Crenulation Cleavage Development in Pukhri Formation of Chamba Area, Western Himachal Pradesh, India

Abstract

The geometric and tectonic significance of crenulation cleavage in Pukhri Formation (mainly pelitic sequence with interbedded thin quartzitic layers) of Chamba area, is studied by taking into account modifications taking place in original class 1-3 fold layers by three theoretical models viz. i) Homogeneous flattening ii) Shearing along the axial plane of folds iii) Volume reduction in multilayers. Theoretical model studies supported by the study of cleavage microstructure and microlithons in microfolds of Class 1-3 pairs point out that volume reduction model is most appropriate in explaining the development of crenulation cleavage, its intensity and frequency in the Chamba area.