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

BÁEZ, W.; BUSTOS, E.; CHIODI, A.; GARCÍA, H.P.A.; ÁLVAREZ, O.; SIMÓN, V.; FOLGUERA, A.

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2023 vol. 129

0895-9811

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 kinematicreconstructions of the Taltal and Copiapo´ 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 Copiapo´ and Taltal ridges.