African superswell

Geological region of exceptional tectonic uplift
The African superswell is a region including the Southern and Eastern African plateaus and the Southeastern Atlantic basin where exceptional tectonic uplift has occurred, resulting in terrain much higher than its surroundings. The average elevation of cratons is about 400–500 meters above sea level. Southern Africa exceeds these elevations by more than 500 m, and stands at over 1 km above sea level. The Southern and Eastern African plateaus show similar uplift histories, allowing them to be considered as one topographic unit. When considered this way, the swell is one of the largest topographic anomalies observed on any continent, and spans an area of over 10 million km2. Uplift extends beyond the continents into the Atlantic Ocean, where extremely shallow ocean depths are visible through bathymetric survey. The region can indeed be considered as one large swell because the bathymetric anomaly to the southwest of Africa is on the same order as the topographic anomaly of the plateaus (approximately 500 m). The superswell is a relatively recent phenomenon, probably beginning between 5 and 30 million years ago.

Various theories have been proposed as to the cause of the superswell. The main debate comes from whether the region of high topography is being supported by thermal isostatic mechanisms or dynamically.

Heating of the lithosphere, and the associated increase in buoyancy, is one possible mechanism proposed for the large degrees of uplift of the African superswell. Evidence of extensive volcanism and rifting in eastern Africa during the Cenozoic supports the idea that lithospheric heating was occurring during the time of uplift. The region of mantle beneath the African superswell would have been insulated by the supercontinent Pangea in the late Paleozoic and Mesozoic, providing a final observation supporting elevated temperature conditions as a mechanism for uplift. and has been interpreted as a low density anomaly coming from the deepest region of the mantle. By predicting the region's topographic response to the low density anomaly using dynamic topography calculations, an almost perfect model of the elevated topography of the superswell is achieved. This provides evidence that, in fact, dynamic response to mantle circulation is likely the cause of the superswell.