Shallow Marine Siliciclastic Sedimentation in the Middle Proterozoic Gandikota Formation, Cuddapah Basin, Andhra Pradesh

The Gandikota Formation consists of 40 - 45 m thick shale - siltstone - quartzite (lower member) and 140 - 190 m thick quartzite and siltstone (upper member). Vertical profile of the lower member represents a coarsening up sequence of prograding shoreline setting. As many as eight qualtzite sheets of 15 to 25 m thickness each, constitue the upper member. The herringbone, tabular and trough cross stratified quartzite, and ripple bedded quartzite and siltstone constitute major sedimentary lithofacies in the upper member quartzite sheets. Palaeocurrent mean was towards NW and NNE. A shallow marine environment with poorly contined tidal channels is envisioned for the deposition of the upper member quartzite sheets.