HIMU geochemical signature originating from the transition zone
HIMU geochemical signature originating from the transition zone
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DOI：
10.1016/j.epsl.2020.116323
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发表时间：
2020-07-15
影响因子：
5.3
通讯作者：
Tischler, Jon
中科院分区：
文献类型：
--
作者：
Huang, Shichun;Tschauner, Oliver;Tischler, Jon
地幔柱火山作用可能比洋中脊和弧火山作用更深的地幔源。洋岛玄武岩（OIBs）通常与地幔柱火山作用有关，其多样的同位素和元素组成可以用有限数量的地幔端元来描述。然而，这些地幔端元的起源和深度是高度有争议的。在这里，我们表明，HIMU（高mu，mu = U-238/Pb-204）端元可能存在于过渡区。具体而言，我们报告了高压多相金刚石包裹体的地球化学特征，包裹在420-440公里的深度和1450 +/- 50 K，这与富含HIMU的OIB的地球化学模式完全匹配。由于几乎所有的OIB都对HIMU成分进行了连续采样，我们的发现意味着过渡带导致了地幔柱地球化学特征的主要叠加。一些地幔柱，如那些喂养百慕大，圣赫勒拿，Tubuai和Mangaia，似乎是由这个来源。此外，我们的发现强调了过渡区在地幔高度不相容元素收支中的重要性。(c)2020爱思唯尔B. V.保留所有权利。
Plume volcanism may sample mantle sources deeper than mid-ocean ridge and arc volcanism. Ocean island basalts (OIBs) are commonly related to plume volcanism, and their diverse isotopic and elemental compositions can be described using a limited number of mantle endmembers. However, the origins and depths of these mantle endmembers are highly debated. Here we show that the HIMU (high mu, mu = U-238/Pb-204) endmember may reside in the transition zone. Specifically, we report the geochemical signature of a high-pressure multiphase diamond inclusion, entrapped at 420-440 km depth and 1450 +/- 50 K, which matches exactly the geochemical patterns of the HIMU-rich OIBs. Since the HIMU component is variably sampled by almost all OIBs, our finding implies that the transition zone causes a major overprint of the geochemical features of mantle plumes. Some mantle plumes, like those feeding Bermuda, St Helena, Tubuai and Mangaia, appear to be dominated by this source. Furthermore, our finding highlights the importance of the transition zone in highly incompatible element budget of the mantle. (c) 2020 Elsevier B.V. All rights reserved.