The lack of knowledge about the enrichment mechanism of rare earth elements and yttrium (REY) in deep-sea sediments is impeding the development of theories and exploration strategies for pelagic REY-rich sediments. Ocean circulation variability seems to be crucial in enriching REY in pelagic sediments, which, however, has not been extensively studied. Here, we examined the Pb-Nd isotopic signals of bottom water recorded by the authigenic ferromanganese oxyhydroxide fractions, as well as the Mn/Al and Mn/Ti ratios of bulk samples from a well-dated sediment core in the northwestern Pacific Ocean. These proxies consistently indicate that enhanced deep-water circulation occurred in the study area at ∼11.5–9.5 Ma, which was most likely to be caused by changes in the flow path of bottom currents. The age of this distinct event consists with the forming age of highly REY-rich sediments. We propose that enhanced deep-water circulation in seamount areas could increase the flux of micronodules and fish debris into the pelagic sediments, facilitating the scavenging of REY from seawater. Our findings establish a connection between enhanced deep-water circulation and the enrichment of REY in pelagic sediments.

中文翻译：

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增强的深水环流促进了西北太平洋中上层沉积物中稀土元素的富集


对深海沉积物中稀土元素和钇 （REY） 富集机制的缺乏阻碍了富含 REY 的远洋沉积物理论和勘探策略的发展。海洋环流变化似乎对于富集中上层沉积物中的 REY 至关重要，然而，这尚未得到广泛研究。在这里，我们检查了自生锰铁氢氧化物馏分记录的底水的 Pb-Nd 同位素信号，以及来自西北太平洋年代明确的沉积物岩心的块状样品的 Mn/Al 和 Mn/Ti 比率。这些代理一致表明，研究区域在 ∼11.5–9.5 马 时发生了增强的深水环流，这很可能是由底流流路径的变化引起的。这一独特事件的年龄包括高度富含 REY 的沉积物的形成年龄。我们提出，加强海山地区的深水循环可以增加微结核和鱼类残骸进入中上层沉积物的通量，从而促进从海水中清除 REY。我们的研究结果确定了深水环流增强与中上层沉积物中 REY 富集之间的联系。