滇东南薄竹山花岗岩的LA-ICP-MS锆石U-Pb定年及地质意义

通过对滇东南薄竹山花岗复式岩体3个代表性花岗岩样品的LA-ICP-MS锆石U-Pb同位素年龄测试，获得了该岩体的形成时代。其中，雷达站单元样品的²⁰⁶Pb-²³⁸U加权平均年龄为（86.51±0.52） Ma(MSWD值为2.4)；所作底单元样品的²⁰⁶Pb-²³⁸U 加权平均年龄为（87.54±0.65）  Ma(MSWD值为1.6)；洋芋树单元样品的²⁰⁶Pb-²³⁸U 加权平均年龄为（87.83±0.39）  Ma (MSWD值为0.15)。这些分布比较集中的年龄数据为薄竹山花岗岩体提供了一个准确的形成时限。这些年龄数据表明，薄竹山花岗岩体同区域内的其它岩浆岩和与之相关的个旧、大厂、都龙超大型锡多金属矿床等都是晚白垩世的产物，均为华南西部地区岩浆-成矿带的重要组成部分，也是华南西部晚白垩世大规模成岩成矿作用在滇东南地区的又一具体表现。

LA-ICP-MS Zircon U-Pb Dating of the Bozhushan Granite in Southeastern Yunnan Province and Its Significance

The LA-ICP-MS zircon U-Pb dating of three samples from the Bozhushan complex granite intrusion, in Southeastern Yunnan Province, constrains the emplacement age of the intrusion. The ²⁰⁶Pb-²³⁸U mean data of the sample CYB0808079 is （86.51 ±0.52） Ma and the MSWD value is 2.4, the sample CYB0808084 is （87.54 ±0.65） Ma and the MSWD value is 1.6, as well as the sample CYB0808079 is （87.83 ±0.89） Ma and the MSWD value is 0.15. These chronology data are consistent with the magmatism and mineralization in the area, and supply the reasonable isotopic age for the Bozhushan complex granite. It is demonstrated that the Bozhushan and other grantic intrusion as well as associated supergiant Gejiu, Dachang and Dulong tin-polymetallic deposits were formed during the Late Cretaceous period. Both the magmatism and large scale mineralization are the components of the western South China metallogenic belt in the Late Cretaceous period.