Faculdade de Geologia - FAGEO/IG
URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/2800
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Navegando Faculdade de Geologia - FAGEO/IG por Autor "ABREU, Francisco de Assis Matos de"
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Item Acesso aberto (Open Access) Estratigrafia da faixa de dobramentos Paraguai-Araguaia no centro-norte do Brasil(1997-12) HASUI, Yociteru; ABREU, Francisco de Assis Matos de; SILVA, José Maurício Rangel daThe Paraguai-Araguaia Fold Belt, constituted during the Brasiliano Cycle, extends to the north of Bananal Island, with submeridian trend. Between the 9º 30'S and 3º30'S parallels, the fold belt is represented by the Baixo Araguaia Group, an ophiolitc belt, some granitic bodies and by the Rio das Barreiras Formation. The Baixo Araguaia Group comprises three formations named, from the bottom to the top, Estrondo, Couto Magalhães and Pequizeiro, the latter one being of magmatic-sedimentary characted related to the ophiolitic belt. The ophiolitic belt is associated to the Tocantins-Araguaia geosuture, which seems to be manifested at the surface only in the northern region by a thrust fault, where glaucophanitic greenschist facies rocks have been recognized. The fold belt evolution shows a western trending polarity for the geosynclinal phenomena, except for the basic-ultrabasic magmatism.Item Acesso aberto (Open Access) Evolução geológica das sequências do embasamento do Cinturão Araguaia na região de Paraíso do Tocantins (TO), Brasil(2013-09) ARCANJO, Silvia Helena de Souza; ABREU, Francisco de Assis Matos de; MOURA, Candido Augusto VelosoIsotopic studies based on single zircon Pb-evaporation and Sm/Nd (whole rock) methodologies, allowed advances at the lithostratigraphic scene and geologic evolution of basement, in the south segment of Araguaia Belt. The identified geological processes took place from the Achaean (2.6 Ga and TDM ages varying between 2.78 and 3.25 Ga) through Neoproterozoic Era. The Paleoproterozoic ortognaisses, represented by Rio dos Mangues Complex, are placed between 2.05 and 2.08 Ga, and they were formed from a mantellic and youthful source, with a small crustal contribution where TDM ages are 2.35 e 2.21 Ga. At the end of the Paleoproterozoic, a strong crustal shortening happened, and a partial melting of isolated and thickening compartments were facilitated, generating some igneous bodies (1.85 and 1.82 Ga) and Serrote Granite (1.86 Ga), that comes from sources situated between 2.50 and 2.43 Ga. At the end of the Mesoproterozoic, the region was marked by taphrogenetic processes, evidenced by the appearance of alkaline magmatism (1.05 Ga), beyond depositional basins, amongst which the one that received the sediments that had originated the supracrustals of Araguaia Belt. Through the inversion in the geodynamic conditions, in the Neoproterozoic, a process of horizontal shortening with crustal thickening and distinct volumetric and spatial melting occurred, which may have generated Matança and Santa Luzia Granites. The Araguaia Belt was built from this tectonic motion. The tectonic mass transport in the Amazonian Craton might have occurred, resulting in the current architecture in the form of imbricate fans.Item Acesso aberto (Open Access) Granitóides proterozóicos como marcadores da evolução geotectônica da região nordeste do Pará, Brasil(2009-12) PALHETA, Edney Smith de Moraes; ABREU, Francisco de Assis Matos de; MOURA, Candido Augusto VelosoGranitoids cropping out inside Phanerozoic sedimentary cover in northeast Pará, Brazil (Gurupi region), records the geotectonic evolution of this region. 207Pb/206Pb single zircon evaporation ages were obtained for different granitoid bodies of the region, besides Sm-Nd isotopic studies. Almost all the plutons are genetically related with regional geological processes operative during this crustal segment formation, which includes the São Luís Craton. Such processes are associated with amalgamation of island arcs and Archean nuclei during the Palaeoproterozoic (2.15 to 2,07 Ga). The reworking of the southwestern margin of the São Luís Craton at the end of the Neoproterozoic formed the Gurupi Belt and is recorded by the occurrence of a granitic pluton of 549 ± 4 Ma.