云南中甸地区烂泥塘低温热液型Cu-Au矿床铂族元素(PGE)地球化学特征

Geochemistry of Platinum-Group Elements of the Lannitang Epithermal Cu-Au Deposit in the Zhongdian Region,Yunnan Province,SW China

采用ICP-MS分析方法研究烂泥塘浅成低温热液型Cu-Au矿床中黄铜矿铂族元素(PGE),结果显示黄铜矿的∑PGE较低,其值为5.46×10-9～19.0×10-9。原始地幔标准化PGE配分模式呈Ru、Pd相对于Ir、Pt富集的趋势。Pd/Ir、Ru/Ir、Pt/Ru、Pd/Pt比值分别变化在2.35～21.9、15.6～42.3、0.02～0.20和4.83～21.8之间。除Pt/Ru比值低于原始地幔外,其他比值均高于原始地幔,这表明黄铜矿的Ir、Ru、Pt和Pd之间发生了分异。黄铜矿中相对高的Ru和Pd含量可能是热液流体对早期矿化斑岩选择淋滤的结果。

The platinum-group elements （PGE） of chalcopyrites from the Lannitang epithermal Cu-Au deposit is studied by using ICP-MS method.The total PGE contents （∑PGE） of the Lannitang chalcopyrites are quite low,ranging from 7.90 × 10-9 to 56.9 × 10-9.The primitive mantle-normalized PGE distribution patterns exhibited a trend of enrichment in Ru and from Pd to Ir and Pt.The ratios of Pd/Ir,Ru/Ir,Pt/Ru and Pd/Pt range from 2.35 to 21.9,15.6 to 42.3,0.02 to 0.20 and 4.83 to 21.8,respectively.With the exception of Pt/Ru ratio,other ratios mentioned above are higher than those of primitive mantle,indicating that the differentiation occurs between Pd and Ir,Ru,and Pt in the chalcopyrites.The relatively high Ru and Pd contents in chalcopyrite separates are probably derived from selective leaching of the early-stage mineralized porphyry by the oxided hydrothermal fluid.