结合了186Os和187Os证据,证明了核心-地幔相互作用的证据
1A. D. Brandon, R. J. Walker, J. W. Morgan, Isotope Geochemistry Laboratory, Department of Geology, University of Maryland, College Park, MD 20742, USA. J. W. Morgan, Department of Earth Resources, Colorado State University, Fort Collins, CO 80.
概括
奥斯同位素分析显示,夏威夷的皮克里特岩含有外部核心材料. 这表明一些地幔羽毛起源于核心-地幔边界,可以通过它们的同位素特征来区分.
科学领域:
- 地质化学 地质化学
- 同位素地质学的同位素.
- 行星科学 行星科学
背景情况:
- 地幔羽毛是通过地球地幔上升的热岩管道.
- 地幔羽毛的起源和组成为深层地球过程提供了洞察力.
- 奥斯同位素 (186Os/188Os和187Os/188Os) 是地幔源的敏感标记物.
研究的目的:
- 通过使用同位素地质化学来调查夏威夷图形岩的起源.
- 为了确定地幔羽毛是否可以吸收来自地球核心的物质.
- 建立同位素作为区分深层和浅层地幔来源的工具.
主要方法:
- 精确测量-186/-188 (186Os/188Os) 和-187/-188 (187Os/188Os) 的比例在夏威夷的图形岩样本中.
- 同位素数据与体上层地幔和潜在的核心材料组成的比较.
- 模拟地幔和核心材料之间的混合场景.
主要成果:
- 来自夏威夷的皮克里特岩对186Os/188Os (0.0080.018%) 和187Os/188Os (5.49.0%) 呈现出相对较高的丰富度.
- 这些结合的同位素丰富最好解释为D"层的一部分添加了0.51重%的外部核心金属.
- 然后混合物上升形成观察到的图形岩.
结论:
- 一些地幔羽毛,如夏威夷下面的那些,可能起源于核心-地幔边界.
- 将外部核心材料纳入地幔是一个可行的过程.
- 奥斯同位素作为一个强大的工具来区分来自浅层和深层地幔区域的地幔羽毛,包括核心-地幔边界.
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