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| West Gondwana | |
|---|---|
| Name | West Gondwana |
| Type | Supercontinent fragment |
| Era | Paleozoic–Mesozoic |
| Caption | Reconstruction of continental fragments |
| Major components | South America, Africa, Iberian Peninsula, Antarctic Peninsula |
| Formed | Late Neoproterozoic |
| Rifted | Mesozoic |
| Successor | Gondwana, Pangaea |
West Gondwana is the southwestern assemblage of continental crust that constituted a major portion of Gondwana during the Paleozoic and Mesozoic. It broadly includes the cratons and orogenic belts of parts of South America, Africa, and adjacent terranes such as the Iberian Peninsula and fragments incorporated into the northern margin of Antarctica. The concept is central to reconstructions of plate tectonics, paleogeography, and the distribution of Paleozoic and Mesozoic biotas and resources.
The term derives from historical usage in geology and paleogeography to contrast the western assemblage of Gondwanan continents with East Gondwana; it appears in literature addressing the configuration of Laurasia and Pangaea during the Permian and Triassic. Early usage ties to studies of the Brazilian Shield, the West African Craton, and the Falkland Islands and follows terminology used in reconstructions by researchers associated with institutions such as the U.S. Geological Survey, the British Geological Survey, and universities in Brazil, Argentina, and South Africa. The definition emphasizes coherent paleomagnetic, stratigraphic, and orogenic links among the São Francisco Craton, Amazonia, Río de la Plata Craton, Congo Craton, and the West African Craton.
West Gondwana's assembly involved collisions during the Neoproterozoic to Early Paleozoic orogenies such as the Brasiliano orogeny, the Pan-African orogeny, and events correlated with the Alleghanian orogeny and Hercynian (Variscan) orogeny. Paleogeographic maps relate West Gondwana to paleomagnetic poles from Ediacaran and Cambrian rocks, and to sedimentary provinces like the Paraná Basin, the Karoo Basin, the Kalahari Basin, and the Tornquist Zone. Marine transgressions recorded in sequences comparable to the Iapetus Ocean margins, the closure of the Rheic Ocean, and the evolution of inland basins reflect the changing geography as West Gondwana became part of Pangaea and later fragmented during the Mesozoic breakup that initiated the opening of the South Atlantic Ocean and the Central Atlantic Ocean.
Plate reconstructions integrate evidence from paleomagnetism, seismic tomography, and structural correlations between terranes such as the Sierra de la Ventana, Cape Fold Belt, Sao Francisco Craton, Kalahari Craton, and the Iberian Massif. Models by researchers at institutions like Lamont–Doherty Earth Observatory, GFZ German Research Centre for Geosciences, and the Geological Survey of Canada use data from the South Atlantic rift, transform margins such as the Romanche Fracture Zone, and conjugate margin fit of the Amazonian Craton and West African Craton. Significant tectonic features include the Transbrasiliano Lineament, the Trans-Saharan Belt, the Sørensen Fracture Zone, and the emplacement of large igneous provinces like the Paraná-Etendeka associated with the Karoo-Ferrar events, which correlate with magmatism adjacent to the South Shetland Islands and Antarctic Peninsula margins.
Paleoclimate reconstructions utilize data from glacial deposits in the Karoo Supergroup, tillites of the Gondwanan glaciation, and coal-bearing strata such as the Karoo Coal Measures and the Amazon Basin peat-forming sequences. Isotopic records from δ13C and δ18O studies in carbonate platforms of the Falkland Islands and Namibia inform models managed by groups at NOAA and IPCC-linked research. Climate gradients across West Gondwana ranged from high-latitude glaciations during the Late Paleozoic Ice Age to humid tropical settings reflected in devonian reef systems and Permian evaporite basins such as those preserved in the Paraná Basin and Kalahari Basin.
Fossil distributions critical to defining West Gondwana include Glossopteris floras of the Permian, Lystrosaurus and Mesosaurus tetrapods, and marine faunas such as trilobites, brachiopods, and conodonts with links between South America and Africa. Paleobotanical records from the Tamengo Formation and Karoo Supergroup tie to biogeographic patterns also observed in the Clarence-Moreton Basin and graphite-rich sequences in the Iberian Peninsula. Vertebrate paleontologists working at institutions like the Field Museum and Natural History Museum, London compare faunal provinciality evidenced by therapsids, dicynodonts, and early dinosaurs across Gondwanan margins to support reconstructions.
West Gondwana hosts major mineral and hydrocarbon provinces: iron formations of the Quadrilátero Ferrífero, copper–gold belts such as the Carajás Mineral Province and Katanga, the Venezuela Basin petroleum systems, and sedimentary basins like the Santos Basin and Espírito Santo Basin with ties to continental margin petroleum plays explored by companies including Petrobras, TotalEnergies, and ExxonMobil. Precambrian shields yield diamond deposits at Kimberley and in Brazil, while the Bushveld Complex and Sao Francisco Craton host platinum-group elements and chromitite layers exploited by Anglo American and national mining agencies. Coal, iron, and evaporite resources in the Karoo Basin and Paraná Basin underpin regional industrialization histories involving governments in Argentina, Brazil, South Africa, and Nigeria.
The breakup of West Gondwana during the Jurassic and Cretaceous led to the opening of the South Atlantic Ocean and the creation of passive margins now studied by marine programs like the International Ocean Discovery Program and mapping efforts by EMODnet. Fragmentation produced microplates and terranes accreted to margins such as the Falkland Plateau, the Scotia Plate region, and the Iberian microcontinent, influencing modern distribution of languages and cultures indirectly through resource-driven migrations and colonial histories involving Portugal, Spain, United Kingdom, France, and Netherlands. Contemporary geoscience integrates West Gondwana reconstructions into hazard assessment by agencies including the United States Geological Survey and Geological Survey of Brazil, and into educational exhibits at museums like the American Museum of Natural History and the Museu Nacional (Brazil).
Category:Paleocontinents