Navegando por Autor "REIS, Yury Haresson da Costa"

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Geoquímica e geocronologia U-Pb shrimp dos granitóides TTG da área de Ourilândia-Tucumã, Província Carajás-SE do cráton amazônico.
(Universidade Federal do Pará, 2023-11-17) REIS, Yury Haresson da Costa; OLIVEIRA, Davis Carvalho de
The rocks that make up the TTG crust in the northern area of Ourilândia do Norte - Tucumã are predominantly tonalitic and show strong petrographic and geochemical affinities with other TTG occurrences in the Carajás Province, which occur in the Rio Maria Domain and Carajás Domain. The granitoids were differentiated based on the occurrence domains of rocks from the Xingu Complex. They exhibit a varied structural pattern, with a tendency towards N-S and concentric patterns. These granitoids are predominantly composed of tonalites with subordinate trondhjemites and granodiorites. The U-Pb zircon crystallization age obtained from the tonalitic variety was 3.00 Ga. The trondhjemites are characterized by higher sodium concentration (Na2O/K2O ratio between 4.24-7.89) and low content of ferromagnesian elements (6 < FeO* + Mg + TiO2 + MnO < 8), while tonalites show sodium depletion (Na2O/K2O ratio between 1.79-3.20) and tend to be enriched in ferromagnesian elements (8 < FeO* + Mg + TiO2 + MnO < 13), with some samples falling within the field of hybrid granitoids, and they are also metaperaluminous (A/NK 1.5-2.0; A/CNK ~1). The Archean is characterized by developing thick sequences of greenstone and TTG plutons, forming dome-like structures and ridges in some cratons, such as those reported in the eastern Pilbara (Australia) and Dharwar (India) cratons. In the model adopted for the Ourilândia-Tucumã area, the generation of the initial stages of TTG magma in the Carajás Province sourced from metabasalts of the Tucumã-Gradaús Group's greenstone belt sequence. This occurred in a scenario involving the partial melting of the base of a thickened mafic oceanic protocrust due to interactions between the lithosphere and convective currents in the asthenospheric mantle, resulting in high-ETRP TTG melt. Dispersed crustal drips formed under increasing pressure and temperature conditions in this context. The partial melting of metabasalt within these drips produced felsic melts that intruded the overlying crust, forming low-ETRP TTG.