Oxygen minimum zones in the early Cambrian ocean
Oxygen minimum zones in the early Cambrian ocean
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DOI：
10.7185/geochemlet.1806
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发表时间：
2018-01-01
影响因子：
4.9
通讯作者：
Butterfield, N. J.
中科院分区：
文献类型：
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作者：
Guilbaud, R.;Slater, B. J.;Butterfield, N. J.
早期动物群落的进化与海洋含氧量之间的关系尚不清楚。特别是，在关键的早寒武纪（541- 5.1亿年前，Ma）的氧化还原条件重建中，不确定性仍然存在，在那里，来自更深海洋环境的相互矛盾的数据集表明海洋缺氧或完全含氧条件。通过将地球化学古氧化还原指标与早寒武世波罗的海盆地异常明确的层序有机壁化石记录相结合，为现代型氧最小带（OMZs）的早期建立提供了证据。内部和外部大陆架环境都是普遍含氧的，而中深度环境的特征是空间振荡缺氧。因此，从个别地点恢复的相互冲突的氧化还原特征很可能源于采样偏差，即缺氧条件代表具有更高生产力的中大陆架环境。这张空间上受限制的缺氧楔形图与全球分层海洋的流行模式形成了对比，为元古宙-显生宙的海洋过渡提供了更细致和现实的描述。
The relationship between the evolution of early animal communities and oceanic oxygen levels remains unclear. In particular, uncertainty persists in reconstructions of redox conditions during the pivotal early Cambrian (541-510 million years ago, Ma), where conflicting datasets from deeper marine settings suggest either ocean anoxia or fully oxygenated conditions. By coupling geochemical palaeo-redox proxies with a record of organic-walled fossils from exceptionally well-defined successions of the early Cambrian Baltic Basin, we provide evidence for the early establishment of modern-type oxygen minimum zones (OMZs). Both inner- and outer-shelf environments were pervasively oxygenated, whereas mid-depth settings were characterised by spatially oscillating anoxia. As such, conflicting redox signatures recovered from individual sites most likely derive from sampling bias, whereby anoxic conditions represent mid-shelf environments with higher productivity. This picture of a spatially restricted anoxic wedge contrasts with prevailing models of globally stratified oceans, offering a more nuanced and realistic account of the Proterozoic-Phanerozoic ocean transition.