Reviewing the geodynamic impact of aseismic ridges subduction on the tectonic-magmatic evolution of the Southern Puna plateau

Abstract

The Southern Puna (∼24° S to 27° S) is an outstanding segment of the Central Andes where the subduction of aseismic ridges, multi-scale lithospheric foundering, and the transition from normal Andean subduction to the Chilean-Pampean flat slab occur. The exponential increase in the volcanological and geophysical knowledge of the Southern Puna provides a unique opportunity to reappraise its geodynamic evolution. This paper presents an updated review of the spatial-temporal distribution of the volcanism along with a reassessment of the main geophysical and morphostructural features of this region. Contrasting our observations with new kinematic reconstructions of the Taltal and Copiapó ridges, we infer that their subduction under the Southern Puna plateau has played a fundamental role in its Neogene-Quaternary geodynamic evolution (e.g shallow subduction, lithospheric delamination). Specifically, we propose a new alternative hypothesis where the Transversal Volcanic Chains (TVCs), characterizing the Southern Puna, are related to slab tearing. Slab tearing is a valid explanation for the occurrence of local anomalous peaks of melt productivity in a relatively cold retreating mantle wedge during slab shallowing. In our model, slab tearing under the Southern Puna was influenced by the flexural deformation related to slab dip changes as a result of the anomalous slab buoyancy during the subduction of Copiapó and Taltal ridges.