Abstract
An analysis of a current kinematic model of similar folding is developed with the purpose of establishing theoretical criteria suitable for comparison with structural data obtained from naturally occurring similar folds. Equations are derived to relate the deformation parameters of the fold-model to the shape and orientation of finite ellipsoids for elemental units of homogeneous deformation within a similar fold. These equations provide a graphical strain-chart for the fold-model, and it is shown that the related deformation and geometric parameters of the elemental strain ellipsoids defining the overall inhomogeneous pattern of strain in any theoretical similar fold, will plot on the strain-chart as points on a straight-line locus. This simple diagnostic criterion of the fold-model is of practical interest where quantitative estimates of the magnitude and orientation of finite strain can be obtained from suitable dimensional markers in different parts of natural similar folds. The strain analysis is used to deduce quantitative information concerning the geometry of slaty cleavage (schistosity or foliation) in theoretical similar folds using the widely-accepted hypothesis that this type of penetrative structure is formed normal to the maximum compressive strain in naturally deformed rocks. The patterns of cleavage defined in this way by the fold-model are related to the geometry of folds derived from layers of any initial orientation to the tectonic axes. It is shown that the relative orientation of cleavage and layering at different points in the ac-tectonic plane of theoretical similar folds can be represented on the strain-chart for the fold-model, and give rise to distinctive patterns which can be regarded as diagnostic criteria for the fold-model and the associated theory of cleavage. Attention is also directed to the changing pattern of strain in response to a progressive development of deformation by the postulated mechanism of similar folding.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
