The layered Sittampundi Anorthosite Complex is covered by mafic and ultramafic rocks including anorthosite, gabbro, pyroxenite and other igneous rocks. The ultramafic terrain has frequently undergone metamorphism. In the present study, laboratory spectral measurements were carried out from mafic, ultramafic and felsic rocks in the 350–2500 nm spectral range to characterise their diagnostic spectral features and for further utilisation for rock-type mapping. In 2016, the Sittampundi complex was covered by an AVIRIS-NG airborne survey jointly conducted by the Space Application Centre (SAC-ISRO) and Jet Propulsion Laboratory (NASA). The level-2 AVIRIS-NG data was obtained from SAC and used to interpret various rock types. ENVI 5.3 software was used for digital image processing of the AVIRIS-NG airborne hyperspectral data. The continuum-removed spectra of major rock types including anorthosite, meta-anorthosite, gabbro, meta-gabbro, pyroxenite, pegmatite, granite, gneiss and migmatite were critically analysed and their diagnostic absorption features correlated with chemistry and mineralogy. The AVIRIS-NG data analyses include bad band removal, minimum noise fraction transformation (MNF) and band combination. Out of various band combinations, the MNF composite images B456, B546 and B561 provided an enhanced output for the delineation of various rock types in the ultramafic terrain.

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The alkaline-carbonatite igneous intrusion occupies a very less aerial extent on the earth's surface; however, it is an important source rock for REE, LILE and radioactive elements. The origin of the alkaline-carbonatite suite is always related to tectonic settings such as continental drift and suture zone. In this context, the Samalpatti and Sevathur alkaline-carbonatite complex is an area of interest among various geoscientists. The moderate resolution Landsat-8 OLI satellite data is digitally processed using ENVI 5.3 image processing software for the interpretation of various lithology in the terrain. The Samalpatti-Sevathur complex is covered by different rock types including syenite, pyroxenites, dunite, carbonatite, and epidote hornblende gneiss. The carbonatites are emplaced as elongated bodies, dykes and scattered nodules in ultramafic formation. The mapping of ultramafic formations is important, since it contains carbonatite emplacement in the complex. The seven band OLI data covered under the visible, near infrared, and shortwave infrared spectrum were processed for the generation of colour composite images, band ratios, principle component analysis (PCA) images, and support vector machine (SVM) classified output. The digitally processed satellite images are useful in the interpretation of different rock types, particularly the ultramafic formation. Out of various outputs, the FCC, the composite image B652, colour composite images from ratio output, PCA composite images in RGB filters, and SVM classified image are suitable for interpretation of different lithology in the terrain.

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