Centre for Earth Science Studies, Trivandrum 695 010, India

The principal mineral assemblages of the laterites are kaolinite, gibbsite, goethite, hematite and quartz with minor amounts of zircon. Amorphous ferric hydroxide, Al-hydroxide and Al-silicate are also present. Samples from various units of the weathering profile have been analysed for major and trace elements. Major-element data show a steady depletion of Si and enrichment of sesquioxides and TiO₂ during weathering. It is also observed that the more the content of the mobile elements (Si, Mg, Ca, K, Na) in the parent rock, the greater is its depletion during lateritisation. The trace elements Co, Cr, V, Cu and Ni show an enrichment while Zn and Ba show depletion over both the rock types. Pb shows almost a consistent behaviour.