Zhang, Shuai and Cottaar, Sanne and Liu, Tao and Stackhouse, Stephen and Militzer, Burkhard (2016) High-pressure, temperature elasticity of Fe- and Al-bearing MgSiO3: Implications for the Earth's lower mantle. Earth and Planetary Science Letters, 434. pp. 264-273. ISSN 0012-821X DOI https://doi.org/10.1016/j.epsl.2015.11.030
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Abstract
Fe and Al are two of the most important rock-forming elements other than Mg, Si, and O. Their presence in the lower mantle's most abundant minerals, MgSiO3 bridgmanite, MgSiO3 post-perovskite and MgO periclase, alters their elastic properties. However, knowledge on the thermoelasticity of Fe- and Al-bearing MgSiO3 bridgmanite, and post-perovskite is scarce. In this study, we perform ab initio molecular dynamics to calculate the elastic and seismic properties of pure, Fe3+- and Fe2+-, and Al3+-bearing MgSiO3 perovskite and post-perovskite, over a wide range of pressures, temperatures, and Fe/Al compositions. Our results show that a mineral assemblage resembling pyrolite fits a 1D seismological model well, down to, at least, a few hundred kilometers above the core�mantle boundary, i.e. the top of the D � region. In D � , a similar composition is still an excellent fit to the average velocities and fairly approximate to the density. We also implement polycrystal plasticity with a geodynamic model to predict resulting seismic anisotropy, and find post-perovskite with predominant (001) slip across all compositions agrees best with seismic observations in the D � .
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | 2015AREP; IA70; weekly list |
| Subjects: | 02 - Geodynamics, Geophysics and Tectonics |
| Divisions: | 02 - Geodynamics, Geophysics and Tectonics |
| Journal or Publication Title: | Earth and Planetary Science Letters |
| Volume: | 434 |
| Page Range: | pp. 264-273 |
| Identification Number: | https://doi.org/10.1016/j.epsl.2015.11.030 |
| Depositing User: | Sarah Humbert |
| Date Deposited: | 17 Jan 2016 02:57 |
| Last Modified: | 16 Feb 2016 12:28 |
| URI: | http://eprints.esc.cam.ac.uk/id/eprint/3545 |
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