证据表明,在一个中期Proterozoic海洋盆地低硫酸盐和无氧
Yanan Shen1, Andrew H Knoll, Malcolm R Walter
1Botanical Museum, Harvard University, 26 Oxford Street, Cambridge, Massachusetts 02138, USA. yshen@oeb.harvard.edu
Nature
|June 6, 2003
概括
地球 地球 地球 地球 地球 地球
科学领域:
- 地质化学 地质化学
- 古海洋学是古海洋学.
- 进化生物学 进化生物学
背景情况:
- 地球经历了两个主要的氧化事件:2,4002,200万年前和800580万年前.
- 这些事件表明,前生代海洋具有独特的化学成分,与无氧的阿凯亚和有氧的法纳生代海洋不同.
- 了解前生代海洋氧化还原化学对于进化研究至关重要,但经验数据有限.
研究的目的:
- 为了研究大洋化学在中期的Proterozoic时代 (1,5001,400万年前).
- 为原生代海洋环境模型提供经验约束.
- 为了分析来自澳大利亚罗珀盆地的页岩中的铁和硫同位素.
主要方法:
- 在罗珀盆地的页岩中分析铁的化学成分.
- 在页岩中检查硫同位素组合物中的矿.
- 地化学数据与古深度梯度的相关性.
主要成果:
- 页岩表明深水无氧与氧化表面水共存.
- 硫同位素的变化显示,在中原生代海洋中,硫酸盐度较低.
- 有证据表明,在原生态时期,海洋化学状态是长期存在的中间状态.
结论:
- 中期Proterozoic海洋保持了一个中间的氧化还原状态,既不是完全无氧的,也不是完全氧化的.
- 这种状态是由早期的氧化形成的,并以晚期的原生代环境变化结束.
- 这些发现支持了长期存在独特的海洋化学物质,影响了生命早期的进化.
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