中太平洋YJB海山富钴结核矿物组成与元素地球化学

研究样品采自马尔库斯（MARCUS）海脊YJB海山。利用等离子光谱、等离子质谱、X射线衍射、红外光谱、场发射电镜等分析测试方法，对其富钴结核中不同构造层的矿物组成和元素地球化学研究表明： 该球状结核核部是玄武岩，向外具四层构造。矿石矿物为水羟锰矿和少量的钙锰矿，脉石矿物为磷灰石、石英、斜长石等，微量矿物有蒙脱石、高岭石、钠沸石、方英石、辉石、束沸石等。老结核相对富TMn、Cu、Ca、P等元素，新结核相对富集TFe、Co、Ni、Si、Al等元素。在老、新结核中，从下部构造层到上部构造层，TMn、Co、Ni、Cu、Ba、Zn、Pb、Mo等的质量分数逐渐减少，TFe逐渐增加。核内玄武岩属大洋板内玄武岩，其成因可能与地幔柱有关。结核的稀土元素总量是1 924.07×10^-6，Ce具明显的正异常。在老、新结核不同构造层中，Ce的演化趋势同TMn等元素，其他稀土元素与Fe等相似。

Mineral Composition and Element Geochemistry of Co-Rich Nodule from YJB Sea Mount in Central Pacific Ocean

The mineral composition and the contents of the ore forming and rare earth elements in different spherical layers of Co-rich nodules, collected from the YJB Sea Mount in the MARCUS Ridge in the central Pacific ocean, were determined using ICP-AES,ICP-MS,XRD,FT-IR and JSM. The results show that the spherical nodules consist of a basalt core and four surrounding spherical layers. In the nodules, the ore minerals include vernadite and a small amount of todorokite, gangue minerals are apatite quartz and plagioclase and minor minerals are montmorillonite, kaolinite, natrolite, cristobalite, pyroxene, stibite and others. TMn, Cu, Ca and P are relativily enriched in the old nodules while TFe, Co, Ni, Si and Al are enriched in new nodules. In both the old and new nodules, the contents of TMn, Co, Ni, Cu, Ba, Zn, Pb and Mo are gradually decreased from the underlying layers outwards and that of TFe is increased. The core basalts belong to WPB. Their total REE contents are measured to be 1 924.07×10^-6 with distinctively positive Ce anomalies. In different spherical layers of both the old and new nodules the varying tendency of Ce is similar to that of TMn while varying tendency of other REE to that of Fe.