Evidences of neotectonic activity along Goriganga River, Higher Central Kumaun Himalaya, India

This paper focuses on the analysis of geomorphic landform development, particularly between the Trans Himadri Fault and the Main Central Thrust including Berinag Thrust and other major NNE–SSW and NW–SE striking faults/thrusts in the Higher Central Kumaun Himalaya. Digital analysis of remote sensing data, field investigations including drainage analysis, and development of landforms have been carried out to understand the morphotectonic evolution and, thereby, the neotectonics in this region. A number of morphometric indices [(stream length‐gradient index (SL), steepness index ( k s ), Chi ( χ )] were computed together with knick point analysis. Offsetting of the major river and tributaries was observed along a NNW–SSE direction. Other tectonic landforms, including truncated saddles and disturbed terrace patterns, show that the area is presently undergoing active deformation. The valley floor morphology in the vicinity of the major thrusts provides evidence for aggradation of recent fluvial activity. Developments of various neotectonic features, such as starth terraces, off‐streams, truncated saddles, disrupted terraces, and palaeolake deposits, are evidences for recent tectonic activities associated with the major thrusts/faults. Cut‐and‐fill terraces with thick alluvial cover, debris‐flow terraces, and alluvial fan terraces are significant aggradational landforms observed within the valley that provide signatures of past climatic records. Our study reveals that the fluvially modified debris‐flow terraces were formed between 5 and 20 ka. We infer that the major phase of valley‐fill happened between 5 and 12 ka, whereas the youngest phase of aggradation may have responded to the Holocene tectonic activity that took place around 5–6 ka. The study is significant to understand the recent geomorphic development and tectonic deformation in the study area and may be helpful for future infrastructural development in the region.

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