大型宝石钻石来自地球深层的金属液体
Evan M Smith1, Steven B Shirey2, Fabrizio Nestola3
1Gemological Institute of America, New York, NY 10036, USA. evan.smith@gia.edu.
概括
特殊的宝石钻石揭示了深层地幔的秘密. 包含显示金属液体的结晶,证实了地球深层的极度减少条件,对行星进化至关重要.
科学领域:
- 地质化学
- 矿物学
- 星球科学
背景情况:
- 由于板块构造的掩盖,地球对流地幔的氧化还原状态尚不清楚.
- 了解地幔氧化还原对于解读地球早期的进化历史至关重要.
研究的目的:
- 调查深层地幔的氧化还原条件.
- 在特殊的宝石钻石中保存的深层地幔过程的直接证据.
主要方法:
- 在大型宝石钻石 (例如,Cullinan,Constellation,Koh-i-Noor) 中分析含量.
- 固化的铁--碳-硫溶液和相关的减少挥发物 (甲±) 的特征.
- 识别地幔矿物质,如大石榴石和前酸盐矿.
主要成果:
- 大型宝石钻石含有金属液体,表明在金属和条件下结晶.
- 在金属融物中发现了减少的挥发性相 (甲±).
- 矿物质组合表明在极度减少的深层地幔环境中形成.
结论:
- 特殊的宝石钻石提供了深层地幔中氧化还原敏感金属液相的直接证据.
- 这些发现证实了深层地幔中能够沉金属铁的高降解区域的存在.
- 这项研究有助于我们更好地了解地球深层地幔的组成和演变.
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