Principal component analysis for alteration mapping: A case study, Jinghong area, Yunnan Province, China

Three Principal Component Analysis (PCA) techniques have been applied on TM data for remote detection of alteration zones related to copper mineralization in the Jinghong area; these techniques are selective two bands PCA, selective four bands PCA and standard six bands PCA. The statistical tables of relevant transformations have been used in selecting the appropriate Principal Component (PC) images for the hydrothermal alteration mapping. The results show that these three PCA techniques are considered to be suitable for alteration mapping in the area. With the support of field information, obvious alteration haloes extracted from these techniques could be interpreted as a result of intruded igneous bodies (mostly granitic) in the medium acidic rocks of the Manghuai formation (T2), their presence is controlled by NW-SE major fault structures and it has a positive association with the mineral deposits especially the copper polymetallic occurrences. Comparing the principal component color composite images, which are created by three PCA techniques, a color composite image created by applying selective two bands PCA technique is more reliable to visually interpret the type and the intensity of alteration haloes around the intrusive igneous bodies.