Geological remote sensing in parts of subarnarekha — baitarani basin, Eastern India

Abstract

Landsat imagery have been interpreted visually and under Additive Colour Viewer to interpret the regional geology and geomorphology in parts of Subarnarekha-Baitarani basin. The area lies south of Singhbhum shear zone and represents Precamrain shield. Important Simlipal ultrabasic volcanic complex of Orissa is included in the area. Although detailed map of the area is available, yet an attempt has been made to interpret the imagery for evaluating the results provided in comparison to the existing maps. Delineation of main lithological groups is possible. Having some data from the existing maps, lithoiogical boundary delineation of Mica Schist-Phyllite-Quartzite, Granites and Gneisses, Dhanjori Lava, Anorthosite-Gabbro Complex and Dolerite dykes, all of Precambrian age, has been done. Laterite and Quaternary sediments are also picked up. Lineament mapping has been carried out from imagery, which is difficult to map in the field. N--S and NNW-SSE lineament system is very prominent in Simlipal complex whereas in other parts NNW-SSE and NNE-SSW trends are common.

The major fault plane running NNE-SSW in the area is responsible for the present-day configuration of Subarnarekha river. Identification of different geomorphological units is perhaps best done on imagery. Several geomorphic units like structural Hill, Denudational Hill, Pediment, Buried Pediment, Lateritic Clay Plain, Laterite upland, Terrace Plain etc have been mapped. Valley fills are wellpicked up from imagery. Hydrogeological potentiality of the different geologic and geomorphic units have been evaluated qualitatively. Ground water occurrence, movement and potentiality are mainly controlled by structural, geological and geomorphological set-up of the area. Buried Pediment, Laterite upland, Laterite clay plain and alluvial fills are the potential zones from the view point of ground water occurrences.

Comparative study of the different Landsat bands and band-filter combinations under Additive Colour Viewer has been undertaken to find out the enhancement capability in delineating features. It is found that small scale geological and geomorphological maps can be prepared from Landsat imagery.