Ice deformed in compression and simple shear: control of temperature and initial fabric

Christopher Wilson, Mark Peternell

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    16 Citations (Scopus)

    Abstract

    Layered and polycrystalline ice was experimentally deformed in general shear involving axial compression (strain magnitude 0.5-17 ) and simple shear (strain magnitude gamma=0.1-1.4). As the temperature is increased from -20 degrees C to -2 degrees C, there is at least a twofold enhancement in octahedral shear strain rate, which coincides with the onset of extensive dynamic recrystallization and a change in grain-size distribution at -15 degrees C. Between -15 degrees C and -10 degrees C the c-axis preferred orientation rapidly evolves with the initiation of two-maxima fabrics in shear zones. From -10 degrees C to -2 degrees C there is progressive evolution of a final c-axis pattern that is asymmetric with respect to the direction of shortening, with a strong maximum at similar to 5 degrees to the pole of the shear zone, a sense of asymmetry in the direction of the shear, and a secondary maximum inclined at similar to 45 degrees to the plane of shearing. An initial c-axis preferred orientation plays a critical role in the initial mechanical evolution. In contrast to established ideas, a strong alignment of basal planes parallel to the plane of easy glide inhibited deformation and there was an increased component of strain hardening until recrystallization processes become dominant.
    Original languageEnglish
    Pages (from-to)11 - 22
    Number of pages12
    JournalJournal of Glaciology
    Volume58
    Issue number207
    DOIs
    Publication statusPublished - 2012

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