Zircon SHRIMP U-Pb age of porphyry granite in the Dongzhongla lead-zinic deposit, Maizhokunggar County, Tibet

Abstract：Located in the Zhaxue-Yaguila metallogenic belt of the Nyainqentanglha Range, Tibet, the Dongzhongla ore deposit is a newly-discovered lead-zinc polymetallic deposit. The exposed porphyry granite has an intimate relationship with the Dongzhongla ore deposit. In order to determine the accurate age of the porphyry granite in Dongzhongla, the authors employed the zircon SHRIMP U-Pb isotope dating technology and obtained the age of 124.4±1.9 Ma（MSWD=5.09）, indicating Cretaceous. This age is essentially in agreement with the event of magmatism in the east of the Gangdise-Nyainqentanglha volcanic-magmatic belt (from 109 Ma to 130 Ma) and the age of granites in the Zhaxue-Jinda lead-zinc polymetallic metallogenic belt. Combined with regional data, it is suggested that the Dongzhongla early Cretaceous porphyry granites resulted from the crustal thickening melting of the intra-arc rift tensional system. This age provides the important evidence for Cretaceous magmatism and helps to direct studies related to lead-zinc molybdenum-copper polymetallic ore exploration in the Nyainqentanglha Range.