一个没有橄素的地幔来源是夏威夷盾石玄武岩
Alexander V Sobolev1, Albrecht W Hofmann, Stephan V Sobolev
1Max-Planck-Institut für Chemie, Postfach 3060, 55020 Mainz, Germany. asobolev@mpch-mainz.mpg.de
Nature
|April 1, 2005
概括
夏威夷的岩石暗示了一个令人惊的起源. 而不是橄丰富的地幔,高和含量指向一个由回收海洋地形成的pyroxenitic来源. 这一修订后的理解影响了地幔融化的模型.
科学领域:
- 地质化学 地质化学
- 石化学 石化学是一门学科.
- 地球科学 地球科学 地球科学
背景情况:
- 地球的上层地幔主要是橄,地幔衍生的融物通常被认为与它形成平衡.
- 父母的夏威夷岩石呈现出异常高的和度.
- 现有的模型很难解释这些高度,如果橄是主要来源的矿物质.
研究的目的:
- 为了调查父母夏威夷岩石中异常高和含量的来源.
- 为了挑战这些岩石的奥利文占主导地位的地幔来源的普遍假设.
- 提出和建模夏威夷火山活动的替代性岩生成模型.
主要方法:
- 岩源组成的地化学建模.
- 对地幔矿物 (奥利文和) 的和缓冲能力的分析.
- 从回收的海洋地中获得的二次火素源中生成的岩的建模.
主要成果:
- 在一个典型的地幔中,奥利文和火氧是和的缓冲和,其水平与观察到的夏威夷岩组成不一致.
- 建模表明,在过去一百万年中,超过50%的夏威夷岩石起源于一种pyroxenitic来源.
- 这种火素源是由橄素与回收海洋地的融化物反应而形成的.
- 在源头的回收海洋地的比例在空间上有所不同,从羽毛中心的30%到边缘的微不足道数量.
- 这些发现与火山体积,岩流量和地震观测的独立数据一致.
结论:
- 夏威夷岩石的高和含量强烈地表明了二次氧化物来源,而不是主要的橄含量来源.
- 回收的海洋地在夏威夷岩石的石化过程中发挥着重要作用,特别是在这种火成源的形成中.
- 这项研究修订了我们对地幔融化过程和夏威夷等羽毛状环境中岩源的组成的理解.
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