کاربرد تحلیل مولفه های انتخابی در شناسایی دگرسانی‌های گرمابی مس-طلای پورفیری و اپی‌ترمال، برگه یکصدهزار کودکان بیرجند ایران

Abstract

This study was conducted in the 1:100000 rectangle sheet of Koodakan in the southwest of Birjand to detect the alteration minerals associated with porphyry and epithermal copper-gold mineralization through false color composites and Selective Principal Component Analysis (SPCA) using ASTER sensor images of Terra satellite. The images were processed after making necessary corrections and preparing mosaics. In the false color composite (RGB: 468), phyllic and argillic alterations were discriminated in red to white pink and propylitic alteration 157 in green. The analysis of SPCA were implemented on the bands 1, 4, 6 , 7; bands 1, 3, 5, 6 and bands 1, 3, 5, 8 for discrimination of argillic, phyllic and propylitic alteration respectively. Furthermore, SPCA on bands 1, 3, 5 and 7 were used for discrimination of alunite alteration. For greater discrimination of alteration zone, two color composites were made from the results of the SPCA. One false color-composite is made from 4th principle components (PC4) of alunite, argillic, and phyllic alterations, and the other one is made from selected Principle Components of propylithic, argillic and phyllic alternations. Bright pixels in the color composite image (high digital number value) indicate the presence of three alterations together. Comparing the results with the geological map, previous studies and different processing methods indicate the acceptable accuracy in detection of the alterations.