An apparatus for measuring nonlinear viscoelasticity of minerals at high temperature

Cao, Ri; Hansen, Louis S.; Thom, Christopher A.; Wallis, David

doi:10.31223/x59w2x

Cited by 3 publications

(5 citation statements)

References 37 publications

(55 reference statements)

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“…Displacements were measured with a linear encoder with resolution of 10 nm and corrected for distortion of the apparatus using the complex compliance of the apparatus calibrated by Cao et al. (2020).…”

Section: Methodsmentioning

confidence: 99%

“…Details of the apparatus design are provided by Cao et al. (2020). Samples were placed in direct contact with alumina platens, which were in direct contact with SiC pistons.…”

Section: Methodsmentioning

confidence: 99%

“…An axial load was applied to the loading column with a piezoelectric actuator using a closed-loop servo-control system, and the load was measured and controlled with a precision of ∼1 N. Changes in sample length were assessed by measuring displacements of the SiC piston relative to the loading frame. Displacements were measured with a linear encoder with resolution of 10 nm and corrected for distortion of the apparatus using the complex compliance of the apparatus calibrated by Cao et al (2020).…”

Section: Deformation Experimentsmentioning

confidence: 99%

“…Deformation experiments were conducted in a 1-atm uniaxial creep apparatus in the Rock Rheology Laboratory at the University of Oxford. Details of the apparatus design are provided by Cao et al (2020). Samples were placed in direct contact with alumina platens, which were in direct contact with SiC pistons.…”

Section: Deformation Experimentsmentioning

confidence: 99%

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Dislocation Creep of Olivine: Backstress Evolution Controls Transient Creep at High Temperatures

et al. 2021

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The evolution of viscosity during flow of mantle rocks at high temperatures is fundamental to a variety of geodynamic processes. For example, transient creep of the upper mantle has been identified as a major contributor to geodetically observed surface deformations during post-seismic creep (Freed et al., 2012;Masuti et al., 2016;Pollitz, 2005;Qiu et al., 2018), for which the strains are typically <10 −3 , and inferred viscosities are one to two orders of magnitude lower than the long-term, steady-state viscosity. Because transient viscosities also continue to evolve during postseismic deformation, they likely cause a time-dependent transfer of stresses to neighboring faults, rather than the instantaneous transfer assumed by popular calculations of Coulomb stress changes (e.g., Freed, 2005). Although sophisticated earthquake forecast models do incorporate time-dependent loading according to average plate motion rates (e.g., Field et al., 2015Field et al., , 2017, they still do not incorporate variable loading rates that would occur due to transient creep of the lithosphere. In addition, transient viscosities are expected to be important, although they have not yet been thoroughly considered, in other small-strain processes including flexure of the lithosphere near volcanic loads (Zhong & Watts, 2013) or in subducting slabs near trenches (Hunter & Watts, 2016), during which the strains rarely exceed 10 −2 .

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Section: Methodsmentioning

confidence: 99%

“…Details of the apparatus design are provided by Cao et al. (2020). Samples were placed in direct contact with alumina platens, which were in direct contact with SiC pistons.…”

Section: Methodsmentioning

confidence: 99%

Section: Deformation Experimentsmentioning

confidence: 99%

Section: Deformation Experimentsmentioning

confidence: 99%

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Dislocation Creep of Olivine: Backstress Evolution Controls Transient Creep at High Temperatures

et al. 2021

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Section: Deformation Experimentsmentioning

confidence: 99%

Dislocation creep of olivine: Backstress evolution controls transient creep at high temperatures

Hansen

Wallis

Breithaupt

et al. 2021

Preprint

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Transient creep occurs during geodynamic processes that impose stress changes on rocks at high temperatures. The transient is manifested as evolution in the viscosity of the rocks until steady-state flow is achieved. Although several phenomenological models of transient creep in rocks have been proposed, the dominant microphysical processes that control such behavior remain poorly constrained. To identify the intragranular processes that contribute to transient creep of olivine, we performed stress-reduction Preprint submitted to ESSOAr and Journal of Geophysical Research -Solid Earth 2 tests on single crystals of olivine at temperatures of 1250-1300°C. In these experiments, samples undergo time-dependent reverse strain after the stress reduction. The magnitude of reverse strain is ~10 -3 and increases with increasing magnitude of the stress reduction. High-angular resolution electron backscatter diffraction analyses of deformed material reveal lattice curvature and heterogeneous stresses associated with the dominant slip system. The mechanical and microstructural data are consistent with transient creep of the single crystals arising from accumulation and release of backstresses among dislocations. These results allow the dislocation-glide component of creep at high temperatures to be isolated, and we use these data to calibrate a flow law for olivine to describe the glide component of creep over a wide temperature range. We argue that this flow law can be used to estimate both transient creep and steadystate viscosities of olivine, with the transient evolution controlled by the evolution of the backstress. This model is able to predict variability in the style of transient (normal versus inverse) and the load-relaxation response observed in previous work.c Cooper et al. Hanson and Spetzler This study Normal Inverse

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Dislocation creep of olivine: Low-temperature plasticity controls transient creep at high temperatures

Hansen¹,

Wallis²,

Breithaupt³

et al. 2020

Preprint

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An apparatus for measuring nonlinear viscoelasticity of minerals at high temperature

Cited by 3 publications

References 37 publications

Dislocation Creep of Olivine: Backstress Evolution Controls Transient Creep at High Temperatures

Dislocation Creep of Olivine: Backstress Evolution Controls Transient Creep at High Temperatures

Dislocation creep of olivine: Backstress evolution controls transient creep at high temperatures

Dislocation creep of olivine: Low-temperature plasticity controls transient creep at high temperatures

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