Evolution of the Western Mediterranean, In "Regional Geology and Tectonics: Phanerozoic Passive Margins, Cratonic Basins and Global Tectonic Maps"

The western Mediterranean is the backarc basin of the Apennines-Maghrebides subduction, which retreated from west to east since Oligocene to present times. The slab transported into the mantle different segments of the oceanic and transitional continental lithosphere, previously stretched during the Mesozoic Tethys realm. The widest extension in the Mediterranean backarc basin occurred where the thinned, possibly oceanic lithosphere was present in the foreland, i.e., the present Ionian basin. The stretching in the Western Mediterranean backarc generated lithospheric boudins as the Corsica-Sardinia microplate. The stretching was asymmetric, being the roots of the boudins shifted eastward relative to the shallow section of the continental lithosphere. The "eastward" rejuvenation of the Western Mediterranean sub-basins, the eastward migration of the slab retreat, and the related magmatism and foredeep depocenters, they all support an eastward sub-lithospheric relative flow of the mantle. The slab retreat and the related backarc extension moved at a speed of few cm/year, being the fastest speed (2-4 cm/yr?) localized at the crest of the arc, presently positioned in the Ionian Sea. Contemporaneous to this process, the counter-clockwise rotation of Africa relative to Europe, generated a N-S convergence of few (2-5) mm/yr, responsible for the Pliocene to present compression acting along the northern offshore of Africa and Sicily. Being the Africa-Europe convergence much slower than the slab retreat, the origin of this latter process must be independent from the relative motion of the two major plates. This supports the coexistence of different geodynamic processes in the same area.