无生物的矿形成产生了大量的Fe同位素分离
Romain Guilbaud1, Ian B Butler, Rob M Ellam
1School of Geosciences, University of Edinburgh, Grant Institute, Edinburgh, UK. R.Guilbaud@sms.ed.ac.uk
概括
铁中铁同位素的组成可以通过非生物过程改变,而不仅仅是微生物活动. 这一发现表明,古代海洋的氧化还原状态可能被误解,影响我们对早期地球环境的理解.
科学领域:
- 地质化学 地质化学
- 生物地质化学生物地质化学
- 古代海洋学 古代海洋学 古代海洋学
背景情况:
- 沉积式矿 (FeS2) 的铁 (Fe) 同位素组成被广泛用作追踪微生物代谢和海洋氧化还原条件的代理物.
- 以前的解释经常将古代沉积物中的负铁同位素外游与微生物异型铁减少联系起来.
研究的目的:
- 为了研究非生物过程在铁同位素分离中的作用,在化形成过程中.
- 重新评估古代沉积体铁同位素记录的解释.
主要方法:
- 在非生物性矿形成过程中实验确定Fe同位素分离因子.
- 基于水性Fe(II),mackinawite和pyrite之间的联合分离因子,对Fe同位素特征进行建模.
主要成果:
- 铁同位素分离发生在非生物性矿形成过程中,即使没有改变Fe(II) 氧化还原状态.
- 无生物过程可以产生具有Fe同位素特征的金石,覆盖了从古时观测到现代沉积物记录的所有范围.
- 结合的分离因子解释了观测到的沉积物 δ ((56) Fe ((pyrite) 值的范围.
结论:
- 古代沉积物中负铁同位素的外流很可能是由于非生物性矿形成期间的部分Fe (II) 使用,而不是微生物Fe (III) 减少.
- 晚期新生代到现代沉积期的铁同位素变化可能反映了Fe (II) 利用率的增加和来源成分的变化,以及潜在的微生物影响.
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