 1996: Il gas radon nelle acque e nei suoli della Sila: implica- zioni geotettoniche e rischio ambientale. Atti XV Convegno GNGTS 1996, Roma - CNR, 11-13 Novembre, 449-454. Cataldi R., Mongelli F., Squarci P., Taffi L., Zito G., Calore C.; 1995: Geothermal ranking of Italian territory - Geothermics, 24, 115-129. Celico P., De Gennaro M., Ghiara M. R., Stanzione D. (1979). Le sorgenti termominerali della Valle del Sele (Salerno): indagini strutturali, idrogeologiche e geochimiche. Rendiconti Società Italiana di Mineralogia e Petrologia, 35, 389- 409. Cerling T.E., Solomon D.K., Quade J., Bowman J.R.; 1991: On the isotopic composition of carbon in soil carbon dioxide. Geochimica et Cosmochimica Acta, 55, 3403-3405. Craig, H.; 1961: Isotopic variations in meteoric waters. Science, 133: 1702-1703. Favara R., Grassa F., Inguaggiato S., Pecoraino G., Capasso G.; 2002: A simple method to determine the ‰13C content of total dissolved inorganic carbon. Geofisica Internacional, 41, 313-320. Giggenbach, W.F., 1988: Geothermal gas equilibria. Derivation of Na-K-Mg-Ca geoindicators . Geochim. Cosmochim. Acta 52, 2749-2765. Giggenbach W.F., Corrales R.S.; 1992: The isotopic and chemical compsition of waters and steam discharges from vol- canicmagmatic-hydrothermal systems of the Guanacoste Geothermal Province, Costa Rica . Applied Geochemistry, 7, 309-322. Italiano F., Bonfanti P., Pizzino L., Quattrocchi F.; 2010: Geochemistry of fluids discharged over the seismic area of Southern Apennines (Calabria region, Southern Italy): implications for Fluid-Fault relationships . Applied Geochemistry, 25, 540-554. Longinelli A., Selmo E.; 2003: Isotopic composition of precipitation in Italy: a first overall map. Journal of Hydrology, 270, 75-88. Mancini C., Quattrocchi F., Guadoni C., Pizzino L., Porfidia B.; 2000: 222Rn study throughout different seismotectonical areas: comparison between different techniques for discrete monitoring. Annali di Geofisica, 43, 1-28. Marini L., Chiodini G., and Cioni R.; 1986: New geothermometers for carbonate-evaporite geothermal reservoirs, Geothermics, 15(1), 77-86. Marotta and Sica; 1933: Classificazione italiana delle acque minerali . Annuali di Chimica applicata. Vol. 19 fasc. 12, 1929; Vol. 23 fasc. 6. Polselli P. (2004): Relazione tra fenomeni di sprofondamento, risalite di fluidi mineralizzati e sismicità in alcune aree di studio dell’Italia centro-meridionale . Tesi di stage APAT 2004, 67 pp. Tansi C., Muto F., Critelli S., Iovine G.; 2007: Neogene-Quaternary strike-slip tectonics in the central Calabrian Arc (southern Italy). Journal of Geodynamics 43 (2007) 393-414. 262 GNGTS 2013 S essione 1.3