发现了37亿年前的微生物结构,证明了生命的迅速出现
Allen P Nutman1,2, Vickie C Bennett3, Clark R L Friend4
1GeoQuEST Research Centre, School of Earth &Environmental Sciences, University of Wollongong, Wollongong, New South Wales 2522, Australia.
Nature
|September 1, 2016
概括
古老的微生物群落形成了树岩,提供了地球上早期生命的证据. 这些有37亿年历史的结构表明地球沉积物记录的开始附近有生物二氧化碳被捕获.
科学领域:
- 地质学
- 古生物学
- 天体生物学
背景情况:
- 生物活动显著影响地球的化学循环,包括二氧化碳捕获和气候调节.
- 确定生命在地球化学循环上的起源和早期影响是地球进化的一个关键问题.
- 最古老生命的先前证据,基于38003700万年前的岩石中的同位素标志,仍然存在争议.
研究的目的:
- 在格陵兰岛的Isua上带 (ISB) 新暴露的甲碳酸盐岩石中调查古代生命的证据.
- 确定ISB中的树岩形成的年龄和环境背景.
- 评估早期生命对地球化学循环和进化的影响.
主要方法:
- 在ISB中新发现的3,700万年历史的甲碳酸盐岩石的地质测绘和分析.
- 在甲碳酸盐中对分层结构 (流石) 的宏观检查.
- 微量元素分析 (稀土元素加上) 来确定沉积环境.
- 对层间的碎石沉积岩进行沉积结构分析 (交叉层分层,突裂).
主要成果:
- 在37亿年前的甲碳酸盐岩石中发现高14厘米的树岩石.
- 据证据显示,岩石是在浅海环境中形成的,
- 层间的沉积岩石表现出与浅海沉积相一致的特征,包括风暴波活动.
- 这些石头早于以前被认为最古老的生命证据2200万年.
结论:
- 它们提供了3.7亿年前生命存在的强有力的证据.
- 这一发现证明了地球历史早期的浅海碳酸盐生产和生物二氧化碳封存.
- 这些发现与分子时钟研究一致,表明生命起源于哈迪时代 (大约4000万年前).
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