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Superposed structural fabrics in the easternmost Fuegian Andes reveal two distinct, non-coaxial deformation phases across the transition from the orogenic core to the thrust-fold belt. Each phase is characterized by different metamorphic conditions and consistently different orientations, which allow the structural correlation between the orogenic core and the internal thrust-fold belt. The first deformation phase was coeval with regional metamorphism reaching upper greenschist facies, and featured simple shear deformation of the basement (Paleozoic and Jurassic) and cover (Cretaceous) in the top of the underthrusting South American plate. The second phase developed during collision of the orogenic wedge with the Río Chico Arch, a promontory in the underthrusting plate; this phase was characterized by thrust sheet emplacement and formation of a crustal duplex, with rock uplift and consequent low to very-low grade metamorphism. Buttressing against the Río Chico Arch is responsible for the change in shortening orientation that distinguishes both phases. of the magmatic arc and the cratonic margin, with deformation of the Paleozoic-Early Cretaceous rocks between them. In the Fuegian Andes, arc-continent collision involved cratonward obduction of the oceanic crust of the back-arc basin, and subduction (underthrusting) of the cratonic margin (Fig. 1D) (Klepeis et al., 2010). Thrusting and stacking of upper crustal rocks in the top of the lower plate formed a major antiformal stack that propagated toward the foreland into a thrust-fold belt (Fig. 1D) (Torres Carbonell and Dimieri, 2013). The latter includes the Rocas Verdes fill, as well as