DEGEO - Departamento de Geologia
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/8
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12 resultados
Resultados da Pesquisa
Item Unravelling the protracted U-Pb zircon geochronological record of high to ultrahigh temperature metamorphic rocks : Implications for provenance investigations.(2023) Tedeschi, Mahyra; Vieira, Pedro Leonardo Rossi; Amaral, Matheus Henrique Kuchenbecker do; Ribeiro, Bruno Vieira; Barrote, Vitor Rodrigues; Reis, Humberto Luis Siqueira; Stutenbecker, Laura; Lana, Cristiano de Carvalho; Soares, Antônio Carlos Pedrosa; Dussin, Ivo AntonioThe assessment of detrital zircon age records is a key method in basin analysis, but it is prone to several biases that may compromise accurate sedimentary provenance investigations. High to ultrahigh temperature (HT-UHT) metamorphism (especially if T > 850 °C) is herein presented as a natural cause of bias in provenance studies based on U-Pb detrital zircon ages, since zircon from rocks submitted to these extreme and often prolonged conditions frequently yield protracted, apparently concordant, geochronological records. Such age spreading can result from disturbance of the primary U-Pb zircon system, likewise from (re)crystallization processes during multiple and/or prolonged metamorphic events. In this contribution, available geochronological data on Archean, Neoproterozoic and Palaeozoic HT-UHT metamorphic rocks, acquired by different techniques (SIMS and LA-ICP-MS) and showing distinct compositions, are reassessed to demonstrate HT-UHT metamorphism may result in modes and age distributions of unclear geological meaning. As a consequence, it may induce misinterpretations on U-Pb detrital zircon provenance analyses, particularly in sedimentary rocks metamorphosed under such extreme temperature conditions. To evaluate the presence of HT-UHT metamorphism-related bias in the detrital zircon record, we suggest a workflow for data acquisition and interpretation, combining a multi-proxy approach with: (i) in situ U-Pb dating coupled with Hf analyses to retrieve the isotopic composition of the sources, and (ii) the integration of a petrochronological investigation to typify fingerprints of the HT-UHT metamorphic event. The proposed workflow is validated in the investigation of one theoretical and one natural example allowing a better characterization of the sedimentary sources, maximum depositional ages, and the tectonic setting of the basin. Our workflow allows to the appraisal of biases imposed by HT-UHT metamorphism and resulting disturbances in the U-Pb detrital zircon record, particularly for sedimentary rocks that underwent HT-UHT metamorphism and, finally, suggests ways to overcome these issues.Item Tectonically-induced strontium isotope changes in ancient restricted seas : the case of the Ediacaran-Cambrian Bambuí foreland basin system, east Brazil.(2021) Guacaneme, Cristian; Babinski, Marly; Bedoya Rueda, Carolina; Santos, Gustavo Macedo de Paula; Caetano Filho, Sergio; Amaral, Matheus Henrique Kuchenbecker do; Reis, Humberto Luis Siqueira; Trindade, Ricardo Ivan Ferreira daThe Bambuí Group is a marine sedimentary record of an intracratonic foreland basin developed at the terminal Ediacaran and early Cambrian during the assembly of West Gondwana. Here we present a basin-scale high- resolution Sr isotope stratigraphy for the basal Bambuí Group, aiming to understand the spatial and temporal var- iations of the 87Sr/86Sr ratios and to explore the controls over the Sr isotope system in intracontinental marine environments. Assessment of the stratigraphic evolution of both Sr concentrations and Sr isotopes shows a major increase in Sr/Ca ratios (up to 0.004) and a decrease in the 87Sr/86Sr ratios from 0.7086 to 0.7076 in the high stand system tract of the basal 2nd-order sequence. These changes precede a large positive δ13C excursion typically found across the basin in the middle Bambuí Group. The high variability of both 87Sr/86Sr and Sr/Ca ra- tios was not caused by globally uniform changes in isotopic compositions of seawater, but rather likely