Near Shore -Shallow Marine (Ophiomorpha and Margaritichnus) Trace Fossils from Fatehgarh Formation of Barmer Basin, Western Rajasthan, India

Abstract

Two trace fossils namely Ophiomorpha and Margaritichnus have been reported from the Bariyara section of the Fatehgarh Formation of Barmer Basin. Here the Margaritichnus trace fossil sp. is the first record from the western Rajasthan. The present study area is located about 6 km south of Fatehgarh town and 70 kms north of Barmer on Bramer–Jaisalmer road. The Ophiomorpha trace fossils are found in white fine grained calcareous sandstone from lower siliciclastic sequence while Margaritichnus trace fossils occurs in dark brown medium to fine grained ferruginous sandstone of middle phosphorite - siliciclastic sequence of the Fatehgarh Formation of Barmer Basin. The Ophiomorpha trace fossils were considered as crustaceans and shrimps whereas Margaritichnus were mainly produced by worm–like deposits feeders such as sipunculids and priapulids or possibly hydrozoa. The ichnological and sedimentological investigations suggests near - coastal shallow marine depositional environment for the Fatehgarh Formation of the Barmer Basin. It is difficult to attribute a more specific age of Bariyara section of Fatehgarh Formation because of the long stratigraphic range of Margaritichnus (Permian-Cretaceous) and Ophiomorpha (Permian-Recent) as attributed the Fatehgarh Formation to the Cretaceous age on the basis of microvertebrate assemblages recorded from the same Bariyara section.