Geomorphology and spatial distribution of monogenetic volcanoes in the southern Puna Plateau (NW Argentina)

Abstract

Monogenetic volcanoes are the most common volcanic landforms on Earth. Several works have shown that the study of geomorphology and spatial distribution of such small volcanoes reveals important aspects related to the volcanic field, from eruption dynamics to tectonic processes. The Altiplano-Puna Plateau (15° to 27° S, Central Andes) comprises the largest non-collisional plateau on Earth. Characterized by intensive deformation, uplift, and volcanism, this region is marked by the presence of hundreds of mafic monogenetic volcanoes. Despite its discrete occurrence, the monogenetic volcanoes show a close relationship with large scale, lithospheric foundering events in the region. In this contribution we applied a Geographic Information System (GIS) approach in order to build the first complete catalog of monogenetic landforms present in the southern Puna Plateau (24° 30′ to 27° 00′ S, NW Argentina), exploring their evolution and relationship with geotectonic events. Combining spatial analysis with a geomorphological study of each volcano, it was possible to identify the presence of 285 monogenetic volcanoes in the region, which could be grouped in seven clusters. Southern Puna shows a predominance of cinder cones and lava domes, suggesting a small influence of water in the eruption dynamics. Despite its high clustering degree, southern Puna monogenetic vents present a low density (8.3 × 10−3 vents/km2) when compared to other monogenetic fields around the world. In addition, Puna Plateau cones show a close relationship with monogenetic cones associated with an extensional environment, considering their back-arc context. Based on relative and available absolute ages, it was possible to map the volcanism evolution through time. The results indicate that the first monogenetic volcanoes appeared in the central region of the Plateau (Sierra de Calalaste), mainly associated with large-scale NNE-SSW reactivated faults. The activity then expanded (Antofalla and Antofagasta regions) and, finally reached the borders of the Plateau (Pasto Ventura and Arizaro regions), which show volcanoes associated with NW-SE normal faults.