The Effect of Secondary‐Phase Fraction on the Deformation of Olivine + Ferropericlase Aggregates: 1. Microstructural Evolution

Wiesman, Harison S.; Zimmerman, M. E.; Kohlstedt, D. L.

doi:10.1029/2022jb025723

Cited by 3 publications

(4 citation statements)

References 59 publications

(178 reference statements)

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“…We anticipate that this fabric-cut effect is a significant source of bias in systems with weak fabric (e.g., magmatic fabric), or in seemingly strong fabrics at low sample size (Figure 5), but is present in all EBSD orientational data. If meaningful interpretations of dynamic processes are to be made from EBSD derived orientations (Bernard et al 2023;Casale et al 2023;Forman et al 2023;Goudy et al 2023;Jenkins et al 2022;Koyama et al 2023;Levy et al 2023;Li et al 2023;Rehman et al 2023;Vukmanovic et al 2018;Wiesman et al 2023), then the fabric-cut effect needs to be corrected for. However, when we apply this method to natural samples, we find that the fabric-cut effect is likely not fully decoupled in a multiplicative manner (i.e., Eq.…”

Section: ) Discussionmentioning

confidence: 99%

“…magmatic sense of shear: Vukmanovic et al 2018;compaction: Bertolett et al 2019;Jenkins et al 2022; grain clustering mechanisms: Wieser et al 2019;Holness et al 2023). Similar applications can be extended into metamorphic systems with rock fabric encoding the deformation history and behavior (Bernard et al 2023;Bestmann et al 2006;Casale et al 2023;Cross et al 2017b, Haertel andHerwegh 2014;Fossen and Cavalcante 2017;Koyama et al 2023;Levy et al 2023;Li et al 2023;Rehman et al 2023;Taylor et al 2023;Wiesman et al 2023), impact dynamics recorded in meteorites (Goudy et al 2023;Forman et al 2023), fluid reactivity with primary minerals (Andreani et al 2009;Etschmann et al 2014;Kang et al 2010), sedimentary processes (McLaren 1981), as well as biosphere/geosphere interaction (Hemkemeyer et al 2018).…”

Section: ) Introductionmentioning

confidence: 99%

“…In particular, this paper focuses on the following question: What are the (if any) stereological biases that can be present when analyzing the crystal orientation datasets from EBSD? An increasing number of studies are using EBSD for rock textural analysis (Bernard et al 2023;Bertolett et al 2019;Casale et al 2023;Cheadle and Gee 2017;Cross et al 2017a;Cross et al 2017b;Forman et al 2023;Goudy et al 2023;Henry et al 2021;Holness et al 2023;Jenkins et al 2022;Koyama et al 2023;Levy et al 2023;Li et al 2023;Rehman et al 2023;Wieser et al 2019;Wiesman et al 2023;Vukmanovic et al 2018;Zavada et al 2009). However, in contrast to 2D thin section size-shape analysis, the need for stereological corrections with EBSD orientation datasets hasn't been thoroughly scrutinized.…”

Section: ) Introductionmentioning

confidence: 99%

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Towards an Integrated Texture Toolkit, 1: Unveiling the Complex Relationship Between Crystal Size, Shape, and Fabric in EBSD Data

Currier,

Mittal,

Hidalgo

2023

Preprint

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Rock textures observed via thin section are skewed from their true 3D nature. This is due to a variety of cut effects—artifacts that are introduced due to the lower dimensional nature of the thin section relative to the rock. Typically, these methods invert crystal shape and crystal size, but with each process performed separately and in sequence. With the ongoing adoption of electron backscatter diffraction (EBSD) by petrologists, an additional data stream has now become available: the 3D orientation of 2D grain sections. For EBSD analysis, no stereological corrections are typically applied for interpreting the data. In this study, we test whether this orientational information is also skewed due to a fabric cut effect. We test this by numerically generating synthetic crystal datasets representative of a number of crystal shapes and population sizes. We find that EBSD orientational data does have a fabric cut effect since crystals oriented with long axes perpendicular to the thin section are more likely to be sampled compared to those with long axes oriented parallel to it. This effect needs to be accounted for to accurately interpret the true 3D fabric. Towards this end, we develop a method of inverting cut fabrics which provides robust error estimations and show its accuracy using a range of synthetic examples. When applied to natural samples, which are inherently more complex than the simplified, synthetic samples, we find that the inversion process does not always produce geologically plausible results. To more faithfully correct for the different cut effects, we argue that the stereological inversion process should not be performed separately or sequentially, as is commonly done at present. Instead, we need a new textural toolkit framework to correct for crystal shape, size, and orientation simultaneously with accurate uncertainty estimates.

