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African Hot Spot Volcanism: Small-Scale Convection in the Upper Mantle Beneath Cratons

2000; American Association for the Advancement of Science; Volume: 290; Issue: 5494 Linguagem: Inglês

10.1126/science.290.5494.1137

1095-9203

Scott D. King, Jeroen Ritsema,

earthquake and tectonic studies

Numerical models demonstrate that small-scale convection develops in the upper mantle beneath the transition of thick cratonic lithosphere and thin oceanic lithosphere. These models explain the location and geochemical characteristics of intraplate volcanos on the African and South American plates. They also explain the presence of relatively high seismic shear wave velocities (cold downwellings) in the mantle transition zone beneath the western margin of African cratons and the eastern margin of South American cratons. Small-scale, edge-driven convection is an alternative to plumes for explaining intraplate African and South American hot spot volcanism, and small-scale convection is consistent with mantle downwellings beneath the African and South American lithosphere.