Rare-earth, major, and trace element geochemistry of deep-sea sediments in the Indian Ocean: Implications for the potential distribution of REY-rich mud in the Indian Ocean
Rare-earth, major, and trace element geochemistry of deep-sea sediments in the Indian Ocean: Implications for the potential distribution of REY-rich mud in the Indian Ocean
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DOI：
10.2343/geochemj.2.0361
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发表时间：
2015-01-01
影响因子：
0.8
通讯作者：
Kato, Yasuhiro
中科院分区：
文献类型：
--
作者：
Yasukawa, Kazutaka;Nakamura, Kentaro;Kato, Yasuhiro
我们分析了来自覆盖印度洋大部分地区的 19 个深海钻探项目/海洋钻探计划地点的 1338 个深海沉积物样本，并构建了一个关于其大量化学成分的新的综合数据集，包括稀土、主量元素和微量元素。富集REY样品的块状沉积物稀土和钇（REY）组成具有相对较小的Ce负异常、几乎没有Y异常以及重稀土元素富集的特点，可以解释为磷灰石和含氢铁锰氧化物的REY组分的叠加。虽然热液成分是太平洋富含 REY 泥浆形成的关键因素，但在印度洋则不太重要，可能是因为那里海底热液喷口输入的羟基氧化铁热液较少。 Fe2O3、MnO、P2O5、Co和REY总含量之间的关系表明，控制深海沉积物中REY富集的主要因素是沉积速率。低沉降速率使得鱼残骸磷灰石和含氢铁锰（羟基）氧化物在表面沉积物中积聚。根据这些结果，我们确定了印度洋表层沉积物中可能存在富含 REY 泥浆的两个潜在区域：沃顿盆地东南部和中印度洋盆地南部。如果富含REY的泥浆和铁锰结核田的分布广泛重叠，则后一地区的资源潜力可能特别高。
We analyzed 1338 deep-sea sediment samples from 19 Deep Sea Drilling Project/Ocean Drilling Program sites covering a large portion of the Indian Ocean, and constructed a new and comprehensive data set of their bulk chemical compositions, including rare-earth, major, and trace elements. The bulk-sediment rare-earth and yttrium (REY) composition of the REY-enriched samples, characterized by relatively small negative Ce anomalies, almost no Y anomalies, and enrichment in heavy rare-earth elements, can be interpreted as the superposition of the REY compositions of apatite and hydrogenous Fe-Mn oxides. Although the hydrothermal component is a key factor in the formation of REY-rich mud in the Pacific Ocean, it is less important in the Indian Ocean, probably because there is less hydrothermal input of Fe-oxyhydroxides from seafloor hydrothermal vents there. The relationships among Fe2O3, MnO, P2O5, Co, and total REY contents suggest that a primary factor controlling REY enrichment in deep-sea sediments is the sedimentation rate. A low sedimentation rate allows both fish debris apatite and hydrogenous Fe-Mn (oxyhydr)oxides to accumulate in the surface sediments. On the basis of these results, we identified two potential areas in the Indian Ocean where REY-rich mud may be present in surface sediments: the south-southeastern Wharton Basin and the southern Central Indian Ocean Basin. The resource potential of the latter area might be particularly high if the distributions of REY-rich mud and Fe-Mn nodule fields broadly overlap.