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Plastic anisotropy and fabric evolution in sheared 2 and recrystallized quartz single crystals

Muto, J. and Hirth, G. and Heilbronner, R. and Tullis, J.. (2011) Plastic anisotropy and fabric evolution in sheared 2 and recrystallized quartz single crystals. Journal of Geophysical Research JGR / B - Solid Earth , 116 (B2). B02206.

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Official URL: http://edoc.unibas.ch/47417/

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Abstract

The effect of a lattice preferred orientation on the flow strength of quartz aggregates dynamically recrystallized from single crystals of synthetic quartz was investigated using general shear experiments in a Griggs apparatus. Experiments were conducted at shear strains (γ) up to 5 at a temperature of 900°C, confining pressure of 1.5 GPa, and shear strain rate of 10−5 s−1. Three starting orientations of crystal were used, to activate three slip systems: basal 〈a〉, prism [c], and prism 〈a〉, although slip-induced rotation of the crystal axes in the first two orientations led to the activation of additional slip systems. For crystals with higher water contents, basal 〈a〉 and prism 〈a〉 orientations are relatively weak and prism [c] orientations are stronger. All three initial crystal orientations undergo dynamic recrystallization with increasing shear strain, although the strain required for 100% recrystallization varies: γ ≈ 2 for prism [c] slip, γ ≈ 3.8 for basal 〈a〉 slip, and γ ≈ 5 for prism 〈a〉 slip. For all three starting orientations, distinct domains of recrystallized grains develop with c axes parallel to Y of the strain ellipsoid (Ymax), replacing recrystallized grains of other orientations; the Ymax domains increase in size with increasing strain. In addition, strain markers show that strain is highly localized within the Ymax domains, indicating geometrical softening of up to an order of magnitude in effective viscosity.
Faculties and Departments:05 Faculty of Science > Departement Umweltwissenschaften > Ehemalige Einheiten Umweltwissenschaften > Rock deformation (Heilbronner)
UniBasel Contributors:Heilbronner, Renée
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Wiley
ISSN:0148-0227
e-ISSN:2156-2202
Note:Publication type according to Uni Basel Research Database: Journal article
Identification Number:
Last Modified:18 Jan 2018 10:55
Deposited On:18 Jan 2018 10:55

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