Proterozoic Kaimur Group, Son Valley: Fluvio-Marine or Fluvio-Lacustrine?

The Kaimur Group of the Vindhyan Supergroup in Son Valley is represented by a 8 to 400 m thick siliciclastic sequence covering an area of around 12,000 sq.km. Following the reinterpretation of the Dhandraul Sandstone (the uppennost unit of the Kaimur Group) as deposits of braided ephemeral river, punctuated by aeolian deposits, the long-prevailing shallow-marine interpretation of the sub-Dhandraul sequences has been reexamined. The sub-Dhandraul sandstones and shales reveal that their deposition took place at different depths in a large lacustrine basin affected by fair-weather as well as storm waves.