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Section: ) Discussionmentioning

confidence: 99%

Section: ) Introductionmentioning

confidence: 99%

Section: ) Introductionmentioning

confidence: 99%

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Towards an Integrated Texture Toolkit, 1: Unveiling the Complex Relationship Between Crystal Size, Shape, and Fabric in EBSD Data

Currier,

Mittal,

Hidalgo

2023

Preprint

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“…All data used in this study are available from the University of Minnesota Digital Conservancy (https://doi. org/10.13020/k0p0-5047, Wiesman et al, 2023).…”

Section: Data Availability Statementmentioning

confidence: 99%

The Effect of Secondary‐Phase Fraction on the Deformation of Olivine + Ferropericlase Aggregates: 2. Mechanical Behavior

2023

Self Cite

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To study the mechanical behavior of polymineralic rocks, we performed deformation experiments on two‐phase aggregates of olivine (Ol) + ferropericlase (Per) with periclase fractions (fPer) between 0.1 and 0.8. Each sample was deformed in torsion at T = 1523 K, P = 300 MPa at a constant strain rate to a final shear strain of γ = 6 to 7. The stress‐strain data and calculated values of the stress exponent, n, indicate that Ol in our samples deformed by dislocation‐accommodated sliding along grain interfaces while Per deformed via dislocation creep. At shear strains of γ < 1, the strengths of samples with fPer > 0.5 match model predictions for both phases deforming at the same stress, the lower‐strength bound for two‐phase materials, while the strengths of samples with fPer < 0.5 are greater than predicted by models for both phases deforming at the same strain rate, the upper‐strength bound. These observations suggest a transition from a weak‐phase supported to a strong‐phase supported regime with decreasing fPer. Above γ = 4, however, the strength of all two‐phase samples is greater than those predicted by either the uniform‐stress or the uniform‐strain rate bound. We hypothesize that the high strengths in the Ol + Per system are due to the presence of phase boundaries in two‐phase samples, for which deformation is rate limited by dislocation motion along interfacial boundaries. This observation contrasts with the mechanical behavior of samples consisting of Ol + pyroxene, which are weaker, possibly due to impurities at phase boundaries.

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Microstructural and Micromechanical Evolution of Olivine Aggregates During Transient Creep

Wiesman,

Breithaupt,

Wallis

et al. 2024

JGR Solid Earth

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To examine the microstructural evolution that occurs during transient creep, we deformed samples of polycrystalline olivine to different strains that spanned the initial transient deformation. Two sets of samples with different initial grain sizes of 5 μm and 20 μm were deformed in torsion at T = 1,523 K, P = 300 MPa, and a constant shear strain rate of 1.5 × 10−4 s−1, during which both sets of samples experienced strain hardening. We characterized the microstructures at the end of each experiment using high‐angular resolution electron backscatter diffraction (HR‐EBSD) and dislocation decoration. In the coarse‐grained samples, dislocation density increased from 1.5 × 1011 m−2 to 3.6 × 1012 m−2 with strain. Although the same final dislocation density was reached in the fine‐grained samples, it did not vary significantly at small strains, potentially due to concurrent grain growth during deformation. In both sets of samples, HR‐EBSD analysis revealed that intragranular stress heterogeneity increased in magnitude with strain and that elevated stresses are associated with regions of high geometrically necessary dislocation density. Further analysis of the stresses and their probability distributions indicate that the stresses are imparted by dislocations and cause long‐range elastic interactions among them. These characteristics indicate that dislocation interactions were the primary cause of strain hardening during transient creep in our samples. A comparison of the results to the predictions of three recent models reveals that the models do not correctly predict the evolution in stress and dislocation density with strain in our experiments due to a lack of previous such data in their calibrations.

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The Effect of Secondary‐Phase Fraction on the Deformation of Olivine + Ferropericlase Aggregates: 1. Microstructural Evolution

Cited by 3 publications

References 59 publications

Towards an Integrated Texture Toolkit, 1: Unveiling the Complex Relationship Between Crystal Size, Shape, and Fabric in EBSD Data

Towards an Integrated Texture Toolkit, 1: Unveiling the Complex Relationship Between Crystal Size, Shape, and Fabric in EBSD Data

The Effect of Secondary‐Phase Fraction on the Deformation of Olivine + Ferropericlase Aggregates: 2. Mechanical Behavior

Microstructural and Micromechanical Evolution of Olivine Aggregates During Transient Creep

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