A sequence of predominantly arenaceous and calcareous sediments was deposited in Bikaner-Nagaur Basin in the west of the Aravalli Range that has been formally named as Marwar Supergroup. This sequence was earlier regarded as equivalent of the Upper Vindhyan Group and was named as the Trans-Aravalli Vindhyans.
It has been divided into three groups : Jodhpur Group, Bilara Group and Nagaur group.
The whole Marwar Supergroup unconformably rests over the Malani Group of middle Neo-proterozoic age and is unconformably overlain by bap boulder bed of permo-carboniferous.
The jodhpur group is an arenaceous succession that is overlain by carbonate sequence comprised of dolomites and limestones and named as Bilara Group. The carbonate facies comprising the bilara group shows characters of shallow marine and deltaic conditions of deposition. The uppermost unit, Nagaur Group consists of sediments laid down in fluctuating environments of shallow marine and fluvial basins.
- The Jodhpur Group shows microbial mats compared to Aspidella sp. and also yielded Ediacaran suggesting the Ediacaran age.
- It has been suggested that the Precambrian-Cambrian boundary lies within the overlying Bilara Group.
- The Nagaur sandstone of the Nagaur Group has well-preserved trace fossils of trilobites, such as Rusophycus, Curziana, Dimorphichnus suggesting an early Cambrian age for the formation.
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