Altiplano-Puna volcanic complex

Altiplano-Puna volcanic complex
The NASA Expedition 23 crew · Public domain · source
Name	Altiplano-Puna volcanic complex
Other name	APVC
Location	Andes Mountains, Altiplano
Country	Bolivia / Chile / Argentina
Elevation m	6000
Type	Volcanic complex, calderas, ignimbrite-forming centers
Age	Miocene–Quaternary
Last eruption	Pleistocene–Holocene (probable)

Altiplano-Puna volcanic complex is a major volcanic province of the central Andes Mountains straddling the high Altiplano plateau across Bolivia, Chile, and Argentina. The complex hosts superlative caldera systems, extensive ignimbrite sheets and long-lived magmatic activity that links regional tectonics with continental-scale magmatism in South America. Research on the complex connects studies by institutions such as the Smithsonian Institution, Universidad de Chile, Servicio Nacional de Geología y Minería (Chile), and Universidad Mayor de San Andrés to global problems addressed at meetings like the American Geophysical Union and International Association of Volcanology and Chemistry of the Earth's Interior.

Geography and Setting

The complex occupies a broad sector of the northern Central Volcanic Zone, centered on the eastern Cordillera Occidental and western Cordillera Oriental of the Andes near regional features including the Salar de Uyuni, Salar de Coipasa, Lago Poopó, Laguna Colorada, and the city of Potosí. Surrounding political divisions include Potosí Department (Bolivia), Antofagasta Region, and Jujuy Province. Climate and landscape are influenced by the South American Monsoon System, high-elevation deserts, and paleoclimatic shifts tied to events recorded in cores from the Bolivian Altiplano, Lake Titicaca, and Playa features studied by teams from University of Cambridge and Massachusetts Institute of Technology.

Geological Background and Tectonics

The province sits above the subduction of the Nazca Plate beneath the South American Plate along the Peru–Chile Trench, a setting that also controls magmatism in the Northern Volcanic Zone and Southern Volcanic Zone. Crustal thickening related to the Andean orogeny produced a high-standing plateau analogous to the Tibetan Plateau, and deformation is accommodated via the Bolivian Orocline, strike-slip faults like the Atacama Fault System, and thrust systems linked to the Andean thrust belt. Paleogeographic reconstructions by groups at Universidad Nacional de San Juan and Instituto de Geología y Minería integrate geochronology from laboratories such as Los Alamos National Laboratory and U.S. Geological Survey.

Volcanism and Caldera Complexes

The complex features nested and overlapping calderas such as those mapped near Sierra de Vilama, Cerro Guacha, Socompa, APVC calderas described in synthesis papers by researchers from Universidad de Buenos Aires and Universidad Católica del Norte. Large explosive eruptions generated extensive ignimbrite sheets including the Toba-like magnitude deposits studied alongside deposits at Chala and Puna. Volcanic centers link to silicic systems at Uturuncu, which has been the focus of campaigns by International Continental Scientific Drilling Program collaborators and seismic arrays deployed by Incorporated Research Institutions for Seismology.

Petrology and Geochemistry

Rocks range from high-silica rhyolite to dacite and andesite; mineralogies include sanidine, biotite, plagioclase, and accessory zircon. Geochemical work by teams at ETH Zurich, University of Arizona, University of Oxford, and Consejo Superior de Investigaciones Científicas documents enrichment in large-ion lithophile elements and isotopic signatures that reflect crustal assimilation and Proterozoic basement interaction, with strontium, neodymium, and lead isotope data comparable to suites reported from Ecuadorian Andes and Altiplano basalts. Petrogenetic models invoke magma differentiation, shallow crustal storage, and repeated recharge processes analogous to interpretations at Yellowstone Caldera and Taupo Volcanic Zone.

Geophysical Structure and Heat Flow

Geophysical imaging using magnetotellurics, seismic tomography, and gravity surveys by groups at Institut de Physique du Globe de Paris, GFZ Potsdam, and Scripps Institution of Oceanography reveals a low-velocity, high-conductivity lithospheric anomaly beneath the complex—often termed the Altiplano-Puna magma body—which is one of the largest crustal magma accumulations known and is associated with elevated surface heat flow and hydrothermal systems similar to those studied at Taupo and Iceland. Satellite geodesy from European Space Agency missions such as Envisat and Sentinel-1, and NASA missions like InSAR analyses using Landsat and TerraSAR-X document uplift and deformation focused on centers including Uturuncu.

Eruption History and Chronology

Volcanism spans Miocene to late Quaternary time with major ignimbrite flare-ups at ~10–2 Ma documented by 40Ar/39Ar and U-Pb zircon dates from laboratories at Australian National University and Lamont–Doherty Earth Observatory. Individual eruptive episodes include massive caldera-forming events comparable in scale to deposits in the Toba Caldera and the Waiheke sector, with younger Holocene activity suggested by stratigraphic correlations near Salar de Coipasa and tephrochronology work coordinated with Quaternary Research groups and the British Geological Survey. Chronostratigraphic frameworks integrate paleomagnetic studies from Universidad de Concepción and regional tephra correlations used by archaeologists working in Andean prehistory.

Hazards and Monitoring Methods

Although most large ignimbrite eruptions are Pleistocene in age, geothermal unrest, ground deformation, and seismicity—monitored by institutions like the Observatorio San Calixto, Servicio Nacional de Geología y Minería (Chile), and international consortia—imply continuing magmatic processes that could pose hazards to communities in Oruro Department (Bolivia), Potosí Department (Bolivia), and transit corridors such as the Carretera Austral and regional airports. Monitoring employs seismic networks by Incorporated Research Institutions for Seismology, GPS campaigns supported by UNAVCO, InSAR from European Space Agency missions, and geochemical sampling of fumaroles and hot springs investigated by teams from Universidad de Antofagasta and Centro de Investigaciones en Geociencias. Risk assessment models draw on protocols from the International Civil Aviation Organization and hazard mapping practices used by the U.S. Geological Survey and Instituto Geográfico Nacional (Argentina).

Category:Volcanic fields of the Andes Category:Calderas of South America