The role of diffusion-driven pure climb creep on the rheology of bridgmanite under lower mantle conditions
Abstract
The viscosity of Earth's lower mantle is poorly constrained due to the lack of knowledge on some fundamental variables that affect the deformation behaviour of its main mineral phases. This study focuses on bridgmanite, the main lower mantle constituent, and assesses its rheology by developing an approach based on mineral physics. Following and revising the recent advances in this field, pure climb creep controlled by diffusion is identified as the key mechanism driving deformation in bridgmanite. The strain rates of this phase under lower mantle pressures, temperatures and stresses are thus calculated by constraining diffusion and implementing a creep theoretical model. The viscosity of MgSiO_3 bridgmanite resulting from pure climb creep is consequently evaluated and compared with the viscosity profiles available from the literature. We show that the inferred variability of viscosity in these profiles can be fully accounted for with the chosen variables of our calculation, e.g., diffusion coefficients, vacancy concentrations and applied stresses. A refinement of these variables is advocated in order to further constrain viscosity and match the observables.
Additional Information
© 2019 The Author(s). This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. Received 27 June 2018; Accepted 17 December 2018; Published 14 February 2019. This work was supported by funding from the European Research Council under the Seventh Framework Programme (FP7), ERC grant N°290424 – RheoMan. J.M.J. is thankful for support from the National Science Foundation (NSF) under EAR–CSEDI–1316362 and W. M. Keck Institute for Space Studies. J.S.P. was supported by NSF EAR−PF #14-52545. We are thankful to the CIDER program set at the Kavli Institute for Theoretical Physics, University of California, Santa Barbara (NSF EAR−1135452, funded under the FESD Program). Author Contributions: P.C. and PhC designed the project and supervised the introduction and creep model sections. J.A.V.O. and J.P. supervised the diffusion section. R.R. performed the modelling with J.P., J.A.V.O. and F.B. All authors discussed and interpreted the results and implications. R.R. prepared figures, tables and wrote the manuscript with contributions of all authors. The authors declare no competing interests.Attached Files
Published - s41598-018-38449-8.pdf
Supplemental Material - 41598_2018_38449_MOESM1_ESM.docx
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Additional details
- PMCID
- PMC6376055
- Eprint ID
- 92965
- Resolver ID
- CaltechAUTHORS:20190219-081030840
- 290424
- European Research Council (ERC)
- EAR-1316362
- NSF
- Keck Institute for Space Studies (KISS)
- EAR-14-52545
- NSF
- EAR-1135452
- NSF
- Created
-
2019-02-19Created from EPrint's datestamp field
- Updated
-
2022-03-01Created from EPrint's last_modified field
- Caltech groups
- Seismological Laboratory, Keck Institute for Space Studies, Division of Geological and Planetary Sciences