西天山望峰金矿床绢云母(40)Ar/(39)Ar年龄及矿床成因研究

^(40)Ar/^(39)Ar age of sericite and genetic study of Wangfeng gold deposite,West Tianshan Mountains

望峰金矿床位于中天山北缘冰达坂韧性剪切带内,成矿单元划分属于博罗科努多金属成矿带内天格尔-可可乃克次级成矿带,矿体主要赋存于糜棱岩化花岗岩中,主要矿石类型为石英脉型和蚀变糜棱岩型矿石。对两种类型矿石中的绢云母进行^(40)Ar/^(39)Ar测年,获得坪年龄分别为(250.9±3.0)Ma、(255.8±3.0)Ma,两个样品正反等时线年龄与坪年龄在误差范围内一致,表明坪年龄结果可信,可以代表成矿年龄,说明望峰金矿床的主成矿期时代为晚二叠世末期,且蚀变糜棱岩型矿石的形成时代比石英脉型矿石略早。结合矿区地质情况及前人的研究结果,认为望峰金矿床是剪切带型金矿床,冰达坂韧性剪切带控制了望峰金矿的成矿过程。

The Wangfeng gold deposite is located in the Bingdaban ductile shear zone,which is in the north edge of Central Tianshan.Metallogenic units belongs to the Tianger-Koknik metallogenic belt,and it is the secondary metallogenic belt of Boluokenu polymetallic metallogenic belt.The gold ore bodies are mainly hosted in mylonitize granite.The （40）Ar/（39）Ar dating results of sericite,which is selected from the two types of ores show that the plateau ages are（ 250.9 ± 3.0） Ma and（ 255.8 ± 3.0） Ma,respectively.The positive and inverse isochron ages are consistent with the plateau age within the error ange,indicating that the plateau ages are reliable and represent.The results of plateau ages are reliable and can represent the formation age of Wangfeng gold deposite.Therefore,the main metallogenic epoch of Wangfeng gold deposite is the end of late Permian,and the formation age of altered mylonite type ore is little older than that of quartz vein type ore.Combining with regional geological background and previous studies on Wangfeng gold deposite,We suggest that Wangfeng gold deposite is shear zone type gold deposit,and Bingdaban ductile shear zone controls the mineralization process of Wangfeng gold deposite.