Mineral chemical characteristics of sphalerites from the Tongshanling Cu-Pb-Zn deposit in southern Hunan and their metallogenic implications
Electron microprobe analyses have been conducted on sphalerites in different types of ores to constrain the ore-forming process of the Tongshanling Cu-Pb-Zn deposit in southern Hunan.The results suggest that Fe occurs mainly in form of direct substitution for Zn and Cd occurs probably in form of coupled substitution with Fe for Zn(Cd2++Fe2+↔2Zn2+)in sphalerite lattice,and submicroscopic chalcopyrite inclusions likely exist in the sphalerites of Cu-bearing ores.The variations of Fe,Cd contents and Fe/Zn,Zn/Cd ratios of sphalerites indicate that the proximal endo skarn,proximal exoskarn,and distal skarn orebodies were sequentially formed,the Cu sulfide-quartz vein,Cu-Pb-Zn sulfide-quartz vein,and Pb-Zn sulfide-quartz vein orebodies were sequentially formed,and the carbonate replacement orebodies were formed in the late stage.Based on characteristics of deposit geology and sphalerite mineralogy,it is believed that there could be two episodes of fluids exsolved from granodioritic magma in the Tongshanling Cu-Pb-Zn deposit.The earlier exsolved fluid was a kind of relatively high-temperature Cu-Pb-Zn-bearing one which resulted in the proximal endoskarn,proximal exoskarn,distal skarn,Cu sulfide-quartz vein,and Cu-Pb-Zn sulfide-quartz vein mineralization;while the later exsolved fluid was a kind of relatively low-temperature Pb-Zn-bearing one which resulted in the Pb-Zn sulfide-quartz vein and carbonate replacement mineralization.
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