The Tálar Caldera and its products: the southernmost flare-up centre of the Altiplano Puna Volcanic Complex (Central Andes)

Abstract

Large ignimbrites are among the most volumetric volcanic deposits on Earth. They are generated by very large explosive eruptions, usually sourced from caldera-collapse volcanic events. Characterizing these sources is then a fundamental task for volcanic hazard evaluation since they may represent long-lived polygenetic volcanic systems. In this contribution we describe the general features of the Tálar Caldera and its most likely products, based on morphostratigraphic relationships and literature review. The caldera erupted on Miocene-to-Pliocene volcanics within a complex arrangement of regional conjugate transtensional structures and encompasses a 29 x 20 km depression (~114 km3 volume). The resulting ignimbrites (Tucúcaro and Patao ignimbrites, ~2.5 Ma), totalizing ~53 km3 of preserved deposits, are considered the southernmost flare-up events of the Altiplano Puna Volcanic Complex (Central Andes of Chile). Renewed post-collapse activity yielded to the formation of intermediate monogenetic and polygenetic Pliocene-Holocene volcanoes that have occupied both the caldera and its structural rim. The remaining depression hosts an oblong, 200 m high and 61 km2 resurgent dome surrounded by a central moat hosting the Tálar, Aguas Calientes and Capur salt flats. This study provides new insights to understand the complex evolution of superimposed Central Andes volcanic systems and the volcanic activity at the Altiplano Puna Volcanic Complex