Re-Os Isotopic Dating of Molybdenite from the Maoping Tungsten-Tin Deposit in Chongyi County of Southern Jiangxi Province andIts Geological Significance

The Maoping tungstentin deposit is located in the eastern section of Nanling metallogenic belt, the Chongyi-Dayu-Shangyou tungsten polymetallic ore concentration area and at the front part of the Tianmenshan rock mass extension with a north trend. Greisen and the quartz vein are the main tungstentin mineralization types in the mine area. Seven molybdenite samples from greisen ore body and quartz vein tungsten ore body associated with black tungsten ore were chosen for Re-Os isotopic dating and model age of (141.4±2.2) Ma～(158.2±2.2) Ma were obtained. The isochrone age of molybdenites from greisen type tungsten-tin ore body is（156.8±3.9） Ma， which indicates that its mineralogenetic epoch is at the Middle Jurassic, corresponds to the second stage of early Yanshanian period. And the model age for the samples from greisen ore body and from quartz vein ore body are （150.7±2.4） Ma～（158.2±2.2） Ma and （141.4±2.2） Ma～（151.0±2.4） Ma respectively, which indicates that the mineralization time of the quartz vein ore body is slightly earlier than that of greisen ore body. Based on the other isotopic dating data from the mine area, the minerogenetic epoch and the time differences for different ore bodies were discussed and a conclusion that the Tianmenshan rock body is a compound complex rock body undergoing repeated ore-forming processes and with minerogenetic epoch span of 133～156 Ma was deduced.