[5] Antofalla lies in the Antofagasta de la Sierra department of the[6][7] northern[8] Catamarca Province, in northwestern Argentina.

[9][7] The towns of Antofalla, Puesto Cuevas, Botijuela and Potrero Grande are east, southeast, south and southwest of the volcano, respectively.

[10][11] Gravel roads run along the northern, northeastern and east-southeast-southern sides of the volcanic complex,[12] but the volcano is difficult to access.

[13] Antofalla is part of the Central Volcanic Zone of the Andes, which runs along the border between Argentina and Chile[1] and whose main expression occurs in the Western Cordillera.

[30] Ignimbrites are also found and one of these forms Cerro Onas,[31] while a more recent one occurs in the Quebrada de las Cuevas area.

[30] It is one of many salt pans that developed within closed basins of the region and its surface lies at an elevation of 3,340 metres (10,960 ft);[36] other such salt pans include Salar Archibarca north-northwest of Antofalla,[37] Salina del Fraile south-southwest and Salar del Rio Grande northwest.

Other warm springs in the area are Vega Antofalla, El Hervidero and Te bén Grande; they may be nourished by thermal waters that ascent on faults.

[54] The oldest volcanic activity occurred during the Permian and early Jurassic, and the present-day manifestations consist mainly of lava and pyroclastic material.

During the Cenozoic, a number of now inactive volcanoes and ignimbrites, the latter of which typically have volumes of less than 10 cubic kilometres (2.4 cu mi), erupted in the region.

[19] Later volcanic activity was characterized by the emplacement of ignimbrites and of monogenetic volcanoes, which consist of cinder cones and lava flows with small volumes.

[62] The terrain beneath the volcano is formed in part by the crystalline basement of Precambrian-Paleozoic ("Antofalla Metamorphites"[63]) age mainly north of the volcano and often interpreted as ophiolite, and by sedimentary units of Eocene-Miocene age that crop out on its southern side and by a conglomerate unit known as the Potrero Grande Formation.

[64] Parts of the basement crop out where it have been exposed by erosion, such as in the Rio Antofalla and the Quebrada de las Minas,[64] and more generally in two sectors north and south of the volcano.

[70] Significant ore deposits may exist at the volcano,[64] but their deep burial in the poorly eroded volcanic complex hampers their exploitation.

[71] Antofalla lies in a region of arid climate, with about 150 millimetres per year (5.9 in/year) precipitation, much of it in the form of snow at high elevations.

Temperatures change drastically from day to night and vice versa,[72] ranging from −20–40 °C (−4–104 °F) in the wider region; the climate has been characterized as continental.

Where water is available, marsh vegetation and the so-called pajonales and tolares form; Deyeuxia, Festuca and Stipa grasses make up the former and Adesmia, Acantholippia, Baccharis, Fabiana, Senecio and Parastrephia thorn-bearing bushes the latter.

[72] Animals in the region include llamas, various rodents and vicuñas, as well as carnivores such as Darwin's rhea, pumas and South American foxes.

[30] There are not many creeks on Antofalla that carry water year round, although deep ravines with evidence of flash flood activity can be discerned.

[72] The Antofalla complex has been active from the Miocene 11 million years ago into the Quaternary and has generated a large variety of volcanic rocks;[1] it is thus considered to be a very long-lived volcano.

[77] Subsequently, lava flows of mafic[a] to trachydacitic composition were emplaced, in part on top of the earlier ignimbrites.

[79] Between 9.09 and 1.59 million years ago activity was continuous and dominated by lava flows of andesitic to dacitic composition, which constructed the main Antofalla volcano and the surrounding vents.