Abstract

Relationships between late Tertiary-Quaternary (8-0 Ma) magmatic activity and regional shear zones in the central Mediterranean (southern Italy) are described. A magmatic shear system is thought to be present from the granite intrusion of Vercelli seamount (7.3 Ma) to Vesuvius volcano (0.8-0.13 Ma), and it may extend towards the Vulture. Another major tectonomagmatic lineation runs along the northern continental slope of Sicily connecting the early Pliocene (5 Ma), intra-plate volcanics of the Aceste seamount to the late Pleistocene (0.43-0.13 Ma) calc-alkaline rocks of Salina island. Progression of calcalkaline volcanism towards the east occurred along the two west-east trending structures of left-lateral strike-slip displacement. The calcalkaline products of the central sector of the Aeolian volcanic archipelago (the islands of Salina, Lipari and Vulcano) are associated with a NNW-SSE oriented shear zone of right lateral strike slip which runs perpendicular to the arc structure. The foreland is characterized by the intraplate volcanism of the Iblean plateau and Mt. Etna and by the important shear zone of the Malta escarpment which separates the continental domain of eastern Sicily from the Ionian oceanic lithosphere. This NNW-SSE oriented "hot" shear zone exhibits dextral strike-slip. Progression of magmatic activity along the regional fault systems towards the front of subduction is most likely related to different rates of roll-back which, in turn, are controlled by the characteristics of the foreland lithosphere: e.g. oceanic crust of the Ionian basin subducts quickly beneath the Calabrian arc, while the southern Apennines and Sicily are underthrusted slowly by thinned continental crust.

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