湘南郴州地区骑田岭花岗岩锆石SHRIMP定年及其地质意义

Zircon SHRIMP dating of the Qitianling granite, Chenzhou, southern Hunan,

对骑田岭岩体主体岩石中细粒斑状角闪黑云二长花岗岩(仰天湖单元)进行了锆石SHRIMPU-Pb年龄测定。结果表明,仰天湖单元的形成年龄为156.7Ma±1.7Ma,结合前人有关年代学和本次花岗岩岩石学、地球化学等资料,认为骑田岭岩体主体——仰天湖单元花岗岩形成时代是中侏罗世末。结合骑田岭地区锡矿与花岗岩的关系,认为永春一带具有寻找锡矿的前景。

Zircon SHRIMP U-Pb dating was performed of medium- and fine-grained, porphyritic hornblende-biotite monzogranite (Yangtianhu granite unit), which constitutes the main part of the Qitianling granite pluton. The results indicate that the age of the Yangtianhu unit is 156.7±1.7 Ma. According to this age, combined with the previous chronological data and the petrological and geochemical data of granite obtained in this study, the authors think that the main part of the Qitianling pluton-the Yangtianhu unit-formed in the terminal Middle Jurassic. On the basis of the relationships between the tin deposit and granites in the Qitianling area, the authors consider that the Yongchun area of the Qitianling granite pluton is promising for prospecting of Sn deposits.