Ichnofacies of the Murree Group in Jammu Area and their Ecological Implications During Late Palaeogene in the NW Himalaya

摘要

The Murree Group is a cyclic succession of alternating argillaceous and arenaceous sediments. Trace fossils recovered from this succession include Chondrites isp., Cosmorhaphe fuchsi, Dendrotichnium cf. Ilarenai, Imbrichnus cf. wattonensis, Ophiomorpha isp., Planolites isp., Skolithos isp. and Thalassinoides isp. The Ichofauna suggests that the sediments of the Murree Group were deposited in coastal environments under brackish to fresh water conditions. The sandstone with Ophiomorpha was deposited in an estuarine channel whereas sandstone containing Cosmorhaphe and small Thalassinoides was deposited on the levee-crest. Siltstones with Skolithos, Chondrites and Imbrichnus were deposited in the inter tidal zone whereas mudstones containing large Thalassinoides were deposited as mudflat/overbank sediments.