Polyphase post-Variscan thinning of the North Pyrenean crust: Constraints from the P-T-t-deformation history of the exhumed Variscan lower crust (Saleix Massif, France)

As part of the Variscan orogen, Pyrenean realm has undergone several rifting episodes, starting from Permian-Carboniferous post-orogenic collapse and culminating with mid-Cretaceous lithospheric mantle exhumation. We present Pressure-Temperature-time-deformation (P-T-t-d) evolution tonalite bodies (here described for first time) intruded in late Carboniferous high pressure (HP) granulites Saleix Complex, forming inner envelope Lherz peridotites (Aulus Basin, Ariège, France), that is used as a proxy to reconstruct post-Hercynian continental crust. By integrating textural investigations metamorphic thermobarometry, zircon titanite UPb geochronology, we (i) constrain timing thermo-baric conditions related transition magma emplacement solid-state syn-tectonic deformation tonalite(s); (ii) discuss implications on polyphase exhumation history granulite host rocks. Emplacement tonalite(s) took place early Permian (ca. 281 Ma), environment (P = 0.5 ± 0.1 GPa T 750–880 20 °C) attesting an important thinning crust at end cycle. Solid-state occurred during 96 shallow crustal depths (≤10 km) under amphibolite facies conditions. These results document events had already thinned prior Cretaceous lower was affected by ductile rifting. Our study demonstrates played very role resulted post-Variscan, Permian-to-Cretaceous episodes.