关于甘肃长城纪地层划分的新认识

甘肃的长城纪地层划分以岩石地层为主。地层区可划分为北山地层区、祁连—北秦岭地层区（包括祁连山西段分区和兰州—天水分区）、华北地层区陇东分区及扬子地层区摩天岭分区。甘肃省长城纪岩石地层共分为７个群级单位（铅炉子沟群、古硐井群、朱龙关群、托来南山群、兴隆山群、碧口岩群、贺兰山群）、７个组级单位（熬油沟组、桦树沟组、南白水河组、葫芦河组、阳坝岩组、秧田坝岩组、黄旗口组）和６个组级非正式岩石地层单位。各单位特征明显，反映了甘肃省长城纪古地理轮廓和地层格架面貌

A NEW COGNITION ON THE STRATIGRAPHIC DIVISION OF CHANGCHENG PERIOD IN GANSU PROVINCE

The stratigraphic division of the Changcheng period is mainly base on lithostratigraphy in Gansu Province. It can be divided into Beishan, Qilian-northern Qinling including the western sectional subprovince of Qilian Mts. and Lanzhou-Tianshui subprovince,Longdong subprovince of the North China province and Motianling subprovince of the Yangtze province. The Changcheng period can be classified into seven group grade units (Qianluzigou, Gutongjing, Zhulongguan ,Tuolannanshan, Xinglongshan, Bikou and Helanshan groups), seven formation grade units (Aoyougou, Huashugou, Nanbaishuihe, Huluhe formations and Yangba, Yangtianba and Huangqikou rock formations) and six formation grade informal lithostratigraphic unites. The characteristics of these units mentioned above are obvious, which reflect the paleogeographic outline and stratigraphic framework of Changcheng period in Gansu Province.