【摘要】 采用镍锍火试金法结合ICP-MS分析了毛屋斜方辉石岩和石榴二辉岩样品中的Ir、Ru、Rh、Pt和Pd的含量,结果显示其铂族元素(PGE)的含量随岩石类型无规律性的变化,原始地幔标准化后的铂族元素分布模式呈负斜率,Pd、Ir发生了分异。毛屋超镁铁岩铂族元素特征的形成受岩石中铂族元素的存在相制约,PPGE富集在富Cu硫化物,而IPGE以类似残留相、不熔的单硫化物固熔体形式存在,其中地壳混染也起了一定的作用;同时,成岩过程中流体的存在造成了Pt和Pd的活化。因此,单硫化物固熔体和流体的共同作用形成了毛屋超镁铁岩类似残留地幔岩的铂族元素分布特征。更多还原

【Abstract】 The contents of platinum group elements (PGE; Ir, Ru, Rh, Pt, Pd) in orthopyroxenite and garnet websterite in Maowu have been determined using the nickel sulfide fire assay, combined with ICP-MS. Analysis indicates that: the PGE abundances are not related to rock types, and the primitive mantle-normalized PGE patterns have negative slopes, showing the fractionation of Pd and Ir. The formation of these PGE characters was constrained by the presence of PGE in rocks. Analysis of the PGE-carrier phases shows that PPGE are concentrated in Cu-rich sulfides, while IPGE occur as quasi-residual, insoluble monosulfide solid solution. Crustal contamination also contributed to the fractionation of platinum-group elements. In addition, the presence of fluids during rock formation resulted in selective mobilization of Pt and Pd. Therefore the combined action of monosulfide solid solutions and fluids produced the characteristics of PGE distribution in quasi-residual pyrolite of the Maowu ultramafic rocks.更多还原