A New Absolute Plate Motion Model for Africa
Abstract
The India-Eurasia collision, a change in relative plate motion between Australia and Antarctica, and the coeval ages of the Hawaiian Emperor Bend (HEB) and Louisville Bend of ~Chron 22-21 all provide convincing evidence of a global tectonic plate reorganization at ~50 Ma. Yet if it were a truly global event, then there should be a contemporaneous change in Africa absolute plate motion (APM) reflected by physical evidence somewhere on the Africa plate. This evidence might be visible in the Reunion-Mascarene bend, which exhibits many HEB-like features such as a large angular change close to ~50 Ma. Recently, the Reunion hotpot trail has been interpreted as a continental feature with incidental hotspot volcanism. Here we propose the alternative hypothesis that the northern portion of the chain between Saya de Malha and the Seychelles (Mascarene Plateau) formed as the Reunion hotspot was situated on the Carlsberg Ridge, contemporaneously forming the Chagos-Laccadive Ridge on the India plate. We have created a 4-stage model that explores how a simple APM model fitting the Mascarene Plateau can also satisfy the age progressions and geometry of other hotspot trails on the Africa plate. This type of model could explain the apparent bifurcation of the Tristan hotspot chain, the age reversals seen along the Walvis Ridge and the diffuse nature of the St. Helena chain. To test this hypothesis we have made a new African APM model that goes back to ~80 Ma using a modified version of the Hybrid Polygonal Finite Rotation Method. This method uses seamount chains and their associated hotspots as geometric constraints for the model, and seamount age dates to determine its motion through time. The positions of the hotspots can be moved to get the best fit for the model and to explore the possibility that the ~50 Ma bend in the Reunion-Mascarene chain reflects Africa plate motion. We will examine how well this model can predict the key features reflecting Africa plate motion and contrast its predictions with other proposed models.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.T41G..03M
- Keywords:
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- 8137 TECTONOPHYSICS Hotspots;
- large igneous provinces;
- and flood basalt volcanism;
- 8120 TECTONOPHYSICS Dynamics of lithosphere and mantle: general;
- 8100 TECTONOPHYSICS