Geometric control of subducted Nazca plate on the Central Andes deformation styles

Along the Nazca-South America convergent margin, the different slab in-homogeneities correlates with the seismicity from small magnitude events to large megathrust earthquakes. In addition, the impact of the subducted slab geometry on the upper plate structure is evidenced, for instance, by the relation between the flat-slab segments and the migration of the continental deformation to the back-arc. In general, the continental plate shows tectonics longitudinal and latitudinal segmentations, which can be paired with the variability of shortening rates, styles and tectonic rotations along the South American margin. From small anticlockwise rotations, linked to the Miocene Peruvian flat-slab, to strong anticlockwise rotations, linked to Eocene-Oligocene bending of the Bolivian Orocline, in southern Peru, and Eocene-Miocene shortenings with some strike-slip deformation, to a big Eocene-Oligocene shortening age around 18°S, followed by the uplift of the Altiplano-Puna Plateau and deformation of the Sub-Andean range. From 18°S to 23°S there is small clockwise tectonic rotation, changing the pattern 23°S, with strong clockwise rotations and Upper Cretaceous-Oligocene shortenings. Near 29°S another strong change in the rotational pattern occurs, from strong to small clockwise rotations, simultaneous to the Pampean flat-slab subduction and a thick skin tectonic style. By a joint analysis of the seismicity catalogues, bathymetry/topography, potential field maps and structural deformation data, along the Central Andes, we present insights about the Nazca-south America subduction process. Results highlights: (1) the high correlation between seismicity and subducted oceanic features (2) the good correlation between intermediate depth seismicity and the upper plate tectonic limits of the Altiplano-Puna deformation zone, suggesting a direct relation between continental thickness and subducted plate geometry, (3) the presence of a strong change in the Central Andean Rotational Pattern (CARP), around 28-29ºS, which can be correlated spatially and temporally with the subduction of the Challenger fault zone and other oceanic features. These observations raise important questions about the first order multiscale feedbacks between subducted plate and continental deformation process.