青海祁漫塔格索拉吉尔矽卡岩型铜钼矿床辉钼矿铼-锇同位素定年及其地质意义

Re-Os Isotopic Dating of Molybdenite from the Suolajier Skarn-type Copper-Molybdenum Deposit of Qimantage Mountain in Qinghai Province and Its Geological Significance

摘要: 索拉吉尔铜钼矿床是青海祁漫塔格成矿带产于中酸性侵入岩与含碳酸盐岩地层接触带中的典型矽卡岩型矿床，矿体规模大、品位高。利用辉钼矿铼-锇同位素定年技术，获得9件样品的模式年龄为（236.9～240.1）Ma，加权平均年龄为（238.8±1.3）Ma，其加权平均方差（MSWD）为0.32，187Re-187Os等时线年龄为（239±11） Ma（MSWD＝0.48），模式年龄和等时线年龄结果集中一致，表明铜钼成矿作用发生于中三叠世。索拉吉尔铜钼矿床辉钼矿样品中铼含量为73.8～98.5 μg/g，指示其成矿物质来源为壳幔混合源。

Abstract: Located in the Qimantage area, Qinghai Province, the Suolajier deposit is a typical skarn-type Cu-Mo deposit which occurred in the contact zone between intermediate to acidic intrusive rock and carbonate-bearing strata. Rhenium and osmium isotopic dating of molybdenite in skarn ores by ICP-MS yields the Re-Os model age of 236.9～240.1Ma and isochron age of (239±11) Ma (n=9, MSWD=0.48), which shows that the deposit formed in the middle Triassic period. The content of rhenium in molybdenite samples ranges from 73.8～98.5 μg/g, which indicates that the ore-forming materials in this deposit are derived from magma mixing of crust and mantle sources.