Utility of Ground Spectral Reflectance Data in Remote Sensing for Discriminating Lithounits

Ground spectral reflectances have been collected over various lithounits in Cuddapah basin and adjoining crystallines, employing the portable spectre-radiometer, designed by the I.S.R.O. Satellite Centre. With the help of the spectral signatures it is found feasible to discriminate the argillaceous, arenaceous and calcareous components, post-kinematic intrusives and gneisses, thus facilitating the intra- and inter-group separabilities

In general, the arenaceous component is characterised by electron transition bands, perhaps indicating relatively low degree of weathering than the calcareous and argillaceous components. Siliceous, nonsiliceous, ferro-dolomites and gossan zones have been identified by their spectral differences. The photon absorption bands in the visible region and lattice absorption bands in the Infra-red region are due to Fe or Mn charge transfer and the formation of secondary minerals during weathering respectively. The molecular absorption bands in the case of quartzites is attributed to the inherent compositional impurity in the rock itself. A carbonate absorption band is identified tentatively around 0.85 to 1.0 micron. The reflectance peak in the green region is attributed to the presence of chlorite/sericite. The field characteristics and spectral reflectance data evaluation for the phosphoritic horizons of Cuddapah basin have not indicated the feasibility of aerial multispectral scanner survey. Differential derivative reflectance quantities have been computed for each lithounit for obtaining optimum enhanced ratioed data products in the computer processing of LANDSAT digital data. This type of ground truth studies are of paramount importance for the purpose of classification of cover types as a basic input in digital processing of remote sensing data.