Deep-sea sediments with high contents of rare-earth elements and yttrium (REY) are expected to serve as a potential resource for REY, which have recently been proved to be mainly contributed by phosphate component. Studies have shown that the carriers of REY in deep-sea sediments include aluminosilicate, Fe-Mn oxyhydroxides, and phosphate components. The ∑REY of the phosphate component is 1–2 orders of magnitude higher than those of the other two carriers, expressed as ∑REY = 0.001 × [Al₂O₃] − 0.002 × [MnO] + 0.056 × [P₂O₅] − 32. The sediment P₂O₅ content of 1.5% explains 89.1% of the total variance of the sediment ∑REY content. According to global data, P has a stronger positive correlation with ∑REY compared with Mn, Fe, Al, etc.; 45.5% of samples have a P₂O₅ content of less than 0.25%, and ∑REY of not higher than 400 ppm. The ∑REY of the phosphate component reaches n × 10⁴ ppm, much higher than that of marine phosphorites and lower than that of REY-phosphate minerals, which are called REY-rich phosphates in this study. The results of microscopic observation and separation by grain size indicate that the REY-rich phosphate component is mainly composed of bioapatite. When ∑REY > 2000 ppm, the average CaO/P₂O₅ ratio of the samples is 1.55, indicating that the phosphate composition is between carbonate fluoroapatite and hydroxyfluorapatite. According to a knowledge map of sediment elements, the phosphate component is mainly composed of P, Ca, Sr, REY, Sc, U, and Th, and its chemical composition is relatively stable. The phosphate component has a negative Ce anomaly and positive Y anomaly, and a REY pattern similar to that of marine phosphorites and seawater. After the early diagenesis process (biogeochemistry, adsorption, desorption, transformation, and migration), the REY enrichment in the phosphate component is completed near the seawater/sediment interface. In the process of REY enrichment, the precipitation and enrichment of P is critical. According to current research progress, the REY enrichment is the result of comprehensive factors, including low sedimentation rate, high ∑REY of the bottom seawater, a non-carbonate depositional environment, oxidation conditions, and certain bottom current conditions.

太平洋深海沉积物中富集稀土元素（REY，包括钇），被认为是富有潜力的新型稀土资源。（含）沸石粘土、深海粘土和多金属软泥是主要的富含REY的沉积物类型，其中（含）沸石粘土和深海粘土在中、西北太平洋海盆大面积分布，而多金属软泥则多分布于靠近东太平洋洋脊热液活动的深海盆地中。目前关于中、西北太平洋海盆的深海粘土和（含）沸石粘土已有较多的研究，但关于多金属软泥中REY的研究较少。不同区域、不同类型深海沉积物中的稀土元素赋存状态有何差异？影响稀土富集的机制又是什么目前尚不清楚，也就进一步影响了对深海沉积物稀土资源的勘查和开发工作。本文分析对比了太平洋不同区域不同类型深海沉积物的地球化学特征及矿物学特征。结果表明，总体上，中、西北太平洋海盆深海沉积物中，尤其是（含）沸石粘土中的REY含量明显高于东太平洋海盆多金属软泥REY含量，其REY的富集主要与磷酸盐有关。超常富集REY （ΣREY>2000×10^-6）的沉积物中的CaO/P₂O₅比值趋向于一致（~1.4），几乎接近于磷灰石CaO/P₂O₅比值（~1.3），因此REY主要赋存载体为磷灰石，该区沉积物中REY的富集可能受到磷酸盐化的影响；东太平洋海盆多金属软泥明显受到热液影响，铁和锰的含量明显增加，但其ΣREY含量集中于500×10^-6~800×10^-6，不随铁和锰的增加而变化，REY的富集仍与磷酸盐关系密切，而与铁锰物质和铝硅酸盐关系不大。中、西北太平洋海盆富稀土的深海沉积物形成时处于较强的氧化环境，同时又有充足的含磷物质补给，才造成REY在该区沉积物中的超常富集；而东太平洋海盆多金属软泥虽然处于氧化环境，但缺少足够的磷补给，所以其ΣREY含量通常低于中、西北太平洋海盆沸石粘土中ΣREY含量。