reflect marine restriction and paleogeographic changes of the depositional environments at basin scale. This would re- sult from the tectonic uplift of Neoproterozoic orogenic belts around the São Francisco craton, which generated an isolated foreland marine basin. Compared to the global ocean, such a smaller intracontinental reservoir would be more sensitive to the Sr isotope composition from the different rock sources. We suggest that changes on the balance between carbonate production and accommodation associated with tectonically-related flexural subsi- dence progressively modified the continental drainage patterns, sedimentary sources and the chemical weathering regimes, altering the strontium influxes and isotopic compositions of the seawater in the early Bambuí basin cycle. Similar anomalies in the strontium isotope record are also recorded in coeval marine basins across West Gondwana and suggest that tectonics might have played an important role on seawater chemistry at the Neoproterozoic-Paleozoic transition.Item The role of tectonic inheritance in the development of a fold-thrust belt and superimposed rift : an example from the São Francisco basin, eastern Brazil.(2021) Rodrigues, Raiza Toledo; Alkmim, Fernando Flecha de; Reis, Humberto Luis Siqueira; Piatti, Bruno GuimarãesThe Sao ̃ Francisco intracratonic basin, eastern Brazil, hosts multiple sedimentary successions younger than 1.8Ga that witnessed major plate reorganizations since its generation. During the Brasiliano/Pan-African Gondwana amalgamation, in the Ediacaran-Cambrian boundary, the western half of the basin was involved in the Brasília foreland fold-thrust belt, which propagated eastwards deforming its Proterozoic-Paleozoic strata. Lately, as the South Atlantic rift evolved giving rise to the Brazilian continental margin, the basin was affected by extensional tectonism leading to the development of the Cretaceous Abaet ́e half-graben. During this episode, elements related to a prominent structure of the Brasília foreland fold-thrust belt, the Joao ̃ Pinheiro fault, were reactivated controlling the graben architecture. Aiming to unravel the evolutionary history of the fault zone since its nucleation until its Cretaceous extensional reactivation, we conducted a structural investigation based on field, well-tied 2D seismic data, and paleostress analysis. Our study revealed that the fault represents an emergent ramp of the basal detachment of the Brasilia foreland fold-thrust belt. Formed under EW-oriented shortening, the structure exhibits a gentle recces-salient geometry in map view, which reflects variations in the detachment depth influenced by pre-orogenic rift structures. Trains of NS-trending chevron folds are abundant and their high symmetry and dominance are expressions of the control exerted by mechanical stratigraphy and low-friction basal detachment. The superposed Abaet ́e half-graben developed under an extensional regime with a NE- trending maximum extension. Under this condition, a stratigraphic interface along the Joao ̃ Pinheiro fault zone was reactivated giving rise to the graben border fault. NS- to NW-oriented preexisting bedding planes were activated as small normal faults. Although newly-formed faults are present, reactivation is the most effective mechanism of extension accommodation. Therefore, this study provides insights on the influence of tectonic inheritance on the architecture, deformation pattern, strain/stress partitioning and evolution of both extensional and compressional intracontinental systems.Item Combined use of Sm–Nd isotopes and lithogeochemistry in the sedimentary provenance of the southern Ediacaran-Cambrian Bambuí foreland basin system, Brazil.