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| South American Shelf | |
|---|---|
| Name | South American Shelf |
| Type | Continental shelf |
| Location | South America, Atlantic Ocean, Pacific Ocean |
| Area | ~? |
South American Shelf The South American Shelf is the extensive continental shelf flanking the coasts of Argentina, Brazil, Uruguay, Venezuela, Colombia, Ecuador, Peru and Chile, forming a principal shallow-water margin between the Atlantic Ocean and the Pacific Ocean. It developed through interactions among the South American Plate, ancient Gondwana, the Andean orogeny, and global sea-level fluctuations associated with the Pleistocene and Holocene epochs. The shelf supports major ports such as Buenos Aires, Rio de Janeiro, Valparaíso, and Callao and underpins fisheries, hydrocarbon production, and biodiversity tied to features like the Río de la Plata, the Amazon River, and the Patagonian Shelf.
The shelf records tectonic processes including rifting linked to the breakup of Pangaea and Gondwana, seafloor spreading at the Mid-Atlantic Ridge, and flexural responses to the Andes uplift during the Cenozoic. Sediment provenance involves contributions from the Amazon Basin, the Orinoco Basin, the La Plata Basin, and glacioeustatic inputs from the Antarctic Peninsula and Patagonia icefields. Structural elements include relict passive-margin architecture, shelf-edge deltas, and incised paleovalleys comparable to features near North Sea and Gulf of Mexico shelves. Large turbidite systems and contourite drifts attest to interactions between sediment gravity flows and boundary currents influenced by the Benguela Current analogues and the Antarctic Circumpolar Current margins.
The shelf extends from the Caribbean Sea margins off Venezuela and Colombia down the eastern flank of South America through the Brazilian coast to the vast Patagonian Shelf off Argentina and Uruguay, and on the western side forms narrower shelves along Peru and Chile. Prominent geomorphic zones include the Amazon Fan influenced continental margin, the wide Río de la Plata estuarine shelf, the Santo Domingo Bend, and the submarine canyons incised opposite major river mouths. Bathymetry varies from intertidal flats near Bahía Blanca and Mar del Plata to shelf breaks typically between 100 m and 300 m depth near the Falkland (Malvinas) region, with underlying substrates of muds, sands, carbonate platforms, and basaltic crust proximal to fracture zones like the Romanche Fracture Zone analogs.
Circulation on the shelf is governed by interactions among the South Atlantic Gyre, the Brazil Current, the Malvinas Current (Falkland Current), the North Brazil Current and coastal upwelling systems such as the Humboldt Current off Peru and Chile. Seasonal variability ties to the El Niño–Southern Oscillation and the South Atlantic Convergence Zone, modulating sea surface temperature, salinity, and nutrient flux. Cross-shelf exchange occurs via wind-driven Ekman transport, mesoscale eddies spawned by the Cape Horn and Rio de Janeiro promontories, and tidal mixing near estuaries like the Amazon River mouth and the Río de la Plata.
The shelf hosts diverse ecosystems including estuaries, mangroves along Amazonas, kelp forests in Chile and Argentina, seagrass beds in Brazilian lagoons, and cold-temperate benthic communities on the Patagonian Shelf. Key species and assemblages intersect with fisheries resources such as anchoveta off Peru, Argentine hake in the Southwestern Atlantic, and pelagic stocks exploited by fleets from Spain, Portugal, Japan, and China. Biodiversity hotspots overlap with protected areas like Galápagos Islands influences near Ecuador, migratory corridors used by humpback whale populations linked to IUCN listings, and seabird colonies associated with Península Valdés. Biogeographic transitions reflect limits between Caribbean Sea and Temperate South America provinces defined in faunal studies by institutions such as the Smithsonian Institution and CONICYT.
The shelf underlies major hydrocarbon provinces explored by companies like Petrobras, YPF, Ecopetrol, and Petroperú with notable discoveries in the Santos Basin, the Campos Basin, and the Pre-salt provinces. Fisheries harvests supply regional markets for Peru’s anchoveta, Brazil’s shrimp and tuna, and Argentina’s squid, while offshore minerals include phosphate, sand, and potential polymetallic resources analogous to those targeted in the Clarion-Clipperton Zone. Maritime routes crossing the shelf connect ports of Montevideo, Santos, Valparaíso, and Cartagena de Indias supporting trade agreements like MERCOSUR and regional energy integration efforts involving OAS member states.
Intensive fishing, offshore hydrocarbon extraction, coastal urbanization in metropolises such as Buenos Aires and Sao Paulo, and pollution from riverine discharge including the Amazon River and Orinoco River have altered shelf ecosystems. Environmental responses include marine protected areas designated under national laws in Chile, Peru, Brazil, and Argentina, multilateral initiatives involving UNESCO and Ramsar Convention designations for wetlands, and fisheries management regimes overseen by regional bodies like CCAMLR analog discussions and national agencies including IBAMA and SERNAPESCA. Conservation challenges engage indigenous and local communities recognized in instruments such as ILO Convention 169.
Investigation employs seismic reflection and refraction surveys conducted by research vessels such as R/V Melville and commercial fleets, multibeam bathymetry from institutions like GEBCO and NOAA, sediment coring by programs analogous to the International Ocean Discovery Program, and remote sensing from satellites operated by NASA and ESA. Collaborative projects between universities including University of São Paulo, Universidad de Chile, Universidad Nacional de La Plata, and international laboratories combine oceanographic moorings, autonomous underwater vehicles, and genetic barcoding led by research centers such as CONICET and the Smithsonian Tropical Research Institute.
Category:Continental shelves of the Atlantic Ocean Category:Physical oceanography