Mineralogy of Laterite-Bauxite Profile of Paduvari Plateau, South Kanara

The laterite-bauxite profile of Paduvari plateau, which bears evidence of having been derived by the in-situ chemical weathering of essentially early Precambrian granodiorite-tonalite gneisses, shows: (1) The overall predominance of gibbsite in the entire profile except in the lithomarge zone, (2) the abundance of kaolinite in the lithomarge zone and enrichment of goethite/hematite in the ferruginous laterite crust, (3) the general downward increase of kaolinite and upward increase of gibbsite, (4) the consistent occurrence of allophane, in minor amounts, in the entire profile, (5) evidence of formation of gibbsite both by direct alteration of feldspars of the precursor rock aqd by desilication of kaolinite, (6) occurrence of nearly all the minerals, which were present in the precursor rock, as resistant relics, (7) occurrence of zircon of the same shape and size as those in the precursor rock, and (8) the high crystallinity and the more common tight framework-type of microtexture of bauxites and aluminous laterites suggesting the formation of these deposits under extremely good leaching conditions, high above the water table.