CARACTERIZAÇÃO DAS FÁCIES DE ALTERAÇÃO DE UMA TOPO-SEQÜÊNCIA NO MACIÇO ALCALINO DE PASSA QUATRO, MG

JOEL BARBUJIANI SÍGOLO, BRUNO BOULANGÉ

Resumo


Two type s of bauxite concentration in the Passa Quatro alkaline massif are known. One results from the in situ evolution (lateritic type). The second results from removal and working by mecanical erosion and their consequent coluvionar deposition (pedimentary type) . The present work describes only the lateritic type in a topossequence taking into account the geomorphological variation and genetic conditions of the deposits. Two maio profils of alteration are identified: 1. isalteritic bauxite profile on nepheline syenlte and 2. isalteritic bauxite profile separated from the parent rocks (nepheline syenite) by a kaolinitic level. The morphoscopic and micromorphological evolution of the primary minerais is presented.

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