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由于新生代巨量陆源物质的堆积,发育完好的多金属结核在南海北部罕见.对南海西北陆缘大型多金属结核进行了矿相显微镜观察,电子探针、X射线粉晶衍射(XRD)、等离子质谱(ICP-MS)等方面的分析和铍同位素测年.结核壳层显微结构类型丰富,呈现柱状、纹层状、叠层状、花瓣状、斑杂状等类型;主要矿物为δMnO2.与东太平洋海盆结核相比,南海样品Fe,Si,Al和REE(稀土元素)含量高,Mn,Cu,Co和Ni含量低,Mn/Fe低;REE平均含量达1370.4ppm,存在较强的Ce正异常;铍同位素测年显示结核的初始生长时间约为3.29～1.83Ma,形成结核的内致密层,纹层状和叠层状构造发育,陆源属性的Fe,Si,REE和Al等含量较低,反映底流活动和氧化条件较弱的古海洋环境.1.83～0.73Ma,结核生长速率提高了约3%,显微结构为叠层状和柱状构造,Si和Al等组分含量升高近10%,指示南海北部陆源物质向海输入的增加;但Ce含量下降约16%,代表海底氧化程度明显降低.0.73～0.69Ma,结核生长速率急剧升高,达平均生长速率的8.27倍,壳层中Fe,Al和REE等含量也迅速上升,形成以鲕状、颗粒状、斑杂状、花瓣状为特征的疏松层,指示南海北部出现沉积速率升高、陆源物质供应充分的古海洋环境;0.69～0.22Ma,结核生长速率骤然减慢,形成外致密层,壳层中Fe,Si,REE,Al及Mn,Cu,Co和Ni等元素含量均明显降低,壳层以纹层状和裂隙充填构造为特征,反映底流活动平稳、环境氧化强度减弱等不利于结核生长的古海洋环境.结核S04-1DG-1的生长历史,对新生代末期南海北部古海洋环境的变化产生了灵敏的响应.
Due to the accumulation of huge amount of terrigenous materials in the Cenozoic, the well-developed polymetallic nodules are rare in the northern part of the South China Sea. The metallographic microscope, electron probe, X-ray powder diffraction (XRD) (ICP-MS) and isotope dating of beryllium.The tuberculous shell is rich in microstructure with columnar, laminar, laminar, petaloid and mottled patterns, and the main minerals are δMnO2 Compared with the marine tuberculosis in the East Pacific, the samples from the South China Sea show high Fe, Si, Al and REE (REE) contents, low contents of Mn, Cu, Co and Ni, and low Mn / Fe contents. The average REE content reaches 1370.4 ppm, . The beryllium isotope dating shows that the initial growth time of TB is about 3.29-1.83Ma, forming the inner dense layer, laminar and laminated structure of TB, Fe, Si, REE and Al of terrigenous properties Lower than normal, reflecting the underflow activity and the weak oxidizing ancient paleoenvironment.1.83 ~ 0.73Ma, the tuberculosis growth rate increased by about 3%, the microstructure of the laminated and columnar structure, Si and Al and other components increased Up nearly 10%, indicating that the import of terrestrial materials in the northern South China Sea increased to the sea; but the Ce content decreased About 16%, representing the seafloor oxidation was significantly reduced .0.73 ~ 0.69Ma, tuberculosis growth rate increased sharply, reaching an average growth rate of 8.27 times, the shell of Fe, Al and REE content also increased rapidly to form the oolitic, Granular, patchy, petal-shaped loose layer, indicating the northern South China Sea sedimentation rate increased, the supply of terrestrial material sufficient ancient marine environment; 0.69 ~ 0.22Ma, the sudden drop in the growth rate of tuberculosis to form an outer dense layer, The contents of Fe, Si, REE, Al and Mn, Cu, Co and Ni all decreased obviously in the shell, and the crust was characterized by laminar and fissure filling structure, which reflected the stable underflow and the weakening of the oxidation intensity of the environment The ancient marine environment of tuberculosis growth.The growth history of tuberculosis S04-1DG-1 produced a sensitive response to the change of ancient marine environment in the northern South China Sea in the late Cenozoic.