Anisotropy of earth's D″ layer and stacking faults in the MgSiO 3 post-perovskite phase

Artem R. Oganov, Roman Martoňák, Alessandro Laio, Paolo Raiteri, Michele Parrinello

Research output: Contribution to journalArticlepeer-review

209 Citations (Scopus)

Abstract

The post-perovskite phase of (Mg,Fe)SiO3 is believed to be the main mineral phase of the Earth's lowermost mantle (the D″ layer). Its properties explain1-6 numerous geophysical observations associated with this layer - for example, the D″ discontinuity7, its topography8 and seismic anisotropy within the layer9. Here we use a novel simulation technique, first-principles metadynamics, to identify a family of low-energy polytypic stacking-fault structures intermediate between the perovskite and post-perovskite phases. Metadynamics trajectories identify plane sliding involving the formation of stacking faults as the most favourable pathway for the phase transition, and as a likely mechanism for plastic deformation of perovskite and post-perovskite. In particular, the predicted slip planes are {010} for perovskite (consistent with experiment10,11) and {110} for post-perovskite (in contrast to the previously expected {010} slip planes1-4). Dominant slip planes define the lattice preferred orientation and elastic anisotropy of the texture. The {110} slip planes in post-perovskite require a much smaller degree of lattice preferred orientation to explain geophysical observations of shear-wave anisotropy in the D″ layer.

Original languageEnglish
Pages (from-to)1142-1144
Number of pages3
JournalNature
Volume438
Issue number7071
DOIs
Publication statusPublished - 22 Dec 2005
Externally publishedYes

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