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Anisotropy of Earth's D″ layer and stacking faults in the MgSiO3 post-perovskite phase

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 explain1,2,3,4,5,6 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 planes1,2,3,4). 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.

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Figure 1: MgSiO 3 polytypes found by metadynamics.
Figure 2: Enthalpies (relative to Pv, per formula unit) of MgSiO 3 polytypes as a function of pressure.
Figure 3: Activation barrier for the Pv–pPv transition at 120 GPa.

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References

  1. Murakami, M., Hirose, K., Kawamura, K., Sata, N. & Ohishi, Y. Post-perovskite phase transition in MgSiO3 . Science 304, 855–858 (2004)

    Article  ADS  CAS  Google Scholar 

  2. Oganov, A. R. & Ono, S. Theoretical and experimental evidence for a post-perovskite phase of MgSiO3 in Earth's D″ layer. Nature 430, 445–448 (2004)

    Article  ADS  CAS  Google Scholar 

  3. Iitaka, T., Hirose, K., Kawamura, K. & Murakami, M. The elasticity of the MgSiO3 post-perovskite phase in the Earth's lowermost mantle. Nature 430, 442–445 (2004)

    Article  ADS  CAS  Google Scholar 

  4. Tsuchiya, T., Tsuchiya, J., Umemoto, K. & Wentzcovitch, R. M. Elasticity of post-perovskite MgSiO3 . Geophys. Res. Lett. 31, L14603 (2004)

    Article  ADS  Google Scholar 

  5. Hernlund, J. W., Thomas, C. & Tackley, P. J. A doubling of the post-perovskite phase boundary and structure of the Earth's lowermost mantle. Nature 434, 882–886 (2005)

    Article  ADS  CAS  Google Scholar 

  6. Ono, S. & Oganov, A. R. In situ observations of phase transition between perovskite and CaIrO3-type phase in MgSiO3 and pyrolitic mantle composition. Earth Planet. Sci. Lett. 236, 914–932 (2005)

    Article  ADS  CAS  Google Scholar 

  7. Lay, T. & Helmberger, D. V. A shear velocity discontinuity in the lower mantle. Geophys. Res. Lett. 10, 63–66 (1983)

    Article  ADS  Google Scholar 

  8. Lay, T., Williams, Q. & Garnero, E. J. The core-mantle boundary layer and deep Earth dynamics. Nature 392, 461–468 (1998)

    Article  ADS  CAS  Google Scholar 

  9. Panning, M. & Romanowicz, B. Inferences on flow at the base of Earth's mantle based on seismic anisotropy. Science 303, 351–353 (2004)

    Article  ADS  CAS  Google Scholar 

  10. Karato, S., Zhang, S. Q. & Wenk, H. R. Superplasticity in Earth's lower mantle—evidence from seismic anisotropy and rock physics. Science 270, 458–461 (1995)

    Article  ADS  CAS  Google Scholar 

  11. Cordier, P., Ungar, T., Zsoldos, L. & Tichy, G. Dislocation creep in MgSiO3 perovskite at conditions of the Earth's uppermost lower mantle. Nature 428, 837–840 (2004)

    Article  ADS  CAS  Google Scholar 

  12. Nakagawa, T. & Tackley, P. J. Effects of a perovskite-post perovskite phase change near core-mantle boundary in compressible mantle convection. Geophys. Res. Lett. 31, L16611 (2004)

    Article  ADS  Google Scholar 

  13. Martoňák, R., Laio, A. & Parrinello, M. Predicting crystal structures: The Parrinello-Rahman method revisited. Phys. Rev. Lett. 90, 075503 (2003)

    Article  ADS  Google Scholar 

  14. Martoňák, R. et al. Simulation of structural phase transitions by metadynamics. Z. Kristallogr. 220, 489–498 (2005)

    Google Scholar 

  15. Laio, A. & Parrinello, M. Escaping free-energy minima. Proc. Natl Acad. Sci. USA 99, 12562–12566 (2002)

    Article  ADS  CAS  Google Scholar 

  16. Oganov, A. R., Brodholt, J. P. & Price, G. D. Comparative study of quasiharmonic lattice dynamics, molecular dynamics and Debye model in application to MgSiO3 perovskite. Phys. Earth Planet. Inter. 122, 277–288 (2000)

