Application Of Mathematical Analysis Method In Research Of Foraminiferal Paleogeography At Tibet Of Cretaceous

Bio-palaeogeography is the study of the distribution of fossils in space and time framework based on the fossil in the certain geographical area. It's important for the authentication of palaeogeography and palaeoclimate reconstruction and for the judgment of the location of the ancient plates. Foraminifer is a important microbios in geologic history, it has main role in the division of stratum and rebuilding of palaeogeography.Tibet is an important distribution area of cretaceous Marine strata, foraminifer has a the depth-study, and has three biological zoning on the basic of qualitative analysis, they are Orbitolina biological zoning in Lhasa and Qiangtang block; mixed of planctonic and benthic foraminifer zoning at shallow sea in Gangba and Dingri; planctonic biological zoning in Jiangzi.In this paper,we can get more accurate foraminiferal zoning in mathematical analysis on the basic of qualititative analysis, not genus but species in cluster analysis. Because of first cluster in species, we use three likeness coefficient they are Jaccard, Dice and Ochiai, so can get biologic zoning in software of SPSS of widely used in non-professional of statistical person.By clustering analysis,in early cretaceous, there are the same answer in three kinds of the similarity coefficient. The biological zoning are Orbitolina zoning in Lhasa and Qiangtang of north of Tibet, mixed planctonic and benthic foraminiferal zoning in Gangba and Dingri of south of Tibet. In late cretaceous, every similarity coefficient get three biological area, they are Orbitolina zoning in Lhasa of north Tibet, mixed planctonic and benthic foraminiferal zoning in Gangba and Dingri of south of Tibet of neritic environment and planctonic foraminiferal zoning in Jiangzi. But in south Tibet, because of different emphasis of likeness coefficient, Daba, Tianba and Angren set of Xigaze are part of different zoning.Biological area with mathematical analysis method is consistent with the result of qualitative analysis. For different of the accuracy and emphasis of mathematical analysis, imperfection of distribution of foraminifer data, identify of human factor, those factors lead to the certain different within the result of mathematical analysis method and qualitative analusis. Therefore, mathematical method combined with qualitative analysis, we can reach the most accurate biological area.