Bauxitisation of anorthosites from Central Brazil

Registro completo de metadados
MetadadosDescriçãoIdioma
Autor(es): dc.creatorOliveira, Fábio Soares de-
Autor(es): dc.creatorVarajão, Angélica Fortes Drummond Chicarino-
Autor(es): dc.creatorVarajão, César Augusto Chicarino-
Autor(es): dc.creatorBoulangé, Bruno-
Autor(es): dc.creatorGomes, Newton Souza-
Data de aceite: dc.date.accessioned2019-11-06T13:24:17Z-
Data de disponibilização: dc.date.available2019-11-06T13:24:17Z-
Data de envio: dc.date.issued2012-07-11-
Data de envio: dc.date.issued2012-07-11-
Data de envio: dc.date.issued2011-
Fonte completa do material: dc.identifierhttp://hdl.handle.net/123456789/1072-
Fonte: dc.identifier.urihttp://educapes.capes.gov.br/handle/capes/554678-
Descrição: dc.descriptionPetrological studies using X-ray diffraction (XRD), X-ray fluorescence (XRF), optical microscopy, scanning electron microscopy (SEM-EDS) and electron microprobe analyzer (WDS) showed the mineralogical, micromorphological and geochemical transformations due to the bauxitisation of anorthosite from the Barro Alto Stratiform Mafic–Ultramafic Complex (Central Brazil). The hydrolytic alteration of the anorthosite occurred in two different stages in accordance with the order of stability of the minerals to the weathering: firstly the bytownite and secondly the ferromagnesian minerals. The weathering solutions, benefited from the existing network of fractures, percolated the weakness zones of the minerals characterising the microsystem of contact in which cores of plagioclase and ferromagnesian minerals were formed. In the first stage, the plagioclases are altered directly to gibbsite, and at an early stage, during the change process, the gibbsite crystals surround the primary ferromagnesian minerals that are totally or partially preserved. The transformation is isalteritic and is responsible for formation of porous alteromorphs consisting of septa of coarse gibbsite and fine gibbsite. As the weathering process advances, the ferromagnesian minerals directly enter to goethite. The boxworks of gibbsite and goethite characterise a primary plasmic microsystem.-
Idioma: dc.languageen-
Direitos: dc.rightsO Periódico Geoderma concede permissão para depósito deste artigo no Repositório Institucional da UFOP. Número da licença: 3333721216360-
Palavras-chave: dc.subjectBarro Alto complex-
Palavras-chave: dc.subjectBauxite-
Palavras-chave: dc.subjectAlitisation-
Palavras-chave: dc.subjectIsalteritic transformation-
Palavras-chave: dc.subjectAnorthosite-
Título: dc.titleBauxitisation of anorthosites from Central Brazil-
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