Nano-Geodynamics: Bridging Atomic Scale Mechanisms and Mantle Convection

The primary geological phenomena that impact our planet's surface are now elucidated in the context of plate tectonics. However, this planetary dynamic is not the norm when we examine the other terrestrial planets in our solar system. It is becoming increasingly evident that this is one of the prerequisites for the emergence of life on a planetary body. It is now understood that plate tectonics represents merely the surface manifestation of the extensive convection currents that stir the Earth's mantle, enabling the dissipation of its internal heat. A primary objective of geodynamics is to describe this convection. The crucial variable is the viscosity of the mantle rocks. In situ, these rocks are subjected to extreme pressure and temperature conditions, and only deform at exceedingly slow strain-rates. Despite notable advancements in recent years in replicating these conditions in the laboratory, they remain largely inaccessible to us. An alternative approach is to model the behavior of matter under these conditions. This is now feasible thanks to multiscale models that can describe the deformation mechanisms of mantle minerals at exceedingly high pressures, down to the atomic scale. In particular, we will present how the extremely low natural strain-rates compel us to conceptualize the mechanisms active in the mantle.

Speaker :  Patrick CORDIER, Université de Lille & Institut Universitaire de France, France