Navegando por Autor "Tavares, Túlio Delôgo"

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Detrital zircon records of the Paleo-Mesoproterozoic rift-sag Tamanduá group in its type-section, Northern Quadrilátero Ferrífero, Minas Gerais, Brazil.
(2020) Dutra, Luiz Fernandes; Dias, Sérgio Patusco; Martins, Maximiliano de Souza; Lana, Cristiano de Carvalho; Batista, Ana Carolina; Tavares, Túlio Delôgo
The Quadrilátero Ferrífero metallogenetic province is located in the southernmost portion of the São Francisco craton, SE Brazil. The Tamanduá and Cambotas ridges stand out topographically in the northeastern portion of Quadrilátero Ferrífero and show NE-SW and N-S directions, respectively. Those ridges involve metasedimentary rocks of the Tamanduá Group bounded by a fault system. Due to stratigraphic and structural complexities, there is little consensus about the maximum sedimentation age and the stratigraphic position in which Tamanduá Group sediments were deposited. In this work, we took advantage of the excellent exposures in the Tamanduá and Cambotas ridges to present detailed stratigraphic observations combined with U-Pb zircon geochronological data from samples of different stratigraphic levels of Tamanduá Group. Furthermore, we provide U-Pb data from samples of the intrusive Pedra Formosa Suite that cut the whole Tamanduá sequence in the study area. Our observations showed that the Tamanduá Group represents a rift-sag basin-fill succession developed along the eastern border of the São Francisco paleoplate. The basal metaconglomerate and metasandstone package grades upward into marine metasandstone and phyllite. Detrital zircon obtained from the basal unit, Antônio dos Santos Formation, reveals maximum depositional ages between ca. 1981 and 1770 Ma. The upper succession, Cambotas Formation, shows a maximum depositional age from 1769 to 1740 Ma. The Pedra Formosa Suite shows zircons that crystallized at ca. 1740 Ma. The stratigraphic framework and the Orosirian-Statherian ages suggest a correlation with the first rifting event within the São Francisco paleoplate, the precursor of Paleo- to Mesoproterozoic Espinhaço basin.
Detrital zircons from the Upper Três Marias Formation, São Francisco basin, SE Brazil : record of foreland deposition during the Cambrian?
(2020) Tavares, Túlio Delôgo; Martins, Maximiliano de Souza; Alkmim, Fernando Flecha de; Lana, Cristiano de Carvalho
The Bambuí Group, a succession of mixed carbonate and siliciclastic rocks, accumulated in the intracratonic and poly-historic São Francisco successor basin by the end of the Neoproterozoic. The São Francisco basin, which occupies a substantial portion of the eponymous craton in southeastern Brazil, was converted into a major foreland depocenter in response to orogenic loads generated along the craton margins during the assembly of West Gondwana in the Ediacaran Period. Various studies carried out in recent years have led to a better understanding of many aspects of the evolution of the São Francisco basin during the Neoproterozoic. However, the age of the Bambuí Group, critical for a better understanding of the basin history and establishment of regional and global correlations, remains poorly constrained and matter of a long-standing debate in the literature. In order to contribute to this debate, we performed U-Pb LA-ICPMS age determinations on detrital zircons extracted from the Três Marias Formation, the youngest unit of the group. Our study, based on a stratigraphic survey, was conducted in an occurrence of the formation located near to the eastern border of the basin, i.e., in a proximal position in relation to its potential source, the Brasiliano Araçuaí orogen. The detrital zircon age spectra (involving 432 concordant ages) of the lower alluvial and upper marine units of the Três Marias Formation are characterized by a unimodal distribution with c.83% of the grains dated between 735 and 522 Ma. These results indicated that lithostratigraphic assemblages of the Araçuaí orogen, namely the 630-580 Ma granitoids of Rio Doce magmatic arc and 585-540 Ma syn-collisional granites were the most important sources of the Três Marias sediments. Moreover, post-collisional granite suites younger than 530 Ma also contribute with sediments to the formation. Using four different metrics, we obtained 527 ± 4 Ma as the most accurate and reliable estimation for maximum depositional age of the Upper Três Marias Formation, an age that has major implications for the developmental history of both the São Francisco basin and Araçuaí orogen
Proveniência sedimentar da Formação Três Marias no Sinclinal de Buenópolis (MG).
