Abstract

In the Southern Apennines, the presence of ocean-derived tectonic units (Frido, North-Calabrian and Sicilide Units), characterized by covers continuous from Late Jurassic-Early Cretaceous to late Chattian-Burdigalian, shows the persistence, West of the Adria Plate, of an oceanic area up to early Miocene. The similarities between the stratigraphic successions and tectonic evolution of these units, the Calvana-Canetolo Units of the Northern Apennines and the Beric-Maghrebian Flysch Basin Units allow us to recognize, in the Central-Western Tethys, the presence of an oceanic belt which deformed in the early Miocene with an Adria-Africa vergence (Lucanian-Maghrebian Basin). This basin was independent from the Piedmont-Ligurian-Nevadofilabride Basin, which deformed in the Latest Cretaceous-Paleogene with a European-Iberian vergence. Moreover, the recognition in some Apennine metamorphic units (Tuscan Metamorphic and Lungro-Verbicaro Units) of HP/LT parageneses, testifying both the subduction of continental crust up to depths of some tens of kms, and a tectono-sedimentary evolution quite similar to that characterizing the Betic-Rifian Alpujarride-Sebtide Units, makes it problematic to refer these units to the western margin of the Adria Plate, laterally continuous with nonmetamorphic and gently deformed platform and pelagic successions. These data allow a paleogeographic restoration, which implies the presence of a microcontinent interposed between a Piedmont-Ligurian branch and a Lucanian branch of the Tethys, to be extended also to the Apennine Domains. This microcontinent, would have originated the units involving a crystalline basement now forming the uppermost tectonic units in all the Western Mediterranean chains. Finally, this microcontinent would have fed, during the Early Cretaceous-early Miocene, both siliciclastic and calciclastic turbidite systems, which cannot be related to the Sardinia-Corsica Massif, to the Alpine Chain or to platforms located on the Adria Plate.

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