Abstract
The study area is located 100 km southeast of Arak and in two structural zones of Central Iran in the north and Sanandaj-Sirjan in the southern part. Regarding its geological structures, the area has become the source of important mines including the Akhtarchi gold mine, Aliabad iron mine, Ochestan feldspar mine, and Dali gold and copper mines. Therefore, promising areas for exploration activities are identified using the analysis of satellite images of ASTER and Landsat ETM + in the region to identify alteration areas. For this purpose, the necessary corrections were applied to the satellite images. Then, to identify the alteration parts related to the gold deposits, different satellite image processing methods of ETM + and ASTER were used. These methods include making a false-color composite, band ratio, Selective Principal Components Analysis (SPCA), Spectral Angle Mapper (SAM) method, Spectral Information Divergence Classification (SID), Endmember Collection Dialog Components (ECDC), and innovative methods such as Principal Component Analysis (PCA) and Spectral Angle Mapper, as well as unsupervised classification methods. In the end, the major alterations in the region were observed. In the obtained images, the prophylitic zone and the phyllic and argillic zones in the region were observed. To introduce the optimal method, the results of the various methods mentioned were compared with each other and with the current situation of the mines. The alteration zones were identified through band ratio and SAM methods and the combined methods with more power. Finally, SAM, 2:1 ratio, and the combined methods were identified as successful methods for more accurate separation of the alteration zones.
Highlights
METHODOLOGYNinomia (2005), according to the spectral absorption properties of different plants, minerals and rocks defined an indicator for vegetation, mineralogical indices based on the first 9 bands of the ASTER sensor (VNIR and SWIR spectral ranges), and lithological indices based on the infrared thermal range of the ASTER sensor (TIR spectral range)
El área de estudio se encuentra a 100 km al sureste de Arak y en dos zonas estructurales del centro de Irán en el norte y Sanandaj-Sirjan en la parte sur
Estos métodos incluyen hacer una composición de color falso, relación de banda, análisis selectivo de componentes principales (SPCA), método de mapeador de ángulo espectral (SAM), clasificación de divergencia de información espectral (SID), componentes de diálogo de colección de miembros finales (ECDC) y métodos innovadores como Análisis de componentes principales (PCA) y mapeador de ángulos espectrales, así como métodos de clasificación no supervisados
Summary
Ninomia (2005), according to the spectral absorption properties of different plants, minerals and rocks defined an indicator for vegetation, mineralogical indices based on the first 9 bands of the ASTER sensor (VNIR and SWIR spectral ranges), and lithological indices based on the infrared thermal range of the ASTER sensor (TIR spectral range). To better separate the alteration zones, the modified images were processed These processes include the false-color composite image, band ratio, PCA, and spectral angle mapper method. Xu et al (2004) identified mineralization zones with hydrothermal alteration around hydrothermal gold deposits using ASTER sensor data in northeast China They used the PCA technique and band ratios of 2.3, 1.4, and 6.4 to separate vegetation, iron oxides, and clay minerals, respectively. 3.3.Spectral Angle Mapping (SAM): Spectral angle mapper is an automatic algebraic method that calculates the similarity of a spectrum between the spectrum of each pixel and the reference spectrum The similarity between these two spectra is the mean angle of the two spectra, where each spectrum corresponds to a vector in a space with dimensions equal to the number of bands. 3.5.The use of Endmember Collection Dialog Components (ECDC) method The ECDC contains a table of spectra that allows you to observe and edit the properties associated with each of the spectra listed (Envi 5 help)
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