A comparison of properties of clay minerals in isalteritic and in degraded facies.

Nenhuma Miniatura Disponível

Data

2013

Título da Revista

ISSN da Revista

Título de Volume

Editor

Resumo

The mineralogical, geochemical and micromorphological features of an isalteritic clay facies, which originated from weathering of an anorthosite, were compared to those of clay facies derived from the degradation of a bauxite developed from the same rock. The isalteritic clay was formed by the hydrolytic alteration of plagioclase, whereas the degraded clays were formed by decomposition of gibbsite and neoformation of kaolinite. This resilification process resulted from the reintroduction of silica via the oscillation of the phreatic level and/or the decomposition of organic matter on the surface. The degradation process was gradual and yielded two different facies: (a) degraded clays with almost total decomposition of gibbsite, and (b) degraded clays with gibbsite nodules. Morphologically, the isalteritic clays differ from the degraded clays because they contain larger hexagonal and pseudo-hexagonal crystals. The degraded clays have more irregular crystal shapes, ranging from laths to anhedral shapes.

Descrição

Palavras-chave

Isalteritic clay facies, Degraded facies, Anorthosite, Bauxite deg

Citação

OLIVEIRA, F. S. de et al. A comparison of properties of clay minerals in isalteritic and in degraded facies. Clay Minerals, v. 48, p. 697-711, 2013. Disponível em: <https://www.cambridge.org/core/journals/clay-minerals/article/comparison-of-properties-of-clay-minerals-in-isalteritic-and-in-degraded-facies/31FF5043B56CC834E4983BD1CA462977#>. Acesso em: 20 de jun. 2017.

Avaliação

Revisão

Suplementado Por

Referenciado Por