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A fixed global reference frame

fixed hotspot animation
Global tectonics for Gondwana is not so much about continents moving as about oceans - or their mid-ocean ridges at least - staying in the same place. A number of mantle plumes are thought to have remained fixed with respect to the earth's rotation axis and hence provide a fixed reference frame for the movements of all the continents. These plumes have each provided geological evidence of (a) an abrupt outbreak with copious supplies of magma at a certain time and (b) a trail of generally diminishing activity (perhaps with some reactivations from time to time) in the form of oceanic islands and submarine edifices lying on the oceanic crust. Mid-ocean ridges, meanwhile, can be shown to have been always located close to the mid-point between separating continents. The resulting model, improved incrementally over many years, is shown in the animation for the period from 200 Ma to the present-day during which the Gondwana continents dispersed. What emerges is the pattern by which the growing network of mid-ocean ridges is related to the constellation of hotspots across the hemisphere that Gondwana and its oceans now occupy. Note in particular the central role of the Bouvet mantle plume which is generally underestimated in the literature. The rationale behind the global reference frame rotation model is explained in Research Update No.21.
Last update: 2024 June 6