Comparison of three principal component analysis techniques to porphyry copper alteration mapping: A case study, Meiduk area, Kerman, Iran

The principal component analysis method is widely used for alteration mapping in metallogenic provinces. The three principal component analysis techniques used for alteration mapping around porphyritic intrusives of Meiduk area are the selective, developed selective or Crosta, and the standard method, This paper compares the results of the three different techniques on Landsat TM bands. The comparison is mainly based on the visual and field observation analysis of the results. Selective principal component analysis using TM bands 5 and 7 is more apporpriate for alteration mapping. However. the vegetated areas are also enhanced in PC2 image. Carrying out the developed selective method on bands 1, 4, 5, 7 of TV for hydroxyl mapping enhances these alteration haloes around the intrusives. but the method for iron-oxide mapping enhances an extensive area with sedimentary lithology. The standard PCA technique however enhances the alterations in PCA image but is time consuming. The hydroxyl mapping thechnique of developed selective or Crosta technique is suggested for alteration mapping around the porphyry intrusive bodies.