Research On The Early Jurassic Stratum Of Jiaojiadian Area In Yunnan

The Jiaojiadian area of Yimen County,Yunnan Province is located in the south-central section of the Kang-Yunnan axis of the southwestern edge of the Yangtze quasi-platform.It is famous in China and foreign countries for the production of Jiaojiadian dinosaur fossils.Fossil important distribution area.This research area belongs to the Mesozoic Basin in Dianzhong,located in the west margin of Dianzhong Basin,and belongs to the sedimentary type of small basin.The stratigraphic studies in this study area are still very rough,the stratigraphic age is not clear enough,and the division of stratigraphic units is not clear enough.The evolution process of the paleoenvironment has yet to be studied,which restricts the study of dinosaur fossils in this area.To determine the burial environment of dinosaurs and provide basic data for the subsequent research of dinosaurs.Therefore,it is necessary to carry out research on the Early Jurassic strata in this area.This article relies on the ongoing"Dinosaur Fossil Geological Park Construction Project in Shijie Township,Yimen County"and the systematic summary of previous research data by the school and the Yimen County Culture,Tourism,Radio,Film and Sports Bureau,and the data from this field field survey,Compared and analyzed with the standard stratum profile measured by predecessors,and divided the Early Jurassic strata in Jiaojiadian area of Yimen County in detail,and the early Jurassic strata in the study area were originally designated as the Lower Jurassic Fengjiahe The strata of the group are re-divided and defined as the Lower Jurassic Lufeng Formation.According to the characteristics of lithology and paleontological fossils,the Lufeng composition is divided into two sections,from bottom to top:the first section of the Lower Jurassic Lufeng Formation?J₁l¹?.The second section of the Lufeng Formation of the Lower Jurassic?J₁l²?.The burial layer of dinosaur fossils was determined.The dinosaur fossils in the study area were mainly buried in the first and second members of the Lufeng Formation of the Lower Jurassic.Through systematic identification and analysis of sporopollen fossils,according to the closest relative species corresponding to sporopollen fossils,the paleoclimate of the Early Jurassic period in Jiaojiadian area of Yimen County was restored and the evolution process of paleoclimate was discussed.By analyzing the lithology and sedimentary cycles of the Early Jurassic strata in the study area,the evolution process of the Early Jurassic sedimentary basins in the study area was discussed.