Rheology of Earth Materials :
Closing the gap between timescales in the laboratory and in the mantle

11 January 2023 - New publication in Nature

In the mantle ferropericlase deforms less than bridgmanite

In the mantle, rocks deform under very low stresses corresponding to extremely low strain-rates of the order of 10-15 s-1. In this work we apply our multiscale numerical modelling techniques to periclase (Per: MgO) and bridgmanite (Bdm: MgSiO3). We show that our techniques, applied at laboratory strain-rates finds the long time observed behavior that periclase is much weaker than bridgmanite.

However, at mantle strain rates the situation is very different. Creep is ultimately controlled by diffusion, and oxygem diffusion being very slow, we find that periclase barely deforms.

In the mantle, the rheology is fully controled by bridgmanite, periclase being hard inclusions following the flow.

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P. Cordier, K. Gouriet, T. Weidner, J. Van Orman, O. Castelnau, J.M. Jackson & P. Carrez (2023) Periclase deforms slower than bridgmanite under mantle conditions. Nature, pages 303–307, https://doi.org/10.1038/s41586-022-05410-9/s41586-022-05410-9