Geological characteristics and ages of granites and related mineralization in the Dajinshan tungsten-tin polymetallic deposit,western Guangdong Province

The Dajinshan tungsten-tin polymetallic deposit in western Guangdong Province is a quartz vein type ore deposit related to granitoids.The ore bodies show a fairly simple shape and mainly occurred as tungsten-tin polymetallic-bearing sulfide quartz veins,including quartz vein,quartz-greisen and sulfide-quartz veins.The main ore types include veinlets and stockworks.The major wall rock alterations include silicification,greisenization and chloritization.In this paper,we present detailed geologic features of the deposit and carry out zircon LA-MC-ICP-MS U-Pb ages for the ore-bearing granitic rocks in the deposit.Zircon U-Pb dating yields ages of 82.89±0.35Ma to 85.6±0.52Ma for the medium to fine grained biotite granite,and 84.17±0.34Ma to 75.01±0.16Ma for the porphyritic biotite granite,respectively.Precise Re-Os dating of molybdenite from the quartz veins related to the medium to fine grained biotite granite in the Dajinshan tungsten-tin polymetallic deposit has also been carried out in this study.The results show that the Re-Os model ages of five samples range from 80.07±1.19Ma to 84.93±1.42Ma.These dating results suggest that the timing for the W-Sn mineralization and granite intrusion are simultaneous,which is corresponding to the period of the large-scale mineralization in the Late Mesozoic in the South China,under a tectonic setting of crust extension system.