Study On Lithologic Units Identification And The Distribution Of Metallic Elements In Malipo Area

The Malipo area in southeastern Yunnan Province is an important tungsten-tin-lead polymetallic ore-forming area in China.Due to the complex geological evolution of the area,varying degrees of metamorphism make it difficult to identify strata and rock masses in different areas.Therefore,this study intends to use the end-member mixing analysis model which was commonly used in the field of remote sensing spectrum unmixing,statistical analysis and other methods to identify the lithologic units,summarize the enrichment rules of metal elements and their main sources.This paper mainly studies 16 kinds of metal elements from the 1:50000 stream sediments geochemical data in the study area.First,the log-ratio transformation of the original data is performed,and then the principal component analysis is further applied to the transformd data.Based on the principal components,a series of Q-type hierarchical cluster analysis was carried out.The cluster results are compared with regional geological information to determine the number of end-members.By establishing the end-member mixing analysis model and parameter inversion,the contribution rate of each end member of each sampling point and the maximum contribution end member of each sampling point are obtained.Finally,combined with the hierarchical cluster results and the end member results,the identification and division of the lithologic units in the area is completed.In addition,through the correlation analysis and R-type hierarchical cluster analysis of 16 kinds of metal elements,the law of element enrichment is summarized.On this basis,the main sources of metal elements are discussed.Based on the above research process,the following research results are obtained:(1)End-member mixing analysis model widely used in hydrogeology and hyperspectral remote sensing are seldom used in the study of stream sediment geochemical data.This paper attempts to apply the model and achieves good results.(2)According to the classification result of the largest contribution end of each sampling point,refer to the hierarchical cluster analysis results,study area basalt,granite,gneissic granite,argillaceous limestone,shale,dolomitic limestone,quartz sandstone,silty mudstone.(3)According to the hierarchical cluster results of 16 kinds of metal elements,it is found that the elements of copper,zinc,manganese,cobalt,titanium and nickel coexisting with iron are enriched and belong to a group of low-temperature elements.The enrichment of tungsten,tin and antimony is a set of high temperature elements.Au,Hg,Sb,and Pb are sulfur-rich elements and belong to a class of low-temperature sulfur-containing elements.The enrichment of metal elements and their main sources are basically consistent with previous research results.The comprehensive results show that it is feasible to identify lithologic units by using the end-member mixing analysis model with the statistical analysis of stream sediments geochemical data.The whole research process has better revealed the correlation between regional basic geology and geochemical information,and provided ideas and references for further exploration and research work.