Comparative Research On Methods For Extracting Weak Alteration Anomalies Information Of Pulang Porphyry Copper Deposit Based On ASTER Data

With the ASTER remote sensing data,and combined with the characteristics of alteration zoning of Pulang porphyry copper,this article analyzed and studied the mineral spectral characteristics of the alteration zoning of Pulang porphyry copper deposit.The principal component analysis and S-A method(energy spectrum-area method)based on fractal and multifractal theory,were applied to extracte five alteration mineral anomalies respectively,such as Quartz,Potassium,Sericite,Chlorite and Epidote,which exist in mineralization alteration zoning in Pulang porphyry copper deposit.According to the field survey,the S-A method is much better than the Principal Component Analysis method in the alteration anomalies information extraction for the porphyry copper deposit.In this research,we achieved the following main results and understanding:(1)This article studied the spectral characteristics of Quartz,Potassim,Sericite,Chlorite and Epidote by referencing USGS spectrum library and analyzing the characteristics of the diagnostic alteration mineral spectra with the ASTER data.The technical processes were established by using principal component analysis and the S-A method and the alteration anomalies information of porphyry copper deposit were extracted as well.By comparing the results,all data in the S-A method are involved in the process and the weak alteration anomalies information under the complicated geological background are enhanced extracted.Therefore,the S-A method is much more better than the Principal Component method for extracting the alteration anomalies information of porphyry copper deposit.(2)The S-A method was applied in the Pulang porphyry copper deposit and the weak alteration anomalies information were extracted.By the high coincidence of the Quartz,Potassium,Sericite,Chlorite and Epidote through field survey,the method is verified feasible and the results are reliable.In summary,this reaserch established the S-A method to extract weak remote sensing alteration anomalies information of alteration zoning,characteristic mineral of porphyry copper deposit,which based on fractal and multifractal theory of "The generalized self-similarity" and "The local singularity".This method with all data involved in the process overcome the shortcomings of the less weak alteration anomalies information finely extracted under the complicated geological background with the incomplete data which deepened the theory and the study of weak anomalies information extraction method.