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Rapid plate motion variations as a probe into plate boundary forces in the South Atlantic basin.

Principal Investigator: Prof. Dr. Hans-Peter Bunge

The South Atlantic preserves a crucial archive of past plate motion due to its passive margin environment. Particularly important are rapid plate motion changes recorded in the spreading history of the mid-Atlantic ridge, and the Scotia and Sandwich back-arc system. Their short duration makes these changes sensitive probes into the force balance of plate motion, especially for plate boundary forces, as mantle related processes evolve on longer time-scales. We will investigate the Bunge7_2mantle/lithosphere force balance using coupled mantle circulation and neo-tectonic models. We will pay particular attention to far-field effects which must be studied with global models to avoid influence from artificial boundary conditions. Far-field effects are expected to be relevant as indicated by preliminary modelling results suggesting that South Atlantic spreading variations are affected by near surface processes in the adjacent continents. We will assemble high-resolution (spatial and temporal) compilations of the South Atlantic spreading history, and exploit their detailed kinematic constraints to test the hypothesis that topography variations in the adjacent continents, such as the rise of the Andes or the topographic high stand of South Africa, are important factors in the tectonic evolution of the South Atlantic. Evolution of the Scotia back-arc basin will be studied with a combination of regional and global mantle flow models. Funds from this proposal will support the post-doctoral training of Stuart Clark, who brings a unique background of regional mantle flow modelling and plate reconstructions through his PhD work with Dietmar Müller, so that advanced plate reconstruction and geodynamic models can be made available to the broader SAMPLE effort.