(2021) Paravidini, Gabriel; Reis, Humberto Luis Siqueira; Heilbron, Monica da Costa Pereira Lavalle; Carvalho, Manuela de Oliveira; Aguiar Neto, Carla Cristine; Valeriano, Claudio de MorissonSedimentary provenance analysis based on lithogeochemistry and isotope data has been extensively applied in the investigation of ancient sedimentary successions. This approach contributes to understand the tectonic setting in which these strata were deposited and to recognize major provenance patterns in time and space. The Ediacaran to Cambrian Bambuí Group is exposed in the Sao ̃ Francisco craton (SE Brazil) and represents the sedimentary record of a foreland basin system developed during the assembly of the West Gondwana. Different lines of evidence indicate that this basin system evolved into a confined setting, due to the overloads imposed on the western and eastern margins of the Sao ̃ Francisco paleoplate by the diachronic Brasília and Araçuaí orogenic systems, respectively. New whole-rock lithogeochemistry and Sm–Nd isotopic data were applied to evaluate the overall sedimentary provenance patterns of the Bambuí strata exposed in the southern portion of the Sao ̃ Francisco craton (i.e., within the Sete Lagoas basement high) and to identify its possible sources. Coupled (La/Yb)n and Th/Sc ratios with 147Sm/144Nd and εNd isotopes allowed the recognition of three contrasting source patterns associated with different 2nd order sequences. The lower sequence comprises carbonate ramp deposits and shows highly heterogeneous and more negative εNd ranging from − 10.5 to − 4.5, as well as Th/Sc and (La/Yb)n ratios between 0.6 and 0.7 and 0.54 and 0.76, respectively. The provenance patterns point toward intermediate-dominated and isotopically evolved crustal sources, with mean TDM model ages between 1.5 and 2.0 Ga. The overlying 2nd-order sequence is composed of fine-to medium-grained siliciclastics grading upward into platformal oolitic calcarenites and calcilutites. This succession exhibits homo- geneous and less negative εNd(t) values between − 6.8 and − 5.2, with low Th/Sc (0.6–0.8) and (La/Yb)n (0.60–0.84) ratios. The uppermost Bambuí 2nd-order sequence, marked by greenish siltstones and arkoses grading upward into storm-bedded arkoses and lithic sandstones, shows homogeneous εNd(t) ranging from − 8.5 to − 6.1, slightly more negative than the underlying successions, and relatively higher Th/Sc and (La/Yb)n ratios ranging from 0.7 to 1.3 and 0.85 to 1.28, respectively. The Sm–Nd isotopic signature of the upper deposits indicates felsic-dominated and more isotopically juvenile crustal sources with TDM model ages of 1.5–1.7 Ga, characteristics compatible with Ediacaran arc-related rocks and post-tectonic granites exposed in the Araçuaí orogen. Our data indicate that the Proterozoic cratonic covers, their correlatives in the surrounding orogens, and magmatic rocks from the Araçuaí orogen acted as major sedimentary sources during the first evolutionary stages of the Bambuí basin-cycle in the Sete Lagoas basement high, which behaved as a forebulge depocenter. During the deposition of the overlying sequences, the Araçuaí orogen rocks became increasingly important in sourcing the Ediacaran- Cambrian foreland system in this depocenter. Besides revealing the major provenance patterns through the evolution of an ancient and partially confined foreland basin system, our data also demonstrates that even minor changes in the Sm–Nd system might be useful as reliable elements on the provenance analysis of sedimentary systems elsewhere.Item A large epeiric methanogenic Bambuí sea in the core of Gondwana supercontinent?(2021) Caetano Filho, Sergio; Sansjofre, Pierre; Ader, Magali; Santos, Gustavo Macedo de Paula; Guacaneme, Cristian; Babinski, Marly; Bedoya Rueda, Carolina; Amaral, Matheus Henrique Kuchenbecker do; Reis, Humberto Luis Siqueira; Trindade, Ricardo Ivan Ferreira daCarbon isotope compositions of both sedimentary carbonate and organic matter can be used as key proxies of the global carbon cycle and of its evolution through time, as long as they are acquired from waters where the dis- solved inorganic carbon (DIC) is in isotope equilibrium with the atmospheric CO2. However, in shallow water platforms and epeiric settings, the influence of local to regional parameters on carbon cycling may lead to DIC isotope variations unrelated to the global carbon cycle. This may be especially true for the terminal Neo- proterozoic, when Gondwana assembly isolated waters masses from the global