Trautner, VE, Stackhouse, S orcid.org/0000-0001-7605-3510, Turner, AR et al. (7 more authors) (2023) Compressibility of ferropericlase at high-temperature: evidence for the iron spin crossover in seismic tomography. Earth and Planetary Science Letters, 618. 118296. ISSN 0012-821X
Abstract
The iron spin crossover in ferropericlase, the second most abundant mineral in Earth's lower mantle, causes changes in a range of physical properties, including seismic wave velocities. Understanding the effect of temperature on the spin crossover is essential to detect its signature in seismic observations and constrain its occurrence in the mantle. Here, we report the first experimental results on the spin crossover-induced bulk modulus softening at high temperatures, derived directly from time-resolved x-ray diffraction measurements during continuous compression of (Mg0.8Fe0.2)O in a resistive-heated dynamic diamond-anvil cell. We present new theoretical calculations of the spin crossover at mantle temperatures benchmarked by the experiments. Based on our results, we create synthetic seismic tomography models to investigate the signature of the spin crossover in global seismic tomography. A tomographic filter is applied to allow for meaningful comparisons between the synthetic models and data-based seismic tomography models, like SP12RTS. A negative anomaly in the correlation between Vs variations and Vc variations (S-C correlation) is found to be the most suitable measure to detect the presence of the spin crossover in tomographic models. When including the effects of the spin crossover, the misfit between the synthetic model and SP12RTS is reduced by 63%, providing strong evidence for the presence of the spin crossover, and hence ferropericlase, in the lower mantle. Future improvement of seismic resolution may facilitate a detailed mapping of spin state using the S-C correlation, providing constraints on mantle temperatures by taking advantage of the temperature sensitivity of the spin crossover.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). |
Keywords: | ferropericlase; lower mantle; spin crossover; elastic softening; ab initio computations; seismic tomography |
Dates: |
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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) |
Funding Information: | Funder Grant number NERC (Natural Environment Research Council) NE/K006290/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 04 Jul 2023 12:53 |
Last Modified: | 04 Aug 2023 14:03 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.epsl.2023.118296 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:201189 |