Paleohydrology of Permian Gondwana Streams in Bokaro Basin, Bihar

The clastic assemblage of Lower Permian Karharbari (70 m thick) and Barakar (800 m thick) Formations of the East Bokaro Basin shows a progressive upward decrease in grain size and scale of cross-bedding, illustrating a fining upward mega-cycle. A paleo-flow analysis reveals that the Gondwana sediments were deposited by streams which flowed towards north-northwest. The azimuthal variability is 2240 for Karharbari, 3304 for Lower Barakar and 4429 for Upper Barakar. Empirical relationships from modern streams are used to estimate various channel morphological and hydraulic attributes of ancient Karharbari and Barakar streams. Results indicate a progressive decrease in channel width and depth, channel slope. flow velocity and Froude number, with consequent increase in sediment load parameter, channel sinuosity for the Gondwana streams. as sedimentation continued from Karharbari through Lower to Upper Barakar. It is suggested that amelioration of climate through time possibly had a great control on river metamorphosis and sedimentation than tectonism.