Stable isotope evidence for crustal recycling as recorded by superdeep diamonds
Stable isotope evidence for crustal recycling as recorded by superdeep diamonds
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DOI：
10.1016/j.epsl.2015.10.023
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发表时间：
2015-12-15
影响因子：
5.3
通讯作者：
Walter, M. J.
中科院分区：
文献类型：
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作者：
Burnham, A. D.;Thomson, A. R.;Walter, M. J.
来自巴西Juina-5和Collier-4金伯利岩和马查多河冲积矿床的亚岩石圈钻石的碳同位素组成与其包裹体的氧同位素组成共同变化，这意味着它们是由混合过程形成的。基于板岩碳酸盐熔体与还原(含碳化物或金属)环境地幔的相互作用，提出的这种混合过程模型解释了这些同位素观测结果。这与观察到的这些地区金刚石包裹体的微量元素化学和碳化俯冲地壳的实验相关系是一致的。包裹体的富含O-18的性质表明，它们包含了以前与海水相互作用的地壳原岩中的物质，从而证实了超深钻石的俯冲成因。这些样品还提供了深部(~gt；=350公里)地幔中存在同位素异常储集层的直接证据。(C)2015爱思唯尔B.V.保留所有权利。
Sub-lithospheric diamonds from the Juina-5 and Collier-4 kimberlites and the Machado River alluvial deposit in Brazil have carbon isotopic compositions that co-vary with the oxygen isotopic compositions of their inclusions, which implies that they formed by a mixing process. The proposed model for this mixing process, based on interaction of slab-derived carbonate melt with reduced (carbide- or metal-bearing) ambient mantle, explains these isotopic observations. It is also consistent with the observed trace element chemistries of diamond inclusions from these localities and with the experimental phase relations of carbonated subducted crust. The O-18-enriched nature of the inclusions demonstrates that they incorporate material from crustal protoliths that previously interacted with seawater, thus confirming the subduction-related origin of superdeep diamonds. These samples also provide direct evidence of an isotopically anomalous reservoir in the deep (>= 350 km) mantle. (C) 2015 Elsevier B.V. All rights reserved.