The feeding system of 1944 eruption of Vesuvius: melt inclusion data from dunitic nodules

Mafic nodules are relatively widespread in the deposits of the 1944 eruptio n of Vesuvius. Mineralogical and melt inclusion studies on mafic cognate xe noliths give information on their depth of formation and consequently on th e feeding system of Vesuvius involved in the 1944 eruption. Mineralogical d ata presented in this work indicate that clinopyroxenites and olivine-clino pyroxenites formed within a shallow magma chamber, following the crystalliz ation of mafic batches of magma rising from depth (MARIANELLI et al. 1995) and differentiating in the lower portions of the shallow reservoir (<100 MP a) of Vesuvius (MARIANELLI et al. 1999). On the contrary, melt inclusion st udies on dunites indicate that these nodules originated at a pressure of ab out 420 MPa by cumulus processes in the deep intracrustal differentiation s ystem identified by MARIANELLI et al. (1999). The presence of dunite nodule s in the erupted products allows a rough estimation of the ascent velocity of the magma from the deep reservoir; velocities of 0.1-0.6 km/h were obtai ned.