PROTEROZOIC BRAIDED EPHEMERAL FLUVIAL DEPOSITS - AN EXAMPLE FROM THE DHANDRAUL SANDSTONE FORMATION OF THE KAIMUR-GROUP, SON-VALLEY, CENTRAL INDIA

The Dhandraul Sandstone Formation of the Middle Proterozoic Kaimur Group, the Vindhyan Supergroup, Son Valley, India, has been reinterpreted to represent a product of braided ephemeral fluvial environment. The previous interpretation was shallow-marine barrier bar. Evidences in favour of braided-river deposition of the Dhandraul Sandstone are: (a) cosets of low-angle planar cross-bed sets are closely associated with cosets of parallel-laminated sets with particle streaming on bedding plane surfaces; (b) vertical recurrence of planar, laterally impersistent erosional surfaces that are invariably carpeted by red-coloured intraformational shale pebble conglomerate; (c) profuse development of ripple marks; (d) sedimentary structures indicative of critical to supercritical flow conditions; and (e) consistent palaeocurrent patterns.