Coupled U–Pb Geochronology of Monazite and Zircon for the Bozhushan Batholith, Southeast Yunnan Province, China: Implications for Regional Metallogeny

Constraining the duration of magmatism is of vital importance to the understanding of the magmatic-hydrothermal mineral system. The Bozhushan batholith, located in the middle section of the southeastern Yunnan ore district, mainly consists of biotite monzogranite and monzogranite. Many Sn–W–polymetallic deposits are developed around the Bozhushan batholith, but their temporal and genetic relationships remain controversial. LA-ICP-MS U–Pb zircon and monazite dating were respectively conducted on the same two samples, yielding weighted mean 206Pb/238U zircon ages of 85.1 ± 0.7 and 85.6 ± 0.9 Ma, and weighted mean 206Pb/238U monazite ages of 87.1 ± 0.9 and 88.1 ± 1.1 Ma. The crystallization ages of S-type granites obtained from the zircon U–Th–Pb system and monazite U–Th–Pb system are consistent within the analytical errors. After combining the new ages obtained in this study with recently published U–Pb zircon and cassiterite ages from the giant Baniuchang Ag–Sn–Pb–Zn deposit in the north, and U–Pb zircon and Re-Os molybdenite ages from the large Guanfang W deposit in the south, a temporal framework of magmatism-mineralization in the Bozhushan region has been established. The duration of magmatic activity at Bozhushan is about 7 Ma, with W mineralization occurring at ca. 92 Ma and Sn mineralization at 88–87 Ma.