铁深入地幔的深度透是由形态不稳定造成的
Kazuhiko Otsuka1, Shun-ichiro Karato
1Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, Connecticut 06511, USA.
Nature
|December 14, 2012
概括
一个新的机制解释了地球地幔深处的铁丰富. 形态不稳定性使富含铁的液体能够透地幔,将铁运送远离核心-地幔边界.
科学领域:
- 地质物理学 地质物理学
- 地球科学 地球科学 地球科学
- 矿物物理 矿物物理
背景情况:
- 核心-地幔界限是地球核心和地幔之间相互作用的关键区域.
- 在地幔底部的铁丰富可以解释观测到的地震和导电异常.
- 以前的铁缩模型,如扩散,被认为是低效的或与核心氧含量不一致的.
研究的目的:
- 在核心-地幔边界提出铁缩的物理机制.
- 为了解释富含铁的化物进入下层地幔的运输.
- 为了使地质观测与化学过程相协调.
主要方法:
- 在核心-地幔边界条件下研究了 (Mg,Fe) O和富含铁的液体之间的相互作用.
- 分析了化学潜能梯度在驱动界面过程中的作用.
- 利用了形态不稳定的原理.
主要成果:
- 证明 (Mg,Fe) O与富含铁的液体接触时会形成形态不稳定.
- 表明这种不稳定性导致富含铁的液体透到氧化物中.
- 量化的潜在运输距离为50-100公里进入地幔.
结论:
- 由化学不平衡驱动的形态不稳定性是铁运输的合理机制.
- 这一过程可以解释地球地幔深处存在富含铁的区域.
- 这些发现为下层地幔的化学演变提供了新的视角.
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