The early to mid-Paleoproterozoic Lomagundi-Jatuli Excursion (LJE) is ostensibly the largest magnitude (approximately +5 to +30‰), longest duration (ca. 130–250 million years) positive carbon isotope excursion measured in carbonate rocks in Earth history. The LJE has been attributed to large nutrient fluxes, an increase in the size of the biosphere, a reorganization of the global carbon cycle, and oxygenation of the atmosphere. However, significant debate remains about its genesis, synchroneity, global-versus-local extent, and role in atmospheric oxygenation. Here we review existing models and mechanisms suggested for the LJE and analyze a compilation of ∼9,400 δ13Ccarb and associated contextual data. These data call into question the interpretation of the LJE as a globally synchronous carbon isotope excursion and suggest that any model for the LJE must account for both the absence of a clearly defined initiation and termination of the excursion and a facies-dependent expression of 13C-enrichment. ▪The Lomagundi-Jatuli Excursion (LJE) continues to challenge current understandings of the carbon cycle.▪Understanding this excursion is critical for reconstructing biogeochemical cycles and atmospheric oxygenation through Earth history.▪Some evidence indicates local rather than global changes in δ13CDIC and raises the possibility of asynchronous, local excursions.▪Resolving whether the LJE was globally synchronous or asynchronous is essential for discriminating between different models.

中文翻译：

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解构 Lomagundi-Jatuli 碳同位素偏移


古元古代早期至中期 Lomagundi-Jatuli 偏移 （LJE） 表面上是地球历史上在碳酸盐岩中测量到的最大幅度（约 +5 至 +30‰）、持续时间最长（约 1.30-2.5 亿年）的正碳同位素偏移。LJE 归因于大营养通量、生物圈规模的增加、全球碳循环的重组和大气的氧化。然而，关于其起源、同步性、全球与局部范围以及在大气氧合中的作用，仍然存在重大争论。在这里，我们回顾了为 LJE 建议的现有模型和机制，并分析了 ∼9,400 δ13Ccarb 的汇编和相关上下文数据。这些数据对将 LJE 解释为全球同步碳同位素偏移的解释提出了质疑，并表明 LJE 的任何模型都必须考虑缺乏明确定义的偏移起始和终止以及 13C 富集的相依赖性表达。▪Lomagundi-Jatuli 偏移 （LJE） 继续挑战当前对碳循环的理解。▪了解这种偏移对于重建地球历史上的生物地球化学循环和大气氧合至关重要。▪一些证据表明 δ13CDIC 是局部变化，而不是全局变化，并增加了异步、局部偏移的可能性。▪解析 LJE 是全局同步还是异步对于区分不同模型至关重要。