Neogene monogenetic volcanism from the Northern Puna region: products and eruptive styles

Abstract

The Neogene mafic volcanism of the Northern Puna region in the Central Andes is represented by scoria cones and lava flows dispersed over a wide region (c. 9150 km2) as isolated or poorly clustered centres. Although all the products are basaltic andesites to andesites, the behaviour of these magmatic systems resembles that seen in basaltic monogenetic fields. These centres were studied with the aim of defining the main volcanic lithofacies and evaluating the eruptive styles. The results suggest that the eruptions developed under a dry strombolian dynamic, with brief periods of lava fountaining and hydrovolcanism, the latter usually restricted to the early stages of cone construction. Changes in eruptive style are thought to be caused by variations in both the internal (e.g. magma ascent) and external (e.g. surficial water availability) conditions. The transitions do not reflect compositional changes, as evidenced by the small chemical differences observed among the products of the studied eruptive centres. Stratigraphic analysis, in addition to a few pre-existing radiometric dates, suggests that this volcanic activity occurred during the Late Miocene to Early Pliocene. This information supports the inference that these eruptions occurred before the peak of Southern Puna mafic volcanism and that they were coeval with eruptions of some of the most important silicic calderas of the Altiplano-Puna Volcanic Complex. The good preservation of volcanic edifices reveals that erosion rates were extremely low, in agreement with the high aridity conditions that have prevailed in the Puna region since the Mid- to Late Miocene.

Chemical and isotopic features of Li-rich brines from the Salar de Olaroz, Central Andes of NW Argentina

“…Paleogene to Lower Miocene reddish fluvial conglomerates, as well as calcareous sandstones of the Log Log, Vizcachera and Peña Colorada Formations (Oligocene to Lower Miocene; Coira et al, 2004: Seggiaro et al, 2015, uncomformably cover the Salta Group rocks. These formations are followed by Middle Miocene to Pleistocene volcanic units (Coira et al, 1993;Seggiaro, 1994;Soler et al, 2007;Seggiaro et al, 2015;Maro and Caffe, 2017), interbedded with fluvial and lacustrine deposits including evaporites of the Loma Blanca and Sijes Formations (Alonso, 1986) and fluvial-alluvial deposits of the Pastos Chicos-Trinchera Formations (Schwab, 1973). The stratigraphic record culminates with Quaternary deposits consisting of alluvial fans (Fig.…”

Tectonic controls on geomorphology and spatial distribution of monogenetic volcanoes in the Central Southern Volcanic Zone of the Andes (Argentina)

“…The monogenetic volcanism in the ZVF is marked by the predominance of cinder cones that present a clear association with local lineaments, suggesting a structural control on the occurrence of the monogenetic vents. The presence of cinder cones suggests a prevalence of the strombolian style as the main eruption dynamics in the ZVF (Németh and Kereszturi, 2015), similarly to the Puna Plateau in the Central Andes Haag et al, 2019;Maro and Caffe, 2016;Morfulis et al, 2020). This dynamic is supported by the number of hydrovolcanic landforms in the region (less than 20%), which denotes a limited, however existing, influence of magma-water interaction through the eruption history of individual vents of the ZVF…”

Tectonic controls on geomorphology and spatial distribution of monogenetic volcanoes in the Central Southern Volcanic Zone of the Andes (Argentina)

“…The monogenetic volcanism in the ZVF is marked by the predominance of cinder cones that present a clear association with local lineaments, suggesting a structural control on the occurrence of the monogenetic vents. The presence of cinder cones suggests a prevalence of the strombolian style as the main eruption dynamics in the ZVF (Németh and Kereszturi, 2015), similarly to the Puna Plateau in the Central Andes (Filipovich et al, 2019;Haag et al, 2019;Maro and Caffe, 2016;Morfulis et al 2020). This dynamic is supported by the number of hydrovolcanic landforms in the region (less than 20%), which denotes a limited, however existing, magma-water influence in the eruption history of individual vents of the ZVF…”

“…Most of these studies have been focused in the Central Volcanic Zone of the Andes (CVZ; 18-28º S; e.g., Maro and Caffe, 2016;Tibaldi et al, 2017;Tibaldi and Bonali, 2018;Filipovich et al, 2019;Haag et al, 2019;Grosse et al, 2020;Morfulis et al, 2020;Ureta et al, 2021c). In contrast, studies involving geomorphologic characterization of monogenetic volcanoes in the Southern Volcanic Zone (SVZ) of the Andes are still scarce.…”