Seminari di Scienze della Terra
Universita’ di Genova
30 Gennaio 2007

 Multidisciplinar Approach to Natural Triggers of Lithosphere Evolution

A West-East petrochemical and isotopic traverse along the volcanism of the Aeolian Island Arc, Southern Tyrrhenian Sea, Italy: inferences on mantle source processes.

Lorella Francalanci

Dipartimento di Scienze della Terra, Università degli Studi di Firenze, via La Pira, 4, I-50121, Firenze, Italy

The Aeolian Island arc, emplaced on continental lithosphere, is constituted by seven islands and several seamounts, whose magmatic activity ranges from 1.3 Ma (Sisifo seamounts) to present time (Vulcano, Stromboli). The rock compositions belong to different magmatic series, showing a large silica range (48-76 wt.%). Calk-alkaline (CA) and high-K calk-alkaline (HKCA) volcanics are present in all the islands, except for Vulcano. Shoshonitic (SHO) are only lacking at Alicudi, Filicudi and Salina. Potassic (KS) volcanics have been erupted at Vulcano and Stromboli. The different parental magmas were originated in a heterogeneous MORB-like mantle wedge, variously metasomatised by subduction related components (oceanic crust + sediments, released as either fluids or sediment melts). Trace element and Sr-Nd isotopic ratios show clear geographical west-east variations among CA rocks. The composition of the mantle source of Stromboli is strongly influenced by the addition of a sedimentary component recycled into the mantle wedge, whose amount is higher (ca. 2%) than in all the other islands (< 0.5%). Furthermore, the islands from the central sector of the arc are characterised by a higher proportion of slab-derived fluids, which promotes higher degree of melting.

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