Crenulation Cleavage in Slate of the Chamba Syncline: Associated Microstructures and Origin

The microstructures associated with the crenulation cleavage in the slates of the Chamba Syncline, Western Himalaya, indicate that metamorphic differentiation following differential plastic flattening and fracturing is largely responsible for its origin. The stress gradient leads to migration of soluble minerals like quartz and calcite from limbs to hinge regions of microfolds as a result of pressure solution leaving behind micarich bands (insoluble) defining the crenulation cleavage.