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| Calderas of South America | |
|---|---|
| Name | South American Calderas |
| Type | Calderas |
| Location | Andes, Patagonia, Central Volcanic Zone, Southern Volcanic Zone |
| Coordinates | various |
| Elevation | variable |
| Last eruption | variable |
Calderas of South America
South American calderas are large collapse structures associated with explosive volcanism across the Andes, the Altiplano–Puna Plateau, and the Southern Volcanic Zone. These features occur in tectonically active regions linked to the subduction of the Nazca Plate beneath the South American Plate and are central to studies by institutions such as the Smithsonian Institution, United States Geological Survey, and regional observatories like the Servicio Nacional de Geología y Minería and Servicio Nacional de Geología y Minería (Argentina). Research integrates data from projects led by universities including the University of Chile, Universidad de Buenos Aires, Universidad Nacional de San Juan, University of California, Berkeley, and international collaborations with the British Geological Survey.
Calderas in South America are classified by morphology, size, eruptive history, and tectonic setting, drawing on schemes used for the Yellowstone Caldera, Aira Caldera, and Long Valley Caldera to compare collapse styles, ignimbrite volumes, and resurgence patterns. Classifications reference volcanic provinces such as the Central Volcanic Zone, Southern Volcanic Zone, and the Puna Plateau, and utilize terminology standardized by the International Association of Volcanology and Chemistry of the Earth's Interior and the International Union of Geological Sciences. Comparative frameworks often contrast calderas associated with composite volcanoes like Ojos del Salado and Llullaillaco versus large ignimbrite-forming complexes like La Pacana, Cerro Galán, and Tocorpuri.
Major calderas are concentrated along the Andean arc from Colombia and Ecuador through Peru, Bolivia, Chile, and Argentina, with prominent examples including Chachani-region systems, Misti, Ampato, Coropuna, and the giant Cerro Galán and La Pacana caldera complexes. In northern Andes contexts, studies reference Pastos Grandes, Mojanda, and Cuicocha; in the Central Andes, the Altiplano–Puna volcanic complex hosts Socompa, Ollagüe, and Salar de Uyuni-adjacent calderas. Southern sectors contain Calbuco, Chaitén, Aucanquilcha, and Tromen-area structures. Offshore and Andean fringe features such as Isla de Pascua-proximal systems and the Patagonian plateau host smaller collapse features and resurgent domes recognized by teams from the Geological Survey of Argentina and the Instituto Geofísico del Perú.
Caldera formation in South America results from large-volume explosive eruptions that evacuate shallow to mid-crustal magma reservoirs, producing ignimbrites, welded tuffs, and collapse structures similar to episodes documented at Mount St. Helens and Krakatoa but on larger scales akin to Toba and Taupo. Magma genesis is influenced by subduction-related fluxing of the mantle wedge beneath the Nazca Plate–South American Plate boundary, slab geometry variations such as flat slab segments near Peru-Chile Trench and crustal thickening beneath the Altiplano, producing calc-alkaline to peraluminous rhyolitic magmas. Evolutionary sequences include magma chamber replenishment, fractional crystallization, crustal assimilation, and volatile-driven eruption triggers explored in studies of Valles Caldera analogs and regional petrogenetic models.
Petrological inventories emphasize high-silica rhyolites, dacites, and ignimbrites with accessory minerals like sanidine, biotite, amphibole, and zircon, with isotopic signatures traced via Sr–Nd–Pb systems in work by researchers at ETH Zurich, Universidad de Concepción, and CONICET. Geophysical imaging using seismic tomography, gravity, and magnetotelluric surveys conducted by IRIS, INGV, and regional observatories reveal complex crustal magma bodies beneath calderas such as La Pacana and Cerro Galán. Structural controls include caldera ring faults, resurgent domes, and intra-caldera lacustrine deposits comparable to those in Ubehebe Crater studies, while hydrothermal alteration produces economically important alteration halos associated with mineralization in the Maricunga Belt and at deposits investigated by Codelco and Barrick Gold.
Caldera-related hazards encompass pyroclastic density currents, widespread ashfall affecting urban centers like Santiago, Chile and Buenos Aires, ash-cloud disruptions to aviation monitored by the International Civil Aviation Organization and regional Volcanic Ash Advisory Centers such as VAAC Buenos Aires, lahars, flank collapses, and long-term geothermal unrest. Monitoring networks operated by Servicio Nacional de Geología y Minería (Chile), Instituto Geofísico del Perú, Observatorio Volcanológico de los Andes del Sur (OVDAS), and the Observatorio Vulcanológico y Sismológico de Costa Rica-linked collaborations deploy seismic arrays, ground deformation GPS, InSAR from satellites like Sentinel-1 and Landsat, and gas flux measurements paralleling techniques used by the USGS Volcano Hazards Program.
Prehistoric and historic eruptions impacted indigenous cultures including the Inca Empire and pre-Incan societies; archaeological research near calderas like Cerro Galán and Potosí-adjacent areas documents ash layers in habitation sites studied by teams from the Smithsonian Institution and regional universities. Calderas constrain water resources and host geothermal systems exploited for renewable energy projects by entities such as Enel and national energy ministries, while mineral deposits formed in caldera-related hydrothermal systems underpin mining operations by companies like Codelco, Goldcorp, and Anglo American with socioeconomic effects in regions governed by provincial authorities like Salta Province and Jujuy Province.
Pioneering surveys by the United States Geological Survey and South American geological surveys in the 20th century established maps later refined by petrological and geochronological work using argon–argon and U–Pb zircon dating performed at laboratories including Lawrence Livermore National Laboratory, Arizona State University, and University of Oxford. Landmark studies on the Altiplano–Puna volcanic complex, La Pacana ignimbrite stratigraphy, and caldera collapse mechanics have been published in journals such as Nature, Science, Journal of Volcanology and Geothermal Research, and Earth and Planetary Science Letters by researchers affiliated with institutions like University of Bristol, Massachusetts Institute of Technology, and Universidad de Chile. Ongoing initiatives combine remote sensing from NASA missions, regional seismology, and petrogenetic modeling to resolve eruption recurrence and magma dynamics.
Category:Volcanoes of South America Category:Volcanic calderas