Characteristics Of The Magnetic Susceptibility And Chemical Of Glacier Accumulation As Well As The Environment In The Bordering Mountains To The Tibetan Plateau

Values of magnetic susceptibility are widely used as an index of environmental changein the continuous deposits such as lake, loess and deep sea. However, the research of thenon-continuous deposit which reflects the climate change such as the glacier accumulation isvery poor. The magnetic susceptibility of eight typical profiles of the glacial deposit to thebordering of the Tibetan Plateau as well as comparison with the lake, loess, deep sea and thesurface soil are studied herein. Adopted the mass magnetic susceptibility and the frequencymagnetic susceptibility as the main indexes, the characteristics of the magnetic susceptibilityof the glacial deposit and the factors which influence the magnetic susceptibility are studied.The results show that the large fluctuation of the magnetic susceptibility in the borderingmountains to the east of the Tibetan Plateau is obvious, that is, the values are between3.01and1808.80×10-8m3kg-1with the mean value of147.84×10-8m3kg-1, while the fluctuation ofthe frequency magnetic susceptibility is small, and the values are between0and6.89%withthe mean value of1.37%. The features of the magnetic susceptibility are different in differenttime and space scale. To be more specific， the change of magnetic susceptibility in thedifferent glacial stages in the same region is not clear, while its change of the same glacialstage in different regions is obvious. The affected factors on the glacial deposits are not onlythe mother lithologic, but also the complicated climate conditions.This paper summarized the chemical element characteristics of glacial till and analyzedthe relationship between geochemical elements of glacial till and environment, using threedifferent methods. They were chemical constant element correlation analysis, R-mode factoranalysis and indexes for indicating climate environment, which were sa.saf, eluvial coefficientand A-CN-K triangle model. The results showed that among the chemistry major elements inthe Eastern edge of Qinghai-Tibet Plateau Mountain glacier sediment, SiO2is most,followed by Al2O3, again as Fe2O3, which indicated the existence of rich ferroaluminumphenomenon in this area. Wherein, the content of SiO2decreases with the increase of latitude,which displays different law from topsoil. In the same mountains, the longer of Glacialdeposits of SiO2, the higher the content of SiO2. The content of CaO was relatively high in theGlacial deposits, with a mean value of6.26. Coarse-grained bioclastic were the major formspresenting in the glacial deposits, and confirmed the low degree of chemical weathering of theglacial deposits. The average aluminosilicate rate, the average iron aluminosilicate rate and the average CIA value of the glacial deposits were6.55,5.76and65.30, respectively, whichshowed that the formation of the glacial deposits environment was dry and cold. A-CN-Kmodel indicated that glacial deposits were in the early stages of chemical weatheringgenerally, with only a small portion in the lower level of the medium weathering.This paper can provide fundamental information for Quaternary glacial andenvironmental research in eastern margin of the Qinghai-Tibet Plateau. It has potentialeconomical and social benifit. Today, it is a hot problem of environmental change and thestudy can improve the level of fundmential research around Qinghai-Tibet Plateau and theeastern part of China. Study work on glacial deposits distribution, characteristic, sequence,environmental reaction. It can help us to recgonize the basis of the ecological environment inQinghai-Tibet Plateau and the eastern part of China and provide important bascial informationfor construction of a natural environment.