Growth and Lateral Propagation of Fault-related folds in the Shiwalik of Kumaon Himalaya: Mechanism and Geomorphic signatures

The Kumaon Himalaya is one of the most seismically dynamic regions of the Central Seismic Gap (CSG), falling into Seismic Zone V along the Himalayan arc. The 21 km long NW-SE trending Kaladungi Anticline in Kumaon Himalaya is the topographic manifestation of an actively growing fault-bend fold formed in the hanging wall of the kaladungi fault (KF). It, a splay of the Himalayan Frontal thrust system, provides an excellent model of forward and lateral propagation of fault and associated folding in laterally opposite directions along the strike of the fault. It nucleates and extends in the northwest and southeast direction resulting in the diversion of the Dabka and Baur rivers respectively, leaving behind the signature of paleo-wind gaps through which these rivers streamed earlier during the recent past. The lateral propagation of Kaladungi Anticline resulted in the diversion of the Dabka River for about 10-12 km from east to west and this is justified by the existence of four Dabka River wind gaps DWG1, DWG2, DWG3 and DWG4. Similarly, the Baur River shifted for about 5-6 km from west to east leaving signatures of two Baur wind gaps BWG1 and BWG2. The existence of more than one windgap formed by the same river, however, is a strong validation of lateral propagation of fault and related folding.