Ocean oxygenation in the wake of the Marinoan glaciation
Ocean oxygenation in the wake of the Marinoan glaciation
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DOI：
10.1038/nature11445
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发表时间：
2012-09
期刊：
影响因子：
64.8
通讯作者：
S. Sahoo;N. Planavsky;B. Kendall;Xinqiang Wang;Xiaoying Shi;C. Scott;A. Anbar;T. Lyons;G. Jiang
中科院分区：
文献类型：
--
作者：
S. Sahoo;N. Planavsky;B. Kendall;Xinqiang Wang;Xiaoying Shi;C. Scott;A. Anbar;T. Lyons;G. Jiang
后生动物很可能起源于成冰期，但在大约 6.35 亿年前的成冰期晚期（马里诺安）冰川结束后不久，新型动物和藻类化石的出现显着增加。有人认为，严重的马里诺冰川作用之后的氧化事件是后生动物早期多样化和生态系统复杂性转变背后的驱动因素。但几乎没有证据表明马里诺冰川作用后海洋或大气中的氧气增加，或者早期动物进化与一般氧化还原条件之间存在直接联系。因此，将早期生物进化趋势与地球系统过程变化联系起来的模型仍然存在争议。在此，我们报告了华南陡山沱组基底早期埃迪卡拉纪富含有机质黑色页岩（约 635-6.3 亿年）的地球化学数据。这些页岩中钼和钒的高富集度以及黄铁矿硫同位素值较低（Δ34S值≥65/密耳）记录了氧化还原敏感金属海洋库存的扩张以及海洋硫酸盐储层的增长，以应对广泛氧化的海洋。这些数据为早期埃迪卡拉纪氧化事件提供了证据，该事件比之前对后马里诺时代氧化事件的估计早了 5000 万年以上。我们的发现似乎支持地球历史上最严重的冰川作用、地球表面环境的氧化和最早的动物多样化之间的联系。
Metazoans are likely to have their roots in the Cryogenian period,,, but there is a marked increase in the appearance of novel animal and algae fossils shortly after the termination of the late Cryogenian (Marinoan) glaciation about 635 million years ago,,. It has been suggested that an oxygenation event in the wake of the severe Marinoan glaciation was the driving factor behind this early diversification of metazoans and the shift in ecosystem complexity,. But there is little evidence for an increase in oceanic or atmospheric oxygen following the Marinoan glaciation, or for a direct link between early animal evolution and redox conditions in general. Models linking trends in early biological evolution to shifts in Earth system processes thus remain controversial. Here we report geochemical data from early Ediacaran organic-rich black shales (∼635–630 million years old) of the basal Doushantuo Formation in South China. High enrichments of molybdenum and vanadium and low pyrite sulphur isotope values (Δ34S values ≥65 per mil) in these shales record expansion of the oceanic inventory of redox-sensitive metals and the growth of the marine sulphate reservoir in response to a widely oxygenated ocean. The data provide evidence for an early Ediacaran oxygenation event, which pre-dates the previous estimates for post-Marinoan oxygenation,,by more than 50 million years. Our findings seem to support a link between the most severe glaciations in Earth’s history, the oxygenation of the Earth’s surface environments, and the earliest diversification of animals.