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| Chilean–Patagonian Basaltic Province | |
|---|---|
| Name | Chilean–Patagonian Basaltic Province |
| Location | Chile; Argentina |
| Type | Large igneous province |
| Area | ~200000 km² |
| Period | Cenozoic |
Chilean–Patagonian Basaltic Province is an extensive Cenozoic basaltic large igneous province spanning southern Chile and Argentina in Patagonia. It comprises widespread flood basalt sheets, plateau basalts, and volcanic fields that record interactions between mantle sources, lithospheric structure, and plate-scale processes during Neogene time. The province is spatially and genetically linked to tectonic features such as the Andes, the South American Plate, and the history of Nazca Plate and Antarctic Plate motions.
The province consists of tholeiitic to transitional basalts, including olivine-, clinopyroxene- and plagioclase-phyric flows and subaerial to subaqueous breccias associated with glaciation-influenced landscapes like the Southern Patagonian Ice Field. Petrographic studies identify phenocryst assemblages of olivine, clinopyroxene, and plagioclase with interstitial glass and fine groundmass textures comparable to basalts from Iceland, Hawaii, and Karoo-Ferrar provinces. Mineral chemistry highlights mantle-derived magmas modified by shallow-level fractional crystallization and crustal assimilation beneath crustal provinces such as the Patagonian Batholith and the Fagnano-Magliore Fault Zone region. Geochemical classification uses major-oxide trends in the tradition of studies conducted at institutions like the Servicio Nacional de Geología y Minería and universities including Universidad de Chile.
Magmatism is controlled by the convergent margin setting of the Andean orogeny and changes in subduction parameters involving the Nazca Plate and the southern Antarctic Plate. Proposed origins invoke slab window formation related to the subduction of the Chile Rise and ridge subduction events, mantle upwelling analogous to processes identified under the Juan Fernández Ridge, and extensional tectonics linked to the opening of the Drake Passage and the development of the Magallanes-Fagnano Fault System. Geodynamic models reference plate reconstructions used by Paleomap Project researchers and consider analogies with the North Atlantic Igneous Province and the Afro-Arabian flood basalts.
Basaltic flows cover lowland plateaus, fjords, and intermontane basins from the Los Lagos Region through Aysén Region to Tierra del Fuego and adjacent Santa Cruz Province (Argentina). Stratigraphic columns integrate marine and terrestrial sediments, basaltic units, and intrusive sills correlated across transects studied by teams from CONICET, Universidad Nacional del Centro de la Provincia de Buenos Aires, and international programs. Key stratigraphic markers include unconformities tied to glacial cycles recognized in cores from the Magellan Strait and seismic reflection profiles across the Argentina Basin.
Volcanic activity spans Miocene to Quaternary intervals with pulses documented in tephra layers, paleomagnetic data, and geomorphologic mapping of lava flow morphologies near volcanic centres such as the Pali Aike volcanic field, Cerro Guanaco, and the Fuegian Andes. Eruption styles ranged from fissure-fed flood basalts to central-vent scoria cones and low-viscosity lava flows, producing lava tubes, pahoehoe-to-ʻaʻā textures, and extensive ʻaʻa fields comparable to those documented at Etna and Mauna Loa. Interaction with ice sheets generated hyaloclastite deposits and tuyas similar to features in Iceland.
Absolute ages derive from K–Ar and Ar–Ar dating supplemented by 40Ar/39Ar incremental heating and radiogenic isotopic studies (Sr–Nd–Pb–Hf) that distinguish depleted-mantle and enriched components. Major- and trace-element patterns show flat rare-earth element profiles and variable incompatible-element enrichments interpreted via mixing of depleted upper mantle and enriched veneer components akin to enriched mantle (EM) signatures recognized in Gough Island and Kerguelen basalts. High-precision geochronology from laboratories associated with Lamont–Doherty Earth Observatory and USGS calibration have constrained eruptive pulses to specific Miocene and Pliocene epochs tied to regional tectonic reorganizations described in papers from Geological Society of America and International Association of Volcanology and Chemistry of the Earth's Interior conferences.
Basaltic terrains host mineral occurrences such as nickel, copper, platinum group elements, and rare earth elements in magmatic and hydrothermal contexts explored by companies like Codelco and Barrick Gold Corporation prospecting in Patagonia. Basaltic bedrock influences soil development, supporting unique ecosystems within protected areas like Torres del Paine National Park and Los Glaciares National Park with implications for biodiversity studies conducted by World Wildlife Fund and regional conservation agencies. Volcanic landscapes also affect freshwater reservoirs, carbon sequestration potential in altered basalt, and paleoenvironmental reconstructions performed by paleoclimate groups at Instituto Antártico Chileno.
Scientific investigation began with 19th-century surveys by explorers such as Charles Darwin and later systematic work by Chilean and Argentine geological surveys; seminal contributions came from researchers affiliated with Universidad de Magallanes, Smithsonian Institution, and European teams from Cambridge University and University of Oxford. Modern multidisciplinary campaigns combining geophysics, geochemistry, and stratigraphy have been funded by agencies including National Science Foundation, FONDAP, and bilateral programs tying groups like CONICET and Fundación Andes to international partners. Major syntheses have been published in journals such as Journal of South American Earth Sciences, Earth and Planetary Science Letters, and Tectonophysics.
Category:Volcanism of Chile Category:Volcanism of Argentina