浙西南毛断铅锌多金属矿床辉钼矿Re-Os年代学及地质意义

毛断铅锌多金属矿床位于浙西南江山-绍兴断裂和政和-大埔断裂间的隆起区，为区内代表性的铅锌多金属矿床之一.应用Re-Os同位素定年方法对该矿床5件辉钼矿样品进行了成矿时代测定，获得辉钼矿Re-Os同位素模式年龄为(138.6±2.0)Ma~(140.0±1.9)Ma，等时线年龄为137.7±2.7 Ma(MSWD=0.7)，模式年龄加权平均值为139.0±0.8 Ma(MSWD=0.5).该年龄与毛断隐伏岩体成岩时代相吻合，表明成矿与成岩关系密切.辉钼矿Re-Os年龄的精确厘定，表明毛断铅锌多金属矿床为早白垩世初期华南岩石圈伸展背景下的产物.同时结合前人同时代的W、Mo、Pb、Zn等矿床的研究成果指出140±7 Ma可能为华南另一重要的成矿时限. 

Re-Os Dating of Molybdenite from the Maoduan Lead-Zinc Polymetallic Deposit in Southwestern Zhejiang Province and Its Geological Significance

The Maoduan lead-zinc polymetallic deposit, located in uplift area between the Jiangshan-Shaoxing and Zhenghe-Dabu deep faults in southwestern Zhejiang Province, is one of typical lead-zinc polymetallic deposits in this region. Re-Os dating of 5 molybdenite separated from the Maoduan lead-zinc polymetallic deposit gave model ages from 138.6±2.0 Ma to 140.0±1.9 Ma. These data yielded an isochron age of 137.7±2.7 Ma with MSWD=0.7, and a weighted average model age of 139.0±0.8 Ma (MSWD=0.5). This result is in good agreement with the Maoduan concealed monzogranite, indicating that Pb-Zn polymetal mineralization was related to granite crystallization. According to the precise Re-Os ages we have reported and previous studies, we interpret the Maoduan Pb-Zn deposit formed in an extensional setting related to lithospheric extension during the Early Cretaceous in South China. Meanwhile, we also point out that 140±7 Ma may be another important time range of tungsten-molybdenite-lead-zinc polymetallic mineralization in South China.