Anne Davaille's seminar, FAST, Orsay

From magma ocean to plate tectonics: the Earth's evolution from laboratory experiments

Anne Davaille's seminar, 2019

Abstract

The cooling and evolution of a planet strongly depend on the convective regime prevailing in its mantle. However, the conditions necessary for convection to generate Plate Tectonics and continental growth are still debated. Both phenomena require subduction, the initiation of which is dicult, due to the complexity of lithosphere rheology.
We study the physics of these processes with laboratory experiments, using colloidal dispersions. Their rheology varies from newtonian to elasto-visco-plastic to brittle, and we can observe subduction, plates and plumes developing naturally from convection. One-sided subduction can be induced by lithosphere buckling, or by the impingement of a hot plume under the lithosphere. Scaling shows that this strong association between plumes and subduction initiation could explain on Venus the association of large coronae (created by hot upwelling mantle plumes) with trenches that have topographic signatures similar to Earth’s subduction trenches. Moreover, the same mechanism may have been instrumental in the nucleation and growth of cratons and the onset of continuous Plate Tectonics on Earth.