The Campania Province

Abstract

The Campania Province (about 0.2 Ma to 1944 AD) consists of stratovolcanoes and multi-centre volcanic complexes (Vesuvio, Campi Flegrei, Procida-Vivara, Ischia) that are built up by mafic to felsic alkaline potassic magmas. Leucite-bearing ultrapotassic rocks are restricted to Somma-Vesuvio. Older lavas (about 2 Ma) with calcalkaline affinity are buried beneath the Campanian Plain. The rocks of the Campania Province define various suites that were generated by polybaric fractional crystallisation, mixing and assimilation of different types of wall rocks, starting from trachybasalt parents. The leucite-bearing rocks of Vesuvio also derive from trachybasalt, but extensive carbonate assimilation induced strong silica undersaturation and crystallisation of leucite. Therefore, primary ultrapotassic magmas, such as those occurring in the Roman Province, seem to be lacking in Campania. In contrast, there is a strong geochemical similarity between Campania and Stromboli, Aeolian arc. Petrological and geochemical data, therefore, argue against the commonly held view that the Campania volcanoes represent the southern extension of the Roman Province and rather indicate they represent the northernmost end of the eastern Aeolian arc. The Campania and Stromboli rocks have intermediate OIB-arc geochemical signatures, which suggest melt generation in a hybrid source, containing both OIB and subduction components. The arc-type components have been provided by fluids released by the subducted Ionian oceanic slab and associated sediments. The OIB-type component is attributed to the inflow of asthenospheric mantle from the foreland onto the subducting and southeastward retreating Ionian slab. Migration of asthenospheric mantle was favoured by opening of a slab window along the Apulian-Ionian plate.