Polyphase deformations along the regional transect Squillace Basin-Crotone swell-Taranto basin-Apulian foreland: a Recent active collisional system in the northeastern Ionian Sea.

The Calabrian Arc (CA) is part of the most active seismic belt in Italy, and the Ionian Sea has been described as the last remaining segment of oceanic crust subduction in the central Mediterranean. The thick sedimentary section of the African and Ionian plate has been scraped off from the descending plate, and piled up along thrust faults resulting in the emplacement of a thick (up to 10 km) and about 200–300 km wide arcuate accretionary complex. In the study area, the accretionary wedge interfers with the Apulian foreland. Here, the continental crust of the Apulian foreland is colliding with the suture zone of the Cretaceous-Paleogene Ligure-Piemontese ocean in Northern Calabria-Southern Apennines. This implies that, at least since late Miocene to Recent, in the northeastern sector of the CA, a foreland basin system was generating, while to the SW , where the Ionian oceanic plate was subducting, thick forearc basins are present. The present work is aimed to analyze the geometry and tectono-stratigraphic evolution of this late Neogene foreland basin system along the transect Squillace Basin- Crotone swell-Taranto Basin-Apulian foreland based on the pre-stack depth migrated multichannel seismic line CROP M5, about 2000 Km of multichannel seismic reflection profiles collected in the past in the coastal region and 20 well logs available from: http://unmig.sviluppoeconomico.gov.it/videpi/. In this sector of the CA, the polyphase deformations are given by alternating phases of extension and compression. NW-SE trending trascurrent fault zones affect the Late Miocene-Recent deposition and form along inherited and pre-Late Miocene deformation zones. All these deformations produce variable and cross-cutting structural trends and many inversion structures active till very recently. Four structural domains will be described; from SW to NE, they are: 1) the Squillace basin; 2) the Crotone swell; 3) the Taranto Gulf; 4) the Apulian foreland. It is remarkable that polyphase deformation (i.e. alternating extension and compression phases and the inversion structures) is common in all of the four domains, from the inner orogenic arc/wedge-top basin (Squillace basin and Crotone swell), to the foredeep basins (Taranto basin) and the foreland area (Apulian foreland). This suggests that the northeastern sector of the CA is colliding and is starting to “accrete” the subducting Apulian plate about 100km east of the presumed continental-oceanic transition.