DELINEATION OF CONCEALED TRANSVERSE BASEMENT FAULTS IN THE GANGA PLAIN AND THE ADJACENT HIMALAYAS THROUGH GEOMORPHOLOGICAL APPROACHES

Abstract

Prior to the docking of the Indian and Eurasian plates, many crustal-scale faults of Precambrian age dissected the Indian peninsular crust, including the Mahendragarh- Dehradun fault (MDF), Moradabad fault (MF), Great Boundary Fault (GBF), and others. These inherited faults played a significant role in configuring the Himalayan orogen during the Himalayan orogeny and have undergone multiple phases of tectonic reactivation, recorded in the stratigraphic successions of the Neoproterozoic Purana basin and later deposits. Till now, the Himalayan system including foreland basin is commonly perceived as laterally continuous; its main geological subdivisions have been viewed as uninterrupted along its entire length despite significant along-strike variations in topography, relief, depositional pattern, seismicity, and geomorphology. Continuous sediment deposition since the formation of the Indo-Gangetic Foreland basin (IGFB) has concealed these inherited faults and ridges, raising questions about their existence, prolongation, reactivation, and influence on seismicity. The scarcity of literature in this domain further underscores the importance of this study. The primary objectives of this research are to find tectono-geomorphic signatures in the fault’s vicinity, understand the influence of basement faults on river channels and quaternary alluvial deposits in the Ganga basin, and elucidate their extension up to the Himalayas. Quaternary deposits of the Ganga plain show field evidence of basement faults' reactivation, indicated by changes in fluvial geomorphology and deformation of young sediments through aseismic or seismic deformation. The ongoing differential compression along the Himalayan arc causes the transverse tearing of Sub-Himalayan rocks and thrust sheets, suggesting that these faults control thrust propagation at the frontal Himalayas.