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

Abstract

Ignimbrites are among the largest, and more extensive products of explosive volcanic eruptions on Earth. They are often associated with caldera-forming volcanic events, meaning that characterising their sources remains a fundamental task for understanding crustal magmatism in volcanic arcs. Mainly, since they may represent long-lived polygenetic volcano-magmatic systems. The Altiplano-Puna Volcanic Complex (APVC) is one of the largest areas of silicic magmatism on Earth, concentrating several calderas and large ignimbrite sheets since the late Miocene. 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 through Miocene volcanics within a complex system of regional conjugate transtensional structures and forms a 29×20 km depression (~114 km3 volume). The resulting ~2.5 Ma Tucúcaro and Patao ignimbrites together equate to ~53 km3 of deposits. After the caldera eruptions, monogenetic and polygenetic Pliocene to recent volcanoes have occupied both the caldera floor and its structural rim. The remaining depression hosts an oblong resurgent dome, 200 m high and ~60 km2 in area, surrounded by a central moat hosting the Tálar and Capur salt flats. We suggest the Tálar Caldera represents the southernmost recognised caldera of the APVC, and their products offer new insights into the boundary conditions of such massive magmatic bodies. This study provides further background information to understand the complex evolution of superimposed Central Andean volcanic systems and the volcanic activity within the APVC.