甘肃省白银地区皋兰岩群微古植物化石新资料及地层时代再认识

1∶25万兰州市幅区域地质调查中,在白银地区的皋兰岩群内采获到以球形藻类为主的微古植物化石,其组合面貌特征明显,广泛见于我国长城系,层位稳定。组合中的部分分子尚显示长城纪—蓟县纪生物演化过渡色彩。含化石地层可与兰州兴隆山地区兴隆山岩群对比。参照同位素测年数据,可将皋兰岩群的时代厘定为中元古代长城纪—蓟县纪。

THE NEW DATA OF MICROPALEOBOTANY FOSSIL OF GAOLAN LITHO-CLUSTER AND UNDERSTAND IT'S TIME AGAIN

During the regional geological surveying in Lanzhou municipality, we collected micropaleobotany fossil as mainly globiferous algae in Gaolan litho-clusterthat occurred in Baiyin region. It's fossil assemblage features have been seen in Chinese Changcheng System widely and the characteristies are distinct and it's stratohorizon is stability too. It showed that transitional appearance from Changcheng Period to Jixian Period. It's bearing faunal succession may contrast with Xinglongshan lith-cluster in Xinglongshan region of Lanzhou. Refferring to the isotopic age determination, the time of Gaolan litho-cluster may be included into Changcheng Period-Jixian Period of Mid-Proterozoic Era.