丰富的Pt-Re-Os同位素系统在羽毛岩中,由metasomatic硫化物解释
Ambre Luguet1, D Graham Pearson, Geoff M Nowell
1Northern Centre for Isotopic and Elemental Tracing, Department of Earth Sciences, University of Durham, South Road, Durham DH1 3LE, UK. ambre.luguet@durham.ac.uk
概括
海洋玄武岩中的高同位素标志可以通过地幔过程来解释,而不是核心-地幔交换. 在地幔源中的体硫化物为这些独特的同位素特征提供了可行的机制.
科学领域:
- 地质化学 地质化学
- 同位素地质学的同位素.
- 石化学 石化学是一门学科.
背景情况:
- 海洋玄武岩表现出高同位素 (186Os-187Os) 签名,此前归因于核心-地幔交换.
- 核心-地幔交换假设提出了挑战与地球的热和动态历史约束.
- 了解这些同位素特征的起源对于破译地幔演变和地球深层过程至关重要.
研究的目的:
- 为了研究海洋玄武岩中186Os-187Os特征升高的替代机制.
- 测试核心-地幔交换的必要性,以解释观察到的同位素变化.
- 为了确定负责在玄武岩源中产生多样化的同位素签名的特定地幔组件.
主要方法:
- 分析火石和生石中的高度 siderophile 元素,包括它们的相关硫化物.
- 测量氧化同位素比率 (186Os/188Os) 在氧化和富合金中的测量.
- 地质化学建模,以评估不同地幔材料对玄武岩同位素特征的贡献.
主要成果:
- 在地幔源中大量氧化的参与可以解释观察到的186Os-187Os签名.
- 从氧化或氧化溶液中提取的氧化,是对同位素特征更有可能的解释.
- 这些地幔衍生材料有效地复制了海洋玄武岩的同位素特征.
结论:
- 核心-地幔交换不需要解释海洋玄武岩中186Os-187Os签名的升高.
- 在地幔内,体硫化物提供了一个强大的机制来产生显著的同位素多样性.
- 这一发现为地幔异质性和塑造玄武岩地质化学的过程提供了新的视角.
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