【摘要】 厘定中祁连地块褶皱基底的时代 ,对探讨中祁连地块构造属性以及研究祁连造山带构造演化有重要意义。长期以来 ,由于缺乏化石依据 ,加上同位素年龄测定受该区岩浆事件扰动的影响 ,中祁连东段褶皱基底皋兰岩群地质时代厘定始终悬而未决 ,本次 1∶ 2 5万兰州市幅区域地质调查 ,采获大量蓟县纪微古植物化石 ,并获得Sm - Nd等时线年龄 1 1 80 Ma。作者根据皋兰岩群岩石组合、同位素年龄、微古植物化石等方面的特征 ,结合区域地层对比 ,将皋兰岩群地层时代厘定为中元古代。更多还原

【Abstract】 Dating the Gaolan Group in the Central Qilian fold basement is important for reconstructing the evolution of the Qilian Orogenic Belt. As a result of the lack of fossil and that isotopic age determination is disordered by magmatism, the geological age of the Gaolan Group has not been determined for a long time. We found a lot of micropaleoplants of the Jixian period in the area. At the same time, a Sm-Nd isochron age of 1180 Ma is obtained. According to the regional stratigraphic correlation, isotopic age and micropaleoplants, we put the Gaolan Group in the Mesoproterozoic.更多还原