The Magnetic Susceptibility Characteristic Of Lake Surface Sediment In Tibet Plateau And Its Environmental Significance

Lake sediments as a carrier of environmental information, record global, regional and local environmental information. Based on the magnetic susceptibility of Tibet Plateau lake surface sediment as the research object, combined with the particle sizes and different mineral characteristics. The environmental significance of magnetic susceptibility were researched. The main conclusions were summed up as follows:(1)The content of the magnetic susceptibility in the lake surface sediment of the Tibet Plateau is low, the overall average of value is1.64×10-8m3kg-1, but the general average content of the magnetic susceptibility in lake surface sediment of the Koh Xil is0.95×10-8m3kg-1; the average content of magnetic susceptibility of the lake surface sediment in the northern Tibet Plateau is2.33×10-8m3kg-1,which suggests in different region, the content of the magnetic mineral of lake surface sediment in Tibet Plateau is differences.The percentage content of the frequency magnetic susceptibility is low, the average of value is2.97%. It indicates the content of fine particles in magnetic mineral of lake surface sediment in the Koh Xil and the Tibetan plateau has little difference.(2)The lake surface sediment of the Tibet Plateau is mainly composed of silty sand and sand particle. The average proportion is12.81%for clay,30.43%for silty sand, and57.76%for the sand particle. The particle size distribution of the lake surface sediment in the Tibet Plateau indicates that the particle size in the lakes comes mainly from the action of the wind.(3)The clay minerals of the lake surface sediments in the Tibet Plateau are mainly illite and chlorite, the non-clay minerals include quartz, feldspar, calcite, aragonite and dolomite. The source of the mineral is mainly weathering products around the basin bedrock. In the deeper water of the lakes in the Tibet plateau has pyrite from the authigenesis generating. (4)Through correlation analysis of the magnetic susceptibility content and the composition of different particle size of the lake surface sediment in the Tibet Plateau shows that the magnetic susceptibility content is not obvious correlation with different particle size composition. The correlation of magnetic susceptibility content and the clay is very weak of the lake surface sediment in the Koh Xil, and other basic is not related to particle size; the magnetic susceptibility and the composition different particle size in lake surface sediments northern Tibet plateau were not associated with, it shows that magnetic minerals of the lake surface sediment in Tibetan plateau is not in a certain particle size, at the same time also shows that the source of the magnetic mineral exist different source. Through the correlation of the magnetic mineral content and mineral content of the lake surface sediment in the Tibet Plateau is not relevant, shows that the inverse magnetic mineral of magnetic mineral side effect is less, it small affected the magnetic minerals in sediments.(5)The magnetic minerals of the lake surface sediment in the Tibet Plateau exist multi-source, the outer edge of detrital minerals is the main influence factor of magnetic minerals, they are carried by wind transportation into the lake. The authigenic magnetic minerals in the lakes surface sediment.