Shallow Marine Trace Fossils from Mandai Formation of the Barmer Basin, District -Jaisalmer, Western Rajasthan, India

Abstract

Thirteen well-preserved trace fossil species namely Thalassinoides horizontalis, Thalassinoides suevicus, Ophiomorpha nodosa, Ophiomorpha borneensis, Palaeophycus heberti, Palaeophycus tubularis, Planolites, Planolites montanus, Planolites beverleyensis, Planolites annularis, Siphonites, Paleomendron, and Phycodes palmatum have been reported from Mandai Formation of the Barmer Basin at Mandai area, western Rajasthan, India. The present study area is located about 15 km southwest of Fatehgarh town on Fatehgarh –Jhinjinyali tar Road. The Mandai Formation is 27 m thick lithostratigraphic unit deposited in the north-western part of the Barmer Basin and overlies on Early Palaeocene Bariyara -Dharvi -Sajit Member of the Akli Formation and overlain by Giral -Thumbli Member of Akli Formation of Early Eocene. The Mandai Formation has mixed siliciclastic, minor carbonate and phosphorite facies and its starts with bioturbated medium to fine grained ferruginous sandstone at the base. These trace fossils are preserved of full relief in yellowish to dark brown medium to fine grained ferruginous sandstone and greyish yellow coarse and coarse to medium grained calcareous sandstone. The entire ichnogenera shows shallow marine depositional environment of Mandai Formation of Barmer Basin. No age can be assigned on the basis of these trace fossil as they have long range (Cambrian to Recent).