Re-Os Isotopic Dating of Molybdenite and Its Implication for Molybdenum Mineralization of Wenquan Porphyry, Wushan, Gansu Province

Wenquan molybdenum deposit is a porphyry type mineral deposit related with Indosinian granite.The Re-Os isotope dating by five samples of molybdenite separate shows that the Os model ages ranging from 212.7±2.6 Ma to 215.1±2.6 Ma with weighted average 214.1±1.1 Ma.The isochron age of 214.4±7.1 Ma calculated by ISOPLOT program is consistent with granite ages of 223 to 226 Ma and 223±7 Ma for K-Ar and SHRIMPU-Pb respectively.The isochron age is within limits of error,and slightly later than the granite age.The facts indicate that Mo mineralization generation was in the later stage of the magma a scending and cooling in crust.The indosinian granite distributed in west Qinling was generated by way of remelting of the basement matter of basaltic rocks with high Kcontent induced by Qinling orogenic process and resulted in element redistribution in crust.This is very important to Mo mineralization generation for granite fractional crystallization.The discovery of Wenquan molybdenum mineral depositplays a revealing and directing role to evaluate the metallogenetic potential of the Indosinian granite in west Qinling.