Shear zones and metamorphic signature of subducted continental crust as tracers of the evolution of the Corsica/northern Apennine orogenic system.

This paper focuses on new data concerning the deformation and metamorphic history of continental margins of the Mesozoic Ligurian Tethys. In the Tenda massif (NE Corsica). a slice of the European-Iberian continental margin, contractional shear zones show HP/LT metamorphic assemblages and top-to-the-west kinematics. These shear zones are overprinted by greenschist facies exhumation-related structures showing top-to-the-SW sense of transport and then top-to-the-NE extensional shearing. The presence of HP/LT metamorphism, together with the kinematics of syncontractional shear zones, supports the classic view Of Cretaceous-Eocene east-vergent 'alpine-subduction' during the early evolution of the Corsica belt. By taking into account structural and metamorphic data on Tuscan continental units belonging to the other side (Adria margin) of the former Mesozoic Ligurian ocean, we ascribe the Corsica/Northern Apennine systent to a polycyclic orogen.