2019-09-032019-09-032012SEMBLANO, Flávio Robson Dias. Estudo isotópico Pb-Pb e Sm-Nd de rochas ígneas da área entre rios-Domínio Iriri-Xingú, SW do Pará. Orientador: Moacir José Buenano Macambira. 2012. 60 f. Trabalho de Curso (Bacharelado em Geologia) - Faculdade de Geologia, Instituto de Geociências, Universidade Federal do Pará, Belém, 2012. Disponível em: http://bdm.ufpa.br/jspui/handle/prefix/1925. Acesso em:.http://bdm.ufpa.br/jspui/handle/prefix/1925The southern part of Central Amazonia Province (Iriri-Xingu Domain) located in Amazonian Craton is one of the geologically less known region in Brazil. The few available geochronological data for this domain are scarce for the precise delimitation of the boundaries of the geotectonic provinces which were defined mainly based in these data. The domain is dominated by paleoproterozoic volcanic rocks and granitoids, not metamorphosed and locally covered by sedimentary sequences, and the regional basement rarely crops out. The inclusion of this domain in the Central Amazonia Province is based in a supposed “pre-transamazonian” age (>2.3 Ga) of the basement proposed according to some >2.5 Ga Sm-Nd model-ages (TDM) and negatives (< -6) εNd values showing significative crustal contribution to the rocks of this domain, which contrasts with the paleoproterozoic TDM from the rocks of the western adjacent Ventuari-Tapajos Province. The general aim of this work is the characterization of crustal evolution and the southern boundary between Central Amazonia and Ventuari-Tapajos provinces of the Iriri and Curuá rivers area, through petrographic and isotope studies (Pb evaporation in single zircon crystal and Sm-Nd on whole rock methods). The petrographic studies and field features enable to determine three rocks units: A-type Granites (monzogranites and quartz-monzonites with biotite and amphibole), I-type Granites (quartzmonzonites with pyroxene to biotite-monzogranites) and Iriri Group (rhyolites and dacites). The Pb-evaporation ages in zircon yielded 1992 ± 3 Ma and 1988 ± 2 Ma, and around 1880 Ma obtained, respectively, for the A-type Granites, volcanic of the Iriri Group and I-type Granites. The 1988 ± 2 Ma rock (Iriri Group) provided Sm-Nd TDM model-age of 2.61 and 3.13 Ga, and εNd of -10 and -5 what allow frame the study region in the Central Amazonia Province. These results show that a 1.99 Ga magmatic event, which is common in Tapajós Domain (Ventuari-Tapajós Province), also occur in Iriri-Xingu Domain, but withstands for its typical archean crustal source. Additionally, the data point out volcanic rocks older than 1.88 Ga accepted belonging to Iriri Group. However, because the dated volcanic rocks come from a area close to the Iriri Group type area, it is proposed to adopt the 1988 ± 2 Ma age for this unit. The younger volcanic rocks (1.88 Ga) must belong to another lithostratigraphic unit.Acesso AbertoRochas ÍgneasRochas OrosirianasProvíncia Amazônia CentralCráton AmazônicoCNPQ::CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::GEOLOGIATrabalho de Curso - Graduação - Monografia