Microstructures of co-axially folded vein segments and crenulation cleavage: Evidence for dissolution phenomena in the Chamba Thrust Sheet, western Himalayas

Abstract

The metasediments in the Chamba region experienced three phases of deformation: DF1, DF2 and DF3. Folded quartz veins are co-folded with the F2 crenulation folds. Their geometric and tectonic significance is studied by microstructures and shortening adjacent to the discrete crenulation cleavage, S2. Microstructures of folded vein segments, their geometric changes and truncation to cleavage (S2) are mainly due to pressure-solution phenomena and the estimated volume loss from reconstructed vein segments range from 16 to 25.5%, which is closely related to volume decrease (26%) calculated from the polydeformed slates of North Wales areas.