ocean, and extreme positive and negative carbon isotope excursions are recorded, potentially decoupled from global signals. To improve our understanding on the type of information recorded by these excursions, we investigate the paired δ13Ccarb and δ13Corg evolution for an increasingly restricted late Ediacaran-Cambrian foreland system in the West Gondwana interior: the basal Bambuí Group. This succession represents a 1st-order sedimentary sequence and records two major δ13Ccarb excursions in its two lowermost lower-rank sequences. The basal cap carbonate interval at the base of the first sequence, deposited when the basin was connected to the ocean, hosts antithetical negative and positive excursions for δ13Ccarb and δ13Corg, respectively, resulting in Δ13C values lower than 25‰. From the top of the basal sequence upwards, an extremely positive δ13Ccarb excursion is coupled to δ13Corg, reaching values of þ14‰ and 14‰, respectively. This positive excursion represents a remarkable basin-wide carbon isotope feature of the Bambuí Group that occurs with only minor changes in Δ13C values, suggesting change in the DIC isotope composition. We argue that this regional isotopic excursion is related to a disconnection between the intrabasinal and the global carbon cycles. This extreme carbon isotope excursion may have been a product of a disequilibria between the basin DIC and atmospheric CO2 induced by an active methanogenesis, favored by the basin restriction. The drawdown of sulfate reservoir by microbial sulfate reduction in a poorly ventilated and dominantly anoxic basin would have triggered methanogenesis and ultimately methane escape to the atmosphere, resulting in a13C-enriched DIC influenced by methanogenic CO2. Isolated basins in the interior of the Gondwana supercontinent may have represented a significant source of methane inputs to the atmosphere, potentially affecting both the global carbon cycle and the climate.Item A large epeiric methanogenic Bambuí sea in the core of Gondwana supercontinent?(2021) Caetano Filho, Sergio; Sansjofre, Pierre; Ader, Magali; Santos, Gustavo Macedo de Paula; Guacaneme, Cristian; Babinski, Marly; Bedoya Rueda, Carolina; Amaral, Matheus Henrique Kuchenbecker do; Reis, Humberto Luis Siqueira; Trindade, Ricardo Ivan Ferreira daCarbon isotope compositions of both sedimentary carbonate and organic matter can be used as key proxies of the global carbon cycle and of its evolution through time, as long as they are acquired from waters where the dissolved inorganic carbon (DIC) is in isotope equilibrium with the atmospheric CO2. However, in shallow water platforms and epeiric settings, the influence of local to regional parameters on carbon cycling may lead to DIC isotope variations unrelated to the global carbon cycle. This may be especially true for the terminal Neoproterozoic, when Gondwana assembly isolated waters masses from the global ocean, and extreme positive and negative carbon isotope excursions are recorded, potentially decoupled from global signals. To improve our understanding on the type of information recorded by these excursions, we investigate the paired δ13Ccarb and δ13Corg evolution for an increasingly restricted late Ediacaran-Cambrian foreland system in the West Gondwana interior: the basal Bambuí Group. This succession represents a 1st-order sedimentary sequence and records two major δ13Ccarb excursions in its two lowermost lower-rank sequences. The basal cap carbonate interval at the base of the first sequence, deposited when the basin was connected to the ocean, hosts antithetical negative and positive excursions for δ13Ccarb and δ13Corg, respectively, resulting in Δ13C values lower than 25‰. From the top of the basal sequence upwards, an extremely positive δ13Ccarb excursion is coupled to δ13Corg, reaching values of þ14‰ and 14‰, respectively. This positive excursion represents a remarkable basin-wide carbon isotope feature of the Bambuí Group that occurs with only minor changes in Δ13C values, suggesting change in the DIC isotope composition. We argue that this regional isotopic excursion is related to a