Statistic and Isotopic Characterization of Deep‐Sea Sediments in the Western North Pacific Ocean: Implications for Genesis of the Sediment Extremely Enriched in Rare Earth Elements
Statistic and Isotopic Characterization of Deep‐Sea Sediments in the Western North Pacific Ocean: Implications for Genesis of the Sediment Extremely Enriched in Rare Earth Elements
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DOI：
10.1029/2019gc008214
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发表时间：
2019-07
期刊：
影响因子：
3.7
通讯作者：
K. Yasukawa;J. Ohta;T. Miyazaki;B. Vaglarov;Q. Chang;K. Ueki;C. Toyama;J. Kimura;E. Tanaka
中科院分区：
文献类型：
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作者：
K. Yasukawa;J. Ohta;T. Miyazaki;B. Vaglarov;Q. Chang;K. Ueki;C. Toyama;J. Kimura;E. Tanaka
某种类型的深海沉积物具有非常高的稀土元素和钇（REY）含量，因此有望成为这些工业必需金属的新资源。在本文中，我们统计分析了从北太平洋西部采集的深海沉积物的整体化学组成。通过对多元素数据集进行独立成分分析，我们提取了三个独立成分（IC），可以解释为Mn氧化物（IC 1），REY富集的生物源磷酸钙（IC 2）以及可能涉及Cu富集的成岩作用（IC 3）对散装沉积物地球化学的影响。随后，根据独立组分分析结果，选取代表性样品，进行了块状沉积物Sr-Nd-Pb同位素分析。结果表明，以IC 2为特征的富REY泥继承了太平洋深海海水的地球化学特征，而以IC 3为特征的非富REY泥具有较少的成岩蚀变，暗示可能来自塔克拉玛干沙漠-中国黄土高原的陆源粉尘的影响。IC 1可以反映沉积速率的变化。IC 1和IC 3分数的特征性井下变化意味着在REY含量峰值处存在沉积物柱的间断和/或侵蚀。推测的原因是增强的底流，它可以物理分离具有非常高的REY含量的粗生物钙磷酸盐颗粒，从而产生非常富含REY的沉积物层。
A certain type of deep‐sea sediment exhibits very high content of rare earth elements and yttrium (REY) and is therefore expected to serve as a novel resource for these industrially essential metals. In this paper, we statistically analyzed the bulk chemical composition of deep‐sea sediments collected from the western North Pacific Ocean. By applying independent component analysis to the multielemental data set, we extracted three independent components (ICs) that can be interpreted as the influence of Mn‐oxides (IC1), REY‐enriched biogenic calcium phosphate (IC2), and possibly a diagenetic effect involving Cu enrichment (IC3) on bulk sediment geochemistry. Subsequently, we selected representative samples based on the independent component analysis result, and implemented Sr–Nd–Pb isotopic analyses of bulk sediments. The results indicate that the extremely REY‐rich mud characterized by IC2 inherits the geochemical signature of deep Pacific seawater, whereas the non‐REY‐rich mud with less diagenetic alterations, characterized by IC3, implies an influence of terrigenous dust probably from the Taklimakan desert–Chinese loess plateau. IC1 may reflect the variation in sedimentation rates. Characteristic downhole variations of IC1 and IC3 scores imply the presence of hiatus and/or erosion of the sediment column across the REY content peak. The putative cause is an enhanced bottom current, which can physically separate coarse biogenic calcium phosphate grains with very high REY content and thus produce an extremely REY‐enriched sediment layer.