一个结晶的密集的岩海洋在地球地幔的底部
S Labrosse1, J W Hernlund, N Coltice
1Laboratoire des sciences de la Terre, Ecole Normale Supérieure de Lyon, Université de Lyon, CNRS UMR 5570, 46 Allée d'Italie, 69364 Lyon Cedex 07, France. stephane.labrosse@ens-lyon.fr
Nature
|December 8, 2007
概括
早期的地球地球.
科学领域:
- 地质化学 地质化学
- 地质物理学 地质物理学
- 行星科学 行星科学
背景情况:
- 地化学物种的分布是由地幔融化和结晶决定的,这与地球的热进化有关.
- 证据表明,在过去,地幔深层有大量的融化,地幔底部有密集的部分融化斑块.
- 核心冷却是地球历史上地力发动机维护所必需的.
研究的目的:
- 为了研究一个深的,早期地球岩海洋在地化学元素分布中的作用.
- 探索基底岩海洋作为未经采样的地球化学储备的潜力.
- 为了协调地质化学数据和热演变模型.
主要方法:
- 建模地球底层深层稳定的融化层的分量结晶.
- 在地石和陆地岩石中分析142Nd/144Nd比率.
- 开发热进化模型,包括放射性热和潜热交换.
主要成果:
- 一个稳定的1000公里厚的基底层将经历缓慢的分数结晶.
- 这个过程可以解释发热元件的"缺失预算"和142Nd/144Nd变化.
- 放射性热和潜热交换防止了核心的早期冷却.
结论:
- 一个早期的基底性岩海洋是未采样的地球化学储库的可行模型.
- 这一层内的分量结晶解释了关键的地化学异常.
- 这种模型支持地质纳摩 (3.4-4 Gyr前) 的延迟发作.
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