Crustal accretion and chain building of an inherited passive margin: insights from the western southern alps

Recently, the influence of lithospheric extension on later orogeny has gained increasing interest. We make use of own geological mapping, interpretations of seismic reflection profiles and deep geophysical data to build an area-balanced cross-section across a key area of the Western Southern Alps and to model a series of structural restorations from the end of Mesozoic rifting to present-day. The interpreted ramp-dominated and basement-involved style results during retro-wedge accretion through reactivation of long-lived inherited structures. Early phases of Alpine orogeny resulted in north-verging reactivation of Early Permian structures and Triassic-Jurassic extensional basins, whereas later phases led to the internal deformation of the orogenic retro-wedge. Our results also suggest that, during the collisional and post-collisional tectonics, lithosphere dynamics drove diachronically the onset of tectonic phases (i.e., wedging and slab retreat), from east to west, across the Western Southern Alps.