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| Andes orogeny | |
|---|---|
| Name | Andes orogeny |
| Caption | Satellite view of the Andes |
| Location | South America |
| Type | Mountain building |
| Age | Cenozoic–Mesozoic |
Andes orogeny The Andes orogeny produced the longest continental mountain chain on Earth, shaping the western margin of South America and influencing Pacific Ocean–Atlantic Ocean interactions, Amazon Basin drainage, and Andean biodiversity. It resulted from ongoing convergence between the Nazca Plate, South American Plate, and interactions with the Caribbean Plate and Antarctic Plate, triggering widespread magmatism, deformation, and uplift that affected societies from Pre-Columbian era polities to modern Republic of Chile economies.
The orogeny developed along a convergent margin where the Nazca Plate subducted beneath the South American Plate along the Peru–Chile Trench, juxtaposing forearc basins like the Pisco Basin with the retroarc Altiplano Plateau, and linking to cratonic fragments such as the Amazonian Craton and Guiana Shield. Plate motions driven by features including the East Pacific Rise and interactions with the Cocos Plate influenced strain partitioning beneath cordilleran domains like the Central Andes, Southern Andes, and Northern Andes, while oceanic plateaus and seamounts such as the Nazca Ridge modified slab geometry and orogenic segmentation.
Orogenic history spans multiple episodes from the Mesozoic to the Cenozoic with Early Andean events tied to the breakup of Pangea and the opening of the South Atlantic Ocean, and Neogene acceleration associated with the Miocene uplift of the Altiplano and the rise of the Andean plateau. Major phases include Jurassic–Cretaceous arc construction linked to the Magallanes Basin, Paleogene contraction recorded in the Chaco Basin and Subandean Ranges, and Quaternary vertical motions preserved in Morocco? — correction: preserved in high-elevation sites like Mount Aconcagua, Cordillera Blanca, and Sierra Nevada de Santa Marta where Pleistocene glaciation and Holocene seismicity recorded continued uplift and deformation.
Mechanisms include oceanic slab rollback like events inferred from comparisons with the Hikurangi Plateau and rollback models, flat-slab subduction as observed beneath central Peru with links to the Nazca Ridge, crustal shortening and thickening similar to processes in the Himalaya and Alps, lithospheric delamination hypothesized for parts of the Central Andes, and magmatic addition analogous to the Cascades Volcanic Arc. Interactions among these processes produced variable topography and episodic uplift across segments such as the Bolivian Orocline and the Coastal Cordillera.
Structural architecture comprises fold-and-thrust belts like the Subandean fold and thrust belt, basement-involved uplifts exemplified by the Sierra de la Ventana analogs, and strike-slip fault systems including the Boconó Fault and Liquiñe-Ofqui Fault where slip partitioning accommodated oblique convergence. Stratigraphic sequences record marine transgressions and regressions in units like the Mesozoic marine sequences of Patagonia and the Paleozoic to Cenozoic successions in the Andean foreland basins such as the Neuquén Basin and Marañón Basin, preserving fossil assemblages comparable to those from the Bahía Inglesa Formation and La Venta.
Andean magmatism produced extensive volcanic arcs with edifices like Ojos del Salado and Nevado del Ruiz and batholiths including the Coastal Batholith of Peru and the Cordillera Blanca Batholith, with geochemical affinities similar to calc-alkaline suites in the Andes Volcanic Belt. Metamorphic gradients and aureoles developed in areas such as the Deseado Massif, and metallogeny yielded world-class deposits like the Escondida mine, Cerro Rico de Potosí, and Chuquicamata, associated with porphyry, epithermal, and skarn systems analogous to those found in the Sierra Norte de Puebla and Yukon comparisons.
Erosion, glaciation, and river incision sculpted the Andes, with Quaternary glacial advances in regions such as the Cordillera Blanca and Patagonian Ice Fields and fluvial capture events reshaping drainages feeding the Amazon River and La Plata Basin. Climate drivers tied to the El Niño–Southern Oscillation and the South American Monsoon System modulated precipitation and sediment flux, influencing mass wasting, lake formation in the Altiplano, and coastal sedimentation along the Atacama Desert margin.
Uplift influenced biogeographic evolution of hotspots like the Tumbes-Chocó-Magdalena and the Yungas, driving speciation seen in taxa studied by researchers at institutions including the Smithsonian Institution and CONICET. Soils and orography shaped pre-Columbian societies such as the Inca Empire and colonial economies centered on mining in Potosí, and modern infrastructure and hazard management in countries like Peru, Ecuador, and Bolivia contend with earthquakes from the 1960 Valdivia earthquake legacy and volcanic eruptions recorded at Nevado del Ruiz. Water resources from glacial and snowpack reservoirs support urban centers like Lima and agricultural zones such as the Central Valley, Chile amid climate change impacts documented by agencies like the Intergovernmental Panel on Climate Change.
Category:Orogenies