Trace Fossils And Sedimentary Environments In The Liujiagou-ermaying Formation Of Jiyuan,yiyang And Dengfeng Area, Henan Province

In this work, the Lower and Middle Triassic Liujiagou- Ermaying formations outcrop of Jiyuan, Yiyang and Dengfeng area,westenn Henan province is regarded as the research object. The sedimentary environment, lithologic character and ichnofossils are analyzed, 8 types of sedimentary sequence are set up and rich continental trace fossils is found in the strata, consist of at least 8 ichnogenus and 10 ichnospecies,including Scoyenia gracilis, Beaconites coronus, Beaconites antarcticus, Taenidium barrettei, Planolites isp., Skolithos linearis, Psilonichnus isp., Arenicolites isp.,Palaeophycus tubularis and Palaeophycus heberti, etc.According to the composition, occurrence and distribution characteristics of trace fossils, five ichnoassemblage are identified:(1) Scoyenia ichnoassemblage, mainly composed of Scoyenia?Skolithos and Beaconites which appeared in the cyclical exposed very shallow water flood land and small river flood lake environment;(2) Arenicolites ichnoassemblage, which is mainly composed of "U" shape dwelling burrows Arenicolites and "Y" type or "J" shape burrows Psilonichnus, produced in lakeshore sedimentary environment in the turmoil of the water body;(3) Skolithos linearis ichnoassemblage, it consists largely of creature living trace, only a large number of development Skolithos linearis trace fossils;(4) Planolites-Psilonichnus ichnoassemblage, which is mainly composed of "Y" or "J" shape domichnia Psilonichnus and fodinichnia Planolites, also existing some Scoyenia and Beaconites fossils. It formes in the farther from the shore,the water energy medium- shore shallow lake sedimentary;(5) Taenidium-Planolites ichnoassemblage, which is mainly composed of Taenidium?Planolites and Beaconites. Formed in the shallow lake sedimentary of relatively calm water environment.