Department of Earth Sciences, University of California, Riverside, California 92521, USA.
Nature. 2011 Sep 7;477(7365):448-51. doi: 10.1038/nature10327.
The chemical composition of the ocean changed markedly with the oxidation of the Earth's surface, and this process has profoundly influenced the evolutionary and ecological history of life. The early Earth was characterized by a reducing ocean-atmosphere system, whereas the Phanerozoic eon (less than 542 million years ago) is known for a stable and oxygenated biosphere conducive to the radiation of animals. The redox characteristics of surface environments during Earth's middle age (1.8-1 billion years ago) are less well known, but it is generally assumed that the mid-Proterozoic was home to a globally sulphidic (euxinic) deep ocean. Here we present iron data from a suite of mid-Proterozoic marine mudstones. Contrary to the popular model, our results indicate that ferruginous (anoxic and Fe(2+)-rich) conditions were both spatially and temporally extensive across diverse palaeogeographic settings in the mid-Proterozoic ocean, inviting new models for the temporal distribution of iron formations and the availability of bioessential trace elements during a critical window for eukaryotic evolution.
海洋的化学成分随着地球表面的氧化而发生显著变化，这一过程深刻影响了生命的进化和生态历史。早期地球的特点是还原性的海洋-大气系统，而显生宙（不到 5.42 亿年前）则以稳定的含氧生物圈为特征，有利于动物的辐射。地球中年（18 亿至 10 亿年前）时期的表面环境的氧化还原特征知之甚少，但通常认为中元古代是全球硫（缺氧）深海的所在地。在这里，我们展示了一系列中元古代海洋泥岩中的铁数据。与流行模型相反，我们的结果表明，富铁（缺氧和富含 Fe(2+)）条件在中元古代海洋的各种古地理环境中具有空间和时间上的广泛分布，这为铁建造物的时间分布以及在真核生物进化的关键窗口期间生物必需微量元素的可用性提供了新的模型。
