A phenomenon of unusual flattening in folds associated with a Himalayan thrust

Abstract

The paper reports a phenomenon of flattening in mesoscopic folds around a major geotectonic element of the Himalaya, called the Main Central Thrust (MCT). The study demonstrates that the amount of flattening of folds gradually increases towards the MCT. The MCT zone itself shows the strongest flattening of associated folds. A direct control of the MCT is established over the fold shape in a zone of 5 to 6 km across. This phenomenon appears significant for the Himalayan terrain. It is held to represent a well-defined zone of ductile deformation around a 'ductile thrust'.