Cerro Panizos (Spanish: [ˈse.ro paˈni.sos], "Maize Hill") is a late Miocene[a]-age shield-shaped volcano spanning the Potosi Department of Bolivia and the Jujuy Province of Argentina.

The Cienago Ignimbrite erupted over 350 cubic kilometres (84 cu mi) from Panizos about 7.9 million years ago, and 6.7 million years ago the Panizos Ignimbrite erupted over 650 cubic kilometres (160 cu mi).

Cerro Panizos lies in the Cordillera de Lipez mountain range of the Andean Altiplano-Puna high plateau.

[6] The mountain named "Cerro Panizos"[d] is a c. 5,300 metres (17,400 ft)[e] high lava dome in the southeastern semicircle.

[13] The 5,158-metre-high (16,923 ft) Limitayoc formed along a north-south trending fault and has an elongated shape,[14] with traces of hydrothermal alteration at its northern end.

[33] The region is a cold, dry desert, with annual precipitation reaching 200–400 millimetres (7.9–15.7 in) per year and only sparse cloud cover.

[35] The native fauna includes guanacos, llamas, tarucas and vicuñas,[32] and smaller animals such chinchillas, vizcachas and several mice genera.

[36] The CVZ consists of two parts: a volcanic arc with stratovolcanoes[38] reaching 6,000 metres (20,000 ft) elevation,[j][40] including the highest volcano in the world, Ojos del Salado;[41] and numerous large calderas in the main arc and farther east,[42] which produced the largest volume of Neogene-Quaternary volcanic rocks in the Andes.

[64] Volcanic activity in the region began during the Jurassic[n] in the Cordillera de la Costa and has migrated eastward since then.

[47] During the late Miocene, subduction under the Puna became steeper, causing the mantle wedge to become thicker and part of the overlying crust to delaminate, increasing the production of melts.

[40] Volcanic activity shifted east into the Puna until the Pliocene,[o] after which it returned to the main arc where it persists to this day.

[65] Numerous ignimbrites were emplaced between 25 and 1 million years ago, with the bulk dating from the late Miocene to Pliocene.

[66] Each of these flare-ups is associated with multiple ignimbrites: The first with the Artola, San Antonio, Lower Rio San Pedro, Divisoco, Granada, Pairique and Coyaguayma; the second with the Sifon and Vilama; the third with the Panizos, Coranzuli, Toconce, Pujsa, Guacha, Chuhuilla, Carcote and Alota; and the fourth with the Atana-Toconao, Tara and Puripicar Ignimbrites.

[68] Volcanism declined during the past 4 million years,[69] yielding smaller ignimbrites such as the Patao, Talabre-Pampa Chamaca, Laguna Colorada, Puripica Chico, Purico, Tatio, Filo Delgado and Tuyajto.

[73] Phenocrysts include biotite and plagioclase, while apatite and zircon form accessory phases[p]; orthopyroxene, quartz and sanidine are less common and clinopyroxene, hercynite, hornblende,[75] hypersthene,[76] ilmenite and magnetite are rare.

[93] It is the source of two major ignimbrites: the first (Cienago[36] or Panizos I[69]) was erupted 7.9 million years ago and forms two flow units[36] with a total volume exceeding 300 cubic kilometres (72 cu mi),[69] each underlaid by pyroclastic fallout deposits[15] several centimetres thick.

[94] Afterwards, lava domes erupted on the southern side of the volcano,[36] including Cerro Limitayoc,[95] where activity continued after the Panizos Ignimbrite.

[98] The Panizos Ignimbrite forms the shield around the central dome complex, reaching as far as the Rio Granada-San Juan de Oro valley east of the volcano.

[30] The Panizos Ignimbrite represents one of several "super-eruptions" in the Central Andes; these are giant volcanic events[102] that exceed the size of all known eruptions of the last 11,700 years.

[103] Ash layers possibly correlated to the Panizos Ignimbrite have been found in the Cordillera de la Costa.

Collapse of the first vent or the opening of a new one caused a break in the eruption; the layer between the units[105] and the downsag caldera formed at this time.

[110] Collapses at the eastern end of the volcano exposed underlying country rocks,[98] and hydrothermal activity took place in the central dome complex.