187 Study on the Remote Sensing Imagery Alteration Information Extracting Technology: Case Study of Gold mineralization in Zhaoyuan City, Shandong Province, China

Alteration extraction of Landsat-ETM+ imageries has been used for many years to explore gold minerals in Zhaoyuan city in Shandong Province. This paper aims to introduce some methods to detect the alteration zones (iron oxides, hydroxyl, and carbonates) in the wall rocks using Landsat-ETM+ imagery. Band selection played an important role in this research. Before choosing the bands, the basic information, the correlation coefficient of all bands, and the correlation between the bands and alteration zones were analyzed. By using the spectral characteristics of the wall rocks and different band ratios (reflected∕absorbed), the alteration zones in the wall rocks could be delineated. Owing to the presence of gossans in Zhaoyuan city, the mixture of iron oxide and clay minerals affects the spectral reflectance of the satellite data. Comparing the research result with existing mines, the technology identified 43 (89.5%) out of the total 48 mines.