Protracted fabric evolution in olivine: Implications for the relationship among strain, crystallographic fabric, and seismic anisotropy

Lars N Hansen, Yong Hong Zhao, Mark E Zimmerman, David L Kohlstedt

Research output: Contribution to journalArticle

52 Citations (Scopus)

Abstract

Crystallographic fabrics in olivine-rich rocks provide critical information on conditions and mechanisms of deformation as well as seismic properties of Earth's upper mantle. Previous interpretations of fabrics produced in laboratory experiments were complicated by uncertainty as to whether the steady-state fabric was attained. To examine the systematics of the evolution of olivine crystallographic fabrics at high strain, we conducted torsion experiments on olivine aggregates to shear strains of up to ~20. Our results demonstrate that a steady-state fabric is not reached until a shear strain >10, a much higher value than previously thought necessary. Fabrics characterized by girdles of [010] and [001] axes or by clusters of [010] and [001] axes are both observed. Until now, these fabrics were associated with either two different deformation mechanisms or two different sets of deformation conditions. Here we establish that both fabrics are, in fact, part of the same evolutionary process. An eigenvalue analysis allows the fabric shape to be quantitatively correlated with the magnitude of shear strain. Misorientation analysis suggests that the observed fabric evolution results from the competition of the two easiest slip systems in olivine, (010)[100] and (001)[100]. Our results open up the possibility of using olivine crystallographic fabrics or seismic anisotropy to quantitatively evaluate strain histories in both field studies and geophysical investigations of upper-mantle rocks.

Original languageEnglish (US)
Pages (from-to)157-168
Number of pages12
JournalEarth and Planetary Science Letters
Volume387
DOIs
StatePublished - Feb 1 2014

Fingerprint

seismic anisotropy
olivine
Anisotropy
anisotropy
shear strain
Shear strain
upper mantle
Earth mantle
fabric
girdles
Rocks
rocks
seismic property
torsion
deformation mechanism
eigenvalue
misalignment
Torsional stress
rock
slip

Keywords

  • Crystallographic-preferred orientation
  • Electron-backscatter diffraction
  • Experimental rock deformation
  • Grain-boundary sliding
  • Torsion
  • Upper-mantle seismic anisotropy

Cite this

@article{2d6631c0d06046029273127d4b328cc7,
title = "Protracted fabric evolution in olivine: Implications for the relationship among strain, crystallographic fabric, and seismic anisotropy",
abstract = "Crystallographic fabrics in olivine-rich rocks provide critical information on conditions and mechanisms of deformation as well as seismic properties of Earth's upper mantle. Previous interpretations of fabrics produced in laboratory experiments were complicated by uncertainty as to whether the steady-state fabric was attained. To examine the systematics of the evolution of olivine crystallographic fabrics at high strain, we conducted torsion experiments on olivine aggregates to shear strains of up to ~20. Our results demonstrate that a steady-state fabric is not reached until a shear strain >10, a much higher value than previously thought necessary. Fabrics characterized by girdles of [010] and [001] axes or by clusters of [010] and [001] axes are both observed. Until now, these fabrics were associated with either two different deformation mechanisms or two different sets of deformation conditions. Here we establish that both fabrics are, in fact, part of the same evolutionary process. An eigenvalue analysis allows the fabric shape to be quantitatively correlated with the magnitude of shear strain. Misorientation analysis suggests that the observed fabric evolution results from the competition of the two easiest slip systems in olivine, (010)[100] and (001)[100]. Our results open up the possibility of using olivine crystallographic fabrics or seismic anisotropy to quantitatively evaluate strain histories in both field studies and geophysical investigations of upper-mantle rocks.",
keywords = "Crystallographic-preferred orientation, Electron-backscatter diffraction, Experimental rock deformation, Grain-boundary sliding, Torsion, Upper-mantle seismic anisotropy",
author = "Hansen, {Lars N} and Zhao, {Yong Hong} and Zimmerman, {Mark E} and Kohlstedt, {David L}",
year = "2014",
month = "2",
day = "1",
doi = "10.1016/j.epsl.2013.11.009",
language = "English (US)",
volume = "387",
pages = "157--168",
journal = "Earth and Planetary Sciences Letters",
issn = "0012-821X",
publisher = "Elsevier",

