中太平洋YJC海山富钴结壳矿物组成与元素地球化学

Mineral composition and element geochemistry of Co-rich crust from the YJC sea mount in the Central Pacific Ocean

运用等离子光谱、等离子质谱、X射线衍射、红外光谱和场发射电镜等分析测试方法,对太平洋威克(Wake)海岭YJC海山中的富钴结壳中不同构造层的矿物组成和元素地球化学研究表明:矿石矿物是水羟锰矿和少量的钙锰矿,脉石矿物是磷灰石、石英和方解石等,微量矿物有蒙脱石、高岭石、钠沸石、斜发沸石、伊利石、水黑云母、磁铁矿和角闪石等。老结壳磷灰石的质量分数>10%,P>1%;新结壳磷灰石<10%,P<1%。老结壳相对富集Cu、Ca、P等元素,新结壳相对富集TMn、TFe、Co、Ni、Ba、Zn、Pb、Mo等元素。结壳内部纹层构造的不同位置及包体内的微区成分变化较大,TMn和TFe呈同消长关系,但TMn/TFe值相对稳定。结壳的稀土元素总量为1761.88×10-6,Ce具明显的正异常。老结壳相对富集稀土元素,新结壳略富Eu。

The mineral composition and the concentration of ore-forming and rare earth elements of Cocrust in different structure layers from the YJC sea mount in the Wake ridge in the Central Pacific Ocean, were studied by means of the ICP-AES,ICP-MS,XRD,FT-IR, JSM. The results show that ore minerals are vernadite and a little todorokite; gangue minerals are apatite, quartz and calcite; minor minerals are montmorillonite, kaolinite, natrolite, clinoptilolite, illite, ehydrobiotite, magnetite and amphibole, etc. In old crusts the mass fraction of apatite is over 10% with P more than 1% ; while in new crusts the contents of apatite is less than 10% with P less than 1%. The contents of Cu, Ca and P are enriched in the old crusts, while TMn, TFe, Co, Ni, Ba, Zn, Pb, Mo are enriched in the new crusts, relatively. The various tendencies of TMn and TFe are similar, but value of TMn/TFe is relatively stable relatively. The total REE content in the crust is 1 761.88 ×10^-6 with Ce in distinctively positive anomaly. The REE are enriched in the old crust, while the Eu is only some enriched in the new crust.