The Geochemistry Analysis Of The Debris Flow Sediments In The Quaternary Period

Debris flow is a geological phenomenon, usually in the mountainous areas. It is a special flood, mixed with some solid matters, such as silt, stones and huge gravel ,caused by rainfall (storm, melted snow and ice glacier), which is also a high concentration of mixed crude flow. Its movement process is a result of national factors , such as geology, geomorphology, hydrology and meteorology, and man-made factors , which is among the movement of landslide , downslide and flood.The sediments of debris flow is a type of Quaternary period, which formed in geological process of Quaternary period and a given geological circumstances. It is a significant foundation for people to recognize and demonstrate the rock, stratum, ancient geographical features and geochemistry of a region in Quaternary period. The sediments possess the conditions and information about their formation, which decide the distribution of its chemical elements and chemical compound. At present, the geochemistry researches on Quaternary period in China mainly concentrate on these kinds of sediments such as loess,lake, sea ,river, glacier, burrow, weathering crust and so on,but the research on sediments of debris flow are comparatively less than others. As a special type of sediment of Quaternary period, the process of weathering, carrying, and accumulation of it is distinct from the other types.This thesis choose Xiaojiang Valley in Yunnan and the white dragon river Valley in Gansu as the researching areas. At first, It gives a exposition of debris flow research history and research content at home and abroad. Then, through researching chemical elements distribution, allocation and migration of debris flow in different ages at the two different areas, the law of enrichment, the contents of every kind of chemical element among the sediments of debris flows(SiO₂, Al₂O₃, Fe₂O₃, K₂0, MgO, P₂O5, CaO, Na₂O, MnO and TiO₂ etc), the coefficient of silicon and aluminium, the coefficient of aluminium and iron, the eluviate coefficient of alkali metals, the eluviate coefficient of alkaline earth, the eluviate coefficient of electropositive gross, the coefficient of eluvium, CaCO₃, PH, organic matter. The thesis presents that geochemistry features of debris flow in Quaternary period are distinct from other types of sediments.According to the result of the analysis of sediments'chemical elements, emigration intensity of chemical elements, CaCO₃ content, the content of organic matter, soluble salt,it explains the relationship between the sediments'chemical elements and the change of circumstances, and the features of ancient climate and ancient geographical circumstances in the mature period of mud-rock flow, and conclude the forming features of geochemistry element of sediment in Quaternary period ,which reflects the ancient climate emigration of the period.