The Apulian Province (Mount Vulture)

Abstract

Mount Vulture (0.75–0.14 Ma) is an isolated stratovolcano with a central caldera sited east of the Apennine chain near to the Apulia foreland, away from other Italian recent volcanoes. Mount Vulture is built up of undersaturated alkaline rocks that show high enrichments in both Na and K. Carbonatitic pyroclastics and a few lavas were erupted late in the history of the volcano. Silicate rocks range from foidite, melilitite and haüynite to haüyne-bearing phonolite. Incompatible element patterns show arc-type negative anomalies of HFSE but also contain relative depletion of K and Rb, a typical feature of OIB magmas. He-isotope ratios (R/RA ~ 6.0) are much higher than other volcanoes in the Italian peninsula and resemble Etna. Carbonatites have similar radiogenic isotope ratios as the silicate rocks supporting an origin by unmixing. Overall, geochemical data suggest a magma origin within an OIB-type upper mantle that was contaminated by subduction-related fluids. OIB components were provided by the asthenospheric mantle from the foreland, whereas the arc-type signatures were furnished by fluids released from the detached Apulia-Ionian slab and associated sediments. Magmas were generated by redox melting in a post-collisional setting above the detached and sinking plate after slab breakoff.