朝阳董家店地区寒武系

朝阳董家店地区寒武系发育,岩石地层单位从下面上分为A组(含燧石结核、燧石条带白云岩组),B组(红色砂页岩、白云岩组),董家店组(C组,鲕粒白云岩组),D组(薄层灰岩组)。生物地层单位从下而上为Probowmania带,Taitzeuia-Crepicephalina带,Blackwelderia-Cyclorenzella,parabola带,Chuangia带,Tsinania带,Tellerina带。年代地层单位可划分为寒武系下统(缺少化石,不能建阶);寒武系中统毛庄阶,张夏阶(因缺少化石,徐庄阶不能建立);寒武系上统崮山阶,长山阶,凤山阶。董家店组是笔者命名的岩组,其命名的主要依据是岩性、岩相特征明显,岩组全为鲕粒白云岩,在该区延展较广,与邻区同层岩组有较大差别。

THE CAMBRIAN OF DONGJIADIAN, CHAOYANG

The Cambrian of lithostratigraphic unit in Dongjiadian, Chaoyang from lower to upper is divided into A formation (dolomite containing chert nodules and bands), B formation (red sandshale and dolomite), Dongjiadian formation(or C formation: dolomite containing oolite), D formation (thin layer limestone). The biostratigraphic unit from lower to upper is divided into Probowmania zone, Taitzeuia-Crepicephalina zone, Black-welderia-Cyclolorenzella parabola zone, Chuangia zone, Tsinaniu zone, Tellerina zone. The chronostratigraphic unit is divided into lower Cambrian, middle Cambrian Maozhuang stage, and Zhangxia stage, uppor Cambrian Gushan stage, Changshan stage Fengshan stage. The Dongjiadian formation is newly named by the author according to the following features. obvious characters of lithology and lithofacies, wide extension and large difference from the adjacent formation in the same layer.