Image Processing of Landsat-8 OLI Satellite Data for Mapping of Alkaline-Carbonatite Complex, Southern India

The alkaline-carbonatite igneous intrusion occupies a very less aerial extent on the earth’s surface. However, it is an important source rock for Rare Earth Elements (REE), Large Ion Lithophile Elements (LILE), and radioactive elements. The origin of the alkaline-carbonatite suite is always related to tectonic settings such as continental drift and suture zones. In this context, the Samalpatti and Sevathur alkaline-carbonatite complex is an interesting area among various geoscientists. The moderate resolution Landsat-8 OLI satellite data is digitally processed using ENVI 5.3 image processing software to interpret various lithologies in the terrain. Different rock types, including syenite, pyroxenite, dunite, carbonatite, and epidote hornblende gneiss, cover the Samalpatti-Sevathur complex. The carbonatites are emplaced as elongated bodies, dykes, and scattered nodules in ultramafic formation. The mapping of ultramafic formations is essential since it contains carbonatite emplacement in the complex. The seven-band OLI data covered under the visible, near-infrared, and shortwave infrared spectrum were used to generate color composite images, band ratios, principal component analysis (PCA) images, and support vector machine (SVM) classified output. The digitally processed satellite images are helpful in the interpretation of different rock types, particularly the ultramafic formation. Out of various outputs, the FCC, the composite image B652, color composite images from ratio output, PCA composite images in RGB filters, and SVM-classified output are suitable for interpreting different lithologies in the terrain. The results obtained through the interpretation of digitally processed satellite outputs were validated with the help of published geology maps, field sample locations, and photomicrographs.