Pervasive oxygenation along late Archaean ocean margins
Pervasive oxygenation along late Archaean ocean margins
复制标题
DOI：
10.1038/ngeo942
复制
发表时间：
2010-09-01
影响因子：
18.3
通讯作者：
Anbar, Ariel D.
中科院分区：
文献类型：
--
作者：
Kendall, Brian;Reinhard, Christopher T.;Anbar, Ariel D.
海洋中氧气的光合作用被认为始于27亿年前，比大气中氧气的明显积累早了数亿年。然而，溶解氧的丰度和分布在晚白垩世海洋是不受约束的。在这里，我们提出了地球化学剖面从2.6至2.5亿年的黑色页岩从坎贝尔兰德-马尔马尼碳酸盐台地在南非。我们发现了高丰度的钼和低丰度的钼，这与沉积铁的形态，指出溶解氧的存在下，在底部沃茨的平台斜坡。斜坡上的水深可能达到几百米，这意味着O-2的输出低于透光层。我们的数据还表明，轻度含氧的表层海洋让位于缺氧的深海。因此，我们认为，当时海洋表层的氧气生产是旺盛的，但不足以完全消耗深海还原剂。根据我们的研究结果和观测结果，从西澳大利亚州的哈默斯利盆地，我们得出结论，生产区域沿着海洋边缘在晚白垩世的网站大量的O-2积累，至少有1亿年前，第一次显着增加大气中的O-2浓度。
The photosynthetic production of oxygen in the oceans is thought to have begun by 2.7 billion years ago, several hundred million years before appreciable accumulation of oxygen in the atmosphere. However, the abundance and distribution of dissolved oxygen in the late Archaean oceans is poorly constrained. Here we present geochemical profiles from 2.6- to 2.5-billion-year-old black shales from the Campbellrand-Malmani carbonate platform in South Africa. We find a high abundance of rhenium and a low abundance of molybdenum, which, together with the speciation of sedimentary iron, points to the presence of dissolved oxygen in the bottom waters on the platform slope. The water depth on the slope probably reached several hundred metres, implying the export of O-2 below the photic zone. Our data also indicate that the mildly oxygenated surface ocean gave way to an anoxic deep ocean. We therefore suggest that the production of oxygen in the surface ocean was vigorous at this time, but was not sufficient to fully consume the deep-sea reductants. On the basis of our results and observations from the Hamersley basin in Western Australia, we conclude that the productive regions along ocean margins during the late Archaean eon were sites of substantial O-2 accumulation, at least 100 million years before the first significant increase in atmospheric O-2 concentration.