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 delta C-13-carb and delta O-18-carb in the Bilara Group vary from -9.0 to 4.1 parts per thousand and from -10.7 to 8.3 parts per thousand respectively. Overall, 457 analyzed samples have delta O-18-carb significantly above -10 parts per thousand, 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 delta C-13-carb pattem is closely similar to that of the Yangtze Gorges platform, South China, where the Ediacaran delta C-13-carb variation profile revealed four negatives (EN1, EN2, EN3, EN4) and three positive excursions (EP1, EP2, EP3). Similarities of delta C-13-carb pattern demonstrate that carbonate succession of the Bilara Group is likely time equivalent to Yangtze Gorges succession.