The Huize ore fi eld, which is the most famous high-grade Mississippi Valley-type Zn-Pb ore fi eld in China, consists of the Kuangshanchang and Qilinchang deposits. The Sm-Nd isotopic compositions of gangue calcite were analyzed to constrain the timing of mineralization. Eight calcite samples from the No. 6 orebody in the Qilinchang deposit have Sm and Nd concentrations of 1.82 -25.93 and 15.25 -79.02 ppm, respectively, and yielded an age of 225 ± 9.9 Ma with epsilon Nd = −10.6 and MSWD = 0.13. Five calcites from the No. 1 orebody in the Kuangshanchang deposit contain 2.37 -2.90 ppm Sm and 8.18 -16.85 ppm Nd, and yielded an age of 228 ± 16 Ma, with epsilon Nd = −10.6 and MSWD = 0.28. These two ages are close to the age of the Emeishan fl ood basalt, which is ca 255 Ma, and agree with the reported 40 Ar/ 39 Ar plateau and isochron ages of the native copper mineralization related to the Emeishan fl ood basalt in this region, which are 226 -228 Ma. Moreover, previous study shows that the magnitude of uplift resulting from the Emeishan fl ood basalts is >1000 m. It indicates that the Kuangshanchang and the Qilinchang deposit formed during the same geological event and originated by fl uid migration during uplift resulting from the Emeishan fl ood basalt.
The giant Huize Zn-Pb ore field in Yunnan Province, southwestern China, comprises the Qilinchang and Kuangshanchang deposits. The deposits are large in scale (more than 5 Mt of Zn and Pb) and high in grade (average grade of total Zn and Pb is 30%). Reported in this paper are the results of Rb-Sr isotopic dating of sphalerite from this ore field. Two precise ages (223.5±3.9 Ma and 226±6.4 Ma) have been obtained from two isochrons. These two ages are close to the reported ages of native copper mineralizations related to the Emeishan flood basalts in this region, which are 226 Ma to 228 Ma. Previous studies showed that the magnitude of uplift resultant from the Emeishan flood basalts is greater than 1000 m, indicating that the Kuangshanchang and Qilinchang deposits were formed during the same geological event and originated by fluid migration during uplifting resultant from the Emeishan flood basalts.
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