Wei Guang-Yi, Zhao Mingyu, Sperling Erik A, Gaines Robert R, Kalderon-Asael Boriana, Shen Jun, Li Chao, Zhang Feifei, Li Gaojun, Zhou Chuanming, Cai Chunfang, Chen Daizhao, Xiao Ke-Qing, Jiang Lei, Ling Hong-Fei, Planavsky Noah J, Tarhan Lidya G
School of Earth Sciences and Engineering, and Frontiers Science Center for Critical Earth Material Cycling, Nanjing University, Nanjing 210023, China.
Department of Earth and Planetary Sciences, Yale University, New Haven, CT 06520-8109, USA.
Sci Adv. 2024 Mar 29;10(13):eadk2152. doi: 10.1126/sciadv.adk2152.
The evolution of oxygen cycles on Earth's surface has been regulated by the balance between molecular oxygen production and consumption. The Neoproterozoic-Paleozoic transition likely marks the second rise in atmospheric and oceanic oxygen levels, widely attributed to enhanced burial of organic carbon. However, it remains disputed how marine organic carbon production and burial respond to global environmental changes and whether these feedbacks trigger global oxygenation during this interval. Here, we report a large lithium isotopic and elemental dataset from marine mudstones spanning the upper Neoproterozoic to middle Cambrian [~660 million years ago (Ma) to 500 Ma]. These data indicate a dramatic increase in continental clay formation after ~525 Ma, likely linked to secular changes in global climate and compositions of the continental crust. Using a global biogeochemical model, we suggest that intensified continental weathering and clay delivery to the oceans could have notably increased the burial efficiency of organic carbon and facilitated greater oxygen accumulation in the earliest Paleozoic oceans.
地球表面氧循环的演化受分子氧产生与消耗之间平衡的调控。新元古代 - 古生代过渡时期可能标志着大气和海洋中氧含量的第二次上升，这一现象普遍归因于有机碳埋藏量的增加。然而，海洋有机碳的产生和埋藏如何响应全球环境变化，以及在这一时期这些反馈是否引发全球氧合作用，仍存在争议。在此，我们报告了一个来自新元古代晚期至寒武纪中期（约6.6亿年前至5亿年前）海相泥岩的大型锂同位素和元素数据集。这些数据表明，在约5.25亿年后大陆黏土形成急剧增加，这可能与全球气候和大陆地壳成分的长期变化有关。通过一个全球生物地球化学模型，我们认为，大陆风化作用的增强以及黏土向海洋的输送可能显著提高了有机碳的埋藏效率，并促进了早古生代海洋中更多氧气的积累。
