在中原生态时期,陆地环境的早期氧化
John Parnell1, Adrian J Boyce, Darren Mark
1School of Geosciences, University of Aberdeen, Aberdeen AB24 3UE, UK. j.parnell@abdn.ac.uk
Nature
|November 12, 2010
概括
地化学数据显示,古老的陆地岩石中存在显著的硫同位素分离,这表明在中原生态时代存在富含氧气的条件. 这表明复杂的硫循环和依赖氧气的生命形式的早期进化.
科学领域:
- 地质化学 地质化学
- 古气候学 古气候学
- 生物地质化学生物地质化学
背景情况:
- 来自古代沉积岩的地球化学数据追踪了地球的大气和海洋的演变.
- 关键的氧化事件被提议用于古新生代和晚期新生代时代,与metazoan进化有关.
- 硫同位素分离 (Δ(34) S) 数据显示,大约1Gyr前,从<25‰转移到≥50‰,解释为微生物硫循环的演变.
研究的目的:
- 为了研究同位素分离在 Mesoproterozoic 陆地继承.
- 为了描述这个地质时期人们对硫循环的了解不足.
- 评估观察到的分化对大气氧气水平和微生物进化的影响.
主要方法:
- 从古代沉积物相继的地化学数据的分析.
- 在苏格兰的陆地Mesoproterozoic岩石 (1.18 Gyr旧) 中测量硫同位素比例 (Δ34S).
- 在微生物硫循环的背景下解释同位素数据 (硫酸还原,硫化物氧化,不成比例).
主要成果:
- 在1.18Gyr古的陆地Mesoproterozoic继承中发现超过50‰的Δ34S值.
- 证据表明硫不成比例,可能涉及硫化物氧化细菌,在红色床和湖泊黑色页岩中.
- 这些发现表明中原生态时期的陆地环境具有足够的氧气来支持专门的生物群.
结论:
- 中原纪陆地环境的氧化时间比以前海洋硫记录所指的要早.
- 显著的硫同位素分离的存在意味着活跃的微生物群落适应了富含氧气的条件.
- 这项研究为地球早期的氧化和微生物生命的演变提供了关键的见解.
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