disconnection between the intrabasinal and the global carbon cycles. This extreme carbon isotope excursion may have been a product of a disequilibria between the basin DIC and atmospheric CO2 induced by an active methanogenesis, favored by the basin restriction. The drawdown of sulfate reservoir by microbial sulfate reduction in a poorly ventilated and dominantly anoxic basin would have triggered methanogenesis and ultimately methane escape to the atmosphere, resulting in a13C-enriched DIC influenced by methanogenic CO2. Isolated basins in the interior of the Gondwana supercontinent may have represented a significant source.Item Rare earth elements in the terminal Ediacaran Bambuí Group carbonate rocks (Brazil) : evidence for high seawater alkalinity during rise of early animals.(2020) Santos, Gustavo Macedo de Paula; Caetano Filho, Sergio; Enzweiler, Jacinta; Navarro, Margareth Sugano; Babinski, Marly; Guacaneme, Cristian; Amaral, Matheus Henrique Kuchenbecker do; Reis, Humberto Luis Siqueira; Trindade, Ricardo Ivan Ferreira daRare earth elements plus yttrium (REY) mass fractions of ancient carbonate rocks are used to track changes in chemistry of past seawater. Here we investigate REY patterns in two carbonate sections from the Ediacaran Bambuí Group, São Francisco Basin (Brazil), which comprise its two lowermost transgressive-regressive secondorder sedimentary sequences. Shale normalised distributions vary with the sequence stratigraphy framework. In the basal 2nd-order sequence, carbonate samples from the basal sequence transgressive systems tract display light REY (LREY) distributions slightly depleted to enriched that reflect input of freshwater, possibly in a post glacial episode. Upwards, carbonate rocks from the early highstand systems tract (EHST) yielded LREY enriched distributions, which progressively turns into LREY shale normalized depleted distributions on samples from the late highstand systems tract (LHST). This portion of the sequence also displays Y positive anomaly in some cases. Carbonate samples from the upper second-order sequence do not display coherent patterns. Ce/Ce* values > 1 in most samples throughout the two sections suggest permanent anoxia of seawater. The REY change from the EHST to LHST in the basal sequence marks an important paleoenvironmental overturn in the basin, with increasing alkalinity in seawater driving REY fractionation and LREY depletion. Confinement of the basin in the inner areas of West Gondwana due the uplift of marginal neoproterozoic orogens probably changed the weathering style of source areas to more congruent, thus delivering a higher ionic influx to a restricted setting, increasing alkalinity during LHST. Cloudina sp. fragments were reported in this stage of the Bambuí Group and in carbonate rocks with high Sr mass fractions in other West Gondwana basins, supporting the hypothesis that the high alkalinity of seawater during late Ediacaran may have driven the appearance of the first biomineralizing organisms.Item Sequence stratigraphy and chemostratigraphy of an Ediacaran-Cambrian foreland-related carbonate ramp (Bambuí Group, Brazil).(2019) Caetano Filho, Sergio; Santos, Gustavo Macedo de Paula; Guacaneme, Cristian; Babinski, Marly; Bedoya Rueda, Carolina; Peloso, Marília; Amorim, Kamilla Borges; Afonso, Jhon Willy Lopes; Amaral, Matheus Henrique Kuchenbecker do; Reis, Humberto Luis Siqueira; Trindade, Ricardo Ivan Ferreira daIn the terminal Neoproterozoic, drastic climate changes associated with biological innovations are coupled to isotope and elemental geochemical anomalies. However, lateral variability and local depositional controls may affect global geochemical signals, which can only be tracked through a proper stratigraphic/paleogeographic assessment. Here, we investigate the sequence stratigraphy and chemostratigraphy of the basal units of the Bambuí Group, central-east Brazil. This stratigraphic unit records a foreland basin system developed during the Ediacaran-Cambrian West Gondwana assembly and represents a 1st-order sequence, in which the two lowermost 2nd-order sequences record major