铅锌矿床中闪锌矿Cd含量及Zn/Cd值的地质意义

以5个典型铅锌矿床为研究对象，测试了其闪锌矿中的Zn和Cd含量，发现同一标本上深色闪锌矿比晚期的浅色闪锌矿更富集Cd，其原因可能与流体中Zn/Cd值变化相关；而对比不同矿床不同颜色闪锌矿之间Cd的富集规律是没有意义的。同时，与岩浆作用相关的铅锌矿床，其闪锌矿中的Zn/Cd值与相关岩浆岩的Zn/Cd值相似，暗示闪锌矿中的Zn/Cd值可指示成矿物质来源。同时，川滇黔地区铅锌矿床显示出2组不同的Zn/Cd值：①高Zn/Cd值型（300～800），以会泽矿床为代表，其Zn/Cd值介于峨眉山玄武岩和该区地层之间，暗示该类型矿床的成矿物质可能主要来源于峨眉山玄武岩和地层。②低Zn/Cd值型（20～70），以富乐矿床为代表，其Zn/Cd值基本与地层相似，暗示该矿床的成矿物质可能主要来源于地层。而对比川滇黔地区铅锌矿床和与岩浆作用相关矿床的Cd含量及Zn/C值发现，成因不同的矿床，其Cd含量和Zn/Cd值具有较大差异。因此，铅锌矿床闪锌矿中的Cd含量及Zn/Cd值对于判别成矿物质来源和矿床成因具有指示意义。

Cd contents and Zn/Cd Ratios of Sphalerites and Their Geological Implications

In this paper, the Zn and Cd contents in sphalerites from five typical Zn-Pb depositshave been investigated and tested. The results show that dark sphalerite (early stage) has higher Cd contents than light one (late stage) in a hand specimen, which may be caused by Zn/Cd decreasing of ore-forming fluids. Meanwhile, the sphalerites from magma-related Zn-Pb deposits have similar Zn/Cd ratios with the source bed, suggesting that Zn/Cd ratios could be a proxy to trace the origins of metallogenic materials. Zn/Cd ratios in sphalerite from major Zn-Pb deposits in Sichuan-Yunnan-Guizhou metallogenic province could be divided into two groups, which are:①High Zn/Cd ratios (e.g. the Huize deposit), the deposits of this group have high Zn/Cd ratios (300-800),which are varied between the ones of the Emeishan basalts (Zn/Cd ratios higher than 1000) and sedimentary rocks (Zn/Cd ratios lower than 100), suggesting that ore-forming metals were derived from the mixture of Emeishan basalts and strata; ②Low Zn/Cd ratios (e.g. the Fule deposit), the deposits of this group have low Zn/Cd ratios (20-70), which are similar to that of sedimentary rocks, indicating that ore-forming metals were derived from the strata. Based on the Cd contents and Zn/Cd ratios, it's found that various ypes of Zn-Pb deposits have different Cd contents and Zn/Cd ratios. Therefore, the Cd content and the Zn/Cd ratio in sphalerite s are indicative in revealing the source of ore-forming materialsand genesis of Pb-Zn deposits.