    Article  ADS  CAS  Google Scholar 

  17. Smith, W., Todorov, I. T. & Leslie, M. The DL_POLY molecular dynamics package. Z. Kristallogr. 220, 563–567 (2005)

    CAS  Google Scholar 

  18. Kresse, G. & Furthmüller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane wave basis set. Phys. Rev. B 54, 11169–11186 (1996)

    Article  ADS  CAS  Google Scholar 

  19. Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865–3868 (1996)

    Article  ADS  CAS  Google Scholar 

  20. Blöchl, P. E. Projector augmented-wave method. Phys. Rev. B 50, 17953–17979 (1994)

    Article  ADS  Google Scholar 

  21. Kresse, G. & Joubert, D. From ultrasoft pseudopotentials to the projector augmented-wave method. Phys. Rev. B59, 1758–1775 (1999)

    Article  ADS  Google Scholar 

  22. Vinet, P., Rose, J. H., Ferrante, J. & Smith, J. R. Universal features of the equation of state of solids. J. Phys. Condens. Matter 1, 1941–1963 (1989)

    Article  ADS  CAS  Google Scholar 

  23. Legrand, B. Relations entre la structure èlectronique et la facilitè de glissement dans les métaux hexagonaux compacts. Phil. Mag. 49, 171–184 (1984)

    Article  CAS  Google Scholar 

  24. Montagner, J.-P. & Nataf, H.-C. A simple method for inverting the azimuthal anisotropy of surface waves. J. Geophys. Res. 91, 511–520 (1986)

    Article  ADS  Google Scholar 

  25. Tsuchiya, T., Tsuchiya, J., Umemoto, K. & Wentzcovitch, R. M. Phase transition in MgSiO3 perovskite in the earth's lower mantle. Earth Planet. Sci. Lett. 224, 241–248 (2004)

    Article  ADS  CAS  Google Scholar 

  26. Garnero, E. J., Maupin, V., Lay, T. & Fouch, M. J. Variable azimuthal anisotropy in Earth's lowermost mantle. Science 306, 259–261 (2004)

    Article  ADS  CAS  Google Scholar 

  27. Wookey, J., Kendall, J.-M. & Rümpker, G. Lowermost mantle anisotropy beneath the north Pacific from differential S-ScS splitting. Geophys. J. Int. 161, 829–838 (2005)

    Article  ADS  Google Scholar 

Download references

Acknowledgements

Calculations were performed at ETH Zurich and CSCS (Manno). A.R.O. is grateful to P. Cordier, T. Ungar, G. Ferraris, T. Balic-Zunic, E. Makovicky and C. Thomas for discussions on various aspects of this work. Author Contributions A.R.O. designed and performed this work and wrote the paper. Many ideas on plasticity and phase transformation mechanisms arose from discussions between A.R.O., R.M., A.L. and M.P.; R.M. and P.R. assisted A.R.O. in technical aspects of this work.

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Correspondence to Artem R. Oganov.

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Supplementary Figure 1

This figure shows ab- and bc- projections of perfect post-perovskite (top) and post-perovskite with the {010} stacking fault (bottom). This stacking fault turns out to be very unfavourable. As discussed in the paper, the {110} stacking faults are preferred instead. SiO6 octahedra are shown in blue, Mg atoms are large pink spheres, Si atoms are small blue spheres, O atoms are small red spheres. (PDF 131 kb)

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Oganov, A., Martoňák, R., Laio, A. et al. Anisotropy of Earth's D″ layer and stacking faults in the MgSiO3 post-perovskite phase. Nature 438, 1142–1144 (2005). https://doi.org/10.1038/nature04439

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