Department of Earth Sciences, University of California, Riverside, CA 92521, USA.
Science. 2010 Apr 2;328(5974):80-3. doi: 10.1126/science.1182369. Epub 2010 Feb 11.
The Ediacaran Period (635 to 542 million years ago) was a time of fundamental environmental and evolutionary change, culminating in the first appearance of macroscopic animals. Here, we present a detailed spatial and temporal record of Ediacaran ocean chemistry for the Doushantuo Formation in the Nanhua Basin, South China. We find evidence for a metastable zone of euxinic (anoxic and sulfidic) waters impinging on the continental shelf and sandwiched within ferruginous [Fe(II)-enriched] deep waters. A stratified ocean with coeval oxic, sulfidic, and ferruginous zones, favored by overall low oceanic sulfate concentrations, was maintained dynamically throughout the Ediacaran Period. Our model reconciles seemingly conflicting geochemical redox conditions proposed previously for Ediacaran deep oceans and helps to explain the patchy temporal record of early metazoan fossils.
埃迪卡拉纪（6.35 亿至 5.42 亿年前）是环境和进化发生根本变化的时期，最终出现了宏观动物。在这里，我们呈现了华南南华盆地陡山沱组埃迪卡拉纪海洋化学的详细时空记录。我们发现了证据，表明缺氧和硫化的海水（缺氧硫化海水）的不稳定带冲击大陆架，并夹在富含铁的（富含二价铁的）深水中。一个分层的海洋，同时存在含氧、含硫和富含铁的区域，这得益于整体上低的海洋硫酸盐浓度，在整个埃迪卡拉纪期间都保持着动态。我们的模型调和了以前为埃迪卡拉深海提出的看似矛盾的地球化学氧化还原条件，有助于解释早期后生动物化石的时断时续的记录。
