湘黔下寒武统黑色岩系不同矿物组合中的铂族元素特征

贵州遵义和湖南张家界黑色岩系中的矿物组合非常复杂,用X射线衍射仪分析并结合前人的研究成果,显示其中的硫化物矿物、粘土矿物和有机质含量较高;经破碎和分选流程对样品进行处理后,用ICP-MS方法测定了黑色页岩和分选后样品中的铂族元素含量,对贵州遵义和湖南张家界黑色岩系中的铂族元素赋存特征进行研究,结果表明:贵州遵义和湖南张家界的黑色页岩系中赋存高含量的铂族元素,且含量表现较高的稳定性;低温氧化条件下,铂族元素的化学活动性足以使之以相当规模活化、迁移并在还原条件下沉淀富集;经强风化淋滤作用,富含碳硫钼矿黑色页岩中铂族各元素含量都有不同程度的降低;绝大部分的铂族元素富集于黑色页岩的有机质和黄铁矿中;铂族元素的分布模式具规律性,铂族元素的明显分异说明此黑色页岩的分布模式不具有地外物质的特征。

Features of platinum-group elements in different mineral assemblages in the Lower Cambrian black rock series in Hunan and Guizhou

The mineral assemblages are very complex in the Lower Cambrian black shale in Zhangjiajie of Hunan and Zunyi of Guizhou. X- ray diffraction analysis combined with previous research results shows that the contents of sulfide minerals, clay minerals and organic matter are relatively high. After crushing and separation of the samples, the ICP-MS method was used to determine the PGE contents of the black shale and separated samples, and in addition, the mode of occurrence of PGE in the black shale in the study areas was studied. Study shows that the content of PGE in the area is high and stable. The chemical activity of PGE is high enough to enable them to be remobilized to a considerable extent under low-temperature, oxidizing conditions and precipitated and concentrated under low-temperature, reducing conditions. The PGE contents of black shale in the primary C/MoS2 mixed-layer mineral-rich black shale decreased to varying extent after strong weathering and leaching. The greater majority of the PGE are concentrated in organic matter and pyrite. The PGE distribution patterns show certain regularity. The remarkable differentiation of PGE demonstrates that the distribution pattern of the black shale does not have the characteristics of extraterrestrial material.