Carbon and oxygen isotope stratigraphy of the Ediacaran Bilara Group, Marwar Supergroup, India: Evidence for high amplitude carbon isotopic negative excursions

Results of a robust high-resolution carbon and oxygen stable isotope studies conducted on the Ediacaran Bilara carbonate sequence of the Marwar Supergroup, Rajasthan, India are presented. The δ13C-carb and δ18O-carb in the Bilara Group vary from −9.0 to 4.1‰ and from −10.7 to 8.3‰ respectively. Overall, 457 analyzed samples have δ18O-carb significantly above −10‰, below which carbonates are considered diagenetically altered. The results are compared with well-dated established high amplitude negative carbon isotope excursions sites in other parts of the world recorded from the Ediacaran successions. The Bilara δ13C-carb pattern is closely similar to that of the Yangtze Gorges platform, South China, where the Ediacaran δ13C-carb variation profile revealed four negatives (EN1, EN2, EN3, EN4) and three positive excursions (EP1, EP2, EP3). Similarities of δ13C-carb pattern demonstrate that carbonate succession of the Bilara Group is likely time equivalent to Yangtze Gorges succession.