Méndez, ASJ, Stackhouse, S orcid.org/0000-0001-7605-3510, Trautner, V et al. (7 more authors) (2022) Broad elastic softening of (Mg,Fe)O ferropericlase across the iron spin crossover and a mixed-spin lower mantle. Journal of Geophysical Research. ISSN 0148-0227
Abstract
The elastic bulk modulus softening of (Mg,Fe)O ferropericlase across the iron spin crossover induces dramatic changes in its physical properties, including seismic P-velocities and viscosity. Here, we performed compression of powders of (Mg0.8-0.9Fe0.2-0.1)O in a piezo-driven dynamic Diamond Anvil Cell (dDAC) and derive the bulk modulus by differentiation of pressure and volume data, providing first data on the broadness of the elastic softening for ferropericlase with mantle-relevant compositions. We complement our experimental results with theoretical calculations that extend previous studies by considering multiple random configurations of iron, and going beyond treating high- and low-spin iron as an ideal solution. Both experiments and computations show a broad and asymmetric softening of the bulk modulus, and suggest that the softening is sensitive to the distribution of iron in the ferropericlase structure. Our high-temperature calculations show that mixed-spin (Mg,Fe)O dominates the lower mantle at all depths below 1000 km. In contrast to most previous works, we find that ferropericlase will not exist in pure low-spin state along a typical mantle geotherm. Based on our model, the physical properties of ferropericlase will show significant lateral variation at depths below 1400 km, with the strongest effects expected between 2000 and 2600 km.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Keywords: | spin crossover; ferropericlase; elastic softening; mixed-spin; lower mantle; dynamic compression |
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) |
Depositing User: | Symplectic Publications |
Date Deposited: | 22 Aug 2022 08:25 |
Last Modified: | 22 Aug 2022 13:54 |
Status: | Published online |
Publisher: | Wiley |
Identification Number: | 10.1029/2021JB023832 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:190091 |