在萨摩亚岩中恢复了沉积的大陆地
Matthew G Jackson1, Stanley R Hart, Anthony A P Koppers
1Massachusetts Institute of Technology, Woods Hole Oceanographic Institution Joint Program, Woods Hole, Massachusetts 02543-1525, USA. mjackson@whoi.edu
Nature
|August 10, 2007
概括
在萨摩亚岩中通过独特的 (Sr) 和 (Nd) 同位素识别的再生大陆地,提供了通过地幔羽毛回到地球表面的沉积物沉积物的证据.
科学领域:
- 地质化学 地质化学
- 同位素地球化学 同位素地球化学
- 世界地幔地力学地力学
背景情况:
- 俯冲区将大量的土壤沉积物回收到地球地幔中.
- 最终的命运和地幔羽毛中沉积沉积物的同位素签名仍然不太清楚.
- 热点岩中的回收沉积物成分很少见,因此它们的识别对于地幔组成研究至关重要.
研究的目的:
- 为了研究萨摩亚岩的同位素和微量元素组成.
- 为了确定萨摩亚地幔羽毛中潜在的回收沉积物成分.
- 重新定义EM2 (富含地幔2) 地幔末端的地化学特征.
主要方法:
- 在西萨摩亚萨瓦伊的海底岩石中分析87Sr/86Sr和143Nd/144Nd同位素比.
- 检查微量元素数据,包括Ce/Pb和Nb/U比率.
- 地化学特征与已知的上大陆地组成的比较.
主要成果:
- 萨摩亚的岩表现出非常丰富的87Sr/86Sr和143Nd/144Nd同位素特征,这是海洋岛屿玄武岩中报告的最极端的.
- 微量元素数据显示与上大陆地的亲和关系,包括低的Ce/Pb和Nb/U比率.
- 这些地化学特征强烈表明,萨摩亚地幔中存在一个回收的上大陆地成分.
结论:
- 来自萨摩亚岩的地化学数据提供了令人信服的证据,证明在萨摩亚地幔羽毛中回收了上大陆地.
- 这些发现显著改进了对EM2地幔末端组成的理解.
- 这项研究强调了同位素和微量元素分析在追踪地球深层沉积物质命运中的重要性.
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