证据表明,最古老的陆地地幔水库仍然存在
Matthew G Jackson1, Richard W Carlson, Mark D Kurz
1Department of Earth Sciences, Boston University, 675 Commonwealth Avenue, Boston, Massachusetts 02215, USA. jacksonm@bu.edu
Nature
|August 13, 2010
概括
原始的地幔材料,在巴芬岛和西格陵兰的岩中通过同位素追踪,揭示了古老的来源年龄. 这些岩提供了地球上最古老的可访问的地幔水库的证据,可以追溯到45亿至45亿年前.
科学领域:
- 地质化学 地质化学
- 同位素地质学的同位素.
- 地球科学 地球科学 地球科学
背景情况:
- 同位素 (3He/4He) 是原始地球地幔物质的关键标记物.
- 具有高3He/4He比率的海洋岛基岩表明没有气体的地幔储库.
- 以前的研究缺乏原始的同位素组成,以证实古代地幔形成年龄.
研究的目的:
- 研究来自巴芬岛和西格陵兰岛的中纪岩的同位素组成.
- 为了确定这些岩是否存在原始的同位素化合物.
- 为了确定这些古老的岩的地幔源的形成年龄.
主要方法:
- 在岩中分析 (3He/4He),同位素和同位素 (143Nd/144Nd) 的比例.
- 同位素数据与早期地球地幔形成模型的比较.
- 同位素签名的地质时间学解释.
主要成果:
- 巴芬岛和西格陵兰的岩呈现了最高的陆地地幔3He/4He比率.
- 这些岩具有原始的同位素比率,表明古代地幔源的年龄为45亿至45亿年.
- 岩还显示了143Nd/144Nd比率,与约45亿年前的陆地地幔水库相一致.
结论:
- 结合的同位素数据表明,巴芬岛和西格陵兰的岩起源于地球上最古老的可访问的地幔水库.
- 这个古老的水库可能是所有现代火山地幔水库的父母.
- 这些发现为地球地幔中早期形成的物质的保存提供了有力的证据.
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