Li County, Gansu Carboniferous Stratigraphy And Paleontology

On the basis of extensive field investigations and laboratory analyses on the Carboniferous strata and fossils in the West Qinling . To the Carboniferous of Lixian , there has systematically been studied in the lithostratigraphy and biostratigraphy. At the same time, a diverse of fossils form this area have detailedly been described and discussed. Thus, it is a significant new contribution on stratigraphy and palaeontology of Carboniferous in Lixian of the West Qinling.Ch.1 Lithostratigraphy7 stratigraphical sections of the Carboniferous has been described Based on the features of development, distribution, petrology and facies of strata, the Carboniferous in this area can be further subdivided into secondary stratigraphical regions. I reconsider the disjoint strata of the early Carboniferous should adopt Badu Formation in Yanghe-Gucheng, the strata of the late Carboniferous should adopt Xijialing Formation and Dongzhakou Formation in Lubanshi. I also define each unite of formation and members. including characters of petrology and regional distribution. Finally, the stratigraphical framework have been constructed based on consistencies of petrology , facies and the relationships of rock units.Ch.2 BiostratigraphyFeatures, distribution and assemblage of three group fossils from many of the 7 geological setions, including conodont, coral and foraminifera fossils, have been comprehensively discussed. And a series of fossil assemblages can be recognized. Finally, integrative correlation has been made.The fossil assemblages and Suassemblages:3. Streptognathodus suberectus- S. expansus-S. parvus- S. gracilis Assemblage2. Idiognathodus delicatus- Idiognathodus shanxiensis- Neognathodusbassleri-Neogondolella clarki AssemblageIdiognathodus shanxiensis- Neognathodus bassleri-Neogondolella clarki SubassemblageIdiognathodus delicatus- Idiognathodus sinuosus Subassemblage2. Declinognathodus noduliferus noduliferus- Idiognathoides sinuatus-Polygnathodella ouachitensis AssemblageIdiognathoides sulcatus- I. sinuatus- I. corrugnatus-Polygnathodella ouachitensis Subassemblage Declinognathodus noduliferus noduliferus SubassemblageCh.3 Description of fossilsFossils discovered from many localities in research area are systematically described. There are 25 genera and 47 species of conodont, 4 genera and 6 species of coral and some foraminifera.Ch.4 Biostratigraphical regionsBased on the study on the conodont, coral and foraminifera fossils in research area, it was discovered that the biota features are resemble to the South China. So a conclusion can be drawn that the research area and South China belong to the same biogeographical region.