Present study of vanadium mineralization in the Sonia sandstone of Jodhpur Group shows first hydrothermal activity in the Sonia sandstone of Marwar Supergroup. The Sonia sandstone served as a host for the mineralizing solutions. The vanadium mineralization occurred in sandstone- gritty sandstone-conglomerate along faults. Field relationship and petrological study suggests that mineralization is filled by epithermal solutions and provide a better understanding of the timing and nature of the alteration processes. Though the source of the vanadium is not well constrained, but is possibly from the partial melting of banded gneissic complex-II (Sirohi Group), the source (crustal) melt had assimilated material from the rocks of Sirohi Group in significant amount. Deposition of tuffs at top of Sonia Formation (Chhoti Khatu) and emplacement of last stage Malani dykes suggest that the last phase of Malani magmatism generated heat for the partial melting of banded gneissic complex-II (Sirohi Group). The occurrence of vanadium in sandstone–gritty sandstone–conglomerate from Sonia Formation of Marwar Supergroup has opened a new chapter to explore uranium which generally occurs after vanadium mineralization in conglomeratic sedimentation.

The present study reports and discusses discoidal Ediacaran body fossils identified as Hiemalora stellaris from the Sonia Sandstone of Jodhpur Group, Marwar Supergroup, Western Rajasthan, India. These are preserved as positive relief on the yellowish-brown to pinkish-brown medium to fine-grained sandstone bedding surfaces in Sursagar area. Morphologically, these are circular to sub-circular, mostly flat-discoidal forms or discs surrounded by numerous radiating arms or appendages resembling tentacles. Hiemalora is reinterpreted and reconstructed as discoidal hold fast of benthic organism but not found the attached fronds or stem-like structures of the hold fasts in the present materials. The systematic palaeontology, palaeobiology, palaeoenvironment and age of the Hiemalora bearing Ediacaran Sonia Sandstone have been also discussed.

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