Alpine Tethys rift-related OIB-type magmatism preserved on Elba Island (Northern Apennines, Italy)

The protoliths of the metabasite bodies exposed in the Mt. Calamita promontory (SE Elba Island, Italy) are postulated to have been formed during a Middle to Upper Triassic mafic magmatic event that intruded the Permo-Triassic sedimentary succession deposited on the thinned Adria paleo-margin during the break-up of Pangea. Although many of the metabasite outcrops in the Northern Apennines have been known since the 1950s, a comprehensive field documentation and an updated geochemical database are still lacking, thus preventing a full assessment of their petrogenesis and leaving the interpretation of the Lower Mesozoic Western Neotethys geodynamic framework incomplete. In this Communication, we describe for the first time the extent of the metabasite bodies and their relationship to the host rocks in Mt. Calamita promontory, thus defining their geochemical features and possible minimum age. Trace element evidence is used to constrain the mantle source and the associated tectonic scenario and indicate an alkaline basalt OIB-type magmatic character developed in an anorogenic divergent/rifted margin setting. When integrated with selected compositional data for Triassic and Early Cretaceous metabasite/mafic rocks from Adria and European paleomargins, a scenario of continental rift-drift and seafloor spreading involving upwelling parcels of enriched mantle is highlighted, defined for the first time as OIB-influenced (plume?) Alpine Tethys rifting.