Dongjie Bi , Xuefa Shi , Mu Huang , Fangyu Shen , Miao Yu , Ying Zhang , Fengdeng Shi , Jihua Liu
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引用次数: 0
Abstract
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.
由于缺乏对深海沉积物中稀土元素和钇(REY)富集机制的了解,阻碍了富含稀土元素和钇的远洋沉积物理论和勘探战略的发展。大洋环流的变化似乎是远洋沉积物中稀土元素富集的关键,但目前对此还没有广泛的研究。在此,我们研究了自生铁锰氧氢氧化物馏分记录的底层水 Pb-Nd 同位素信号,以及来自西北太平洋一个年代久远的沉积物岩芯的大量样品的 Mn/Al 和 Mn/Ti 比率。这些代用指标一致表明,在 ∼11.5-9.5 Ma 时,研究区域的深水环流增强,这很可能是由底流的流动路径变化引起的。这一独特事件的年龄与高REY沉积物的形成年龄一致。我们认为,海山地区深水环流的增强可能会增加微粒和鱼类碎屑进入浮游沉积物的通量,从而促进海水中 REY 的清除。我们的研究结果确定了深水环流增强与浮游沉积物中 REY 富集之间的联系。
期刊介绍:
The objective of the journal Global and Planetary Change is to provide a multi-disciplinary overview of the processes taking place in the Earth System and involved in planetary change over time. The journal focuses on records of the past and current state of the earth system, and future scenarios , and their link to global environmental change. Regional or process-oriented studies are welcome if they discuss global implications. Topics include, but are not limited to, changes in the dynamics and composition of the atmosphere, oceans and cryosphere, as well as climate change, sea level variation, observations/modelling of Earth processes from deep to (near-)surface and their coupling, global ecology, biogeography and the resilience/thresholds in ecosystems.
Key criteria for the consideration of manuscripts are (a) the relevance for the global scientific community and/or (b) the wider implications for global scale problems, preferably combined with (c) having a significance beyond a single discipline. A clear focus on key processes associated with planetary scale change is strongly encouraged.
Manuscripts can be submitted as either research contributions or as a review article. Every effort should be made towards the presentation of research outcomes in an understandable way for a broad readership.