Vapor-Buffered Volcanic Activity of Southern Italy and Mantle Degassing

Widespread mantle degassing is active in many areas of Earth, contributing to volcanic and seismic processes. The Italian territory is invested dramatically by deep degassing, at both volcanic and non-volcanic sites, with huge punctual as well as diffuse emissions of carbon dioxide. The pery-thyrrenian area of southern Italy is the place where these emissions are accompanied by active volcanism. A global look at melt inclusions from southern Italian volcanoes, particularly from the Campanian volcanic district, suggests that these volcanoes produce magmas under nearly common fluid buffered conditions that initiate in the litospheric mantle. Although the role and nature of components added to the mantle source is as debated as the mantle source itself, volcanic volatiles and the ensemble of petrologic evidences promote the prevailing hypothesis involving the subduction of a continental crust and/or oceanic sediments carrying both pelagic and non-pelagic fractions. The observed extended mantle degassing suggests that volcanism is an ‘occasional’ consequence that pierces the surface at some preferential degassing sites, depending on connected geological structures, including veined mantle paths, and regional stress conditions. Despite these complexities, magma fluxes can be still used to test simple hypotheses on the homogeneity of the volatile source metasomatising the local mantle.