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Strongly Anisotropic Magnesiowüstite in Earth's Lower Mantle

Finkelstein, Gregory J. and Jackson, Jennifer M. and Said, Ayman and Alatas, Ahmet and Leu, Bogdan M. and Sturhahn, Wolfgang and Toellner, Thomas S. (2018) Strongly Anisotropic Magnesiowüstite in Earth's Lower Mantle. Journal of Geophysical Research. Solid Earth, 123 (6). pp. 4740-4750. ISSN 2169-9313. http://resolver.caltech.edu/CaltechAUTHORS:20180521-074455380

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Abstract

The juxtaposition of a liquid iron‐dominant alloy against a mixture of silicate and oxide minerals at Earth's core‐mantle boundary is associated with a wide range of complex seismological features. One category of observed structures is ultralow‐velocity zones, which are thought to correspond to either aggregates of partially molten material or solid, iron‐enriched assemblages. We measured the phonon dispersion relations of (Mg,Fe) O magnesiowüstite containing 76 mol % FeO, a candidate ultralow‐velocity zone phase, at high pressures using high‐energy resolution inelastic X‐ray scattering. From these measurements, we find that magnesiowüstite becomes strongly elastically anisotropic with increasing pressure, potentially contributing to a significant proportion of seismic anisotropy detected near the base of the mantle.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1029/2017JB015349DOIArticle
ORCID:
AuthorORCID
Finkelstein, Gregory J.0000-0001-7343-7527
Jackson, Jennifer M.0000-0002-8256-6336
Alatas, Ahmet0000-0001-6521-856X
Sturhahn, Wolfgang0000-0002-9606-4740
Additional Information:© 2018 American Geophysical Union. Received 12 DEC 2017; Accepted 13 MAY 2018; Accepted article online 18 MAY 2018; Published online 16 JUN 2018. We thank Stephen J. Mackwell for providing the single crystals for this study and Rachel A. Morrison for help in conducting experiments. We are thankful to NSF‐CSEDI‐EAR‐1161046 and 1600956, the W. M. Keck Institute for Space Studies for financial support, and two anonymous reviewers for their helpful comments. G. J. Finkelstein is also partially supported by the Caltech Seismological Laboratory Director's Postdoctoral Fellowship. We acknowledge COMPRES for partial support of Sector 3 and Sector 30 at the Advanced Photon Source (APS). Ruby fluorescence measurements were conducted at GSECARS, which is supported by NSF‐EAR‐1128799 and U.S. DOE, Geosciences (DE‐FG02‐94ER14466. Use of the APS is supported by U.S. DOE, Office of Science (DE‐AC02‐06CH11357). The spectra corresponding to the results reported in this paper are provided in the supporting information.
Group:Seismological Laboratory, Keck Institute for Space Studies
Funders:
Funding AgencyGrant Number
NSFEAR-1161046
NSFEAR-1600956
Keck Institute for Space Studies (KISS)UNSPECIFIED
Caltech Seismological LaboratoryUNSPECIFIED
NSFEAR-1128799
Department of Energy (DOE)DE-FG02-94ER14466
Department of Energy (DOE)DE-AC02-06CH11357
Subject Keywords:magnesiowüstite; high pressure; inelastic x‐ray scattering; elasticity; elastic anisotropy; periclase
Record Number:CaltechAUTHORS:20180521-074455380
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20180521-074455380
Official Citation:Finkelstein, G. J., Jackson, J. M., Said, A., Alatas, A., Leu, B. M., Sturhahn, W., & Toellner, T. S. (2018). Strongly anisotropic magnesiowüstite in Earth's lower mantle. Journal of Geophysical Research: Solid Earth, 123, 4740–4750. https://doi.org/10.1029/2017JB015349
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:86486
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:21 May 2018 14:59
Last Modified:02 Jan 2019 21:11

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