Syn-collisional peraluminous magmatism in the Rio Doce region : mineralogy, geochemistry and isotopic data of the Urucum suite (eastern Minas Gerais state, Brazil).
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2000
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The Urucum Suite granitoids (Rio Doce region, southeastern Brazil) contains four main facies: megafeldspar granites, deformed medium- to coarse-grained granites, tourmaline, and pegmatitic facies. They intrude both the staurolite-garnet-muscovite-biotite schist of the São Tomé Formation (Rio Doce Group) and the Galiléia metaluminous suite (596 ±4 Ma). Detailed structural studies suggest that the Urucum Suite emplaced during an important dextral strike-slip movement (Dl phase) of the Brasiliano orogeny (650-450Ma). Modal and chemical mineralogical variations suggest an evolution from the megafeldspar facies to the pegmatitic facies. Whole-rock geochemistry indicates the peraluminous character of the Urucum Suite granitoids, the evolution from the megafeldspar facies granites to pegmatitic facies granites and suggests the syn-collisional character of this suite. U-Pb zircon (582 ± 2 Ma) and monazite (576-573 ± 4Ma) data indicate that the Urucum Suite emplaced during the Brasiliano orogeny. The peraluminous nature of the Suite and isotopic-rich character in the Rb-Sr (87Sr/86Sr = 0.7114 to 0.7165) and Sm-Nd (eNd = -7.4 and -8.2) systems indicate that it formed by partial melting of older intermediate to felsic crustal sources. Based on early Proterozoic model-ages (2.3 to 1.8 Ga) and on 2.0 Ga U-Pb inherited signature, granitoids of the Suite are probably derived from a rocks with a long crustal residence (Transamazonian basement), without extensive mantle contribution.
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Granitoids, Peraluminous, Geochemistry, Isotopic data, Neoproterozoic
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NALINI JÚNIOR, H. A.; BILAL, E.; NEVES, J. M. C. Syn-collisional peraluminous magmatism in the Rio Doce region: mineralogy, geochemistry and isotopic data of the Urucum suite (eastern Minas Gerais state, Brazil). Revista Brasileira de Geociências, v. 30, n.1, p. 120-125, 2000. Disponível em: <http://www.sbgeo.org.br/pub_sbg/rbg/vol30_down/3001/3001120.pdf>. Acesso em: 24 set. 2014.