DEGEO - Departamento de Geologia

URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/8

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2006 - 20072

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Assunto: search.filters.subject.Deferruginization

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    Mineralogical, micromorphological and geochemical evolution of the kaolin facies deposit from the Capim region (northern Brazil).
    (2007) Sousa, Daniel José Lima de; Varajão, Angélica Fortes Drummond Chicarino; Jacques, Yvon; Costa, Geraldo Magela da
    The Capim Kaolin District (eastern Brazilian Amazon), is one of the largest kaolin deposits in the world; with the kaolin used mainly for paper coating. The kaolin developed at the expense of Cretaceous sandy-clayey sediments of the Ipixuna formation, through intense lateritization from the Mesozoic to Cenozoic times. This work describes the morphological, mineralogical, crystallochemical and geochemical evolution of the Capim kaolin facies. Based on the profile analysis in the open pit fronts, it encompasses X-ray diffraction, thin-section optical analysis, EDS-assisted scanning electron microscopy and transmission electron microscopy, chemical analysis, infrared and Mo¨ssbauer spectroscopies. Six facies were defined as different stages of the supergene process. Ferruginization led to a thick duricrust on the soft kaolin, which in turn evolved from sandy-clayey sediments of the Ipixuna Formation. A subsequent deferruginization event degraded the duricrust, resulting in the flint kaolin facies.
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    Geochemistry of a sedimentary lateritic kaolin deposit in Quadrilátero Ferrífero, Brazil.
    (2006) Santos, Maria do Carmo; Varajão, Angélica Fortes Drummond Chicarino; Yvon, Jacques
    The present study deals with the mineralogy and geochemistry of the clayey facies of the Água Limpa kaolin deposit, situated in the Moeda Syncline, Quadrilátero Ferrífero, Minas Gerais, Brazil. Kaolinite, quartz, oxides and iron hydroxides (hematite and goethite) represent the mineral assembly of the five facies of the deposit. White mica, rutile, anatase and gibbsite are heterogeneously distributed along the profile. Despite the variable behavior of the chemical elements along the profile, the geochemical patterns for major and rare earth elements enable to define the filiations generated by the laterization process that affected the sediments.