}

TY - JOUR

T1 - Protracted fabric evolution in olivine

T2 - Implications for the relationship among strain, crystallographic fabric, and seismic anisotropy

AU - Hansen, Lars N

AU - Zhao, Yong Hong

AU - Zimmerman, Mark E

AU - Kohlstedt, David L

PY - 2014/2/1

Y1 - 2014/2/1

N2 - Crystallographic fabrics in olivine-rich rocks provide critical information on conditions and mechanisms of deformation as well as seismic properties of Earth's upper mantle. Previous interpretations of fabrics produced in laboratory experiments were complicated by uncertainty as to whether the steady-state fabric was attained. To examine the systematics of the evolution of olivine crystallographic fabrics at high strain, we conducted torsion experiments on olivine aggregates to shear strains of up to ~20. Our results demonstrate that a steady-state fabric is not reached until a shear strain >10, a much higher value than previously thought necessary. Fabrics characterized by girdles of [010] and [001] axes or by clusters of [010] and [001] axes are both observed. Until now, these fabrics were associated with either two different deformation mechanisms or two different sets of deformation conditions. Here we establish that both fabrics are, in fact, part of the same evolutionary process. An eigenvalue analysis allows the fabric shape to be quantitatively correlated with the magnitude of shear strain. Misorientation analysis suggests that the observed fabric evolution results from the competition of the two easiest slip systems in olivine, (010)[100] and (001)[100]. Our results open up the possibility of using olivine crystallographic fabrics or seismic anisotropy to quantitatively evaluate strain histories in both field studies and geophysical investigations of upper-mantle rocks.

AB - Crystallographic fabrics in olivine-rich rocks provide critical information on conditions and mechanisms of deformation as well as seismic properties of Earth's upper mantle. Previous interpretations of fabrics produced in laboratory experiments were complicated by uncertainty as to whether the steady-state fabric was attained. To examine the systematics of the evolution of olivine crystallographic fabrics at high strain, we conducted torsion experiments on olivine aggregates to shear strains of up to ~20. Our results demonstrate that a steady-state fabric is not reached until a shear strain >10, a much higher value than previously thought necessary. Fabrics characterized by girdles of [010] and [001] axes or by clusters of [010] and [001] axes are both observed. Until now, these fabrics were associated with either two different deformation mechanisms or two different sets of deformation conditions. Here we establish that both fabrics are, in fact, part of the same evolutionary process. An eigenvalue analysis allows the fabric shape to be quantitatively correlated with the magnitude of shear strain. Misorientation analysis suggests that the observed fabric evolution results from the competition of the two easiest slip systems in olivine, (010)[100] and (001)[100]. Our results open up the possibility of using olivine crystallographic fabrics or seismic anisotropy to quantitatively evaluate strain histories in both field studies and geophysical investigations of upper-mantle rocks.

KW - Crystallographic-preferred orientation

KW - Electron-backscatter diffraction

KW - Experimental rock deformation

KW - Grain-boundary sliding

KW - Torsion

KW - Upper-mantle seismic anisotropy

UR - http://www.scopus.com/inward/record.url?scp=84890072371&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84890072371&partnerID=8YFLogxK

U2 - 10.1016/j.epsl.2013.11.009

DO - 10.1016/j.epsl.2013.11.009

M3 - Article

AN - SCOPUS:84890072371

VL - 387

SP - 157

EP - 168

JO - Earth and Planetary Sciences Letters

JF - Earth and Planetary Sciences Letters

SN - 0012-821X

ER -