(2019) Tavares, Túlio Delôgo; Alkmim, Fernando Flecha de; Martins, Maximiliano de Souza; Reis, Humberto Luis Siqueira; Martins, Maximiliano de Souza; Alkmim, Fernando Flecha de
O Grupo Bambuí, uma sucessão mista de rochas carbonáticas e siliciclásticas, acumulouse na bacia intracratônica do São Francisco até o final do Neoproterozóico. A bacia do São Francisco, que ocupa uma parte substancial do cráton homônimo no sudeste do Brasil, foi convertida em um grande depocentro de foreland em resposta às cargas orogênicas geradas ao longo das margens do cráton durante a aglutinação de Gondwana Ocidental no período Ediacarano. Vários estudos realizados nos últimos anos levaram a um melhor entendimento de muitos aspectos da evolução da bacia do São Francisco durante o Neoproterozóico. No entanto, a idade do Grupo Bambuí, crítica para uma melhor compreensão da história da bacia e estabelecimento de correlações regionais e globais, permanece pouco balizada e é assunto de um debate de longa data na literatura. Para contribuir com este debate, foram realizadas determinações de idade U-Pb LA-ICPMS em zircões detríticos extraídos da Formação Três Marias, a unidade mais jovem do grupo. O estudo ora apresentado foi baseado em levantamentos estratigráficos realizado em uma ocorrência singular da Formação Três Marias localizada próxima à borda leste da bacia, ou seja, em posição proximal em relação à sua fonte potencial, o orógeno Brasiliano Araçuaí. Os espectros de idade do zircão detrítico (envolvendo 432 idades concordantes) das unidades aluviais e marinhas superiores da Formação Três Marias são caracterizados por uma distribuição unimodal com cerca de 83% dos grãos datados entre 735 e 522 Ma. Estes resultados indicaram que as assembleias litoestratigráficas do orógeno Araçuaí, a saber, os granitóides de 630-580 Ma do arco magmático do Rio Doce e os granitos sin-colisionais 585-540 Ma foram as fontes mais importantes dos sedimentos de Três Marias. Além disso, os conjuntos de granito pós-colisionais mais jovens que de 530 Ma também contribuem com sedimentos para a formação. Utilizando quatro diferentes métricas, obtivemos 527 ± 4 Ma como a estimativa mais precisa e confiável para a máxima idade deposicional da Formação Três Marias, uma idade que têm grandes implicações na história do desenvolvimento da bacia do São Francisco e do orógeno Araçuaí. Estudos petrográficos realizados nos arenitos da Formação Três Marias classificaram estas rochas como arenitos arcosianos. Os arenitos mostram imaturidade mineralócia e textural. Três fases diagenéticas podem ser reconhecidas: diagênese do soterramento superficial (eodiagênese); diagenese de soterramento efetivo (mesodiagenesia) e diagênese tardia (telodiagnética) associada ao soerguimento e/ou exumação das rochas da Formação Três Marias. A evolução diagenética pode ser representada pelos seguintes eventos: infiltração mecânica de argila, cimentação por hematita, compactação mecânica, sobrecrescimento de quartzo e de feldspato, porosidade e cimentação secundárias, clorita autogênica, turmalina autigênica, além de oxidação e dissolução das fases telodiagenéticas.
Stratigraphic, isotopic, and geochronological record of a superposed pro- foreland basin in the eastern São Francisco craton during west Gondwana amalgamation.
(2020) Rossi, Ariadne Verônica Andrade; Danderfer Filho, André; Bersan, Samuel Moreira; Kelmer, Luiza Rocha; Tavares, Túlio Delôgo; Lana, Cristiano de Carvalho
The Três Marias Formation, a siliciclastic succession that occurs at the top of the Bambuí Group, has recorded the filling of the Brasiliano foreland basin that developed on the São Francisco craton. At the eastern portion of this craton, the Três Marias Formation outcrops in Gorutuba ridge, north of Minas Gerais, which area was in- vestigated by using field work, stratigraphic analysis, and isotopic U–Pb and Lu–Hf analysis. In this area, the Três Marias Formation includes molasse deposits composed mainly of arkoses and hybrid conglomerates. The arkose sediments came into the basin through a fluvio–deltaic system located to the northeast and were reworked in a siliciclastic shelf under the influence of waves, tides and storm currents. The paleocurrents indicate a coastline around the NW and NE directions, with current flows reworking sediments parallel and transversal to the coast. The detrital zircon grains indicate a 555 ± 17 Ma maximum age of the deposition for this unit, and its main sources are related to granitoids from the pre-orogenic and pre-to syn-collisional stages of the Araçuaí orogen (ca. 630–560 Ma). The filling of the foreland basin system created in response to the Araçuaí fold–thrust belt is younger than the one existing in the occidental portion of Bambuí basin, which is related to the Brasília fold and thrust belt. Therefore, the final filling of the Bambuí basin would have been controlled by the development of these two-fold–thrust belts throughout the margins of the São Francisco craton during the assembly of West Gondwana.
Stratigraphic, isotopic, and geochronological record of a superposed proforeland basin in the eastern São Francisco craton during west Gondwana amalgamation.
(2020) Rossi, Ariadne Verônica Andrade; Danderfer Filho, André; Bersan, Samuel Moreira; Kelmer, Luiza Rocha; Tavares, Túlio Delôgo; Lana, Cristiano de Carvalho
The Três Marias Formation, a siliciclastic succession that occurs at the top of the Bambuí Group, has recorded the filling of the Brasiliano foreland basin that developed on the São Francisco craton. At the eastern portion of this craton, the Três Marias Formation outcrops in Gorutuba ridge, north of Minas Gerais, which area was investigated by using field work, stratigraphic analysis, and isotopic U–Pb and Lu–Hf analysis. In this area, the Três Marias Formation includes molasse deposits composed mainly of arkoses and hybrid conglomerates. The arkose sediments came into the basin through a fluvio–deltaic system located to the northeast and were reworked in a siliciclastic shelf under the influence of waves, tides and storm currents. The paleocurrents indicate a coastline around the NW and NE directions, with current flows reworking sediments parallel and transversal to the coast. The detrital zircon grains indicate a 555 ± 17 Ma maximum age of the deposition for this unit, and its main sources are related to granitoids from the pre-orogenic and pre-to syn-collisional stages of the Araçuaí orogen (ca. 630–560 Ma). The filling of the foreland basin system created in response to the Araçuaí fold–thrust belt is younger than the one existing in the occidental portion of Bambuí basin, which is related to the Brasília fold and thrust belt. Therefore, the final filling of the Bambuí basin would have been controlled by the development of these two-fold–thrust belts throughout the margins of the São Francisco craton during the assembly of West Gondwana.