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| Geologic formations of Chile | |
|---|---|
| Name | Chilean Geologic Formations |
| Period | Paleozoic–Quaternary |
| Type | Regional stratigraphy |
| Region | Chile |
Geologic formations of Chile describe the diverse stratigraphic, tectonic, volcanic, and sedimentary units that record the geologic evolution of Chile from the Paleozoic through the Quaternary. The record encompasses Paleozoic marine sequences, Mesozoic rift-related basins, Cenozoic arc magmatism, Andean uplift, and glacial-interglacial deposits, with exposures ranging from the Atacama Desert to the Patagonian Andes. Research integrates field mapping, geochronology, paleontology, and geophysics conducted by institutions such as the Servicio Nacional de Geología y Minería (SERNAGEOMIN), the Universidad de Chile, and international teams from the Smithsonian Institution, US Geological Survey, and Natural History Museum, London.
Chile lies along the active margin between the Nazca Plate and the South American Plate, producing a long-lived accretionary and magmatic arc system juxtaposed with extensional basins and forearc highs. The Chilean margin records major events including the Andean orogeny, the breakup of Gondwana, the formation of the South Atlantic Ocean, and Cenozoic subduction variations tied to the emplacement of the Juan Fernández Ridge and the Nazca Ridge. Key physiographic provinces include the Coastal Cordillera, the Chilean Central Valley, the Andes, and the Patagonian Ice Fields, each preserving characteristic formations such as Paleozoic basement complexes, Mesozoic marine platforms, and Neogene volcanic successions.
Stratigraphy comprises crystalline basement units like the Chilenia-related terranes, the Elqui-Limarí Batholith exposures, and the Coastal Metamorphic Complex, overlain by Paleozoic sequences including the Bahía Mansa Metamorphic Complex and the Santa Lucía Formation. Mesozoic formations include the marine Chañarcillo Formation, the Panguipulli Group, the Toqui Formation, and the Salir Formation associated with rift and backarc basins. Cenozoic units include the widespread Loa Group, the Atacama Gravels, the Quiriquina Formation, the Ranquil Formation, the Chilean Central Valley Neogene fillings, and glacial sediments of the Ayacara Formation and the Seno Última Esperanza Formation in Patagonia. Volcaniclastic and ignimbrite sheets such as the Altiplano-Puna Volcanic Complex units and calc-alkaline sequences of the Llaima and Villarrica areas mark Neogene–Quaternary activity.
Structural architecture is governed by subduction-driven shortening, terrane accretion, and crustal-scale fault systems including the Atacama Fault System, the Liquiñe-Ofqui Fault Zone, and the Pedro Aguirre Cerda Fault segments. The tectonic evolution integrates processes manifest in the Aconcagua Metamorphic Complex, Mesozoic extensional detachments related to the Roca Basin evolution, and Cenozoic transpressional deformation linked to the Bolivian orocline. Plate interactions have produced oblique convergence, trench morphology variations near the Iquique and Valparaíso regions, and seismicity exemplified by events like the 1960 Valdivia earthquake and the 2010 Maule earthquake, which test models of megathrust coupling and forearc deformation.
Chile hosts part of the Andean Volcanic Belt with segments including the Northern Volcanic Zone, the Central Volcanic Zone, and the Southern Volcanic Zone featuring volcanoes such as Ojos del Salado, Parinacota, Láscar, Licancabur, Villarrica, and Calbuco. Magmatic provinces include the high-elevation Altiplano-Puna ignimbrite province, the coastal plutonic belts like the Coastal Batholith of Central Chile, and island-arc influences from the Juan Fernández Archipelago magmatism. Petrogenesis studies of andesites, dacites, and rhyolites involve correlations with crustal assimilation recorded in the Darwin Range exposures and isotopic data from laboratories at the Universidad de Concepción and the University of California, Berkeley.
Important basins include the forearc Atacama Basin, the backarc Neuquén Basin extensions, the Magallanes Basin, the Aysen Basin, and coastal basins preserving Cenozoic marine transgressions recorded in the Caldera and Coquimbo regions. Basin fills record climatic shifts, sea-level changes, and biotic turnovers captured by fossils in formations such as the Bahía Inglesa Formation, the Quiriquina Formation, and the Toqui and Santa Cruz sequences, yielding marine mammals, seabirds, and invertebrate assemblages studied in museums like the Museo Nacional de Historia Natural (Santiago). Glacial and interglacial sequences in Patagonia include moraines and tills correlated with the Last Glacial Maximum and tied to paleoclimate reconstructions from the Southern Ocean and Antarctic records.
Chile’s formations host world-class mineral deposits including porphyry copper systems at El Teniente, Chuquicamata, and Escondida, epithermal gold-silver occurrences like El Indio, and iron-oxide copper-gold deposits such as Sierra Gorda and Pascua-Lama-related prospects. Mineralization styles relate to Mesozoic–Cenozoic magmatism, hydrothermal alteration in the Atacama Desert supergene zones, and sediment-hosted nitrate and copper occurrences in the Loa Province. Exploration and mining enterprises include Codelco, Antofagasta PLC, and BHP, with environmental studies coordinated with agencies like the Comisión Chilena del Cobre and regional administrations.
Mapping and stratigraphic synthesis began with 19th-century expeditions by figures associated with institutions such as the British Geological Survey and the Smithsonian Institution, evolved through contributions from Chilean geologists at the Universidad de Chile and the Universidad Católica de Chile, and expanded with plate tectonic frameworks introduced by researchers at the US Geological Survey and Universidad de Concepción. Modern methods integrate radiometric dating from facilities like the Laboratorio de Geocronología de la Universidad de Chile, seismic imaging by the Centro Sismológico Nacional, and regional syntheses published in journals such as Andean Geology and reports from SERNAGEOMIN, enabling high-resolution maps, stratigraphic columns, and basin models used by academia and industry.
Category:Geology of Chile Category:Stratigraphy Category:Andes