Alpine structural evolution of the Internal Piedmont Zone in the Upper Viù Valley (Lanzo Valleys Ophiolite, Western Alps)

Abstract

New structural data have been collected in the high-pressure meta-ophiolites exposed in the Lanzo Valleys (i.e., the Lanzo Valleys Ophiolite, LVO) and tectonically overlying the continental crust of the Dora-Maira and Gran Paradiso massifs in the Western Alps. Detailed geological mapping and structural analysis carried out in the south-western sector of the LVO (i.e., the Upper Viù Valley) allow to distinguish four ductile deformation phases, corresponding to the subduction-related D1 phase, the early exhumation-related D2-phase and the late exhumation-related D3 and D4 phases. The geometry of structures and kinematics have been reconstructed, and their regional tectonic meaning is discussed in the frame of the Alpine tectonic evolution of the Internal Piedmont Zone (i.e., the remnants of the Alpine Tethyan oceanic lithosphere) in the Western Alps.