滇西北普朗斑岩铜矿锆石离子探针U-Pb年龄：成矿时限及地质意义  

Zircon SHRIMP U-Pb dating of the Pulang porphyry copper deposit,northwestern Yunnan,China:The ore-forming time limitation and geological significance

作　　者：王守旭[1,2,3] 张兴春[1] 冷成彪[1,2] 秦朝建[1] 马德云[3] 王外全 

机构地区：[1]中国科学院地球化学研究所,矿床地球化学国家重点实验室,贵阳550002 [2]中国科学院研究生院,北京100039 [3]山东黄金集团有限公司,济南250014 [4]云南地勘局第三地质大队,大理671000

出　　处：《岩石学报》2008年第10期2313-2321,共9页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(40372049);国家“973”项目课题(2002CB412605);中科院知识创新工程重要方向项目(KZCX3-SW-125)资助

摘　　要：应用高精度离子探针锆石U-Pb测年方法,获得普朗斑岩铜矿床中3件矿化石英二长斑岩的锆石年龄分别为228±3Ma、226.3±2.8Ma、226±3Ma。锆石形态和铀钍参数均属典型的岩浆锆石特征,年龄值在误差范围内近似一致,表明形成矿化斑岩的中酸性岩浆从岩浆房快速上升侵位。结合前人已发表的矿化斑岩的黑云母Ar-Ar坪年龄及辉钼矿Re-Os同位素年龄等数据,推测普朗斑岩铜矿的岩浆—热液系统从岩浆侵入至矿化阶段的持续时间可能长达10Ma以上,主成矿期约为216～214Ma。从岩浆房分异出的富合成矿物质和挥发份的岩浆流体在相对较晚阶段对普朗复式岩体发生了强烈的蚀变作用并可能进一步萃取了岩体中的成矿物质。The high precision Zircon SHRIMP U-Pb dating method has been applied to measure the ages of the copper mineralized monzonite porphyry in the Pulang porphyry copper deposit, northwestern Yunnan, China, with the dated ages of 228 ± 3Ma, 226. 3 ± 2. 8Ma and 226 ± 3Ma. The shapes of the zircon samples and the parameters of their contained uranium and thorium are in accordance with the characteristics of the typical magmatic zircon. The dated ages of zircon samples are almost identical within the range of deviation. This indicates that the magma, which formed the copper mineralized monzonite porphyry, was emplaced rapidly from its magma chamber. In the combination of the zircon SHRIMP U-Pb dating ages of the porphyry samples, and the previously published data of the Ar-Ar plateau ages of biotite samples and the Re-Os isochronism age of molybdenite sample, it is believed that the main oreforming stage of the Pulang porphyry copper deposit occurred at 216 - 214Ma, and then it is inferred that the magma-hydrothermal fluid system of the Pulang porphyry copper deposit could have been lasted over 10Ma from its magma emplacement stage to the magmatic hydrothermal mineralization stage. The magmatic hydrothermal fluid, which was derived from the magma chamber and rich in oreforming materials and volatiles, had strongly altered the Pulang porphyry complex and extracted some ore-forming material form it at the relative later stage.

关 键 词：锆石 离子探针U—Ph测年 斑岩铜矿 中句普朗 

分 类 号：P597.3[天文地球—地球化学] P588.132[天文地球—地质学]