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Research Advances and Correlations of Carbon Isotopic Compositions in the Ediacaran Doushantuo Formation, East Yangtze Gorges, South China
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///Carbonates of the Doushantuo Formation in the East Yangtze Gorges have recorded three remarkable negative and two positive carbon isotope anomalies: 1) a negative δ13C excursion (EN1);  whose values vary from -0.9‰ to -41.166‰ in the Doushantuo cap carbonate (MemberⅠ);  is characterized by tepee-like structures, stromatacties -like cavities, sheet cracks, cemented breccias and tube structures and can be correlated with the other carbon isotope excursion which appears in the Marinoan cap carbonates in the whole world; 2) a positive δ13C excursion (EP1) in the lower-middle part of MemberⅡof the Doushantuo Formation, whose values range from 0 to +6‰, includes the acritarchs assemblage characterized by Tianzhushania, multicellular algal and macroscopic alga; 3) a negative δ13C excursion (EN2) in the uppermost part of MemberⅡof the Doushantuo Formation, whose values range from 0 to -2.1‰, where Tianzhushania went into extinction; 4) a positiveδ13C excursion (EP2) occurs in lower Member Ⅲ, which includes a ...更多different acritarchs assemblage characterized by the occurrence of some new taxa, e.g., Ceratosphaeridium and Tanarium. The Ediacaran acritarchs went into extinction at the end of EP2; 5) a negative δ13C excursion (EN3) occurs from the uppermost part of Member Ⅲ to MemberⅣ with a nadir of -8.7‰, which is considered to be the largest carbon isotope trend in the geological record and can be correlated with the negative δ13C excursion in Australia, Oman, Namibia, California, Siberian and Scotland. The Ediacaran body fossils appear in this gradation and, in addition, the macroscopic algae become abundant and diverse. Both the EN2 and EN3 are related to the oxidation events, which probably cause the eukaryote diversity in the Ediacaran oceans, so that they may serve as useful symbols for the correlation of the Ediacaran system worldwide.  

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