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| Cerro Galán | |
|---|---|
| Name | Cerro Galán |
| Elevation m | 5800 |
| Location | Catamarca Province, Argentina |
| Range | Andes |
| Type | Caldera |
| Last eruption | ~2.2 million years ago |
Cerro Galán is a large ignimbrite caldera in the Puna de Atacama region of the Andes in Catamarca Province, Argentina. The structure is one of the world's largest Quaternary calderas and is a key locality for studies of silicic volcanism, caldera collapse, and high‑altitude hydrothermal systems. Its significance spans geology, paleoclimate reconstruction, and archaeology in the southern Altiplano.
The caldera lies within the Puna plateau near the border with Salta Province and is framed by regional features such as the Antofalla volcanic complex, Sierra de Antofalla, Salar de Antofalla, and the Tocorpuri–Sairecabur volcanic chain. It is part of the Neogene–Quaternary volcanic belt associated with the Subduction of the Nazca Plate beneath the South American Plate, and is proximal to the Altiplano‑Puna plateau uplift and the Lagoa Real area. Regional mapping links the caldera to the Ojos del Salado sector and the Puna de Atacama Basin, with drainage into endorheic systems like the Salar del Hombre Muerto and Salar del Rincón. The surrounding terrain shows ignimbrite sheets, resurgent domes, and post‑caldera lava domes that connect to the Central Volcanic Zone.
The principal caldera‑forming eruption occurred in the early Pleistocene ~2.2 million years ago, producing one of the largest ignimbrite sheets known in South America, often referred to in regional literature alongside events at La Pacana and Altiplano ignimbrite province. The catastrophic eruption produced extensive pyroclastic density current deposits that blanketed the Puna and flowed toward basins such as the Salar de Antofalla. Collapse produced a resurgent central uplift and ring fractures that later localized intrusive activity, comparable to collapse dynamics described for Long Valley Caldera, Yellowstone Caldera, and Valles Caldera. Subsequent volcanic activity emplaced rhyodacitic domes and smaller eruptions that modified the caldera floor and margins, with ties to tectonism associated with the Calama‑Olacapato‑El Toro fault zone and regional strike‑slip systems such as the Vicuña Pampa Fault.
Eruptive materials are dominated by high‑silica rhyolite to rhyodacite ignimbrites, pumice fall, and ash beds, with geochemical affinities comparable to other Peralkaline and metaluminous systems in the Central Andes. Mineral assemblages commonly include sanidine, quartz, biotite, amphibole, and accessory titanite and zircon, with trace element signatures utilized for correlation with deposits across Catamarca and Salta. Geochronology using argon‑argon dating and zircon U–Pb methods constrains eruptive phases and links to plutonism beneath the caldera. Isotopic studies compare strontium‑neodymium‑lead ratios with neighboring systems like Antofalla and Tocomar, demonstrating crustal assimilation and magma chamber differentiation processes observed in large silicic systems.
Post‑caldera systems exhibit extensive hydrothermal alteration, sinter deposits, fumarolic activity, and evidence for high‑temperature fluids that have produced argillic and advanced argillic alteration zones, similar to features at El Tatio and Sol de Mañana. Hydrothermal alteration is concentrated along ring fractures and resurgent structures and has been investigated with geophysical surveys including magnetotellurics and gravity, as in studies comparing to Los Azufres and El Salvador (Chile). Geochemical sampling of hydrothermal fluids and alteration minerals yields clues to subsurface temperatures and circulation patterns relevant to geothermal energy assessments and mineralization, paralleling exploration paradigms used at El Indio and Pascua‑Lama.
The caldera occupies a high‑altitude arid environment characterized by puna grasslands, sparse tussock grass communities, and salt‑tolerant halophyte assemblages similar to those on the Altiplano. Climate is cold and hyperarid with large diurnal temperature ranges, influenced by the South American summer monsoon and Southern Hemisphere westerlies, yielding low annual precipitation primarily as snow. Faunal elements include high‑altitude specialists recorded across the Andes such as vicuña, viscacha, and numerous passerine birds that utilize wetland remnants in nearby salars akin to habitats at Salar de Uyuni and Salar de Atacama.
Archeological evidence on high Andean summits and within calderas documents pre‑Columbian occupation and ritual use by indigenous societies such as the Inca and preceding populations like the Diaguita and Atacama people, with parallels to summit offerings found on Llullaillaco and Aconcagua. Archaeological surveys have recorded lithic scatters, obsidian sourcing that relates to regional networks including the Antofalla obsidian, and transient pastoral use during the Prehispanic period and Colonial period. Modern human activity includes scientific expeditions from institutions such as the Consejo Nacional de Investigaciones Científicas y Técnicas and universities in Argentina and abroad.
Cerro Galán is a focus for multidisciplinary research involving volcanology, geochronology, petrology, remote sensing, and hazard assessment by teams from universities and research bodies such as CONICET, University of Buenos Aires, University of Salta, and international collaborators from institutions like the Smithsonian Institution and University of California. Monitoring is limited compared with active volcanic centers; nevertheless, mapping, satellite interferometry (InSAR), seismic surveys, and geochemical sampling inform models of long‑term magmatic and hydrothermal evolution, following methodological frameworks applied at Long Valley, Taupo Volcanic Zone, and Campi Flegrei. Potential hazards include renewed explosive silicic eruptions, pyroclastic density currents, widespread ashfall affecting communities and infrastructure across Catamarca and Salta, and hydrothermal hazards including phreatic explosions, echoing risks documented at Uturunku and Tungurahua. Continued integration of geological, geophysical, and archeological data remains essential for regional hazard preparedness and scientific understanding.
Category:Calderas of Argentina Category:Volcanoes of Catamarca Province