Lateral variations of strain in experimental forced folds

    Research output: Contribution to journalArticle

    Abstract

    Packages of rock layers, deformed under confining pressure by the uplift and rotation of a steel-block forcing assembly, translate both towards, and away from, the margin of the principal uplifted block. The resulting asymmetric forced folds, and especially their long, planar limbs, exhibit along-layer variations in strain. Alternations of layer elongation and contraction occur along profiles extending away from the antiform/synform couplet. Layer-normal strains are mostly nil, so the longitudinal strains largely equate to volume strains in these plane-strain models. Spaced anomalies in outcrops, indicating either increased cementation, or erosional weakness, may suggest that similar processes operate in nature to produce variations in damage caused during the flexural-slip process. Two, non-exclusive explanations are offered to account for the patterns of strain observed in the experiments: (1) they may be caused by decaying wavetrains of small-scale flexural deflections (and their local strain patterns) related to the bending of the major forced folds; or (2) they may be caused by a 'patchy' development of layer-parallel slip, and the consequent spatial variability in displacements.

    Original languageEnglish
    Pages (from-to)79-91
    Number of pages13
    JournalTectonophysics
    Volume295
    Issue number1-2
    DOIs
    Publication statusPublished - 30 Sep 1998

    Fingerprint

    fold
    synform
    antiform
    plane strain
    confining pressure
    cementation
    deflection
    contraction
    limb
    outcrop
    uplift
    steel
    anomaly
    damage
    rock
    experiment

    Keywords

    • Bedding plane faults
    • Experimental models
    • Flexural slip
    • Strain analysis

    Cite this

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    abstract = "Packages of rock layers, deformed under confining pressure by the uplift and rotation of a steel-block forcing assembly, translate both towards, and away from, the margin of the principal uplifted block. The resulting asymmetric forced folds, and especially their long, planar limbs, exhibit along-layer variations in strain. Alternations of layer elongation and contraction occur along profiles extending away from the antiform/synform couplet. Layer-normal strains are mostly nil, so the longitudinal strains largely equate to volume strains in these plane-strain models. Spaced anomalies in outcrops, indicating either increased cementation, or erosional weakness, may suggest that similar processes operate in nature to produce variations in damage caused during the flexural-slip process. Two, non-exclusive explanations are offered to account for the patterns of strain observed in the experiments: (1) they may be caused by decaying wavetrains of small-scale flexural deflections (and their local strain patterns) related to the bending of the major forced folds; or (2) they may be caused by a 'patchy' development of layer-parallel slip, and the consequent spatial variability in displacements.",
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    Lateral variations of strain in experimental forced folds. / Couples, Gary Douglas; Lewis, Margaret Helen.

    In: Tectonophysics, Vol. 295, No. 1-2, 30.09.1998, p. 79-91.

    Research output: Contribution to journalArticle

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