Basement-involved tectonism in the western Central Andes: Insights from the eastern Domeyko and Frontal cordilleras, and the Salar de Atacama Basin

Northern Chile is a natural laboratory to understand the relation between different basement-involved structural styles, mechanisms of basement uplift, and the interaction of Pre-Andean rift-related and Andean contractional structures. Field and geophysical data (two-dimensional seismic profiles) are key to understanding the geometry and kinematics of these structures in the subsurface. Herein, we analyzed the basement-involved tectonism in the easternmost part of the Domeyko Cordillera, the southern end of the Salar de Atacama Basin and the Frontal Cordillera in northern Chile based on an updated revision of the structures exposed on the surface and the other ones present in depth. Our results indicate that the Pre-Andean configuration of the region was the first-order factor controlling the basement-involved deformation. Late Permian to Jurassic rift-related, basement rooted, normal faults accommodated much of the shortening in the upper plate, thus triggering their partial and/or full reverse reactivation, situation that in some places was accompanied by purely reverse faulting, thus allowing the exhumation of large Paleozoic basement granitic blocks. This event occurred in a similar manner in the studied regions from Late Cretaceous to Paleocene in an arc-system geological context. The initial distribution of half-grabens, syn-rift and post-rift sequences governed the variations in the basement-involved structural styles ranging from basement-cored anticlines to tectonic wedges, among others. However, the flat-slab process has frequently been invoked as the main process responsible for the basement-involved tectonism in northern Chile. Our results suggest a strong control exerted by inherited stratigraphic and structural features more than variations in slab geometry.