南海边缘海多金属结核与大洋多金属结核对比

本文通过系统对比分析前人研究成果，研究了南海边缘海多金属结核的成矿特征，结果表明：南海边缘海结核的矿物组成与大洋结核相似，均主要由锰相矿物和铁相矿物组成，其中锰相矿物主要为水羟锰矿和钡镁锰矿，铁相矿物主要以无定型铁氧化/氢氧化物形式存在，另外南海边缘海结核中含有大量硅酸盐矿物，表明在南海结核成矿过程中受到大量的陆源碎屑矿物混杂；相对于大洋主要经济成矿区的多金属结核，南海边缘海多金属结核中主要的经济元素如Mn、Cu、Co、Ni和Zn质量分数较低，而亲陆源性元素如Fe、Ti、P、Nb、Pb、Rb、Sc、Ta、Sr、Th和REY（REE和Y）等质量分数较高；南海边缘海多金属结核的元素地球化学特征和REE配分模式显示其为水成成因，并呈现更低的Mn/Fe值；同时南海边缘海结核也具有较快的平均生长速率及较高的δCe正异常，表明其生长在更为氧化的海水环境。虽然较快的沉积物沉积速率和动荡的海水环境影响了南海边缘海结核的成矿，但大量陆源物质进入海洋也为南海边缘海结核提供了丰富的成矿物质来源，便于南海边缘海结核的快速生长成矿。南海边缘海结核富集有Fe、Ti、Pb、Rb、Th和REY等金属元素，同样可以作为极具潜力的海洋矿产资源。南海边缘海多金属结核具有其独特的地球化学特征，与大洋多金属结核存在着明显差异。

Comparison Between the Marginal-Sea Polymetallic Nodules in South China Sea and Ocean Polymetallic Nodules

With the discovery of more and more polymetallic nodule mineralization zones in the South China Sea (SCS) in recent years, the researches of marine polymetallic nodules in this area have become deeper. The SCS marginal-sea polymetallic nodules have their own unique characteristics, which are very different from those in the oceanic environment. Based on the comparative analysis of the previous research results, the authors studied the metallogenetic characteristics of the SCS polymetallic nodules, and provided theoretical guidance for the evaluation of the SCS submarine polymetallic mineral resources. The results show that the mineral composition of the SCS marginal nodules is basically similar to that of oceanic nodules, mainly composed of Mn-and Fe-phase minerals, but the SCS nodules contain a large amount of silicate minerals, indicating that they are greatly affected by terrestrial detrital minerals. Compared to the oceanic nodules in the main economic mineralization zones, the content of the main economic elements such as Mn, Cu, Co, Ni and Zn in the SCS nodules are relatively low, while the contents of terrestrial-derived elements such as Fe, Ti, P, Nb, Pb, Rb, Sc, Ta, Sr, Th and REY (REE and Y) are relatively high. The elemental geochemical characteristics and REE shale-normalized patterns of the SCS polymetallic nodules show that they are of hydrogenetic origin with lower Mn/Fe ratios, high average growth rate, and relatively higher positive δCe anomalies, indicating that the SCS nodules grew in more oxidizing seawater environment. Although the high sediment accumulation rate and turbulent seawater environment affect the mineralization of the SCS nodules, the entry of a large number of terrestrial material provides a rich source of metallogenetic material for the rapid growth of nodules. The SCS marginal polymetallic nodules are rich in a variety of economic metal elements, and can be used as potential marine mineral resources.