The Geochemistry of Volcanic Rocks from Pantelleria Island, Sicily Channel: Petrogenesis and Characteristics of the Mantle Source Region

Major and trace element, Sr–Nd–Pb isotope and mineral chemical at least two distinct geochemical components: a mid-ocean ridge basalt (MORB) source, relatively depleted component, and adata are presented for mafic and felsic volcanic rocks from the island of Pantelleria. The mafic rocks, mostly basalts, range from hy- HIMU-like enriched component. A further enriched component, normative transitional basalts, through alkali basalts, to basanites. similar to the Enriched Mantle 1 (EM 1) component, could also Clinopyroxene in the mafic rocks varies in composition from Al, Ti- have been involved. According to geophysical data, the lithosphere poor diopside to Al, Ti-rich augite. These two populations can be is thinned beneath the island, and the asthenospheric mantle rises present simultaneously in the same sample and even in the same to a depth of 60 km. Rare earth element data require residual garnet crystal, suggesting polybaric fractionation in the pressure range 0–4 in the source and constrain the melting process to a depth of kbar, or mixing between basaltic magmas with different degrees of 70–80 km. The petrological and geochemical data suggest that the alkalinity. On the basis of their major and trace element and mafic magmas are generated within the asthenospheric mantle, from Sr–Nd–Pb isotope composition and age of eruption, two groups of a deep plume bringing the HIMU–EM 1 isotopic and trace element basalts are distinguished: a high TiO2–P2O5 group, erupted before signatures. Interaction of these OIB-like magmas with the shallower 50 ka BP, and a low TiO2–P2O5 group, erupted after 50 ka BP, asthenospheric mantle, providing a depleted MORB signature, separated by a caldera collapse. The felsic volcanic rocks have gives rise to magmas with the observed isotopic and geochemical