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.