Superswell

A superswell is a large region of unusually high topography and shallow ocean floor produced by a substantial upwelling of mantle material rising from the core-mantle boundary in what is called a superplume. Two superswells are currently active, the African superswell and the South Pacific superswell, while the Darwin Rise in the south-central Pacific Ocean is regarded as a paleosuperswell, an ancient example whose uplift relative to the surrounding old ocean floor is still visible today. Superswell activity is linked to sharp increases in the production of new crust, most notably during the mid-Cretaceous period, roughly 125 to 120 million years ago to 70 million years ago, along the East Pacific Rise and other mid-ocean ridge systems, with the associated superplume peaking between about 120 and 100 million years ago before fading out over some thirty million years; the South Pacific superswell is considered the last remnant of that ancient episode, and superswells are studied through seismic surveys, isotopic sampling and the mapping of hotspot and volcanic island chains.