The south-western alpine foreland: Correlation between two sectors of the variscan chain belonging to ?stable Europe?: Sardinia(-)Corsica and the maures massif (south-eastern France)

The post-collisional Variscan evolution in Sardinia (Italy)-Corsica is characterized by Late Carboniferous-Permian extensional tectonics that affected the whole belt and was due to gravitational collapse of the previously thickened crust. Evidence of this late Hercynian extensional tectonism is widespread throughout the basement and its development is chronologically constrained by radiometric, sedimentary and paleontological data. Extensional tectonism in Sardinia may be related to a composite shear framework characterized by two events: an Early Shear Event (ESE) and a Late Shear Event (LSE). The ESE is characterized by shear zones in amphibolite facies conditions with a top-to S/SE shearing in relation to a dome structure. The LSE consists of strike slip ductile shear zones (mainly dextral shear zones) associated with retrograde metamorphism, commonly coeval with syntectonic plutons. The ESE accommodated the exhumation of the Variscan belt in Sardinia, while the LSE belongs to the Late Variscan strike-s,lip faulting common in SW Europe. The Late Variscan geodynamic evolution of the Mantes Massif (south-eastern France) is characterized by extensional tectonism related to non-coaxial deformation in HT to LT metamorphic conditions: the close relationships between these two areas suggests that they belong to the same segment of the Variscan belt. (C) 2004 Lavoisier SAS. All rights reserved.