Study On The Relationship Between The Jurassic Sporopollen Component Types And Palaeobathymetric Changes In Junggar Basin

Junggar basin,located in the western China,is one of the large complex superimposed basins.The Jurassic stratum is the main research object for oil and gas exploration.During the Jurassic period,the Junggar basin developed abundant rivers,lakes and swamp facies.It also contains abundant fossils,such as spores,pollens and algae.The microfossils are of great significance for stratigraphic classification and correlation of ancient climate and ancient vegetation analysis,in recent years,people began to try to use sporopollen component types to study the the palaeobathymetric change.In this paper,by studing the relationship between the Jurassic sporopollen and palaeobathymetric change,we get the following main achievements and cognition:(1)Principle analysis: sporopollen is usually a long-distance buried handling fossil collections,by analyzing the vegetation types and the composition structure of sporopollen,we thought that the two have different ways of handling,spore to surface runoff carrying commonly,and pollen by wind.So spores and pollens,and different types of pollen,the handling distance is different,thus different water depth has the different combinations of sporopollen.(2)Method: considering the complex diversity of pollen type,based on the pollen morphology structure type,complex degree of differentiation and component type: three different methods to study the relationship of the ancient water depth and the palaeobathymetric change.Compared with the results of the study of sedimentary facies,the results show that although the three methods all can establish the correlation between sporopollen and palaeobathymetric change,we found that the former two methods can only reflect the palaeobathymetric change's trend,the sporopollen composition types not only can well reflect the palaeobathymetric change,and have certain corresponding relationship and the types of sedimentary facies,is the best results.(3)Specific research: based on the statistics of sporopollen fossil in 6 Wells(141 genera and 229 species),and the number of detailed identification and computed for various types of pollen morphology in the sample(4),the compound types and sporopollen components(3)percentage change of well depth,and compared with the results of the study of sedimentary facies,the results show that in the long term it has a good corresponding relation,on this basis,through the comparison between Wells, the lateral changes of the water depth are discussed.