Discrimination of the lower and the upper Nimar Sandstone (Upper Cretaceous Bagh Group), Madhya Pradesh, India based on lithofacies and ichnofauna

Integrated lithofacies analysis and systematic trace fossil analysis has been done of the Nimar Sandstone of the Bagh Group, Madhya Pradesh, India in three sections viz. the Bagh Cave section, the Naingaon section, and the Hathni River section. The thickness of the Nimar Sandstone varies from 10m to 30m in the studied sections. Based on the lithofacies and trace fossil characters, the Nimar Sandstone can be further subdivided into ferruginous sandstone in the lower part as the lower Nimar Sandstone (lNS) and calcareous sandstone as the upper Nimar Sandstone (uNS) in the upper part. The lNS is characterized by eight following lithofacies (i) cross-bedded gravely sandstone, (ii) planar cross-bedded sandstone, (iii) herringbone cross-bedded sandstone, (iv) ripple cross-laminated sandstone, (v) horizontal bedded sandstone, (vi) interbedded sandstone-siltstonemudstone, (vii) gravelly mudstone, (viii) bioturbated mottled mudstone having trace fossil of Arenicolites, Diplocraterion, Laevicyclus, Ophiomorpha, Skolithos, and Thalassinoides ichnogenera. The uNS includes four lithofacies (i) sandstone with the tidal bundle, (ii) small-scale cross-bedded calcareous sandstone, (iii) interbedded calcareous sandstone-siltstone-mudstone, (iv) fossiliferous calcareous sandstone characterized by ichnogenera of Arenicolites, Asterosoma, Dactylophycus, Skolithos, Taenidium, Teichichnus, Thalassinoides, and Zoophycos. Lithofacies association, different sedimentological attributes, and ichnological data indicate a complete evaluation of the river-dominated estuary to tide-dominated estuary from the base to the top during the deposition of the lower Nimar Sandstone. The upper Nimar Sandstone was deposited under subtidal inner neritic conditions where carbonate could precipitate. The whole succession of the Nimar Sandstone represents a Transgressive Systems Tract (TST) deposit of a 3(rd) sea-level cycle.