Degree of Lateritisation and Quantifying Weathering Intensity of Laterites from Swarnagadde Plateau, Karnataka.

Abstract: Chemical weathering of rocks is one of the major processes which modify the Earth's surface and is one of the major processes in the geochemical cycling of elements. Laterites are the product of intensive and long lasting tropical rock weathering which is intensified by the high rainfall and elevated temperatures, initially product of weathering are essentially Kaolinised saprolite. Weathering is a combination of processes caused by mechanical, chemical and biological disintegration of a rock upon its interaction with the atmosphere. Significantly, the scheme recognises the importance of the nature of the protolith upon the composition of the weathering product; it also requires that the weathering products are entirely the result of in situ alteration processes. Using a SiO2-Al2O3-Fe2O3 ternary diagram, four stages of alteration are recognised in the lateritisation process: (a) kaolinitisation, (b) weak lateritisation, (c) moderate lateritisation, and (d) strong lateritisation. The behaviour of major and minor elements during the development of laterites have been suitably summarised and relates the leaching and retention of a range of elements to mineral transformations in the principal horizons of the weathering profile.

Keywords: Weathering, Kaolinisation, Laterites, Minerals, Development.