Fig. 16

Conceptual representation of the evolution of Rocca Canavese Thrust Sheets Unit (RCTU), Eclogitic Micaschists Complex (EMC) and Lanzo Massif (LM) within the tectonic frame of the South-Western Alps. a Hyperextended passive margin of Adria Plate before the Alpine subduction. The North Lanzo Massif is considered as a portion of mantle deriving from an ocean-continent transition zone (OCT) formed during Triassic-Jurassic rifting (Müntener et al. 2005; Piccardo 2010; Guarnieri et al. 2012; McCarthy and Müntener 2015), the South Lanzo Massif is considered a portion of the oceanic lithosphere of the Alpine Tethys (Piccardo 2010) and the EMC represents the continental crust of the Adria plate. b During subduction of the Alpine Tethys below the Adria plate, EMC and LM are subducted within the subduction channel, at different depths, and under a cold thermal regime. The RCTU is interpreted as a mélange formed in the subduction channel (Roda et al. 2018; Luoni et al. 2020; Roda et al. 2020). The LM metamorphic peak is dated at 55–46 Ma (Rubatto et al. 2008) while no chronological data is available for the EMC in this part of the SLZ. c The coupling between EMC, RCTU and LM occurred along the shear zones of the MZ, during the exhumation within the subduction channel, still under a cold thermal regime and formed a single tectono-metamorphic unit. d During the collision between Adria and European plates, LM, EMC and RCTU are involved in the orogenic wedge (i.e., a tectonic mixture of oceanic and continental rocks buried at different depths and exhumed to crustal levels) up to reach the present-day structural configuration