geochemical disturbances. The first 2nd-order sequence started with the deposition of a transgresive systems tract, possibly in a postglacial scenario, which accompanies a negative-topositive δ13Ccarb excursion. The early highstand systems tract represents the establishment of a marine carbonate ramp throughout the basin. In terms of chemostratigraphy, it corresponds to a δ13Ccarb plateau close to 0‰ and Sr/Ca ratios around 0.001. The late highstand stage coincides with a remarkable increase in Sr content and Sr/Ca ratios at basinal scale. Occurrences of the Cloudina sp. late Ediacaran index fossil were reported in this stage. An erosional unconformity associated with a dolomitic interval, locally including subaerial exposure features, marks the top of the first 2nd-order sequence. This sequence boundary heralds an abrupt increase in δ13Ccarb values, up to +14‰. These extremely high δ13Ccarb values and high Sr/Ca ratios persist throughout the overlying sequence, as a result of progressive and enhanced restriction of the foreland basin system. Basin restriction at this stage has implications for the paleontological and chemostratigraphic record of epicontinental basins of the West Gondwana in the terminal Ediacaran. Late Ediacaran Sr-rich intervals in these basins show unusually nonradiogenic 87Sr/86Sr ratios, which may represent local depositional controls and deviations from the modern oceanographic models. Physiographic barriers and stressful conditions likely represented extreme environments for metazoan colonization.Item Microbialitos fósseis da formação Jaíba, grupo Bambuí, Minas Gerais, Brasil.(2018) Sanchez, Evelyn Aparecida Mecenero; Vieira, Thaís A.; Reis, Humberto Luis Siqueira; Amaral, Matheus Henrique Kuchenbecker doMicrobialites are carbonatic deposits, whose genesis is organosedimentary, deposited by benthic microbial mats. Microbialites are the most common fossils in rocks of the Proterozoic, worldwide and in Brazil. They exhibit morphological diversity since the oldest Archean forms, and are fundamental in studies concerning the biota and environmental aspects of past times, allowing better comprehension of biological and carbonate biosedimentary evolution through time. Microbial laminites and thrombolites of the Jaíba Formation, upper Bambuí Group, are described. Thrombolites show columnar and irregular shape, centimetric size, and are locally coalescent. Laminites, overlying the thrombolitic strata, display smooth, wavy, and crenulate synoptic relief. Five microfabrics and microfossils of two distinct morphologies, coccoidal and filamentous, were identified. Microfabrics may be of biogenic or abiogenic origin, representing different processes involved in the formation of microbialites. Thus, microbialites and microfossils of the Jaíba Formation show potential to better understand the producer biota in the context of the Ediacaran-Cambrian transition, probable age of this unit, and an important moment of profound changes in biosphere, due to the diversification of metazoans.Item Neoproterozoic evolution of the São Francisco Basin, SE Brazil : effects of tectonic inheritance on foreland sedimentation and deformation.(2016) Reis, Humberto Luis Siqueira; Alkmim, Fernando Flecha de; Alkmim, Fernando Flecha de; Valeriano, Claudio de Morisson; Trindade, Ricardo Ivan Ferreira da; Martins, Maximiliano de Souza; Danderfer Filho, AndréA Bacia intracratônica do São Francisco ocupa a porção sul do cráton homônimo e se estende por cerca de 350.000 km2 no sudeste do Brasil. Correspondendo a um típico depocentro poli-histórico, a bacia registra os principais eventos tectônicos e climáticos (alguns de importância global) que afetaram a Placa do São Francisco após 1,8 Ga. Sucessivos episódios extensionais proterozoicos, aparentemente associados à quebra dos supercontinentes Columbia e Rodinia, culminaram na formação de três grandes estruturas de embasamento. Estendendo-se ao longo da direção NW-SE na porção central da bacia, o Aulacógeno Pirapora hospeda os mais espessos depósitos sedimentares encontrados no domínio cratônico e é limitado a sul e a norte pelos