甘肃的寒武系

寒武系主要分布于北山、祁连山、河西走廊及陕甘宁盆地。根据沉积岩相及动物地理区系分为三大沉积区和７个沉积分区：北山沉积区分为下统双鹰山组、中统大豁落井组、上统西双鹰山组；祁连山沉积区未见下统，中统月牙山群、黑茨沟群和格尔莫沟群，上统香毛山群；华北沉积区下统未分，中统毛庄组、徐庄组和张夏组，上统仅见崮山组。三大沉积区的动物群分别为东南型（除早寒武世外）、过渡型和华北型。寒武系下界相当于滇东的沧浪铺阶之底界，并与震旦系冰碛层呈平行不整合接触。寒武纪岩相古地理轮廓受当时的地壳变动和气候条件所控制。早寒武世中晚期开始海侵，在北山沉积区之西部呈海湾，在陕甘宁盆地西缘呈浅海陆棚，省内其余地区（除西秦岭外）呈古陆状态。中寒武世广泛海侵，在祁连山形成海槽，且地壳运动加剧，火山喷发活动频繁。晚寒武世大规模海退，仅在北山局部地区、祁连山西段和陕甘宁盆地有沉积，其余均为古陆状态。

THE CAMBRIAN SYSTEM IN GANSU PROVINCE

Cambrian system of Gansu is distributed mainly Beishan mountain,Qilian mountains,Hexi Corridor and Shaanxi-Gansu-Ningxia Basin. In accordance with sedimentary lithofaciesand geographic fauna,it is divided into three sedimentary province and seven sedimentarysubprovinces:Beishan sedimentary province consisted of sedimentary subprovince of WesternMazongshan and sedimentary subprovince of Heiyingshan-Honggeerji;Qilianshan sedimenta-ry province included sedimentary subprovince of Eastern Mazongshan and Jiuquan-Wuwei-Zhongning,sedimentary subprovince of South Gansu-Qilian,Changma;North China sediinen-tary province consisted of sedimentary subprovince of Shaanxi-Gansu-Ningxia Basin only.The sequence of the faunal province of three sedimentary provinces is type of S E China,transitionaI type and type of North China. Cambrian system of Gansu is divided as follows:Beishan sedimentary province is classified into three series : Lower series is Shuangying-shan formation; Middle series is Dahuoluojing formation; Upper series is Xishuangyingshanformation.Qilianshan sedimentary province : Lower series is not seen; Middle series is Yueyashangroup ,Heicigou group and Geermogou group;Upper series is Xiangmaoshan group. North China sedimentary province : Lower series is not subdivided; Middle series is divi-ded into Maozhuang formation, Xuzhuang formation and Zhangxia formation; Gushan forma-tion has been seen only in the upper series. The lower bound of Cambrian corresponds to it which is bottom boundary of Canglang-pu Stage in eastern Yunnan,and it with moraine bed of Sinian system appears as parallel un-conformable contact.