CaIrO3 Deformation: Insights into the Dynamics of the Earth’s Core-Mantle Boundary

The David Dobson Laboratory, University College London

The post perovskite phase of MgSiO3 controls the dynamics the lower thermal boundary layer of the Earth's mantle, determining core-mantle interaction and, ultimately, giving rise to hot-spot volcanism. A combined analogue experimental and theoretical approach is the only way to determine many of its physical properties. Here we determined the relative strength of perovskite and post-perovskite of a structural analogue, CaIrO3: The post perovskite phase is significantly weaker than the perovskite phase, meaning that we will have to fundamentally revisit the dynamics of the D'' region at the base of the Earth's mantle.

Figure: Relative strength of the perovskite and post-perovskite phase during transformation.

This research was partially supported by COMPRES, EAR 10-43050

Hunt, S.A., Weidner, D.J., Li, L., Wang, L., Walte, N.P. Brodholt, J.P. and Dobson, D.P. (2009) Weakening of CaIrO3 during the perovskite-post perovskite transformation. Nature Geoscience, 10.1038/NGEO663.

Ammann, M.W., Brodholt, J.P., Wookey, J. and Dobson, D.P. (2010) First Principles Constraints on Diffusion in Lower Mantle Minerals and a Weak D’’ Layer. Nature, 465, 462-465.

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