altos de Sete Lagoas e Januária, respectivamente. Durante a amalgamação do Gondwana Ocidental, ao fim do Neoproterozoico/início do Paleozoico, a subsidência flexural causada pela edificação dos múltiplos orógenos brasilianos que margeiam a Bacia do São Francisco foi responsável pelo desenvolvimento de um extenso sistema de antepáis. Este sistema recebeu os depósitos carbonáticos e siliciclasticos ediacaranos da Sequencia Bambuí (i.e Grupo Bambuí), cuja evolução e dispersão sedimentar guardam uma íntima relação com a Faixa Brasília, a oeste. Ainda durante o fim do Neoproterozoico, o embasamento e as coberturas sedimentares da bacia foram localmente envolvidos nos cinturões de antepaís das faixas Brasília e Araçuaí, expostos nas porções oeste e leste da bacia, respectivamente. Com vergência centrípeta, estes cinturões definem duas grandes curvas antitaxiais que culminam na porção central da Bacia do São Francisco e exibem estilos tectônicos consideravelmente distintos. Análises estruturais e estratigráficas de detalhe baseadas em novos dados sísmicos, aerogeofísicos e de superfície indicam que o registro neoproterozoico da Bacia do São Francisco evoluiu sob forte influencia de estruturas pré-existentes. Na porção sul da bacia, os sedimentos carbonáticos e siliciclasticos marinhos da Sequencia Bambuí recobrem discordantemente rochas do embasamento arqueano/paleproterozoico e sua sedimentação foi controlada por sucessivos episódios de soerguimento flexural e migração do Alto de Sete Lagoas. Estes episódios foram responsáveis pelo desenvolvimento de um sistema de riftes quilométricos e com direção NE-SW, os Grábens de Pompéu, que se formaram à custa da reativação de estruturas antigas do embasamento. Combinados a mecanismos regionais de acomodação, pulsos tectônicos relacionados a estas calhas controlaram a sedimentação e arquitetura estratigráfica dos depósitos ediacaranos. O comportamento do Alto de Sete Lagoas como uma intumescência flexural mediante as cargas impostas pelas faixas brasilianas marginais ao Cráton do São Francisco e reconstruções paleotectonicas disponíveis podem explicar, pelo menos parcialmente, a preservação incomum de espessas sucessões sedimentares neste depocentro de antepaís e a aparente incongruência temporal entre o ciclo bacinal ediacarano e o desenvolvimento da Faixa Brasília. Conforme este estudo, os estilos estruturais dos cinturões de antepáis das faixas Brasília e Araçuaí também foram fortemente influenciados por elementos cratônicos pré-existentes. Na zona de culminação do Cinturão epidérmico de antepaís da Faixa Brasília, a Saliência de Três Marias afeta predominantemente os depósitos ediacaranos da Sequencia Bambuí e corresponde a uma curvatura orogênica não-rotacional e controlada pela bacia. Tal estrutura se desenvolveu em função de variações de espessura dos estratos pré-orogênicos, contrastes reológicos junto aos depósitos proterozoicos da bacia e a interação local com anteparos rígidos no antepaís. Diferentemente dos seus segmentos epidérmicos norte e sul, a porção central do Cinturão de antepáis da Faixa Araçuaí afeta a extremidade leste do Aulacógeno Pirapora e corresponde a um sistema compressivo do tipo thick-skinned. Nesta porção da bacia, o cinturão de antepaís descreve em mapa uma grande curva antitaxial e seu estilo tectônico resulta da interação entre o sistema orogênico N-S e o gráben pré-existente e de direção NW-SE. As análises apresentadas neste estudo demonstram a influencia de estruturas herdadas na evolução de sistemas de antepáis, seja causando a partição da deformação em escala local e/ou crustal ou influenciando no balanço entre a acomodação e o aporte sedimentar. Tais características parecem ser especialmente observadas em áreas cratônicas onde extensos conjuntos de estruturas e elementos formados em múltiplos ciclos tectônicos podem estar disponíveis durante os episódios de reativação. Uma vez que a herança tectônica desempenha papel importante na evolução de bacias sedimentares, a mesma deve ser considerada nas campanhas de exploração de hidrocarbonetos atualmente em curso na Bacia do São Francisco.