Syn‐convergence exhumation of continental crust: evidence from structural and metamorphic analysis of the Monte Cecu area, Alpine Corsica (Northern Corsica, France)

Abstract

In the Corsica Island, a stack of metamorphic continental units derived from the European continental margin is thrust over a pre‐Alpine basement during the convergence‐related processes in the Late Eocene–Early Miocene time span. The Piedigriggio‐Prato Unit is representative of these units. Its tectono‐metamorphic history has been reconstructed by an integrated approach, ranging from map‐ to meso‐ and microscopic scale analyses. This unit is characterized by a polyphase deformation history that consists of three deformation phases developed under retrograde metamorphism ranging from blueschist to sub‐greenschist facies metamorphic conditions. At the map‐scale, the Piedigriggio‐Prato Unit is characterized by km‐size isoclinal folds deformed by open to closed recumbent folds producing Type 3 fold interference pattern. The features of the deformations and the P–T conditions suggest that the first two phases were acquired during the ductile extrusion of the Piedigriggio‐Prato Unit. Before the Early Miocene, the gravitational collapse of over‐thickened continental crust produced vertical shortening and the consequently recumbent F3 folds. The exhumation history of the Piedigriggio‐Prato Unit can be viewed as representative for the exhumation of a continental crust fragment during the transition from the continental subduction to the continental collision. Copyright © 2016 John Wiley & Sons, Ltd.