The geodynamics of the Italian area are part of the larger Mediterranean evolution. The movie included in this article tries to synthetize our interpretation on the geodynamic and magmatic evolution of the Mediterranean during the Tertiary. The Alpine subduction generated a double-verging elevated orogen and developed from the Early Cretaceous to Present. The Apennines nucleated along the retro-belt of the Alps, from the Marittime Alps in western Liguria moving southward, where oceanic or thinned continental lithosphere was present (Fig. 23). The Apennines subduction had the subduction hinge migrating away relative to the European upper plate, and hence generated the back-arc basin that constitutes the entire western Mediterranean (Fig. 24). The back-arc rift was associated to asymmetric boudinage. The Apennines subduction retreat generated an arc characterized by second order undulations, i.e., salients and recesses that were controlled by the inherited lithospheric structures. The largest salient occurred in the Calabria arc and its offshore accretionary prism propagation, where there was the most subductable foreland, i.e., the likely oceanic Ionian/Mesogean Basin. The most prominent recess rather occurred at the intersection of the migrating Apenninic arc with the thick continental Adriatic lithosphere, which is resisting subduction since Pleoistocene, possibly due to its more effective buoyancy. The southern branch of the arc in Sicily is presently subject to the subduction hinge moving toward the upper plate (Devoti et al., 2008). This generated an inversion of the system; as a result, the northern Sicily offshore-southern Tyrrhenian Sea is now under compression, in spite of being located in the extending backarc basin (Scrocca et al. 2008). This inversion likely occurred since Pleistocene.

The Alpine and Apennines Belts were accompanied by igneous activity since Paleocene. The most ancient products are volcanic and sub-volcanic rocks emplaced in the Veneto Region (NE Italy; ~65-25 Ma), Punta delle Pietre Nere (Gargano peninsula; central-eastern Italy; ~62-56 Ma), Mt. Queglia (Abruzzi region, central Italy; <54 Ma) and Sulcis district (south-west Sardinia; ~61-51 Ma). These products have major and trace element content as well as Sr-Nd-Pb isotopic ratios compatible with a derivation from mantle sources not sensibly modified by subduction-related processes (i.e., are considered to be “anorogenic” or “intra-plate-like”). Other igneous products with roughly similar compositions are emplaced much later mostly in north-east Sicily (Mt. Etna; <1 Ma), in the Sicily Channel (Pantelleria and Linosa Islands plus minor seamounts; mostly <1 Ma), in south-west Tyrrhenian Sea (Ustica Island; <1 Ma). In south-eastern Sicily a long-lasting igneous activity with “anorogenic” geochemical characteristics is recorded in the Iblean Mts. area. The last area where “anorogenic” volcanic rocks crop out is Sardinia. Here detailed isotopic investigation allowed to distinguish two different igneous phases, the first dated late Middle Miocene-Early Pliocene (~12-4.4 Ma), the second dated Early Pliocene-Quaternary (~3.9-0.1 Ma). The products of the first phase crop out only on the southernmost sectors of the Island and constitutes <<1% of the volcanic rocks, wherease the products of the second phase crop out in central-northern Sardinia and are by far the most exotic composition ever recorded in the entire circum-Mediterranean area. To summarize, “anorogenic” magmatism has been active in the Italian area from ~65 to ~25 Ma and from ~12 Ma to Present. With the exception of the igneous activity in north-east Italy (Veneto Region) no “anorogenic” igneous rocks have been produced during the 51 to 12 Ma interval.

The volume of “subduction-related” or “orogenic” igneous rocks are three to five orders of magnitude larger than the volumes of “anorogenic” magmas produced during the Cenozoic in the Italian area. Most of the “orogenic” igneous activity is concentrated in three periods: Early Oligocene (~33-27 Ma) along the Insubric Line in the Alps, Early Miocene (~22-18 Ma) in Sardinia (and possibly in the Ligurian-Provençal Basin), and Plio-Quaternary (<2 Ma) along peninsular Italy and in south-eastern Tyrrhenian Sea (Aeolian Islands). The major and trace element compositions, as well as key isotopic systematics, are different in the three areas, depending on the thermal state, the composition and the age of the local mantle(s), the composition and the age of the subducting material and the styles of interaction between subduction-related metasomatic agents and the peridotitic matrix. In some cases a sort of geochemical inheritance of the mantle sources seems to have had a stronger effect in determining the final composition of the magmas compared to the potential modifications related to geological processes coeval to the igneous activity.