Constraining the oxygen history of Earth’s middle years using redox sensitive tracers

：沉积岩，如果解释正确，可以提供一个时间轴动荡的海洋和大气条件的演变地球。大气中氧气的第一次长期积累开始于24亿年前（Ga），经典上被称为大氧化事件。尽管这一事件已经记录了一段时间，但越来越多的证据表明，氧气的动态趋势比以前认为的要多。有几条证据暗示此时的高含氧量，包括对氧化和还原反应敏感的元素的高现代浓度以及海洋页岩中的高有机碳。最近的研究表明，这些氧合趋势逆转后~2.05镓相反，长期持有的观点，氧气随着时间的推移增加。这个脱氧事件的解决很差，但可能提供重要的联系，以了解如何表面条件是不足以复杂的生物进化。它还可以提供海洋化学快速变化的类似物，让人想起现代气候变化。

: Sedimentary rocks, if interpreted correctly, can provide a timeline of the tumultuous oceanic and atmospheric conditions on the evolving Earth. The first long-lived accumulation of atmospheric oxygen began ~2.4 billion years ago (Ga), classically known as the Great Oxidation Event. Although this event has been documented for some time, mounting evidence points to more dynamic oxygen trends than previously thought. High oxygen levels at this time are implied by several lines of evidence, including high, modern-like concentrations of elements sensitive to oxidation and reduction (redox) reactions and high organic carbon in marine shales. Recent research shows a reversal of these oxygenation trends after ~2.05 Ga—contrary to a long-held view that oxygen increased with time. This de-oxygenation event is poorly-resolved, but might provide important links to understanding how surface conditions were inadequate for complex biological evolution. It could also provide analogues for rapid changes in ocean chemistry reminiscent of that attendant with modern climate change.