Volcaniclastites as a key for geodynamic constraints in the evolution of the central-western Mediterranean Region: an overview.

In the central-western peri-Mediterranean chains, a consistent latest Chattian-Langhian orogenic calc-alkaline magmatism generated a high amount of volcaniclastites interbedded within penecontemporaneous marine successions. Emplacement of volcaniclastites is due mainly to epiclastic processes, implying paleogeographic constraints that instead do not control the distribution of fall-out pyroclastic deposits. Current knowledge does not allow direct correlations to be established between specific volcanic events and related secondary products; thus, reconstructions are based on field and analytic data. The volcanic activity occurred: (i) in the Adria Plate (during continental collision between the Mesomediterranean Microplate and the Adria-Africa Plate); (ii) along active subduction margins with different volcanic arc systems (“Mesomediterranean Microplate” Margin); (iii) back-arc basins (Apennine-Maghrebian-Betic systems; southwestern Corsica Margin and Sardinia Trough) due to rollback of the subductional slab; (iv) rifting (SE European Margin; e.g. Valencia and Provençal Basins) and (v) basins related to a strike-slip fault zone (Subbetic Basin). In this context it bears noting the scarcity at present of potential source areas consisting of primary products, suggesting that explosive volcanic arcs were quickly effaced during subduction. Instead, in rifting zones in the back arc areas the volcanic activity continues also in successive times and is testified to by several primary volcanic products. Paleogeographic and depositional constraints indicate multiple volcanic sources (arcs) located in different contexts but always near sedimentary basins. The study helps elucidate the evolution of interconnected geodynamic events in an original paleogeographic-paleotectonic framework.