Cleavage and Penecontemporaneous Deformation Structures in Sedimentary Rocks
1969; University of Chicago Press; Volume: 77; Issue: 4 Linguagem: Inglês
10.1086/628367
ISSN1537-5269
AutoresPaul F. Williams, Allison Collins, R. G. Wiltshire,
Tópico(s)Geological Studies and Exploration
ResumoAn occurrence of convolute laminations is described from Devonian sediments exposed along the south coast of New South Wales, Australia. In many of the folds there is an axial plane cleavage which developed prior to consolidation of the sediment and closely resembles the cleavage commonly found in tectonites of low metamorphic grade. The style of individual folds, even to their fabric, is indistinguishable from that of many tectonic folds. From a discussion of the criteria used for distinguishing between penecontemporaneous and tectonic deformation structures, it is concluded that the folds are convolute laminations formed by load deformation of a semifluid sediment. The axial plane cleavage has probably developed by rotation of preexisting inequant grains, rather than by recrystallization of layer silicate minerals in a stress field.
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