Hypothesis on the Origin of Steam and on the Deep Temperatures of the Fluids of Pozzuoli Solfatara (Campania, Italy)

Abstract

A series of chemical and isotopic analyses conducted on fluid samples from the Pozzuoli solfatara between November 1982 and November 1983 has provided interesting information on the origin of the fluid and on deep temperatures. Earlier hypotheses that the water originated from a seawater within the volcanites have been modified as a result of this survey; the isotopic composition indicates hat the steam derives from meteoric water that remains in the reservoir for more than 25 years, and undergoes a strong water rock reaction. Application o the isotopic geothermometers indicates that the temperature in the productive horizons feeding the surface manifestations is around 280°C, whereas isotopic equilibrium at depth between some chemical species is established at about 400°C.