Introduction of continental ichnofacies from Neogene alluvial deposits of Birjand city

In recent years, continental ichnology has gained great importance in the stratigraphy, basin analysis and paleogeography studies and widely used in understanding environmental parameters and paleoecological conditions. The study area in the Birjand city is a part of the sedimentary-structural zone of eastern Iran and includes alluvial sedimentary deposits with Neogene age. Based on the previous studies, the above-mentioned alluvial deposits include conglomerate, sandstone and mudstone lithofacies which were deposited in the fluvial system based on their textural features and sedimentary structures. Lithofacies, facies associations and the abundance of sediment gravity flow and channel-fill deposits, in the studied alluvial deposits indicate the existence of a braided fluvial system close to the source during the Neogene time. Field observations of the sand and mud deposits of the studied alluvial terraces indicate the presence of continental trace fossils in these sediments. Based on the observed burrows of these sediments, two Coprinisphaera and Skolithos ichnofacies and six distinct ichnogenus can be distinguished in these continental deposits, which confirm the deposition of these sediments in the adjacent parts of active channel and floodplain of fluvial system.