The Division And Comparison About Sanmen Formation And The Research On Ostracodes In Songjiabeigou, Weinan, Shannxi

On the base of the extensive collection of the Cenozoic strata and fossils in the Fen-Wei basin,this text made a systemic study on the strata of the Sanmen Formation in the Songjiabeigou,Weinan,Shannxi.After dealing, identification and description with the fossils,and making the fix quantify test on the magnetic susceptibility about the sample,the study provide new abundant Sanmen Formation's information.1, Make a systemic study on the strata of the Sanmen Formation with characters of the rock-stratigraphic, the biostratigrapic and the magnetostratigraphy. Then make a clarify that the Sanmen Formation should be divided into two members,as the "Yellow Sanmen", "Green Sanmen" which pointed by formers. But as Sanmen Formation strata of the "wear," and used "yellow" and "green" is not a universal nature and therefore the author divided it into Sanmen Formation High Member and Sanmen Formation Lower Member.2, Make a systemic study on the ostracode fossils which collected from the section. 12genus 27 species of fossil insects are described, and the spatial and temporal distribution of their character, portfolio characteristics, fossil abundance and sub-degrees, from the exploration, establish 2 ostracode worms fossils assemblage in the Songjiabeigou Sanmen Formation profile.3, Comprehensive study in the area and the profile of the predecessors of this research obtained new information on the environment and climate change to the preliminary examination from the Neogene to Quaternary Sanmen Age in Weinan areas.Consider that:a, The profile of Sanmen Formation High Member and Lower Member, which the differences resulting from different sediment environment, then this exactly reflect the evolution of ancient lakes environmental change; b, Frequency Susceptibilities can sensitively reflect environmental changesdetails of Sanmen Formation; c, Ostracode fossils from the abundance of sub-degree and the region could wellreflect the environmental evolution of Sanmen Formation; d, The environment of Sanmen Age in the region from warm, hot and damp, to dry and cold.