Deep crustal framework of the Borborema Province, NE Brazil, derived from gravity and magnetic data

Oliveira, Roberto Gusmão de; Medeiros, Walter E.

doi:10.1016/j.precamres.2018.07.004

Cited by 73 publications

(35 citation statements)

References 119 publications

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“…The core of the TSZ includes a set of anastomosing sheets of porphyritic granitoids (Pedra Lisa suite) which defines a linear magnetic low following most of the length of TSZ (inset of Figure 2), from the Nova Russas pluton southward. This magnetic low indicates a magma-laden character for the shear zone core at depth and in addition to gravity data (Oliveira & Medeiros, 2018) reveal how the TSZ causes an offset to the Tamboril-Santa Quitéria arc, juxtaposing it to the schist complex to the east. The TSZ is underlain by east dipping seismic reflectors with slightly folded geometries (Daly et al, 2014) at fairly shallow depths.…”

Section: The Senador Pompeu and Tauá Shear Zonesmentioning

confidence: 69%

Zippered Shear Zone Model for Interacting Shear Zones in the Borborema Province, Brazil, as Constrained by U‐Pb Dating

et al. 2019

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Shear zones typically interact to form connected systems or networks to accommodate crustal deformation, but our knowledge of how this happens is fragmentary. Understanding branching and interacting shear zones requires knowledge of timing, deformation kinematics, and rheology. The Senador Pompeu, Tauá, and Cococi strike‐slip shear zones of the Borborema Province (NE Brazil) have a central role and location in the Neoproterozoic assembly of Gondwana and provide a means to understand shear zone interaction. We apply (i) U‐Pb in situ SHRIMP analysis of zircons from syntectonic plutons and dykes to constrain the timing of shearing and (ii) vorticity and strain analysis on pluton's megacrystic facies deformed in the magmatic state and during final stages of crystallization. Obtained ages show that the shear zone pair was active under high temperature at 583.5±4.6 Ma, while felsic dykes were emplaced in the brittle regime in the wall rocks. Average vorticity estimates of 0.70 indicate a strong component of pure shear in the shear zones. Despite the transpressional character, the dispersion in estimates of thinning and thickening for the Senador Pompeu shear zone highlights variations of offset rate for the interacting branches that leads to localized transtension. We conclude that the kinematic framework of the Senador Pompeu and Tauá conjugate pair involves the formation of a dextrally closing zipper structure involving the trailing Cococi shear zone to the southwest, which in turn caused the northeastward extrusion of the enclosed crustal wedge and possibly activation of the nappe system of the Ceará Central domain.

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Section: The Senador Pompeu and Tauá Shear Zonesmentioning

confidence: 69%

Zippered Shear Zone Model for Interacting Shear Zones in the Borborema Province, Brazil, as Constrained by U‐Pb Dating

et al. 2019

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“…820 Ma (Sm-Nd whole-rock isochron), marking the development of new oceanic crust separating the Borborema Province from the São Francisco paleocontinent to the south. The geophysical signature of the central zone is marked by the inflection of a paired positive-negative Bougher anomaly which is typical of Precambrian suture zones (Oliveira 2008, Oliveira andMedeiros 2018) representing the site where ancient plates agglutinated. In this case, the lower plate (São Francisco paleocontinent) is represented by lower Bouguer values to the south while the upper one (western edge of the Pernambuco-Alagoas domain) is represented by higher Bouguer values to the north (Oliveira 2008, Caxito et al 2014c, Oliveira and Medeiros 2018.…”

Section: Geological Contextmentioning

confidence: 99%

New U-Pb (SHRIMP) and first Hf isotope constraints on the Tonian (1000-920 Ma) Cariris Velhos event, Borborema Province, NE Brazil

