The Cerro Aguas Calientes caldera, NW Argentina: an example of a tectonically controlled, polygenetic, collapse caldera, and its regional significance

PETRINOVIC, I. A.; MARTI, J; AGUIRRE-DÍAZ, G.; GUZMÁN, S.; GEYER,A.; SALADO PAZ, N.

JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH

Elsevier

Lugar: doi:10.1016 / j.jvolgeores. 2010.04.012.; Año: 2009

0377-0273

Polygenetic, silicic collapse calderas such as Cerro Galán, Pastos Grandes, La Pacana, 41 Vilama, Negra Muerta, Farallón Negro, Cerro Guacha, among others are common in the central 42 Andes. Here we describe in detail the Cerro Aguas Calientes caldera in NW Argentina, which 43 comprises two caldera-forming episodes occurred at 17.15 Ma and 10.3 Ma, respectively. We 44 analyse the significance of its structural setting, composition, size and the subsidence style of 45 both caldera episodes. Our results reveal that the caldera eruptions had a tectonic trigger. In both 46 cases, an homogeneous dacitic crystal-rich (>60 vol. % of crystals) reservoir of batholitic size 47 became unstable due to the effect of increasing regional transpression, favouring local dilation 48 throughout minor strike slip faults from which ring faults nucleated and permitted caldera 49 collapse. 50 Both episodes are similar in shape, location and products of the resulting calderas. The 17.15 51 Ma caldera has an elliptical shape (17 × 14 km) and is elongated in a N30º trend; both intracaldera and extracaldera ignimbrites covered an area of around 620 km2 52 with a minimum volume estimate of 138 km3 53 (DRE). The 10.3 Ma episode generated another elliptical caldera 54 (19 ×14 km), with the same orientation as the previous one, from which intracaldera and outflow ignimbrites covered a total area of about 1,700 km255 , representing a minimum eruption volume of 341 km356 (DRE). 57 In this paper we discuss the significance of the Cerro Aguas Calientes caldera in comparison 58 with other well known examples from the central Andes in terms of tectonic setting, eruption 59 mechanisms, and volumes of related ignimbrites. We suggest that our kinematic model is a 60 common volcano-tectonic scenario during the Cenozoic in the Puna and Altiplano, which may 61 be applied to explain the origin of other large calderas in the same region.