Palaeogeographic implications and relations between tectonics and sedimentation in satellite basins (Northern Apennines): insights from Neogene Epiligurian arcs.

Starting from late Oligocene the migration of the Northern Apennine thrust belt was coupled with the counterclockwise rotation of the Corsica-Sardinia block, as shown by various palaeogeographic reconstructions. A further support to the palaeogeographic reconstructions comes from the tectonic transport direction registered by oroclinal bendings occurring in the Val Marecchia thrust sheet, cropping out between the Tuscan and Romagna-Marche Apennines. In the allochthonous sheet some antitaxial arcs are characterized by different directions of tectonic transport, reflecting a change of about 40 degrees (from N-S to NW-SE) in the direction of the Apennine deformational front during early Serravallian-early Tortonian. The timing of this change can be desumed both from the age of deposits underlying the allochthonus sheet and from arcuate Epiligurian deposits located on top of arcuate thrust faults.The unconformities separating the depositional sequences of these particular syntectonic deposits registered different Neogene tectonic events, related to the step-wise advancements of the Ligurian thrust sheet. These characteristics make them an excellent natural laboratory for gaining insight into arc-development processes and tectonic control on sequence boundaries in orogenic wedges. Following these data, a palaeogeographic reconstruction of the timing of the various stages of Neogene rotations of the Northern Apennine deformational front is proposed