Magmatismo cálcio - alcalino calimiano no embasamento do terreno Jauru (Província Rondoniana San Ignácio), Craton Amazônico : geoquímica e geocronologia Sm-Nd e U-Pb

• Ano de defesa: 2015
• Autor(a) principal: Fachetti, Frankie James Serrano
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Mato Grosso; Brasil; Instituto de Ciências Exatas e da Terra (ICET); UFMT CUC - Cuiabá; Programa de Pós-Graduação em Geociências
• Palavras-chave em Português: Gnaisse Taquarussu; Geoquímica; Geocronologia U-Pb; Geocronologia Sm-Nd; CNPQ::CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS; Taquarussu Gnaiss; Geochemistry; Geochronology U-Pb; Geochronology Sm-Nd
• Link de acesso: http://ri.ufmt.br/handle/1/121

The Taquarussu orthogneiss and the Guadalupe Granodiorite part of Rondonian-San Ignacio Province basement, southweast of Amazonian Craton, correspond to oriented bodies according to a NW/SE trend. The rocks are granodiorite composition with subordinate monzogranites, fine to coarse grained, consisting essentially of plagioclase, quartz, microcline, orthoclase and biotite. The accessory minerals are amphibole, titanite, garnet, apatite, epidote, zircon and opaque minerals. There is evidence of at least three phases of ductile deformation where the main structure is related to D1 stage (foliation S1), represented by a compositional banding, or by schistosity. The second phase is a crenulation cleavage transposing the foliation S1 and the third phase is exemplified by the deployment of shear zones that generated a foliation/fracturing on a local scale. The geochemical study indicates that the rocks are classify as granodiorites and monzogranites, coming from an intermediate to acid magmatism, sub-alkaline character calc-alkaline to high-K calc-alkaline series, with alumina ratios ranging from metaluminous to lightly peraluminous. The rocks were generate in a volcanic islands arc environment and the UPb data (Shrimp zircon) show a concord age 1575 ± 6Ma. The Sm-Nd model age (TDM) is 1.63Ga with εNd (t = 1.57Ga) ranging between -1.52 and +0.78. These data indicate that these rocks probably are a juvenile crust with a possible contamination of crustal rocks. Keyword: Geology, Gneiss Taquarussu, Granodiorite Guadalupe.