Drainage response to active tectonics and evolution of tectonic geomorphology across the Himalayan Frontal Thrust, Kumaun Himalaya

作者：Luirei, Khayingshing^*; Bhakuni, Surendra S.; Kothyari, Girish Ch

来源：Geomorphology, 2015, 239: 58-72.

DOI：10.1016/j.geomorph.2015.03.011

• Kumaun Himalaya
• Himalayan Frontal Thrust
• Palaeochannels
• Stream migration
• Escarpment

We present the results of integrated studies of geomorphic indices of drainage networks and landforms developed across the mountain front along the Himalayan Frontal Thrust (HFT) between the Dabka and Baur rivers, Kumaun Himalaya. The HFT is a morphogenic structure in nature, creating a 100-m-high E-W trending escarpment that extends similar to 21 km. Geomorphological evidence indicates similar to 10.5 km westward migration of the Dabka River and similar to 5.2 km eastward migration of the Baur River. These migrations are a result of uplift of the hanging wall along the HFF. The HFT is offset by a transverse fault, which suggests that the latter postdates the reactivation of the HFT between 500 and 100 ka, Presence of different levels of strath terraces along the mountain front suggests the active nature of the HET. To assess the relative tectonic activity, morphometric indices such as stream gradient (SL) index, mountain front sinuosity (S-mf) index, and ratio of valley floor width to valley height (Vf) have been analyzed. Results of the former two are consistent with the tectonic landforms developed in thrust zones. Paleochannels of the Dabka and Baur rivers are characterized by high Vf values while other valleys show low Vf values. Quaternary alluvial sediments have been deformed along the Pawalgarth Thrust, a splay of the HFT. Deformation has resulted in the formation of the Pawalgarh Anticline, a thrust-related asymmetric fold.

• 出版日期2015-6-15
• 单位中国地震局地震研究所