The Vilama caldera lies on the border between Argentina and Bolivia in the Puna-Altiplano, a high plateau in the Central Andes.

[7] Many of these are part of the main volcanic arc, which consists of stratovolcanoes such as Coropuna, the Nevados de Payachata, Ojos del Salado and Ollagüe and frequently reach heights of above 6,000 metres (20,000 ft).

[8] The Central Volcanic Zone is also the site of a number of large calderas, such as Los Frailes, Kari-Kari, Pastos Grandes, Cerro Panizos, Cerro Guacha, Purico complex, Coranzulí, La Pacana, Aguas Calientes, Negra Muerta volcanic complex, Galán, Wheelwright caldera and Incapillo.

[1] Younger volcanic rocks have almost entirely obscured its margins, with the exception of a 250–400-metre (820–1,310 ft) high escarpment on the western side of the caldera.

The latter form the so-called Altiplano-Puna volcanic complex[14] centered around the Chile-Bolivia-Argentina tripoint,[6] which was mainly active in the Miocene to Pleistocene[14] and is one of the largest such ignimbrite provinces in the world.

[26] Seismic imaging shows the existence of a partially molten magma body in the crust beneath the Altiplano-Puna volcanic complex.

[13] In terms of tectonics, during the Cenozoic the region was substantially uplifted, forming a high plateau with an average elevation of about 4 kilometres (2.5 mi).

[31] The ignimbrite contains phenocrysts consisting of biotite, hornblende, andesine plagioclase, pyroxene quartz and opaque components.

[34] A mixing between mantle derived and crustal melts has been suggested to be the source of the magma for both Vilama and other Altiplano-Puna volcanic complex systems.

[37] Vegetation consists of shrub steppe,[38] with Festuca, quenoa, tola, Prosopis ferox and yareta being typical members.

The volcanically dominated terrain is free of vegetation, with most life occurring close to waterbodies (including the grasses Oxychloe andina and Werneria pygmaea).

[14] The eruption occurred between 8.4–8.5 million years ago, but with substantial scatter of the radiometric dates which according to Soler et al. 2007 may be due to excess argon contaminating biotites and thus resulting in spurious age data.

These units together are at least 400–700 metres (1,300–2,300 ft) thick and form a uniform layer of densely welded ignimbrites with poorly preserved pumice and lithic fragments.

The ignimbrite deposit inside the caldera shows evidence of flow forms and alteration by vapour interactions.

[55] Based on such sizes, the caldera-forming eruption is considered to be a supereruption with a volcanic explosivity index of 8 and Vilama caldera is thus a supervolcano.

[9] Additionally, it has been proposed that the 1,000 cubic kilometres (240 cu mi) Sifon ignimbrite, which was erupted 8.33 ± 0.06 million years ago,[56] may originate in the Vilama caldera.

[60] Magnetotelluric imaging of the area has identified a low electrical conductivity anomaly beneath the caldera, which may be a solidified magma body.