3He/4He Ratio in Olivines from Linosa, Ustica, and PantelleriaIslands (Southern Italy)

We report helium isotope data for 0.03–1Ma olivine-bearing basaltic hawaiites from three volcanoes of the southern Italy magmaticprovince (Ustica, Pantelleria, and Linosa Islands). Homogenous 3He/4He ratios (range: 7.3–7.6 Ra) for the three islands, andtheir similarity with the ratio of modern volcanic gases on Pantelleria, indicate a common magmatic end-member. In particular,Ustica (7.6 ± 0.2Ra) clearly differs from the nearby Aeolian Islands Arc volcanism, despite its location on the Tyrrhenian side ofthe plate boundary. Although limited in size, our data set complements the large existing database for helium isotope in southernItaly and adds further constraints upon the spatial extent of intraplate alkaline volcanism in southern Mediterranea. As alreadydiscussed by others, the He-Pb isotopic signature of this magmatic province indicates a derivation from a mantle diapir of aOIB-type that is partially diluted by the depleted upper mantle (MORB mantle) at its periphery.