Figure 2
PC1, PC2 and PC3 transformed to HSI space with I, H and S in RGB image.
The black arrows point to two of the NW-SE-oriented secondary faults. The red arrow points to a typical SW-NE-oriented lineament. The map was generated using ArcMap v10.2 (http://www.esri.com/software/arcgis/arcgis-for-desktop) on the basis of ETM+ data courtesy of the U.S. Geological Survey (http://landsat.usgs.gov). Figure 2 shows the lineaments of study area, mainly SW-NE-oriented, were clearly extracted in the HSI image which could reflect the strike, extension and flexure of the strata (Tailegula and Baogutu Formation). ETM+ data, acquired on 19th July 2002, were chosen and processed to interpret regional faults. By using the PCA and HSI color model transformation, PC1, PC2 and PC3 were transformed from RGB to HSI space and the false color composite imagery of I, H and S in RGB allowed discrimination of the major faults, secondary faults and even lineaments. The major faults, Hatu fault, Anqi fault and Darbut fault, were recognized based on the differences of tone and texture between their hanging walls and footwalls. Moreover, another SW-NE-oriented major fault, named Baobei fault, was interpreted for the first time.
