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

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.