Quaternary foreland tectonics and geomorphic landscape evolution- A case study of North East Himalayan Piedmont zone, India

Abstract

The Main Boundary Thrust (MBT) and Main Frontal Thrust (MFT) along the east–west direction have been reanalysed under the frame of the Jiti–Khuji Diana interfluve of the Himalayan foreland basin. This area is sharply dissected by three main streams under the Jaldhaka system, i.e. river Jiti, Khuji Diana, and Thaljhora, amongst which the Thalhjora flows from east to west and the other two rivers flow roughly from NNE (north-north-east) to SSW (south-south-west). The present research focuses on the control of active Thaljora and Chalsa fault scarps, which predominantly represent the monocline fault on the landscape deformation. This fault was propagated by the folding of two opposite limb directions, forming a synform that uplifted over time and formed river terraces by incision process. The linear and basin morphometric indices confirm the neotectonic activeness in addition to the deformed landform, which emerges as terrace and Doon-shaped valley in between Jiti fault (JF) and Thaljhora fault (TS). In the studied area, Thaljhora Fault Scarp is noted as Main Boundary Thrust (MBT) and Main Frontal Thrust has been noted near Chalsa (Kar et al. 2014). This study has deciphered the application of morphometric indices to indicate active tectonics with well-exposed landforms. The two tire river terraces and the reframed alluvial fans were caused by uplift and erosion sequences that were assembled by slope differentiation and flow/velocity alteration. The alluvial fan in a fan formation stretched southward and featured three well defined geomorphic units: lobes, mid-fan, and apex. These fans are categorised as mega fans and range in size from meso to micro.To ensure that the morphological units of the study's results are clearly understood, the results are summarised in a single graphical image. Artificially induced water flow with variable discharge (Q) has been tested in the field to establish a notion of an enlarged coverage area during the monsoon and flood season