Zhang, S, Cottaar, S, Liu, T et al. (2 more authors) (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
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′′.
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Copyright, Publisher and Additional Information: | © 2015, Elsevier. This is an author produced version of a paper published in Earth and Planetary Science Letters. Uploaded in accordance with the publisher's self-archiving policy. | ||||
Keywords: | Lower mantle; pyrolite; bridgmanite; post-perovskite; elastic properties; first-principles | ||||
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Institution: | The University of Leeds | ||||
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst of Geophysics and Tectonics (IGT) (Leeds) | ||||
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Depositing User: | Symplectic Publications | ||||
Date Deposited: | 20 Nov 2015 10:14 | ||||
Last Modified: | 05 Nov 2017 20:05 | ||||
Published Version: | http://dx.doi.org/10.1016/j.epsl.2015.11.030 | ||||
Status: | Published | ||||
Publisher: | Elsevier | ||||
Identification Number: | https://doi.org/10.1016/j.epsl.2015.11.030 |