Proterozoic braided ephemeral fluvial deposits: an example from the Dhandraul Sandstone Formation of the Kaimur Group, Son Valley, central India

Abstract

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.