Stress evolution and associated microstructure during transient creep of olivine at 1000–1200 °C

Thieme, Manuel; Demouchy, Sylvie; Mainprice, David; Barou, Fabrice; Cordier, Patrick

doi:10.1016/j.pepi.2018.03.002

Cited by 43 publications

(42 citation statements)

References 107 publications

(145 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Inconsistency between misorientation axes data and LPO has been observed in many natural samples and experimental results (Demouchy et al, ; Faul et al, ; Fliervoet et al, ; Précigout & Hirth, ), which is attributed to that misorientation axes only represent the preserved geometrically necessary dislocations stacked in the subgrain boundaries, and most are not the systematical results of dominant active slip systems (Demouchy et al, ; Soustelle et al, ; Tommasi et al, ). The activation of free dislocations with at least two different Burgers vectors ([001] and [100]) in the deformed olivine grains (Figure ) was also reported in the melt‐free compression experiments on olivine aggregates at 300 MPa and 900–1,350 °C (Demouchy et al, ; Faul et al, ; Thieme et al, ). Activation of different slip systems is controlled by the grain crystallographic orientation relative to the compression axis, as well as the local stress field due to interaction between neighboring grains in the polycrystalline aggregates (Demouchy et al, ; Faul et al, ).…”

Section: Discussionmentioning

confidence: 60%

Weak B‐Type Olivine Fabric Induced by Fast Compaction of Crystal Mush in a Crustal Magma Reservoir

et al. 2019

View full text Add to dashboard Cite

Understanding the deformation mechanisms of olivine has been considered as the crucial factor in tracing the dynamic processes from seismic anisotropy. Due to extensive overprinting of deformation and alteration, natural examples of original magmatic fabric of olivine are scarce. In this study we selected one wehrlite and three dunite samples from a deep borehole in the Poyi mafic-ultramafic intrusion in the Tarim Craton. The fresh samples show adcumulate texture and plastic deformation of dry olivine (≤10 ppm H 2 O). Thermobarometer calculations yield crystallization conditions at 200-400 MPa and >1,124-1,275°C. Olivine developed a B-type fabric characterized by a concentration of [001] axes parallel to the interpreted lineation and that of [010] axes normal to the interpreted foliation. Activation of [001] and [100] dislocations is confirmed by microstructural observations. Simulation of gravity-driven compaction process reveals extremely rapid compaction of kilometer-scale crystal mush in the Poyi magmatic system. During the early compaction with high porosity, crystallographic habit of olivine may produce shape-preferred orientation and the related B-type fabric. In the final stage of compaction and crystallization, the initial shape-preferred orientation was gradually overprinted, whereas the weak B-type fabric has remained with dislocation creep and dislocation-accommodated grain boundary sliding. Calculated seismic velocities of peridotite samples show low P and S wave anisotropies, with the fastest S wave polarization direction normal to the foliation. Hence, a mush-dominated ultramafic intrusion exhibits weak seismic anisotropy, which has potential to better understand seismic anisotropy in the transcrustal magmatic systems.

show abstract

Section: Discussionmentioning

confidence: 60%

Weak B‐Type Olivine Fabric Induced by Fast Compaction of Crystal Mush in a Crustal Magma Reservoir

et al. 2019

View full text Add to dashboard Cite

show abstract

“…The model of Li (1963) and Bata and Pereloma (2004) are particularly interesting because they involve the nucleation of dislocations at grain boundaries. Recent nanoindentation experiments using spherical indenters (Kumamoto et al, 2017) and transmission electron microscopy of deformed olivine aggregates (Thieme et al, 2018) suggest that grain and subgrain boundaries are dislocation sources in olivine.…”

Section: Journal Of Geophysical Research: Solid Earthmentioning

confidence: 99%

Low‐Temperature Plasticity in Olivine: Grain Size, Strain Hardening, and the Strength of the Lithosphere

et al. 2019

View full text Add to dashboard Cite

Plastic deformation of olivine at relatively low temperatures (i.e., low‐temperature plasticity) likely controls the strength of the lithospheric mantle in a variety of geodynamic contexts. Unfortunately, laboratory estimates of the strength of olivine deforming by low‐temperature plasticity vary considerably from study to study, limiting confidence in extrapolation to geological conditions. Here we present the results of deformation experiments on olivine single crystals and aggregates conducted in a deformation‐DIA at confining pressures of 5 to 9 GPa and temperatures of 298 to 1473 K. These results demonstrate that, under conditions in which low‐temperature plasticity is the dominant deformation mechanism, fine‐grained samples are stronger at yield than coarse‐grained samples, and the yield stress decreases with increasing temperature. All samples exhibited significant strain hardening until an approximately constant flow stress was reached. The magnitude of the increase in stress from the yield stress to the flow stress was independent of grain size and temperature. Cyclical loading experiments revealed a Bauschinger effect, wherein the initial yield strength is higher than the yield strength during subsequent cycles. Both strain hardening and the Bauschinger effect are interpreted to result from the development of back stresses associated with long‐range dislocation interactions. We calibrated a constitutive model based on these observations, and extrapolation of the model to geological conditions predicts that the strength of the lithosphere at yield is low compared to previous experimental predictions but increases significantly with increasing strain. Our results resolve apparent discrepancies in recent observational estimates of the strength of the oceanic lithosphere.

show abstract

“…Hardening is not considered in the present models since in most high-temperature ( 1200 °C) deformation experiments on olivine aggregates, in the absence of significant microstructural changes, steady-state mechanical behavior is achieved after relatively small strains (e.g., Chopra and Paterson, 1984;Hansen et al, 2012b;Thieme et al, 2018). In the present models, diffusive processes are therefore implicitly ac-counted for in two ways: via their contribution to avoid hardening by dislocation entanglements and via the activation of the dummy slip systems.…”

Section: Modeling Viscoplastic Behavior and Texture Evolutionmentioning

confidence: 99%

Predicting viscoplastic anisotropy in the upper mantle: a comparison between experiments and polycrystal plasticity models

Mameri

Tommasi

Signorelli

et al. 2019

Physics of the Earth and Planetary Interiors

View full text Add to dashboard Cite

show abstract

Stress evolution and associated microstructure during transient creep of olivine at 1000–1200 °C

Cited by 43 publications

References 107 publications

Weak B‐Type Olivine Fabric Induced by Fast Compaction of Crystal Mush in a Crustal Magma Reservoir

Weak B‐Type Olivine Fabric Induced by Fast Compaction of Crystal Mush in a Crustal Magma Reservoir

Low‐Temperature Plasticity in Olivine: Grain Size, Strain Hardening, and the Strength of the Lithosphere

Predicting viscoplastic anisotropy in the upper mantle: a comparison between experiments and polycrystal plasticity models

Contact Info

Product

Resources

About

Stress evolution and associated microstructure during transient creep of olivine at 1000–1200 °C

Cited by 43 publications

References 107 publications

Weak B‐Type Olivine Fabric Induced by Fast Compaction of Crystal Mush in a Crustal Magma Reservoir

Weak B‐Type Olivine Fabric Induced by Fast Compaction of Crystal Mush in a Crustal Magma Reservoir

Low‐Temperature Plasticity in Olivine: Grain Size, Strain Hardening, and the Strength of the Lithosphere

Predicting viscoplastic anisotropy in the upper mantle: a comparison between experiments and polycrystal plasticity models

Contact Info

Product

Resources

About

Stress evolution and associated microstructure during transient creep of olivine at 1000–1200 °C