Viscous anisotropy of textured olivine aggregates: 2. Micromechanical model

Author(s)Hansen, Lars N.
Author(s)Conrad, Clinton P.
Author(s)Boneh, Yuval
Author(s)Skemer, Philip
Author(s)Warren, Jessica M.
Author(s)Kohlstedt, David L.
Ordered AuthorLars N. Hansen, Clinton P. Conrad, Yuval Boneh, Philip Skemer, Jessica M. Warren, and David L. Kohlstedt
UD AuthorWarren, Jessica M.en_US
Date Accessioned2017-05-08T15:43:23Z
Date Available2017-05-08T15:43:23Z
Copyright DateCopyright © 2016. The Authors.en_US
Publication Date2016-10-25
DescriptionPublisher's PDFen_US
AbstractThe significant viscous anisotropy that results from crystallographic alignment (texture) of olivine grains in deformed upper mantle rocks strongly influences a large variety of geodynamic processes. Our ability to explore the effects of anisotropic viscosity in simulations of these processes requires a mechanical model that can predict the magnitude of anisotropy and its evolution. Unfortunately, existing models of olivine textural evolution and viscous anisotropy are calibrated for relatively small deformations and simple strain paths, making them less general than desired for many large-scale geodynamic scenarios. Here we develop a new set of micromechanical models to describe the mechanical behavior and textural evolution of olivine through a large range of strains and complex strain histories. For the mechanical behavior, we explore two extreme scenarios, one in which each grain experiences the same stress tensor (Sachs model) and one in which each grain undergoes a strain rate as close as possible to the macroscopic strain rate (pseudo-Taylor model). For the textural evolution, we develop a new model in which the director method is used to control the rate of grain rotation and the available slip systems in olivine are used to control the axis of rotation. Only recently has enough laboratory data on the deformation of olivine become available to calibrate these models. We use these new data to conduct inversions for the best parameters to characterize both the mechanical and textural evolution models. These inversions demonstrate that the calibrated pseudo-Taylor model best reproduces the mechanical observations. Additionally, the pseudo-Taylor textural evolution model can reasonably reproduce the observed texture strength, shape, and orientation after large and complex deformations. A quantitative comparison between our calibrated models and previously published models reveals that our new models excel in predicting the magnitude of viscous anisotropy and the details of the textural evolution. In addition, we demonstrate that the mechanical and textural evolution models can be coupled and used to reproduce mechanical evolution during large-strain torsion tests. This set of models therefore provides a new geodynamic tool for incorporating viscous anisotropy into large-scale numerical simulations.en_US
DepartmentUniversity of Delaware. Department of Geological Sciences.en_US
CitationHansen, L. N., C. P. Conrad, Y. Boneh, P. Skemer, J. M. Warren, and D. L. Kohlstedt (2016), Viscous anisotropy of textured olivine aggregates: 2. Micromechanical model, J. Geophys. Res. Solid Earth, 121, 7137–7160, doi:10.1002/2016JB013240.en_US
DOIdoi:10.1002/2016JB013240en_US
ISSN2169-9356en_US
URLhttp://udspace.udel.edu/handle/19716/21304
Languageen_USen_US
PublisherAGU Publicationsen_US
dc.rightsCC-BYen_US
dc.sourceJournal of Geophysical Research: Solid Earthen_US
dc.source.urihttp://agupubs.onlinelibrary.wiley.com/hub/jgr/journal/10.1002/(ISSN)2169-9356/en_US
TitleViscous anisotropy of textured olivine aggregates: 2. Micromechanical modelen_US
TypeArticleen_US
Files
Original bundle
Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
04252017 Warren_1493233836T9822.pdf
Size:
3.53 MB
Format:
Adobe Portable Document Format
Description:
License bundle
Now showing 1 - 1 of 1
No Thumbnail Available
Name:
license.txt
Size:
2.22 KB
Format:
Item-specific license agreed upon to submission
Description: