中文摘要：

四川丹巴地区是中国最重要的白云母产地之一，所产白云母以质量好、晶体大而闻名于世，是^40Ar-^39Ar测年的理想对象。文章通过野外调查和同位紊年代学研究，获得该区二道桥和李家工地伟晶岩脉内白云母的^40Ar-^39Ar法坪年龄，分别为（125．01±0．58）Ma和（114．68±0．32）Ma，属燕山中晚期产物。丹巴伟晶岩脉的形成与区域地壳活动构成构造→岩浆→变质→伟晶岩脉的旋回，形成于喜马拉雅运动开始之前。因此，丹巴白云母矿化伟晶岩脉是地壳活动相对宁静期的产物，与世界上一些重要伟晶岩型矿床的成矿规律一致。

英文摘要：

As one of the most important muscovite-producing areas in China, Danba is famous for its good quality and large crystal muscovite. The muscovite crystal there is an ideal object for^40Ar-^39Ar dating. Based on geological survey and isotope chronology, the authors obtained ^40Ar-^39Ar plateau ages of （125.01 ± 0.58） Ma and （114.68±0.32） Ma for Erdaoqiao and Lijiagongdi pegrnatite dikes respectively, indicating that the pegrnatite dikes in Danba are products of middle and late Yanshanian period. The pegmatite dikes and regional crustal movement constitute a circle of tectonic activity→magmatism→metamorphism→pegrnatite formation, and the pegmatite dikes were formed before the Himalayan movement. Thus, the pegmatite type muscovite deposit must have been formed in a stable period of crustal movement, and hence its metallogenic regularity is consistent with that of some important pegmatite type deposits in the world.