Study On Cenozoic Charophyta&Paleoecological Characteristics And Paleoclimatic Conditions In Dongping,Qaidam Basin

Through fossil indentificaiton and research of chara in 10 Wells in Dongping area,Qaidam basin,also compared with fossil assemblages of the whole basin and other area,this paper talks about Cenozoic chara fossil assemblage in Dongping area,at the meantime,dicusses about their times.Based on throught analysis of productive layers,characteristics of fossil assemblages and lithologic features,chara communities are eatablised and their relationships with factors of sedimentary environment are mentioned in this paper.The main achievements are as follows:1.Based on fossil analysis of 1166 samples from 9 wells in 6 sections in dongping area,qaidam basin,20 genera and 106 species of chara have been identified and 3 fossil charts were completed.2.Based on fossil identification,the characteristics of the chara fossil assemblage,simple differentiation index,composite differentiation index,abundance index,4 fossil assemblages and 3 sub fossil assemblages were classified in this area.The classification also makes references to the order of the taxa in the formation,the flourishing degree and the distribution interval of chara species,the previous classification results of the Cenozoic cypris combination.3.Through analysis of character species,dominant species and massive structure of chara assemblages,and comparasion with related chara assemblages in the whole qaidam basin and other areas,this paper talks about the times of each chara assemblage.4.6 communites of chara species have been divided in Dongping Well 1 according to horizon of chara fossil,chara fossil composition structure,taphonomy,lithological characters and paleoautecology.Chara belongs to submerged aquatic vegetation,and its development is strictly controlled by water salinity,water depth,the degree of clarity.5.Relationship between chara communites and sea level fluctuation is talked about in this essay based on analysis of chara community structure,changement of advantage species and characteristic species,lithological characters and sedimentary environment characteristics.Prosperous and rarity of chara mumbers in communites can reflect the rise and fall of the lake level.