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The present study records the triangular-shaped Ediacaran fossil identified as Thectardis avalonensis from the Sonia Sandstone of Jodhpur Group, Marwar Supergroup, western India. These Ediacaran fossil specimens are preserved in convex (positive) relief, but one is in negative relief on the bedding planes of sandstone in the Sursagar mines area. T. avalonensis is well-preserved, unskeletonized, elongated and triangular in shape, with sharp, raised marginal rims or ridges that widen at the triangular base and taper towards the apex of the organism. This Ediacaran triangular-shaped T. avalonensis organism is recorded for the first time from India. The phylogenetic affinity of T. avalonensis is still uncertain, as some have interpreted it as a sponge based on a body plan consistent with the hydrodynamics of the sponge water-canal system, which lacked a mouth or movement and its length-width ratio of more than 1.6. As well as these, T. avalonensis may also belong to Diskagma-like lichen or living Cladonia-like lichen group and the Auroralumina-like cnidarian organisms of the Ediacaran crown group. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this study, we report well-preserved fossil remains of Nimbia from the Ediacaran Sonia Sandstone of Jodhpur Group, Marwar Supergroup in the Sursagar area of Jodhpur district, Rajasthan, western India. Here, two species of Nimbia, namely Nimbia occlusa and Nimbia dniesteri, have been recorded on medium- to fine-grained sandstone bedding surfaces. The N. occlusa forms are circular to ovate and elliptical imprints with a smooth and flat central part and enclosed by a single thick, annular marginal rim, whereas the N. dniesteri remains are circular to sub-circular discoid impressions with a trapezoidal structure. Here, the recorded N. occlusa is common compared to the N. dniesteri fossil forms in the Ediacaran Sonia Sandstone. These Nimbia fossil forms are found in the Sonia Sandstone in terrestrial to marginal marine habitats with moderate hydrodynamic forces. [ABSTRACT FROM AUTHOR]