Dislocation interactions in olivine control postseismic creep of the upper mantle

Wallis, D. and Hansen, L and Wilkinson, AJ and Lebensohn, RA (2017) Dislocation interactions in olivine control postseismic creep of the upper mantle. Journal of Geophysical Research-Solid Earth. ISSN 0148-0227 DOI https://doi.org/10.1002/2017JB014513

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Abstract

Changes in stress applied to mantle rocks, such as those imposed by earthquakes, induce a period of evolution in viscosity and microstructure. This transient creep is often modelled based on stress transfer among slip systems due to grain interactions. However, recent experiments have demonstrated that the intragranular accumulation of stresses among dislocations is the dominant cause of strain hardening in olivine at low temperatures, raising the question of whether the same process contributes to transient creep at higher temperatures. Here, we demonstrate that olivine samples deformed at 25°C or 1150–1250°C both contain stress heterogeneities of ~1 GPa that are imparted by dislocations and have correlation lengths of ~1 μm. The similar stress distributions formed in both temperature regimes indicate that accumulation of stresses among dislocations also provides a contribution to transient creep at high temperatures. The results motivate a new generation of models that capture these intragranular processes and may refine predictions of evolving mantle viscosity over the earthquake cycle.</p>

Item Type:	Article
Uncontrolled Keywords:	NILAREP; IA76
Subjects:	05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Divisions:	05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Journal or Publication Title:	Journal of Geophysical Research-Solid Earth
Identification Number:	https://doi.org/10.1002/2017JB014513
Depositing User:	Sarah Humbert
Date Deposited:	12 Aug 2020 13:09
Last Modified:	12 Aug 2020 13:09
URI:	http://eprints.esc.cam.ac.uk/id/eprint/4854

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