2024-10-082024-10-082023-02-15MIRANDA, Sarah Silva. Geocronologia U-Pb em monazita e zircão do metamorfismo de alto grau do Complexo Tartarugal Grande, região centro-leste do Amapá. Orientador: João Marinho Milhomem Neto. Coorientador: Jean-Michel Lafon. 2023. 94 f. Trabalho de Curso (Bacharelado em Geologia) - Faculdade de Geologia, Instituto de Geociências, Universidade Federal do Pará, Belém, 2023. Disponível em:https://bdm.ufpa.br/jspui/handle/prefix/7318. Acesso em:.https://bdm.ufpa.br/jspui/handle/prefix/7318The Tartarugal Grande Complex (TGC) is inserted in the context of the southeastern Guiana Shield (SGS), in the northeastern portion of the Amazonian Craton. In the state of Amapá, the SGS is divided into the Paleoproterozoic Lourenço domain (north), which evolution involved subduction stages in an island arc environment and/or continental magmatic arcs, and in the Archean Amapá block (south), reworked during the Transamazonian orogeny (2.26-1.95 Ga). The TGC is situated in the transition region between these two domains. This unit consists of elongated bodies following the NW-SE regional trend and represents a metamorphic association of felsic granulites and leucogneisses, sometimes migmatized. In addition, mafic rocks occur subordinately. The TGC presents both Archean and Paleoproterozoic protoliths. This unit was involved in a tectono-thermal event at the end of the Rhyacian (~2.10- 2.05 Ga) that generated regional metamorphism in upper amphibolite to granulite facies, deformation with heterogeneous character in pre-existing lithotypes and rebalancing of minerals In this work, the neosome of a migmatitic leucogneiss from the CTG was dated using the U-Pb method in monazite and zircon by LA-ICP-MS to investigate and compare the age of metamorphism obtained with these accessory minerals, with the previous data available for the unit and with those of the metamorphic events recorded in the SGS. This neosome has a quartz-feldspathic composition, coarse granulation, and occurs as pockets in a garnet-biotite leucogneiss (paleosome) that makes contact with an enderbitic granulite. The U-Pb data obtained on monazites from the neosome yielded a 207Pb/206Pb weighted average age of 2058 ± 7 Ma (n = 30, MSWD = 0.15), which was correlated with data from the literature and interpreted as the age of the peak of regional metamorphism recorded in CTG rocks. The concordant 207Pb/206Pb ages obtained on zircon ranged from 2064 ± 16 to 2167 ± 28 Ma (n = 18), making it impossible to calculate an average age. The younger ages are interpreted as resulting from the reopening of the U-Pb system by metamorphism and the older ones as remnants of the protolith. Only one zircon grain had a Neoarchean age of 2676 ± 26 Ma, interpreted as inherited. The results obtained in this work confirm that this metamorphic event registered in the TGC is coeval with the ultra-high temperature metamorphism event of the Bakhuis Belt, in Suriname, and with the metamorphism event already registered in the southwest of the Amapá Block.Acesso AbertoGeocronologia U-PbLA-ICP-MSSudeste do escudo das GuianasComplexo Tartarugal GrandeU-Pb GeochronologySoutheast Guiana ShieldCNPQ::CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::GEOLOGIATrabalho de Curso - Graduação - Monografia