Altiplano–Puna plateau

Altiplano–Puna plateau
Name	Altiplano–Puna plateau
Location	Bolivia, Chile, Argentina

Altiplano–Puna plateau is a high-elevation intermontane plateau in the central Andes spanning parts of Bolivia, Chile, and Argentina. It forms a contiguous highland region adjoining the Altiplano and the Puna de Atacama and interlinks with major South American geological and cultural features such as the Andean orogeny and the Atacama Desert. The plateau influences regional climate, hydrology, and biogeography and has hosted pre-Columbian polities, colonial expeditions, and modern scientific research by institutions like the Smithsonian Institution, CONICET, and Universidad Mayor de San Andrés.

Geography and extent

The plateau occupies a broad intermontane basin between the eastern Cordillera Oriental (Bolivia) and the western Cordillera Occidental (Andes), bordering landscapes like the Salar de Uyuni, Salar de Coipasa, Laguna Colorada, and Laguna Verde. It connects northward toward the Bolivian Altiplano and southward toward the Puna de Atacama and adjoins transit corridors such as the Abra del Acay and passes linking to Cochabamba, Oruro, La Paz (Bolivia), San Pedro de Atacama, and Salta. Political boundaries intersect the plateau: the Department of Potosí, Tarija Department, Antofagasta Region, and Jujuy Province administer portions, while transport routes like the Tren a las Nubes and highways near Uyuni traverse its margins. Major ranges and volcanic chains including the Cordillera Real (Bolivia), Los Andes volcanic chain, Sierra de los Frailes, and isolated massifs define its geomorphology and link to neighboring features such as the Titicaca Basin and the Sierra de Aconquija.

Geology and tectonic evolution

The plateau sits above a complex subduction zone where the Nazca Plate converges with the South American Plate, producing crustal shortening associated with the Andean orogeny, flattened subduction segments, and magmatic arcs like the Central Volcanic Zone. Its basement comprises Paleozoic units intruded by Mesozoic plutons related to the Andean magmatism and overprinted by Cenozoic ignimbrites linked to the Altiplano–Puna volcanic complex (APVC), an extensive silicic province analogous to the South Atlantic Anomaly in scope of thermal anomalies. The region exhibits thickened crust, crustal delamination hypotheses championed by researchers from ETH Zurich, Caltech, and University of Chile, and structural features such as large-scale thrust belts, strike-slip faults like the Vicuña-Puripica Fault system, and high-elevation calderas exemplified by Galán caldera and volcanic centers such as Licancabur, Uturuncu, Ojos del Salado, and Llullaillaco. Geochronological studies using argon–argon dating, uranium–lead dating, and seismic profiles by teams from GFZ Potsdam and USGS show episodic ignimbrite flare-ups, crustal melting, and uplift phases tied to mantle dynamics and plate kinematics documented since the Eocene and intensified in the Miocene.

Climate and hydrology

The plateau experiences an arid to semi-arid highland climate influenced by the South Pacific High, El Niño–Southern Oscillation, South American Summer Monsoon, and rainshadowing from the Andes. Precipitation is highly seasonal with convective summer rains and winter dryness, producing saline endorheic basins such as the Salar de Uyuni and closed lake systems like Lake Poopó and ephemeral playas studied by climate groups at University of Exeter and National Observatory of Brazil. Glacial and periglacial features on peaks such as Nevado Sajama and Illimani contribute meltwater to wetlands called bofedales, which feed springs, aquifers, and depositional systems tied to hydrochemical basins monitored by UNESCO programs. Paleoclimate reconstructions using lake sediment cores, ice cores from Tunia Grande and isotopic analyses by teams from Lamont–Doherty Earth Observatory reveal Holocene aridity fluctuations, Pleistocene glaciations, and rapid desiccation events linked to Younger Dryas-scale variability and high-latitude teleconnections.

Ecology and land use

High-elevation puna grasslands, salt flats, and puna wetlands host specialized flora and fauna adapted to hypoxic, cold, and saline conditions; characteristic taxa include Lupinus mutabilis relatives, Polylepis tarapacana, and fauna such as Vicugna vicugna (vicuña), Lama glama (llama), Hippocamelus antisensis (taruca), Phoenicoparrus andinus (Andean flamingo), and endemic rodent and amphibian species catalogued by CONAMA and IUCN. Pastoral economies employing traditional pastoralists, Aymara and Quechua communities, and indigenous land tenure systems interact with land uses such as smallholder agriculture near El Alto (Bolivia), salar salt extraction at Salar de Uyuni and Salar de Atacama, and mining concessions held by companies like COMIBOL and multinational firms active in the Lithium Triangle. Conservation efforts by organizations including World Wildlife Fund, BirdLife International, and national protected areas like Reserva Nacional Los Flamencos seek to balance biodiversity protection, cultural heritage, and resource extraction.

Human history and populations

Archaeological evidence documents human occupation since the Late Pleistocene and early Holocene with hunter-gatherer sites, agro-pastoral transitions, and complex societies such as the Tiwanaku civilization, which constructed ceremonial centers near Lake Titicaca, and later integration into the Inca Empire and colonial systems controlled by the Spanish Empire via audiencias and corregimientos centered on Potosí and Lima (viceroyalty). Colonial silver mining at Potosí (Cerro Rico) reshaped demography and labor regimes, linking the plateau to Atlantic and Pacific trade networks mediated by institutions like the Casa de Contratación and the Royal Audiencia of Charcas. Contemporary populations include urban migrants in Potosí (city), Oruro (city), and Uyuni (town) alongside rural communities practicing transhumance, with social movements represented by organizations such as the Movimiento al Socialismo and indigenous federations engaging with state actors like the Bolivian government and NGOs.

Natural resources and hazards

The plateau hosts substantial mineral resources—tin, silver, gold, copper, and borates exploited historically by Potosí mines and modern extractive projects run by companies including Yacimientos Petrolíferos Fiscales-era entities and private multinationals—plus vast lithium brine reserves within the Lithium Triangle that attract investment from firms in China, United States, and Europe. Geothermal potential near volcanic centers such as Lascar and Tebenquiche draws interest from energy consortia and research collaborations with IDB-funded studies. Hazards include seismicity linked to the Nazca–South American Plate boundary, volcanic eruptions from the Central Volcanic Zone, large-scale landslides, hydrothermal unrest at calderas like Coranzulí, and anthropogenic impacts including water table drawdown and contamination associated with mining disputes adjudicated in courts influenced by legal frameworks such as those emanating from Plurinational State of Bolivia legislatures and international environmental law bodies.

Category:Plateaus of South America