Ichnofossils from the Miocene Middle Bhuban Formation, Mizoram,Northeast India and their Paleoenvironmental Significance

An ichnofossil assemblage is preserved in sediments of the Middle Bhuban Formation, Surma Group, of Miocene age from the Durtlang and Chanmari sections, Aizawl district, Mizoram, northeastern India. The studied sections comprise a thick, bioturbated and thinly bedded sandstone–silty shale facies. The preserved ichnofossils show high density and low diversity with the assemblage represented by feeding and resting traces, i.e., Psilonichnus upsilon Frey et al., 1984, Ophiomorpha isp., Teichichnus spiralis Mikulá?. 1990, Skolithos isp., Palaeophycus isp., and other horizontal burrows. Sedimentary structures associated with these traces are mainly cross bedding, flaser bedding and slump structures. Considering the distribution of the Psilonichnus ichnogenus across an integrated ichnological‐sedimentological framework, the stratigraphic interval of the Middle Bhuban Formation, in which they occur, are interpreted to have been deposited under a shallow, marginal‐marine channel complex dominated by tidal channels developed in quiet, brackish‐water portions of a delta plain.