Geomorphic positioning and depositional dynamics of river systems in Lower Siwalik basin,Kumaun Himalaya

Qualitative and quantitative analysis of river systems in the Lower Siwalik sequence has enabled characterization of channel patterns, river metamorphosis and resulting sandstone body evolution in time and space. Processes related six lithofacies repeat to generate 8–10 m thick multistoried sandstone complexes deposited in perennial channel belts. Based on lateral mapping of the sandstone bodies, the surfaces of genetic significance ranging from 3^rd, 4^th and 5^th order, suggest presence of meandering, braided and anastomosing river patterns that were responsible for the Lower Siwalik sedimentation. Variation in local base-level in response to allogenic factors including climate and tectonics forced river systems to acquire different patterns. Eustasy seems to control large-scale basin level changes. Quantitatively reconstructed morphological parameters and their comparison with modern and ancient analogues, supported by other independent evidences such as stratigraphical position of sandstone bodies in vertically measured columns and mineralogical characteristics of channel sandstones, enabled to decipher the geomorphic positioning of the Lower Siwalik channels in distal parts of megafan and interfluve areas within the foreland basin setting.