The Aeolian Arc

Abstract

The Aeolian arc volcanic province consists of seven main islands and several seamounts in the Southern Tyrrhenian Sea. Rock compositions range from calcalkaline to shoshonitic and potassic alkaline, with an increase in potassium from the western to the central-eastern islands. 87Sr/86Sr increases and Nd–Pb–He isotope ratios decrease with potassium. Geochemical compositions of rocks from Stromboli resemble closely those of Campania volcanoes. Range of silica contents of single volcanoes reaches a maximum in the central islands of Vulcano and Lipari where abundant rhyolites have been erupted. These volcanoes were constructed along the Tindari-Letojanni strike-slip fault, a main tectonic feature that divides the Aeolian arc into two compositionally, volcanologically and structurally distinct sectors. Active volcanism is restricted to the central-eastern arc under which there is an active seismic Wadati-Benioff zone with depth of earthquake foci increasing northwestward. Aeolian arc magmas were generated in a heterogeneous upper mantle that was metasomatised by various types of fluids released from the Ionian subduction zone and associated sediments. The role of sediment increases significantly from the western islands of Alicudi and Filicudi to the eastern island of Stromboli. Pre-metasomatic mantle had OIB to MORB-type composition, with OIB components increasing at the margins of the arc. The rock compositional variation within single islands reflects both the characteristics of parental magmas and the shallow-level evolution history. In particular, the occurrence of abundant silicic volcanics in the central Aeolian islands results from extensive fractional crystallisation of magmas in large shallow reservoirs developed along pull-apart basins of the Tindari-Letojanni fault.