Lithological Mapping using Landsat 8 OLI and ASTER TIR Multispectral Data- A Comparative Study

Abstract

Lithological mapping is a fundamental step in various mineral prospecting studies because it forms the basis of the interpretation and validation of retrieved results. This study utilizes the Advanced Space borne Thermal Emission and Reflection Radiometer (ASTER) and Landsat 8 Operational Land Imager (OLI) multispectral data to map lithological units in the Ananthapur District of Andhra Pradesh. Geologically, the area is made up Archaean rocks consisting of Peninsular gneiss, Dharwarsupracrustal rocks, Proterozoic meta sedimentary basin (consisting of quartzite, slate and dolomites) and younger granitoids, mafic dike and kimberlite. The band ratios, also known as Mineral indices, specially catered to discriminate mafic, and felsic mineral such as, Mafic Index (MI), Quartz index (QIand feldspar Rock Index (FRI) were applied to ASTER Thermal Infrared (TIR) bands and Band ratiocolour composite were generated. MNF transformation was applied over the Landsat 8 OLI image and MNF component color composite was generated. Geological mapping was carried out by visual interpretation and onscreen digitization. Geological map of a Ramgiri schist belt prepared from the ASTER TIR mineral indices colour composite and Landsat 8 MNF colour composites were compared with the existing Geological map prepared by Geological Survey of India. The results show an excellent correlation with the existing geological map of the study area. ASTER TIR band ratio colour composite could effectively demarcate silica rich rocks such as Quartz veins, quartzites, granites and granitic gneisses from and Mafic rocks such as dolerite/gabbro dykes, amphibolites and carbonate rocks (including Calcite and dolomite). The Landsat8 OLI MNF colour composite generated using MNF bands 523 were found to discriminate lithology effectively. However, TIR based geological mapping was found superior to the MNF based mapping. The structural details were enhanced in Landsat images compared to ASTER TIR data, owing to its higher radiometric and spatial resolution. Geological map prepared by combination of ASTER TIR and Landsat OLI will help in updating the existing geological map. The work demonstrates the utility of ASTER TIR and Landsat 8 OLI data in preparing/updating the geological map of an area. Keywords Anantapur district; ASTER TIR; Band Ratio; Geological mapping; Landsat 8 OLI; MNF DOI: https://doi.org/10.23953/cloud.ijarsg.369