西太平洋海山玄武岩的岩石学特征及与上覆富钴结壳的关系

通过对西太平洋海山玄武岩和玄武质火山角砾岩的岩石学特征及其气孔充填物成分变化的研究,讨论了海山玄武岩与上覆富钴结壳的关系。富钴结壳的基岩火山岩主要为碱性玄武岩和玄武质火山角砾岩。碱性玄武岩中气孔充填物为S型和C型,S型和C型气孔充填物不共存在同一个气孔中。S型气孔充填物的物质成分富Si、Fe、K、Mg、Al,Co含量一般为0.17%~0.46%,其成分与碱性玄武岩的组成类似,其物质来源可能与碱性玄武岩有关。C型气孔充填物为O、Ca、C及少量Si、Al、Mg、Fe、K等元素,C型气孔充填物可能与海水中物质的沉积有关。由Si、Al、Fe、Mg、K等元素变化曲线反映出的S型气孔充填物沉积过程与富钴结壳早期的沉积过程具有相似的趋势,说明富钴结壳早期沉积物的物质来源可能与碱性玄武岩有关,富钴结壳物质来源可能是碱性玄武岩和海水共同作用的结果。

Characteristics of the Basaltic Petrology from Western Pacific Ocean Seamount and Relation Between Overlying Co-rich Crust and Basalt

On the basis of characteristics of the basalt and basaltic volcanic breccia from western Pacific Ocean seamount and the composition changes of the vesicle filling,this paper will discuss relation between the overlying cobalt crust and the seamounts basalt.The bedrocks for cobalt-rich crusts are the alkaline basalt and basaltic volcanic breccia.The alkaline basaltic vesicle filling with S-type and C-type.S-type and C-type vesicle fillings do not exist in one vesicle.S-type vesicle filling composition rich in Si,Fe,K,Mg,Al and Co content generally changes between 0.17% and 0.46%.S-type vesicle filling composition is similar to the composition of alkali basalt.S-type vesicle filling source may be the alkali basalt.C-type vesicle filling composition is rich in O,Ca,C and with a small amount of Si,Al,Mg,Fe,K and other elements,which may be related to ocean water material deposition.The deposition process of the S-type vesicle filling reflected Si,Al,Fe,Mg,K and other elements is similar to the early trends of the deposition process of cobalt-rich crusts.The source of early deposition of cobalt-rich crusts may have relation to the alkali basalt.The source of early deposition of cobalt-rich crusts may be a result of the joint deposition of alkaline basalts and ocean water.