Re-OsAge of Molybdenite from the SouthernOre Zone of theWushan Copper Deposit,Jiangxi Province, and Its Geological Significance
LI Jinwen1), LI Xuhui2), PEI Rongfu1), MEI Yanxiong1), WANG Yonglei1), QU Wenjun3), HUANG Xiubao1), ZANG Wenshuan4)1) Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing, 1000372) NorthwestJiangxi GeologicalTeam of JBEDGMR, Jiujiang, Jiangxi, 3320003) National Research Center of Geoanalysis, Beijing, 1000374) China University of Geosciences, Beijing, 100083
In this paper, a precise Re-Os ageis given for the southern ore zone of the Wushan copper deposit for the first time. Themode ages of five molybdenite samples vary from 144.0 Ma to 145.7 Ma, and the isochron age is146.4±2.6 Ma. These age data are concordant withSISM age, 145 3.9 Ma, of the granodiorite porphyry, which indicates that the southern ore zone ofthe Wushan copper deposit is a product of late Jurassic intermediate-acid magmatism. Exhalative-sedimentary mineralization occurred on the northern ore zone ofthe Wushan copper depositin the Hcrcynian period. And it is very important for the northern ore zone that was telescoped and remobilized in the post-magmatic processes in the Yanshanian period. Thus, at last the Wushan copperdeposit was formedin the late Jurassic period. Mineralization in the Wushan copper deposit shows mainly skarn-type and strataform-type, and shows mainly porphyry-type and strataform-type in the Chengmenshan copper deposit which is located in the same oredistrictwith the former. Along with lithospheric thinning in the lower Yangtze craton, ore-forming in Wushan is earlier than that in Chengmenshan. The time span is about 4 Ma to 6 Ma which might result in different mineralizationin the two deposits. The ages of intrusive rocks are close to the ages of the deposits in the Wushan copper deposit and Jiurui, Tongling, Anqing, Edongnan oredistricts which are products of the Yanshanian syntectonic-magmatic activity.