The Early Cambrian Late Stage 2 to Stage 3 (ca. 526–514 Ma) was characterized by the peak of the Cambrian Explosion and a large-scale global transgression that resulted in the deposition of organic-rich black shales, which have important implications for Earth-system science and petroleum/economic geology. However, there are many uncertainties regarding the spatiotemporal evolution of structural model, and driving mechanisms of the paleo-oceanic environment during this period, requiring more examples and research constraints. To fill the knowledge gap, high-resolution elemental, carbon isotope, and biogeochemical data were obtained from two continuous drill cores, along with redox-sensitive proxy data from additional 21 cores/sections of different sedimentary facies in the Yangtze Platform, South China, provide a comprehensive and detailed spatiotemporal window into this issue. It demonstrates that the dynamic evolution process of redox conditions varied between shallow- and deep-water regions, and temporal variations in chemical weathering intensity and spatiotemporal differences in upwelling currents controlled the redox state of the ocean, which was closely related to the relative contents of organic carbon (TOC), SO, and Fe. The mechanisms that controlled the scale of sulfidic wedges differed among different regions and stages. During intervals I (Late Stage 2) and II (Early–Middle Stage 3), shallow and deep waters were controlled mainly by TOC and SO contents, respectively. Deep waters during interval III (Late Stage 3) were controlled mainly by TOC contents. The spatiotemporal heterogeneity of the Early Cambrian paleo-ocean redox state partly controlled the spatiotemporal distribution of the fossil record. Primary productivity was the main controlling factor on the spatiotemporal variations in hydrocarbon source rock quality, followed by the organic matter preservation conditions. This study highlights the Earth-system science research on the deep-time ocean environment and its resource effects.

中文翻译：

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寒武纪大爆发期间的海洋化学结构

早寒武世晚期第2阶段至第3阶段（约526~514Ma）以寒武纪爆发高峰和大规模全球海侵为特征，导致富含有机质的黑色页岩沉积，这对地球系统科学和石油/经济地质学。但这一时期古海洋环境的结构模式时空演化和驱动机制存在诸多不确定性，需要更多的实例和研究约束。为了填补这一知识空白，我们从两个连续钻探岩心获得了高分辨率元素、碳同位素和生物地球化学数据，以及从华南扬子地台不同沉积相的另外 21 个岩心/剖面获得的氧化还原敏感代理数据，为这个问题提供全面而详细的时空窗口。表明浅水区和深水区氧化还原条件的动态演化过程存在差异，化学风化强度的时间变化和上升流的时空差异控制了海洋的氧化还原状态，这与氧化还原状态的相对含量密切相关。有机碳 (TOC)、SO 和 Fe。不同地区、不同阶段，控制硫化物楔形物规模的机制有所不同。在 I 期（2 后期）和 II 期（3 早中期），浅水区和深水区分别主要受 TOC 和 SO 含量控制。Ⅲ期（第三阶段后期）深水区主要受TOC含量控制。早寒武世古海洋氧化还原状态的时空异质性部分控制了化石记录的时空分布。初级生产力是烃源岩质量时空变化的主要控制因素，其次是有机质保存条件。本研究重点关注深部海洋环境及其资源效应的地球系统科学研究。