Abstract

P>New apatite fission track (AFT) and (U-Th)/He ages from the Argentera-Mercantour External Crystalline Massif of the SW Alps document an exhumation history along transcurrent dextral faults. Significant AFT age differences across the strikes of the main faults have been obtained from the NE (12.9 Ma) to the SW (5.2 Ma) and are linked to vertical uplifts along these right-lateral transpressional structures. Such segmentation is not observed in AHe ages. AHe ages have preserved younger ages (4-5 Ma) on the eastern hangingwall side of the High Durance extensional system. Such an exhumation history is interpreted to result from a transition of transpressional to transtensional regimes at 8-5 Ma during continuing Adria-Europe convergence. These data show that recent extensional deformation in the SW Alps can be related to the development of a transtensional domain in the Ubaye-Embrunais depression linked to ongoing strike-slip deformation along the Argentera-Mercantour.