Ridge-hotspot interactions and the formation and evolution of oceanic plateaus
Abstract
Mid-oceanic ridges and hotspots are major features of the Earth's dynamics, involved on the building of the oceanic lithosphere. The recognition of the particular characteristics displayed by the oceanic lithosphere where mid-oceanic ridges undergo the influence of hotspots led to models suggesting the existence of connections between ridges and hotspots, that allow plume material to reach the ridge axis. Interactions between ridges and hotspots result in thick crust, high topography, due to excess temperatures and to the presence of a more fertile mantle and crust chemical compositions that reveal the presence of a "plume" component. The most impressive consequence from ridge-hotspot interactions is the building of major volcanic plateaus such as Iceland, Azores and Saint Paul-Amsterdam. Detailed studies reveal that the building of these plateaus result from both the evolution of the ridge-hotspot relative movement and temporal variations in the strength of the hotspot source. The major phase of the plateau construction is linked to an increase in the melt production at the ridge axis, yielding thick crust and high topography. The excess volcanism also results in a smooth morphology. This phase is associated with short ridge-hotspot distances. When the ridge migrates away from the hotspot, the distance increases, reducing the amount of melt production and resulting in the breakup of the plateau. The critical distances depend both on the ridge spreading rate and on the ridge-hotspot migration rate but also depend on the strength of the hotspot. Temporal variations in the strength of the hotspot source, with a period of about 3 m.y. were observed both at the Azores and Saint Paul-Amsterdam and contribute to increase the complexity of the evolution of the plateaus.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFM.T34D..08M
- Keywords:
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- 8120 TECTONOPHYSICS / Dynamics of lithosphere and mantle: general;
- 8137 TECTONOPHYSICS / Hotspots;
- large igneous provinces;
- and flood basalt volcanism;
- 8178 TECTONOPHYSICS / Tectonics and magmatism;
- 8416 VOLCANOLOGY / Mid-oceanic ridge processes