Wang Haiyang, Peng Yongbo, Li Chao, Cao Xiaobin, Cheng Meng, Bao Huiming
International Center for Isotope Effects Research, Nanjing University, Nanjing, China.
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation & Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu, China.
Nat Commun. 2023 Jul 18;14(1):4315. doi: 10.1038/s41467-023-39962-9.
The largest negative inorganic carbon isotope excursion in Earth's history, namely the Ediacaran Shuram Excursion (SE), closely followed by early animal radiation, has been widely interpreted as a consequence of oceanic oxidation. However, the primary nature of the signature, source of oxidants, and tempo of the event remain contested. Here, we show that carbonate-associated sulfate (CAS) from three different paleocontinents all have conspicuous negative O anomalies (Δ'O values down to -0.53‰) during the SE. Furthermore, the Δ'O varies in correlation with its corresponding δS and δO as well as the carbonate δC, decreasing initially followed by a recovery over the ~7-Myr SE duration. In a box-model examination, we argue for a period of sustained water-column ventilation and consequently enhanced sulfur oxidation in the SE ocean. Our findings reveal a direct involvement of mass-anomalously O-depleted atmospheric O in marine sulfate formation and thus a primary global oceanic oxygenation event during the SE.
地球历史上最大的负无机碳同位素偏移，即埃迪卡拉纪舒拉姆偏移（SE），紧随早期动物辐射之后，被广泛解释为海洋氧化的结果。然而，该特征的主要性质、氧化剂来源以及事件的节奏仍存在争议。在此，我们表明来自三个不同古大陆的碳酸盐相关硫酸盐（CAS）在SE期间均具有明显的负氧异常（Δ'O值低至-0.53‰）。此外，Δ'O与其相应的δS和δO以及碳酸盐δC相关变化，在约700万年的SE持续时间内先下降后恢复。在箱式模型检验中，我们认为在SE海洋中存在一段持续的水柱通风期，从而增强了硫的氧化。我们的研究结果揭示了质量异常贫氧的大气氧直接参与了海洋硫酸盐的形成，因此在SE期间发生了一次主要的全球海洋氧化事件。
