A journey of the continental crust to and from mantle depth: The P–T–t‐d path of Venaco unit, Alpine Corsica (France)

Abstract

This work presents the first pressure–temperature‐deformation‐time (P–T‐d‐t) path obtained for the Lower Units (Alpine Corsica, France) including the Tenda Massif that represent fragments of the European continental margin involved in the east‐dipping Alpine subduction. The new thermobarometric data applied to metapelites and the new 40Ar/39Ar dating of syn‐kinematic muscovite sampled from metagranitoids allowed us to define the P–T conditions and the age of the metamorphism of the Venaco Unit, a Lower Unit located in the southernmost sector of the Alpine Corsica. The outcoming scenario indicates that the Venaco Unit reached the baric peak at ≈ 33 km depth, not before Bartonian time. At 35.7 Ma (i.e., during the middle Priabonian), it was exhumed to a shallower structural level (i.e., at ≈ 26 km depth), mainly through the activation of the top‐to‐W shear zones. This retrograde path suggests that the Venaco Unit experienced fast exhumation, unlike the Tenda Massif which had been involved in subduction during the Ypresian and was stationary at 25–30 km, before its exhumation in the Priabonian.