The Response Of The Foraminifer Evolution At The Turn Of Permian-triassic In The Zhijin Section Of Guizhou To The Ancient Marine Chemical State

The Guizhou section of Zhijin volcano tuff clay rock development,continuous formation,sedimentary characteristics of Triassic in Southern China area of Permian strata or slope facies basin facies strata,and provides very good conditions of biological evolution and ancient ocean chemistry characteristics.Taking Guizhou section of Zhijin as the research object,through data collection,field investigation observation,laboratory analysis and microscope on the foraminifera type and research response to ancient marine chemical state.According to statistics,a total of Guizhou Zhijin section authenticate 15 foraminiferal genera and 38 species,divided into 3 zones.The foraminiferal assemblage evolution in the region: according to the foraminifera foraminifera appeared a total of two biological plummeted after the first drop,there is a small amount of foraminifera extended to the overlying strata,after the second plummeted the overlying strata of foraminifera rarely or extinct;compared with Zhejiang Meishan section,Guizhou section of Zhijin first biological arc extinction the vast line of fifth top layer,second times in the eighth layer,the P-T boundary is determined in the 7-1 top 7-2 bottom layer.The iron components and trace elements test of Guizhou,Zhijin Late Permian-Early Triassic oxygen content in water was shock changes,but overall the end Permian oxidation environment,anoxic environment is the Early Triassic and the distribution of foraminifera in seawater.The oxygen content in a good correlation,when the oxygen content is relatively increased,foraminifera flourish,when the oxygen content is relatively reduced,foraminifera decay.At the same time,it is discussed that the cause of the mass extinction at the end of the Permian and the change of the chemical state of the ancient ocean may be the large-scale volcanic activity at the end of Permian.