Coupling Stdudy Of Remote Sensing Alteration Anomalies And Geochemical Anomaly In Copper Polymetallic Ore District

This article selects the middle part of Sanjiang basin in southwest of China,Derong-Binchuan region as the study area, which including Ganzi-Litang Au metallogenic belt,Dege-Xiangcheng Cu-Pb-Zn-Au-Ag metallogenic belt,the zhong za-Shangri-la Cu-Pb-Zn metallogenic belt,Jiangda-Weixi-lvchun Fe-Cu-Pb-Zn metallogenic belt, Changdu-Pu 'er Cu-Pb-Zn-Hg metallogenic belt.The region has dip topography and high vegetation coverage.The rainfall is rich,the drainage system is advanced, with economy backward,the fieldwork conditions is hard.Geochemical prospecting precision is relatively high,but need a lot of manpower and material resources,and in harsh conditions of the Mountion,it is not suitable for human to sample exploration.Remote sensing image as an effective method for pro-specting, has a broad horizon, can prospect by some indicates,the mineralization alteration information and interpretation for geological structure for example.But in some region with high vegetation coverage,it needs further research.Two methods have their own advantages and disadvantages,but both is effective and feasible,some experts and scholars have made a series of achievements.This article will combine the multispectral OLI remote sensing image of the region,1:200000 stream sediment geochemical data and regional geologicalbackground,geological structure for the experiment,extract anomaly information and do relaitivity analysis.On the basis of correction analysis,combining the pro ven metallogenic facts,endow taget weights.remote sensing anomaly information and geochemical anomality can becoupled,information of geochemical anomaly and remote sensing can be gotten,the ore-forming indicator of the results of the two coupling can be evaluated.The concrete research is as follows:1) The article select the multispectrum OLI remote sensing image in the study area,calibrate the radiation and correct the atmospheric,remove the interference information such as, the quaternary system, the clouds, the shadow,high coverage of vegetation, using principal component analysis(PCA), extracting information of iron and hydroxyl alteration,and classify the alteration information;2) In ENVI 5.1,do correlation analysis between extraction of alteration inform ation and occurrences' buffer area in the research area, do alteration infor mation density analysis in the Arc GIS,and make thematic map;3) Checking the data of 16364 stream sediment samples in the area,and studyi ng on the association relationship between these elements.Combined with th e existing metallogenic facts, determine the geochemical elements: Cu,Nb, Ti,Ni,Pb,Zn,Ag,Li,Mo,and geochemical constants:Mg O,Na2 O,Ca O,Fe2O3,these 13 kinds of objects for next study;4) In Grapher,using the content-area method of multifractal theory to calculate the single element's abnormalistic lower limits, cumulative frequency meth od is used to determine the abnormalistic lower when limits the elements do not meet the conditions of multifractal,and treat the Na2 O,Ca O negative abnormality as a supplementary study,make single element anomaly maps and the multi-elementary anomaly map;5) Do the correlation analysis about the remote sensing alteration anomaly inf ormation,geochemical integrated anomaly information and occurrences' buffer area in the research area,evaluating the ore-forming indicator of remote sen sing and geochemical anomaly information.According to the correlation of abnormal information,endow taget weights in Arc GIS,remote sensing and ge ochemical anomaly coupling information can be gotten.In the process of research,the technology route of the remote sensing alterat ion information extraction is optimized.At the same time,in order to use more scientific methods, we used the multifractal method to determine element anom aly threshold in the geochemicalanomaly information extraction.The introduction of Na2 O,Ca O negative anomaly information is as supplement for this research. Combining remote sensing with geochemistry in the process of prospecting effe ctively, improves the precision of mineral deposit prediction, provides technical support for metallogenic prospect areas division and field survey lately.