Records of the Ediacaran carbon cycle (635–541 million years ago) include the Shuram excursion (SE), the largest negative carbonate carbon isotope excursion in Earth history (down to −12‰). The nature of this excursion remains enigmatic given the difficulties of interpreting a perceived extreme global decrease in the δ¹³C of seawater dissolved inorganic carbon. Here, we present carbonate and organic carbon isotope (δ¹³C_carb and δ¹³C_org) records from the Ediacaran Doushantuo Formation along a proximal‐to‐distal transect across the Yangtze Platform of South China as a test of the spatial variation of the SE. Contrary to expectations, our results show that the magnitude and morphology of this excursion and its relationship with coexisting δ¹³C_org are highly heterogeneous across the platform. Integrated geochemical, mineralogical, petrographic, and stratigraphic evidence indicates that the SE is a primary marine signature. Data compilations demonstrate that the SE was also accompanied globally by parallel negative shifts of δ³⁴S of carbonate‐associated sulfate (CAS) and increased ⁸⁷Sr/⁸⁶Sr ratio and coastal CAS concentration, suggesting elevated continental weathering and coastal marine sulfate concentration during the SE. In light of these observations, we propose a heterogeneous oxidation model to explain the high spatial heterogeneity of the SE and coexisting δ¹³C_org records of the Doushantuo, with likely relevance to the SE in other regions. In this model, we infer continued marine redox stratification through the SE but with increased availability of oxidants (e.g., O₂ and sulfate) limited to marginal near‐surface marine environments. Oxidation of limited spatiotemporal extent provides a mechanism to drive heterogeneous oxidation of subsurface reduced carbon mostly in shelf areas. Regardless of the mechanism driving the SE, future models must consider the evidence for spatial heterogeneity in δ¹³C presented in this study.

中文翻译：

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揭示了Ediacaran碳循环的空间异质性。

Ediacaran碳循环的记录（635-5.41亿年前）包括Shuram偏移（SE），这是地球历史上最大的负碳酸盐碳同位素偏移（低至-12‰）。给定在δ解释感知极端全球减少的困难这个偏移的性质仍然是不清楚的¹³海水溶解的无机碳的C 在这里，我们本碳酸盐和有机碳同位素（δ ¹³ C ^_{碳水化合物}和δ ¹³ C ^_有机）记录了华南扬子地台沿近端到远端样带的Ediacaran Doushantuo组的记录，以作为SE的空间变化的检验。与预期相反，我们的结果表明，这种摆动的幅度和形态及其与共存δ关系¹³ Ç_组织是高度跨平台异构。综合的地球化学，矿物学，岩石学和地层学证据表明SE是主要的海洋特征。数据汇编证明SE也被δ的平行移位负全局伴随³⁴碳酸盐相关硫酸（CAS）的S和增加⁸⁷ SR / ⁸⁶Sr比率和沿海CAS浓度，表明SE期间大陆风化和沿海海洋硫酸盐浓度升高。在这些意见的光，我们提出了一个异质氧化模型来解释SE的高空间异质性并存δ ¹³ C ^，_有机陡山沱组的记录，可能与其他地区的相关东南。在此模型中，我们推断通过SE继续进行海洋氧化还原分层，但是氧化剂（例如O ₂和硫酸盐）仅限于边缘近海环境。有限的时空范围内的氧化提供了一种机制，以驱动主要在架子区域的地下还原碳的异质氧化。无论机构驱动的SE的，未来的模型必须考虑在δ空间异质性的证据，¹³在这一研究中提出℃。