Antofagasta Volcanic Field

Geological summary

This volcanic field has produced multiple monogenetic back-arc mafic centers within the Antofagasta de la Sierra Basin, a tectonic depression NE of Cerro Blanco volcano in the Southern Puna region of Argentina. The field contains several basaltic andesite scoria cones and lava flows, which Francis (1982) and de Silva and Francis (1991) suggested may only be a few thousand years old. The youngest cones, De La Laguna and Alumbrera, are roughly in the middle of the field. A sample from De La Laguna Ar-Ar dated by Risse et al. (2008) to 0.34 ± 0.06 Ma was considered to be a mixed age with older phenocrysts; another sample from a morphologically young flow at the La Falda cone (~20 km NW of Laguna) was assigned an estimate of less than 0.1 Ma with zero-age values. In their stratigraphic and morphological study, Baez et al. (2016) also considered Alumbrera to be the younger than De La Laguna, and noted that ventifact analysis suggested "a probable Holocene age" for the most recent activity. However, no radiometric age dates confirming Holocene eruptions are known.