滇西腾冲地块东南缘高黎贡山群片麻岩LA-ICP-MS锆石U-Pb年龄及其地质意义

LA-ICP-MS zircon U-Pb age of gneiss from Gaoligong Mountain Group on the southeastern margin of Tengchong block in western Yunnan Province

摘要: 分布于腾冲地块东南缘的高黎贡山群片麻岩经历了多期变质作用，深熔和糜棱岩化作用表现得十分明显，片麻岩中的锆石具有深熔锆石的特征。在取得的15个锆石年龄数据中，14个数据的206Pb/238U年龄为454.4~546.7Ma，平均年龄为489Ma±16Ma，仅1个数据为261.9Ma。测试结果表明，腾冲地块东南缘的高黎贡山群岩石在早古生代遭受强烈的区域变质作用（包括混合岩化），而这正是泛非事件在腾冲地块上的反映。

Abstract: Gaoligong gneiss from southeastern Tengchong block has experienced multi-stage metamorphism, and hence shows evident anatexis and mylonitization. 14 of the 15 zircon points yielded 206Pb/238U age of 454.4-546.7Ma, with the average age of 489Ma±16Ma. The result suggests that the Gaoligong Mountain Group in southeastern Tengchong block underwent intense regional metamorphism including migmatization in Early Paleozoic, which reflected the Pan-African event in the Tengchong block.