Zircon U-Pb and Molybdenite Re-Os Geochronology of the Pangushan Tungsten Deposit in South Jiangxi Province and Its Significance

The Pangushan tungsten deposit is a well-known old and large ore deposit which has attracted many researchers and exploration geologists both in China and abroad.In order to determine the ages of magmatism and mineralization in the deposit and thus to gain insights into the relationship between magmatic process and tungsten mineralization,the association of endocontact mineralization with exocontact mineralization as well as their geodynamic setting,the authors conducted LA-ICP-MS zircon U-Pb and ICP-MS molybdenite Re-Os isotopic measurement of Pangushan concealed granite and its endocontact-mineralized quartz veins discovered by 2000 m Nanling Scientific Drilling(SP-NLSD-2).The results indicate that the weighted average ages of zircon 206Pb/238U ages for Pangushan granite and of molybdenite Re-Os isotopic model ages for the quartz veins are(161.7±1.6) Ma and(155.3±2.8) Ma,respectively,both subordinate to Mid-late Jurassic.The determinations,together with previous data,suggest that the mineralized quartz veins were produced by terminal magma evolution,which is supported by the fact that the ages of mineralization and magmatism were basically in accordance,the mineralization all occurred spatially at the inner- and outer-contacts of the granite,and the gradient relationship of granite→feldspar quartz vein→quartz vein was detected in the deposit.Endocontact and exocontact ore-bearing quartz veins were both produced by the same mineralization.Geodynamically,the Pangushan tungsten deposit is one of many important tungsten-polymetallic deposits formed from 165 Ma to 150 Ma associated with large-scale lithospheric extension in South China.