【作者】 宋先腾；

【导师】 王训练； 景秀春；

【作者基本信息】 中国地质大学(北京) ， 地质工程， 2012， 硕士

【摘要】 四川盆地北缘广元市旺苍县罐子坝剖面下三叠统发育，沉积厚度大，是四川盆地下三叠统出露较为完整的剖面之一，并且发育了许多重要的牙形石属种。本文系统采集了该剖面上灰岩层牙形石样品，经处理共获得牙形石200余枚，经鉴定共有9属18种。这些属分别是Ellisonia，Furnishius，Neogondolella，Hindeodus， Isarcicella， Parachirognathus， Pachycladina， Hadrodontina和Neospathodus。将该剖面下三叠统划分为3个牙形石带，自下而上依次为：Isarcicella isarcica带，Parachirognathus delicatulus-Pachycladina obliqua带和Neospathodus triangularis带，并与广西平果、安徽巢湖和意大利南阿尔卑斯等典型地区同期地层进行对比，此外，还对比了中国不同相区和国际标准下三叠统牙形石序列。确定了各牙形石带的年代：Isarcicella isarcica带属Griesbachian早期，Parachirognathus delicatulus-Pachycladina obliqua带属Smithian期，Neospathodus triangularis带属Spathian期。讨论了Smithian-Spathian亚阶的界线，以Neospathodus triangularis的首现点定义界线位置，标定在距第122层底2m处。讨论了旺苍罐子坝地区早三叠世Ellisoniidae科各属种演化关系，认为Hadrodontina，Pachycladina，Furnishius和Parachirognathus可能均由Ellisonia演化而来。Parachirognathus始于Dienerian期，Hadrodontina，Furnishius和Pachycladina均始于Smithian早期。这些成果为四川盆地下三叠统牙形石序列的建立提供了依据。更多还原

【Abstract】 The Guan Ziba section is located in Wangcang County, Guangyuan City,northern margin of the Sichuan Basin, China. The Lower Triassic System is wellexposed at the Guan Ziba section with the quite thicker sediment. And the sectioncontains a lot of important Lower Triassic conodont species, and it is one of thesections which involve complete Lower Triassic sediment in the Sichuan Basin.Conodont biostratigraphy is utilized as the primary approach to study the LowerTriassic sediment of the section. Many samples were collected systematically fromlimestone layers of the section. Then, the careful handling and accurate identificationof the conodont was made. The extracted200conodont elements include18stratigraphically significant species referable to9genera: Ellisonia, Furnishius,Neogondolella, Hindeodus, Isarcicella, Parachirognathus, Pachycladina, Hadrodon-tina and Neospathodus. Three conodont zones of the Lower Triassic had beendistinguished. In ascending order, they are: Isarcicella isarcica zone, Parachi-rognathus delicatulus-Pachycladina obliqua zone, Neospathodus triangularis zone.They may be precisely correlated with contemporaneous ones in the Pingguo(Guangxi Province), Chaohu (Anhui Province), China and Southern Alps of Italyand also with the Lower Triassic conodont sequences from different facies in Chinaand of international standard. The age of each zone was determined and respectivelybelonged to early Griesbachian, Smitian and Spathian. Smitian-Spathian Boudarywas discussed and defined by the first occurrence of Neospathodus triangulariswhich was placed at2m above the boundary between the Bed121and the Bed122.The relationship of the genera in Ellisoniidae was also discussed and Hadrodontina,Pachycladina, Furnishius and Parachirognathus may be all evolved from Ellisonia.The last one started from Dienerian and the others started from early Smitian. Thesedata are evidence for erecting the Lower Triassic biostratigraphy sequence ofSichuan Basin.更多还原