Transient Creep in Subduction Zones by Long-Range Dislocation Interactions in Olivine
Publication Date
2022Journal Title
Journal of Geophysical Research: Solid Earth
ISSN
2169-9313
Publisher
American Geophysical Union
Volume
127
Issue
1
Language
en
Type
Article
This Version
AO
VoR
Metadata
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Wallis, D., Sep, M., & Hansen, L. (2022). Transient Creep in Subduction Zones by Long-Range Dislocation Interactions in Olivine. Journal of Geophysical Research: Solid Earth, 127 (1) https://doi.org/10.1029/2021JB022618
Abstract
Large earthquakes transfer stress from the shallow lithosphere to the underlying viscoelastic lower crust and upper mantle, inducing transient creep during the postseismic interval. Recent experiments on olivine have provided a new rheological model for this transient creep based on accumulation and release of back stresses among dislocations. Here, we test whether natural rocks preserve dislocation-induced stress heterogeneity consistent with the back-stress hypothesis by mapping olivine from the palaeosubduction interface of the Oman-UAE ophiolite with high-angular resolution electron backscatter diffraction. The olivine preserves heterogeneous residual stresses that vary in magnitude by several hundred megapascals over length scales of a few micrometres. Large stresses are commonly spatially associated with elevated densities of geometrically necessary dislocations within subgrain interiors. These spatial relationships, along with characteristic probability distributions of the stresses, confirm that the stress heterogeneity is generated by the dislocations and records their long-range elastic interactions. Images of dislocations decorated by oxidation display bands of high and low dislocation density, suggesting that dislocation interactions contributed to organisation of the substructure. These results support the applicability of the back-stress model of transient creep to deformation in the mantle portion of plate-boundary shear zones. The model predicts that rapid stress changes, such as those imposed by large earthquakes, can induce order-of-magnitude changes in viscosity that depend nonlinearly on the stress change, consistent with inferences of mantle rheology from geodetic observations.
Keywords
Chemistry and Physics of Minerals and Rocks/Volcanology, EXPLORATION GEOPHYSICS, Gravity methods, GEODESY AND GRAVITY, Transient deformation, Tectonic deformation, Time variable gravity, Gravity anomalies and Earth structure, Satellite geodesy: results, Seismic cycle related deformations, HYDROLOGY, Estimation and forecasting, INFORMATICS, Forecasting, IONOSPHERE, MAGNETOSPHERIC PHYSICS, MARINE GEOLOGY AND GEOPHYSICS, Ophiolites, MATHEMATICAL GEOPHYSICS, Prediction, Probabilistic forecasting, OCEANOGRAPHY: GENERAL, Ocean predictability and prediction, NATURAL HAZARDS, Monitoring, forecasting, prediction, POLICY SCIENCES, RADIO SCIENCE, Interferometry, Ionospheric physics, SEISMOLOGY, Continental crust, Earthquake dynamics, Earthquake source observations, Earthquake interaction, forecasting, and prediction, Seismicity and tectonics, Subduction zones, SPACE WEATHER, Policy, STRUCTURAL GEOLOGY, Microstructures, Rheology: mantle, TECTONOPHYSICS, Stresses: crust and lithosphere, Research Article, transient creep, olivine, Oman‐UAE ophiolite, stress heterogeneity, geometrically necessary dislocation, high‐angular resolution electron backscatter diffraction
Sponsorship
This work was supported by the Natural Environment Research Council, grant NE/M000966/1; the Netherlands Organisation for Scientific Research, User Support Programme Space Research, grant ALWGO.2018.038; and startup funds from Utrecht University.
Funder references
UKRI, Natural Environment Research Council (NERC) (NE/M000966/1)
NWO, Aard‐en Levenswetenschappen, Nederlandse Organisatie voor Wetenschappelijk Onderzoek (ALW‐NOW) (ALWGO.2018.038)
UK Research and Innovation Future Leaders Fellowship (MR/V021788/1)
Identifiers
jgrb55428, 2021jb022618
External DOI: https://doi.org/10.1029/2021JB022618
This record's URL: https://www.repository.cam.ac.uk/handle/1810/333284
Rights
Licence:
http://creativecommons.org/licenses/by/4.0/
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