论文部分内容阅读
总结和重新研究了我国华北地区奥陶纪牙形刺生物地层,修订了安太庠等(1983)和安太庠、郑昭昌(1990)建立的牙形刺带序列。修订后的牙形刺带由下而上可划分为:特马豆克阶(Tremadocian)的Iapetognathus jilinensis-Cordylodus lindstromi带,C.angulatus带,Chosonodina herfurthi带,Rossodus manitouensis带,Glyptoconus quadraplicatus带和Scalpellodus tersus-Triangulodus aff.bifidus带;弗洛阶(Floian)的Serratognathus bilobatus带,S.extensus带,Paraserratognathus obesus带和Jumudontus gananda带;达瑞威尔阶(Darriwilian)的Histiodella holodentata-Tangshanodus tangshanensis带,Eoplacognathus suecicus-Histiodella kristinae带,Pygodus anitae带和P.serra带;桑比阶(Sandbian)的P.anserinus带,Plectodina aculeata带,Erismodus quadridactylus带,Belodina compressa带和Phragmodus undatus带,以及凯迪阶(Katian)的Belodina confluens带,Yaoxianognathus neimengguensis带和Y.yaoxianensis带;同时把寒武系-奥陶系界线置于Iapetognathus jilinensis-Cordylodus lindstromi带之底界。这一新的牙形刺序列,可以在更大范围内更精准地划分和对比华北地区的奥陶纪地层,如奥陶系中、上统除其顶部两个带只能在国内直接对比外,几乎所有的牙形刺带都可与国内外奥陶纪的牙形刺带逐带对比。同时,从这一新的牙形刺序列中也可明显看出,其中缺失了大坪阶(Dapingian)的牙形刺带,证明华北地区在奥陶纪大坪期由于怀远运动的抬升而未接受沉积,从而改变了华北地区奥陶系下、中统间地层为连续沉积的看法,纠正了把下马家沟期北庵庄组归入大坪期并与华南扬子区大湾组对比的认识。
Summed up and re-studied the Ordovician tooth-shaped stratosphere biosphere in North China, revised the sequence of conodont-type spines established by Antai (1983) and An Taiji and Zheng Zhaochang (1990). The revised conodonts can be classified from bottom to top as follows: Iapetognathus jilinensis-Cordylodus lindstromi, C. angulatus, Chosonodina herfurthi, Rossodus manitouensis, Glyptoconus quadraplicatus and Scalpellodus tersus -Triangulodus aff.bifidus band, Serratognathus bilobatus band, S. extensus band, Paraserratognathus obesus band and Jumudontus ganda band in the Floian, Histiodella holodentata-Tangshanodus tangshanensis band in the Darriwilian order, Eoplacognathus suecicus- Histiodella kristinae, Pygodus anitae and P. serra belts; P. anserinus belts of the Sandbian, Plectodina aculeata, Erismodus quadridactylus, Belodina compressa and Phragmodus undatus belts, and Beltiina confluens of the Katian Yaoxianognathus neimengguensis belt and Y.yaoxianensis belt. At the same time, the Cambrian-Ordovician boundary line was placed on the bottom of Iapetognathus jilinensis-Cordylodus lindstromi belt. This new conodont sequence can divide and contrast the Ordovician strata in North China more accurately. For example, in the Ordovician system, the top two bands except the top two can only be compared directly in China Almost all of the conical spines with the Ordovician tooth-shaped spines at home and abroad by-band contrast. At the same time, it is also evident from this new conodont sequence that the conodont of the Dapingian is absent, demonstrating that the North China did not receive sediment during the Ordovician ramp during the Huaiyuan Campaign , Thus changing the view that the Lower Ordovician and the Lower Middle Ordovician strata in North China are continuous deposits, and corrected the understanding that the North An Zhuang Formation in the Lower Majiagou period was classified into the Daping Period and compared with the Dawan Formation in the Yangtze Region of South China.