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vol.47 número2Estratigrafia, tectônica e geocronologia U-Pb (LA-ICP-MS) em zircão detrítico da faixa Rio Preto e porção norte do corredor do Paramirim, NE, BrasilPetrogênese e idade de escarnitos associados a diques félsicos e metamáficos do Complexo Paraíba do Sul, sul do Espírito Santo índice de autoresíndice de assuntospesquisa de artigos
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Brazilian Journal of Geology

versão impressa ISSN 2317-4889versão On-line ISSN 2317-4692

Resumo

NOGUEIRA, Bruna Karine Correa et al. Rhyacian evolution of the eastern São Luís Craton: petrography, geochemistry and geochronology of the Rosário Suite. Braz. J. Geol. [online]. 2017, vol.47, n.2, pp.275-299. ISSN 2317-4889.  http://dx.doi.org/10.1590/2317-4889201720160114.

The São Luís Cráton comprises an area between northeast Pará state and northwest Maranhão that exposes Paleoproterozoic granitic suites and meta-volcanosedimentary sequences. In the east of this geotectonic unit, about 70 km south of São Luís, there is a portion of the São Luís Craton, represented by the intrusive Rosario Suite (RS). This work is focused on rocks of this suite, including petrographic, lithochemical and geochronological studies to understand the crustal evolution of these granitoid rocks. The rock spectrum varies from tonalitic to granodioritic, quartz dioritic and granitic compositions, and there are partial structural and mineralogical changes related to deformation along transcurrent shear zones. The geochemical studies show granitic metaluminous compositions of the calc-alkaline series with I-type affinity typical of magmatic arc. Rare earth elements show marked fractionation and slight Eu positive or negative anomalies (Eu/Eu* = 0.82 to 1.1). Zircon U-Pb data provided consistent ages of 2165 ± 7 Ma, 2170 ± 7 Ma, 2170 ± 7 Ma, 2161 ± 4 Ma and 2175 ± 8 Ma, dating emplacement of these granitoids as Paleoproterozoic (Rhyacian). Sm-Nd isotopic data provided model ages (TDM) of 2.21 to 2.31 Ga with positive values of εNd +1.9 to +3.2 (t = 2.17 Ga), indicating predominantly Rhyacian crustal sources for the parental magmas, similar to those ones found in other areas of the São Luís Craton. The data, integrated with published geological and geochronological information, indicate the occurrence of an important continental crust formation event in this area. The Paleoproterozoic evolution between 2.17 and 2.15 Ga is related to the Transamazonian orogeny. The granitoids of the Rosario Suite represent the main phase of continental arc magmatism that has continuity in other parts of the São Luís Craton and can be correlated with Rhyacian accretionary magmatism in the northwestern portion of the Amazonian Craton that amalgamated Archean terrains during the Transamazonian orogeny.

Palavras-chave : Rosário Suite; São Luís Craton; Petrology; U-Pb geochronology; Sm-Nd TDM.

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