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Chapter 11 Geology, volcanic history and petrology of Vulcano (central Aeolian archipelago)

2013; Zoological Society of London; Volume: 37; Issue: 1 Linguagem: Inglês

10.1144/m37.11

2041-4722

G. De Astis, Federico Lucchi, Pierfrancesco Dellino, L. La Volpe, C. A. Tranne, Maria Luce Frezzotti, Angelο Peccerillo,

earthquake and tectonic studies

Abstract Vulcano is an active NW–SE-elongated composite volcano located in the central Aeolian archipelago. Based on available radiometric ages and tephrochronology, the exposed volcanism started at c. 127 ka and spread through eight Eruptive Epochs separated by volcano-tectonic events and major quiescent stages. Various eruptive centres and two intersecting multi-stage calderas resulted from such evolution. Vulcano geological history displays several changes of eruption magnitude, eruption styles and composition of magmas through time. Vulcano rocks range from basalt to rhyolite and show variable alkali contents, roughly increasing during time. Magmas with low to intermediate SiO 2 contents and high-K to shoshonite affinity prevail in the early Epochs 1–5 ( c. 127–28 ka), whereas intermediate to high-SiO 2 shoshonite and potassic alkaline products dominate the last three Epochs (<30 ka). This sharp increase in silicic products is related to the shallowing of the plumbing system and resulting major role of the differentiation processes in shallow-level reservoirs. Radiogenic isotope compositions are variable ( 87 Sr/ 86 Sr=0.70424–0.70587, 143 Nd/ 144 Nd=0.51254–0.51276, 206 Pb/ 204 Pb=19.305–19.759, 207 Pb/ 204 Pb=15.659–15.752, 208 Pb/ 204 Pb=39.208–39.559) as a result of both source heterogeneities and shallow-level interaction of magmas with continental crust. The compositional variations of mafic magmatism with time suggest that the source zone changed from a metasomatized, fertile, ocean island basalt- (OIB-) like mantle to a metasomatized depleted lithospheric mantle. DVD: The 10 000 scale geological map of Vulcano is included on the DVD in the printed book and can also be accessed online at http://www.geolsoc.org.uk/Memoir37-electronic . Also included is a full geochemical data set for Vulcano.