2019-08-302019-08-302011FERREIRA, Wagner Vitor Araújo. Estudo petrográfico, mineralógico e da alteração hidrotermal associada à fácies HORBLENDA, BIÓTICA ÀLCALI,FELDSPATO,GRANITO (Furo F18-Gb) do Pluton. Água boa, província estarífera de Pitinoa (AM). Orientador: Régis Munhoz Krás Borges. 2011. 120 f. Trabalho de Curso (Bacharelado em Geologia) -Faculdade de Geologia, Instituto de Geociências, Universidade Federal do Pará, Belém, 2011. Disponível em: http://bdm.ufpa.br/jspui/handle/prefix/1816. Acesso em:.http://bdm.ufpa.br/jspui/handle/prefix/1816The petrographic study of samples from hole F18-GB, the mineralized area Guinho-Baixão, identified seven types of rocks: 1) porphyritic coarse-medium-grained granite (GPmg), the predominant lithology of the rocks and enclosing hydrothermalized, 2) porphyritic fine-grained granite ( GPf), 3) equigranular coarse-medium-grained granite (GEmg), 4) albite-granite (AbG) and topaz-albite-granite (TAbG), 5) sodic episyenite (EpsNa), 6) sodic episyenite greisenized (EpsNaG) and 7 ) potassic episyenite (EpsK). The contact between the GPmg and GEmg is gradational, whereas the GPf and the topaz-albite-granite (TAbG) are intrusive in the GPmg. We characterized three hydrothermal processes: sodic episyenitization, the most important, potassic episyenitization and greisenization, the latter occurring more restricted. The rock is a leucocratic EpsNa composed of albite chessboard, resulting from the replacement of perthitic feldspar the GPmg, as well as cavities generated by the dissolution of magmatic quartz and filled by albite laths, euhedral quartz, phengite, fluorite, hematite, cassiterite, rutile and titanite. These cavities are cut by late fractures filled by fluorite and beryl. The EpsNa greisenization is marked by the replacement of albite for quartz, siderophyllite, phengite, sphalerite, chlorite, fluorite and topaz. The potassic episyenitization generated a rich rock adularia, chlorite and hematite, with traces of perthitic feldspar and cassiterite, precipitated during the EpsK chloritization. The main events of mineralization are associated with the formation EpsNaG and EpsK. Chemical compositions obtained by EDS were used in a study of the compositional variation of trioctahedral micas and zircons from granites and episyenitic rocks. Micas of the GPmg, GPf and GEmg have annite composition transitioning to annite aluminous, while the micas of EpsNaG and TAbG were classified as siderophyllite with wide compositional variation. In EpsNaG, cassiterite is associated with the stage of formation of brown siderophyllite (type I), relatively richer in Al2O3 and poorer in FeO than siderophyllite green (type II). Micas type I are chemically similar to the siderophyllite of more evolved granites and greisens present in other mineralized areas of the Agua Boa pluton. The zircons from granites revealed reasons Zr/Hf average intermediate between those of zircons from the biotite-granite (more evolved), host rock of greisens and sodic episyenites Queixada area and those of the zircons of the amphibole-biotite-granite (less evolved), enclosing the greisens and potassic episyenites Baixão-Guinho area. The topaz-albite granite characterized in this work is being reported for the first time in the mining district of Pitinga. It is texturally similar to the peralkaline albite granite of Madeira pluton, however, is peraluminous and is not mineralized. Probably the TAbG represents the most xiv evolved of the liquid phase related to magmatic crystallization of topaz-granite facies. The separation of one or more fluid phases from this fluid may have originated sodic episyenitization in an early stage and, at lower temperatures, the greisenization of sodic episyenite, culminating with the potassic episyenite chloritization and the formation of zones of oxidation in the portions more fractured of GPmg.Acesso AbertoPetrologiaEpissienitizaçãoGreisenizaçãoMineralizaçãoCNPQ::CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::GEOLOGIATrabalho de Curso - Graduação - Monografia