Remote Sensing Interpretation of Altera-tion Anomaly Based on Fractal Theory:A Case Study of Yangshan County,Guangdong Prov-ince
The abnormal information of wall rock alteration is an important prospecting indicator for hydro-thermal deposits.The interpretation of wall rock alteration information by remote sensing technology is an important method to extract alteration information.This article used principal component analysis to extract iron contamination and mud alteration information from Landsat-5 TM remote sensing images in the Yang-shan area of Guangdong Province.The abnormal principal components extracted from the images were divid-ed into"pixel-area"and the number of pixels was counted.Then,the abnormal threshold was divided into fractal nonlinear divisions to achieve a more accurate classification method.The threshold method is based on the mutation point selection threshold for grading.The results of extracting alteration anomalies often con-tain a large amount of background information,impact of which was reduced by using the fractal theory to de-termine the critical value for grading.This study compared threshold method with fractal method used in the alteration anomalies in the study area.Finally,based on the fractal characteristics of the alteration anomaly information,the summation method was used to classify the iron staining and mud alteration anomaly infor-mation in the study area.The results show that compared with the threshold method,the fractal method en-hances the accuracy of threshold selection in the extraction of remote sensing alteration information.It is found that the mud alteration and iron staining alteration in the study area are mainly distributed in the north-eastern and northern regions,and are scattered in a small area in other regions,which provides better techni-cal support and data support for mineral exploration.
alteration anomalyremote sensing interpretationfractal theoryprincipal component analysisthreshold methodYangshan county,Guangdong Province
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