Strain localization and porphyroclast rotation

Albert Griera*, Paul D Bons, Mark W Jessell, Ricardo A Lebensohn, Lynn Evans, Enrique Gomez-Rivas

*Corresponding author for this work

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

It has been debated for decades whether rigid inclusions, such as porphyroclasts and porphyroblasts, do or do not rotate in a softer matrix during deformation. Experiments and numerical simulations with viscous matrix rheologies show ongoing rotation of circular inclusions, whereas using Mohr-Coulomb plasticity results in nonrotation. Because the rocks in which inclusions are found normally undergo deformation by dislocation creep, we applied a full-field crystal plasticity approach to investigate the rotation behavior of rigid circular inclusions. We show that the inclusion's rotation strongly depends on the anisotropy of the matrix minerals. Strongly anisotropic minerals will develop shear bands that reduce the rotation of inclusions. Inhibition of rotation can only occur after a significant amount of strain. Our results may help to explain why geologic rigid objects often show evidence for rotation, but not necessarily in accordance with the viscous theory that is usually applied to these systems.

Original languageEnglish
Pages (from-to)275-278
Number of pages4
JournalGeology
Volume39
Issue number3
Early online date3 Feb 2011
DOIs
Publication statusPublished - Mar 2011

Keywords

  • simple shear-flow
  • porphyroblast rotation
  • rigid particles
  • analog experiments
  • anisotropic grain
  • deformation
  • behavior
  • inclusions
  • interface
  • patterns

Cite this

Griera, A., Bons, P. D., Jessell, M. W., Lebensohn, R. A., Evans, L., & Gomez-Rivas, E. (2011). Strain localization and porphyroclast rotation. Geology, 39(3), 275-278. https://doi.org/10.1130/G31549.1