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A mantle plume beneath the Paraná may feed both the Fernando de Noronha, the Martin Vaz and some continental volcanic fields. [28] Seismic tomography suggests that this mantle plume is actually the remnant of the plume associated with the Tristan hotspot. [36] Edge-driven convection may be occurring at the margin of Brazil. This would be ...
It was later postulated that hotspots are fed by streams of hot mantle rising from the Earth's core–mantle boundary in a structure called a mantle plume. [6] Whether or not such mantle plumes exist has been the subject of a major controversy in Earth science, [4] [7] but seismic images consistent with evolving theory now exist. [8]
Earth cross-section showing location of upper (3) and lower (5) mantle, D″-layer (6), and outer (7) and inner (9) core. The chemical and isotopic composition of basalts found at hotspots differs subtly from mid-ocean-ridge basalts. [20]
The movement of the Nazca and Cocos plates have been tracked. The Nazca plate moves at 90 degrees at a rate of 58±2 km per million years. The Cocos Plate moves at 41 degrees at a rate of 83±3 km per million years. [3] The location of the hotspot over time is recorded in the oceanic plate as the Carnegie and Cocos Ridges.
There is an ongoing discussion about whether the hotspot is caused by a deep mantle plume or originates at a much shallower depth. [3] Recently, seismic tomography studies have found seismic wave speed anomalies under Iceland, consistent with a hot conduit 100 km (62 mi) across that extends to the lower mantle. [4]
It has been suggested that, as the Earth's lithospheric plates moved over the mantle plume (the Iceland plume), the plume had earlier produced the Viluy Traps to the east, then the Siberian Traps in the Permian and Triassic periods, and later going on to produce volcanic activity on the floor of the Arctic Ocean in the Jurassic and Cretaceous ...
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Support for a plume origin includes petrological, geochemical, and isotopic evidence for a deep-mantle source, [2] [3] high heat flow in the area, [4] high volcanic output, [5] domal uplift, [6] [7] and seismic anomalies in the upper mantle consistent with a plume approximately 250 to 300 km (160 to 190 mi) in diameter extending 200 km (120 mi ...