Facies-trace fossil relationships in a plio-pleistocene fluvial sequence-the upper Siwalik subgroup, punjab sub-Himalaya, India

Abstract

Documentation of the ichnofauna of a Plio-Pleistocene fluvial sedimentary sequence has been made from the "molasse" belt of the Himalayan Orogenic System. Ten types of ichnogenera have been recognised in addition to rhizoliths and tracks. Similarities to materials described previously from fluvial sequences are indicated. The relationships of the ichnofauna with the various lithofacies of the fluvial depositional system are established. This has resulted in the recognition of five ichnofacies and six bioturbate textures. Facies specificity of the ichnofossils is demonstrated in the case of overbank, levee and palaeosol deposits. A synthesis of the information on fluvial trace fossils has been attempted by summarizing the data on their toponomy, orientation and fill. A high incidence of vertical endichnial forms with meniscate fill is recognised in the channel facies, and a similar situation exists in the levee facies but for the structureless character of the fill. Hypichnial and epichnial horizontal traces are seen to dominate in the overbank facies.