Abstract 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 μ, μ = 238 U/204Pb) 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.

中文翻译：

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源自过渡带的HIMU地球化学特征

摘要 羽状火山活动可能采集到比大洋中脊和弧形火山活动更深的地幔源。大洋岛玄武岩 (OIB) 通常与羽状火山活动有关，并且可以使用数量有限的地幔端元来描述其多样的同位素和元素组成。然而，这些地幔端元的起源和深度存在很大争议。在这里，我们表明 HIMU（高 μ，μ = 238 U/204Pb）端元可能位于过渡区。具体来说，我们报告了高压多相金刚石内含物的地球化学特征，在 420-440 公里深度和 1450 ± 50 K 处被捕获，这与富含 HIMU 的 OIB 的地球化学模式完全匹配。由于几乎所有 OIB 都对 HIMU 分量进行了可变采样，因此我们的发现意味着过渡带导致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、图布艾和曼盖亚的地幔柱，似乎以这种来源为主。此外，我们的发现强调了过渡带在地幔高度不相容的元素预算中的重要性。