Zircon U-Pb dating for the granite prophyries in Hongshan prophry copper deposit and Tongkenzhang porphyry molybdenum deposits in East Jiangxi Province and their significance

Abstract

The Tongkengzhang molybdenum deposit and Hongshan copper deposit are two important porphyry deposits in the Wuyishan metallogenic belt in Southeast China. After performance of LA-ICP-MS zircon U-Pb dating, we obtained 138 ± 1Ma for the granite-prophyry in Tongkengzhang porphyry Mo deposit, and 99Ma and 49Ma for the granite prophyry in Hongshan porphyry Cu mine. The LA-ICP-MS zircon U-Pb dating of the granite prophyry in Hongshan deposit gives two distinguishing ages, which possibly represent the granite porphyry crystallization and disturb of post-mineralization thermal event, respectively. The data show the ages of the granite porphyry are consistent with those molybdenite Re-Os dating achieved by previous studies, which reflects the Cretaceous rock- and oreforming event. Based on compiled data from previous researches, we suggest that the Tongkengzhang Mo porphyry and the Hongshan Cu porphyry occurred in the extensional belt of the continental back arc and in the extensional faulted basins trigged by lithospheric thinning, respectively