这是酸盐地球早期 (>4.53亿年前) 全球分化的第142个证据
1Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, N.W., Washington, DC 20015, USA. boyet@dtm.ciw.edu
概括
新的石数据显示,地球的地幔在某些元素中已经耗尽,这表明早期的全球差异化. 这一发现影响了行星形成模型和地球,月球和火星的早期分化时间线.
科学领域:
- 地质化学 地质化学
- 行星科学 行星科学
- 同位素地质学的同位素.
背景情况:
- 体石为早期太阳系组成提供了洞察力.
- - (Sm-Nd) 同位素系统是约会和追踪地幔演变的关键工具.
- 地球早期分化的先前模型仍在争论中.
研究的目的:
- 为了研究地球地幔的早期分化,使用高精度的Sm-Nd同位素数据从体石.
- 将石的同位素组成与陆地岩石进行比较,以推断地幔特征.
- 改进地球组成结构和早期行星分化的模型.
主要方法:
- 获取高精度的三-新 (Sm-Nd) 同位素数据.
- 对体石的分析和与陆地岩石组成的比较.
- 建模地球地幔的组成和差异化过程.
主要成果:
- 体石的142Nd/144Nd比率大约比大多数陆地岩石低20百万分之一.
- 这种同位素差异表明,地球地幔的70-95%类似于不兼容的元素枯竭来源.
- 全球差异化事件很可能发生在地球形成的300万年内 (4.53亿年前).
结论:
- 地球的地幔在很大程度上已经耗尽,在地幔底部可能被隔离的补充丰富的水库.
- 早期地球经历了快速和广泛的分化,影响了其今天的组成结构.
- 地球,月球和火星的早期分化的时间需要根据这些发现进行修订.
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