Water in the mantle controls mantle convection and chemical transport processes within Earth's interior. However, whether the water in the lower mantle is primordial or recycled remains an open question. Here we report an electrical structure consisting of two stepped high-conductivity anomalies crossing the 660-km interface beneath northeastern Asia. The sheet-like first-step conductor locates in the mantle transition zone that can be best interpreted as hydrated stagnant Pacific slab, whereas the funnel-like second-step anomaly occurs in the uppermost lower mantle that is inferred to be a water reservoir replenished by the collapsed stagnant slab. The pivotal mechanism of this water transport process could be the dehydration reaction of dense hydrous magnesium silicates and the rehydration of stishovite and liebermannite in the transition zone. Our findings provide evidence for recycled lower-mantle water reservoirs, and together with seismological and mineralogical studies, illustrate the deep-mantle water plumbing system operated by cold slab subduction.

中文翻译：

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东北亚地下地幔的水库


地幔中的水控制着地球内部的地幔对流和化学传输过程。然而，下地幔中的水是原始的还是循环的仍然是一个悬而未决的问题。在这里，我们报告了一个由两个阶梯状高电导率异常组成的电气结构，它穿过东北亚下方 660 公里的界面。片状的第一步导体位于地幔过渡区，最好解释为水合的停滞太平洋板块，而漏斗状的第二步异常发生在最上层的下地幔，被推断为由坍塌的停滞板补充的水库。这种水传输过程的关键机制可能是致密含水硅酸镁的脱水反应以及过渡区中 stishovite 和 liebermannite 的再水化。我们的研究结果为回收的下地幔水储层提供了证据，并与地震学和矿物学研究一起说明了由冷板俯冲作的深地幔水管道系统。