2019-02-252019-02-252015-10-16PEREIRA, Carla Braga. Mineralogia e geoquímica dos perfis bauxíticos da mina Miltônia 3, região de Paragominas/PA. Orientador: Rômulo Simões Angélica. 2015. 77 f. Dissertação (Mestrado em Geologia e Geoquímica) – Instituto de Geociências, Universidade Federal do Pará, Belém, 2015. Disponível em: http://repositorio.ufpa.br/jspui/handle/2011/10692. Acesso em:.https://repositorio.ufpa.br/handle/2011/10692The Paragominas Bauxite Province is located in eastern of Pará state and western of Maranhão state, occupying the NW portion of Grajaú Basin and the southern of Bragantina platform, with an area of approximately 50.000 km2. The important bauxite deposites from that area were originated by an intense chemistry weathering above siliciclastic rocks from Cretaceous age. This research focus on the mineralogical e geochemistry studies of bauxite profiles in the area of Bauxite mine that belongs to the Norsk Hydro Company, in Miltonia 3 mine, municipality of Paragominas, Pará state. This research aims to contribute to understanding of the origin and developing of these profiles. Were conducted two sample collections of lateritic profiles representatives of Miltonia 3 mine, following the chemistry, mineralogy and texture differences of the horizons that structures the studied profiles. We used the following methodological procedures and/or instrumental techniques: X-rays Diffraction (XRD), Scanning Electron Microscopy (SEM), petrology and chemical analysis. The lateritic profiles studied in this research were described according to their horizons structuring: Amorphous Bauxite (AB), Crystallized Amorphous Bauxite (CAB), Crystallized Bauxite (CB), Ferruginous Laterite (FL). In the profile 1, the overlying horizon to FL is described as Nodular Bauxite (NB), while in the profile 2, it is the Crystallized Nodular Bauxite (BNC). Both of these profiles are covered by unconsolidated sandy-clay horizon, with an orange red coloring, called by many authors as Belterra clay. Petrographically, the horizons show the following typical mineral of a bauxitic/lateritic profile: gibbsite, kaolinite, goethite, hematite e anatase. This paragenesis was confirmed by XRD analysis, which the mineral content varies for each horizon. Allied to the SEM analysis it is possible to describe the morphologic aspect of gibbsite and kaolinite crystals. It is noticeable the presence of three gibbsite generations, which the precocious phase is part of matrix, sometimes, associated with iron oxide-hydroxide, showing a cryptocrystalline character. The second generation comprises microcrystalline crystals that fill partially or totally pores. The latest generation is cryptocrystalline crystal found occupying totally or covering the cavity walls of cutans. The geochemical pattern of Al2O3, Fe2O3, SiO2 and TiO2 residual phases are similar in both profiles, as well as the contents of Al2O3_available e SiO2_reactive. Over the profile, the contents of SiO2 e SiO2_reactive are more expressive in the most clayey layers, and they reflect the kaolinite content. The content of Al2O3_available has the same Al2O3 behavior due to: the first is related to gibbsite, the most elevated contents are in top of AB, CAB e CB, and the last represents the most economically exploitable level. According to the order/disorder degree of this kaolinite in the soil profile, it was verified an elevation of the FWHM (Full Width at Half Maximum) results from base towards top, that showed the possibilities of: 1) kaolinite degradation with the process of developing of lateritic profile; and/or neoformations of new kaolinite generations with low crystallinity. The new data furnished during the analysis give support to understand the process that produced the mineralogical, chemistry and textural differences and similarities that exist between bauxite horizons, as well as the recovery of bauxitization process (two phases of bauxitization) that resulted in formation of Nodular Bauxite (NB) and Crystallized Nodular Bauxite horizons, leading the hypothesis of polyphasic and complex evolution of studied profile, wich culminated in the origin of bauxitic/lateritic deposits.Acesso AbertoProvíncia BauxitíferaParagominas (PA)Caulinita - Paragominas (PA)DissertaçãoCNPQ::CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::GEOLOGIA::MINERALOGIAMINERALOGIA E GEOQUÍMICAGEOQUÍMICA E PETROLOGIA