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从东太平洋中国开辟区南部挑选了4个铁锰结核(地理坐标,北纬7.7533°～8.6866°,西经143.875°～146.937°),每个结核以内部较容易剥离面和密集的铁锰质纹层为界,分成核部、中部和边部3部分,共12个样品做了Ce、Nd同位素组成和REE浓度测定。另外,从相同站位上又选择了3个结核进行了全结核的常量和微量元素浓度测定。常量与微量元素浓度测定结果证明,被研究结核属于早期成岩型。稀土元素图形特征与以前报道不同,从较广泛区域内挑选出的样品,除一个基本上无Ce异常外,其他都显示弱的负Ce异常,平均δCe为0.85。更重要的特征是,被测定的12个样品ε_(Ce)和ε_(Nd)都呈负值,同时,ε_(Nd)值高于其他大洋,它们分别为-0.80～-1.9和-1.4～-4.6,在ε_(Ne)-ε_(Nd)坐标图上位于第Ⅲ象限。根据这些特征,结合洋底地质环境,可能暗示直接或间接来源于大洋亏损地幔的成矿物质在太平洋结核中占有绝对优势。结核内部壳层之间的Ce、Nd同位素组成和Ce异常强度的变化,可能说明,在整个结核形成期间,成矿组分的来源曾发生过较大变化,幔源组分的强烈活动出现在结核的形成过程中。
Four ferromanganese nodules (geographical coordinates, latitude 7.7533 ° ~ 8.6866 ° north, longitude 143.875 ° ~ 146.937 ° N) were selected from the southern part of the eastern Pacific Pioneer in the Eastern Pacific. Each nodule was characterized by an easily peelable surface and an intensive ferromanganese texture Layer into three parts, divided into three parts, a total of 12 samples of Ce, Nd isotope composition and REE concentration determination. In addition, three nodules were selected from the same stations for the determination of total nodules and trace element concentrations. The results of constant and trace element concentrations confirm that the studied tuberculosis belongs to the early diagenetic type. The characteristics of rare earth elements are different from the previous reports. Samples from a wider area show weak negative Ce anomaly except for one without any Ce anomaly, with an average δCe of 0.85. More importantly, all of the 12 samples tested have negative ε ε (Ce) and ε Nd (Nd) values, while ε Nd values are higher than those of other oceans. They are -0.80 -1.9 and -1.4 ~ -4.6, located in the third quadrant on ε_ (Ne) -ε_ (Nd). According to these characteristics, in combination with the geological environment of the ocean floor, it may be suggested that ore-forming materials derived directly or indirectly from the oceanic depleted mantle have an absolute advantage in Pacific tuberculosis. The changes of Ce, Nd isotopic compositions and Ce anomalies between the inner tubers of the nodules may indicate that the source of the ore-forming components has undergone major changes during the entire nodule formation and intense activities of the mantle source components occur at Tuberculosis formation process.