The evolution of the atmospheric oxygen content through Earth's history is a key issue in paleoclimatic and pa-leoenvironmental research. There were at least two oxygenation events in the Precambrian that involved fundamental changes in both biotic innovation and the surface environment. However, a large dissolved organic carbon (DOC) pool maintained in deep oceans during the Neoproterozoic may have extended the time interval between the two oxygenation events. To test the DOC hypothesis, we conducted detailed micro-drilled analyses of carbonate carbon isotopes (δ13Ccarb) of a long Ediacaran drill core (the Wangji drill core), for which whole-rock δ13Ccarb and organic carbon isotope (δ13Corg) records were available. The micro-drilled δ13Ccarb values obtained in this study are consistent with whole-rock δ13Ccarb res-ults, precluding the influence of severe authigenic carbonate incorporation. Importantly, the multiple negative δ13Ccarb ex-cursions in the Wangji drill core were likely linked with upwelling events, during which DOC was supplied to the surface water and oxidized. Using box models, we estimate that ～3.6 × 1019 mol and ～2.0 × 1019 mol DOC were converted to bicar-bonate during two negative δ13Ccarb excursions spanning millions of years. The estimations are approximately 1000 times the modern marine DOC reservoir. Our results support a relatively high oxidation capacity (elevated atmospheric pO2 and/or oceanic [SO24?]) of the Earth's surface during the early Ediacaran Period.

Yunpei Gao;Yizhe Gong;Xiaoyan Chen

School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,China

中国科学技术大学学报

[1]Yunpei Gao;Yizhe Gong;Xiaoyan Chen-.Constraining the Ediacaran oceanic dissolved organic carbon reservoir: Insights from carbon isotopic records from a drill core from South China)[J].中国科学技术大学学报,2022(02):42-53

leoenvironmental,Wangji,cursions,bicar

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