Campus Units

Geological and Atmospheric Sciences

Document Type

Article

Publication Version

Published Version

Publication Date

5-2015

Journal or Book Title

Journal of Geophysical Research: Solid Earth

Volume

120

Issue

5

First Page

3649

Last Page

3663

DOI

10.1002/2015JB011890

Abstract

We investigate how localization and delocalization of deformation occurs in a bimineralic material composed of a strong plagioclase and a weaker quartz phase. We perform numerical, meter-scale shear experiments in which we vary the temperature and the ratio of the two mineral phases. Three micromechanical deformation fields are identified according to the mechanical behavior of the minerals at play (brittle or ductile when both phases are in the brittle or ductile regime, respectively, and semibrittle when one phase is in the brittle and the other in the ductile regime). Besides these micromechanical deformation fields, we identify three deformation types characterizing the degree of localization (type I: localized shear zone, type II: localized anastomosing shear zone, and type III: delocalized shear zone). Type I is expected in the brittle deformation field. In the semibrittle field, all deformation types can be observed depending on the amount of weak phase present. In the ductile field, deformation is dependent on the strength ratio between the two phases. For a low strength ratio, deformation of type III is always observed. For high-strength ratios, deformation of type II can be observed for a moderate amount of weak phase. A small amount of weak phase (<10%) reverses the mechanical behavior of the strong phase and leads to the formation of a narrow anastomosing shear zone (type II) where fully ductile (type III) behavior is expected. This highlights the importance of a bimineralic material for the deformation localization and overall large-scale deformation processes.

Comments

This article is published as Jammes, Suzon, Luc L. Lavier, and Jacqueline E. Reber. "Localization and delocalization of deformation in a bimineralic material." Journal of Geophysical Research: Solid Earth 120, no. 5 (2015): 3649-3663. DOI:10.1002/2015JB011890. Posted with permission.

Copyright Owner

American Geophysical Union

Language

en

File Format

application/pdf

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