滇西腾冲-梁河地区花岗岩锆石稀土元素组成和U-Pb同位素年龄

在详细的区域地质调查基础上，对滇西腾冲-梁河地区花岗岩的锆石进行了阴极发光观察，并通过LA-ICP-MS分析了其稀土元素组成和U-Pb同位素年龄。花岗岩中大部分锆石具有振荡环带，锆石稀土元素表现为亏损轻稀土、阶梯式富集重稀土、强烈正Ce异常及强烈负Eu异常，表明锆石为典型的岩浆锆石。花岗岩（D0053）锆石的²⁰⁶Pb/²³⁸U加权平均年龄为（127.9±1.0） Ma (MSWD=2.9，27个点)，花岗岩（D4310）锆石的²⁰⁶Pb/²³⁸U加权平均年龄为（58.3±0.5） Ma (MSWD=1.8，21个点)，表明腾冲-梁河地区存在大量早白垩世和早第三纪花岗岩浆活动，它们是特提斯演化过程的岩浆响应。

Rare Earth Element Geochemistry and U-Pb Age of Zircons from Granites in Tengchong-Lianghe Area, Western Yunnan

Based on detailed regional geological survey, the internal textures, rare earth element composition and U-Pb age of zircons from granites in Tengchong-Lianghe area, western Yunnan, were studied by cathodoluminescence (CL) and LA-ICP-MS, respectively. Both the oscillatory zoning and chondrite-normalized REE pattern characterized by a steeply rising slope from the LREE to the HREE with the obviously positive Ce anomaly and negative Eu anomaly, indicate the magmatic genesis of these zircons from the granites. The zircons in the granite (D0053) yield a weighted mean ²⁰⁶Pb/²³⁸U age of (127.9±1.0) Ma (MSWD=2.9, n=27). Those in granite (D4310) yield a weighted mean ²⁰⁶Pb/²³⁸U age of (58.3±0.5) Ma (MSWD=1.8, n=21). The results indicate that there happened widely the Early Cretaceous and Early Tertiary granitic magmatisms in Tengchong-Lianghe area, western Yunnan, as the magmatic response to the tethys evolution.