DISTRIBUTION OF KAOLINITE AND GIBBSITE IN THE COMPLEX OF ITATIAIA AND SIGNIFICANCE GEOCHEMISTRY AND GEOMORPHOLOGY

Kaolinite and gibbsite deposits at Itatiaia Alkaline Complex distributed in strongly contrasting geomorphological and elevation domains: Highland above 2300m, Transitional, Massena plateau, 2300-2100m, Lateritic, Macieira plateau 2100-1800m, and Talus below 1800m. At Highland domain relief is rugged and scarp, at Transitional and Lateritic domains the topography is gentle, with interspersed blocks and boulders of fresh alkaline rock and Talus consists of steep slopes composed of a confused mixture of clay material with sparse boulders of alkaline rocks. Remarkable differences between the domains are: Highland: built in rocky mountains and ranges (Agulhas Negras=Black Needles), characterized by mechanical erosion, grooving, and gelifraction facilitated by a sparsely grassy vegetation, separated by hanging valleys filled with yellowish white kaolinite-rich, peat-like, Fe hydroxide, liesegang type structure. Gibbsite is insignificant in general and peat like material contains abundant fragments of feldspar and kaolinite with metahalloysite, illite, montmorrilonite and larger vermiculite flakes and absence of concretions. Massena consists of a gentle relief with incipient gullies, grassy vegetation, denser than the Highlands, scarce bushes, concretions more developed: mixture of yellow kaolinite and gibbsite, sparse goethite “cuirasses”, metahalloysite and illite rarer and finer-grained vermiculite flakes. Macieira plateau described as a residual, relatively thick, red bauxite (nordstrandite-type) blankets at gentle mountain tops, tropical rain forest predominant with sparse grass, abundant gibbsite, small amounts of kaolinite, at saprolite zone, halloysite, metahalloysite and illite completely absent and vermiculite only finely disseminated. REE and trace elements are relatively enriched at Macieira. Talus marked by a steep slope consisting of loose red, kaolinite-gibbsite clays, with boulder fields of alkaline rock, active gully development responsible for frequent landslides during summertime, concretions cobbles of the upper domains denote laminar and solifluction erosion in process. Tertiary Basin of Resende, which owes part of its evolution to the Itatiaia Alkaline Complex, results from deposition of unconsolidated clays fo Itatiaia.