et al. 2020

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Orthogneisses associated with metavolcanosedimentary successions related to the 1000-920 Ma Cariris Velhos event occur mainly in a ca. 700 km-long sigmoidal-shaped belt that crosscuts the Transversal Zone of the Borborema Province and extends to the fold belts located in its southern or external zone (part of the Riacho do Pontal and Sergipano orogens). Despite its importance, the tectonic setting and the role of those rocks in the geological evolution of the Borborema Province are contentious and not yet well understood. New zircon U-Pb SHRIMP data on an augen-gneiss sill of the Afeição Suite intruding mica-schists mapped as part of the Santa Filomena Complex yielded a Concordia Age of 974 ± 11 Ma, indicating that at least part of the metasedimentary rocks in the internal zone of the Riacho do Pontal Orogen are Tonian or older and possibly related to the Cariris Velhos event. Hf-in-zircon isotope data are presented for the first time for Cariris Velhos-related ortho-derived rocks of the Afeição Suite. Analyzed samples yielded εHf(t) in a narrow range between-1.51 and +2.41, with associated T DMHf of 1.6-1.4 Ga, similar to previously obtained Nd isotope data with εNd(t) =-1.0 to +3.1 and T DMNd of 1.5-1.2 Ga. A possible scenario to explain both the geochemical features and the moderately juvenile to slightly evolved, near-chondritic Hf and Nd isotope signatures is a continental arc setting, where fractionated melts produced in the supra-subduction zone mantle wedge carrying a Tonian juvenile signature became contaminated with discrete amounts of Archean-Paleoproterozoic continental crust during ascent, producing Mesoproterozoic model ages which represent the mixture of those two end-members.

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“…A origem do soerguimento do escudo continental formado pela Província Borborema ainda é motivo de debate (Oliveira & Medeiros, 2018;Garcia et al, 2019). Entretanto, estudos recentes comprovaram que o processo de arqueamento crustal e uma erosão continental ocorreu após o cretáceo (Corrêa, 2001;Corrêa et al, 2010;Peulvast & Bétard, 2015), alguns estudos sugerem que o interior da Província Borborema tenha alcançado um soerguimento de cerca de 600 a 800 m, uma vez que carbonatos transicionais afloram nestas cotas topográficas na Bacia do Araripe (Davis & Kusznir, 2004;Morais Neto et al, 2008;Morais Neto et al, 2009; Engelmann de Oliveira & Jelinek, 2017).…”

Section: Reativação Tectônica Quaternária No Domínio Sul Da Provínciaunclassified

Quaternary Tectonic Reactivation in the Southern Domain of Borborema Province, NE Brazil: Integration of Morphometric, Geological and Geophysical Data From the Una River Drainage Basin

et al. 2019

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ResumoIntegração de dados em diferentes escalas foi realizada com o objetivo de identificar possíveis efeitos de reativações tectônicas cenozoicas (pós-rifte), relacionadas ao embasamento adjacente à Bacia Pernambuco, sobre o qual está localizada a bacia hidrográfica do Rio Una. O estudo foi baseado na integração de parâmetros morfométricos do canal do Rio Una, modelados a partir de imagens de radar, dados de geologia de superfície e dados de sísmica de reflexão multicanal 2D adquiridos no canal do rio, próximo às cidades de Barreiros e Palmares. A análise morfométrica se baseou no cálculo da relação declividade vs. extensão (RDE) ao longo do perfil longitudinal do Rio Una. Dados geológicos foram coletados em afloramentos no embasamento próximo aos municípios de Barreiros e Palmares. Também foram investigados os depósitos da Formação Barreiras na região costeira, próximo ao município de São José da Coroa Grande. A análise do perfil longitudinal mostrou que o Rio Una está implantado sobre três superfícies criadas por eventos sucessivos de soerguimento e erosão, as quais controlaram a compartimentação de sua bacia hidrográfica. O estudo do índice RDE mostrou a ocorrência de anomalias de primeira ordem, no médio curso, e de segunda ordem, no médio e baixo curso do rio. As anomalias de primeira e segunda ordem estão localizadas sobre as principais zonas de cisalhamento pré-cambrianas que cortam o embasamento com orientação NE-SW. As anomalias também estão relacionadas a falhas e fraturas mais jovens com direção NW-SE. A interpretação dos dados sísmicos mostrou um arranjo de falhas e fraturas de alto ângulo no embasamento que afetaram depósitos sedimentares de idade quaternária e holocênica. Também foram observadas falhas em depósitos da Formação Barreiras (Mioceno) depositados sobre o embasamento próximo a borda da Bacia Pernambuco. A geometria dos planos de falha é indicativa de estruturas do tipo flor, relacionadas a um regime de reativação transcorrente que está atuando sobre a margem continental, com compressão máxima E-W e extensão N-S. Este regime afetou a morfologia do canal do Rio Una, bem como os depósitos sedimentares associados à sua bacia de drenagem. AbstractAn integration of data in different scales was built aiming to identify possible effects of tectonic reactivations of Cenozoic origin (post-rift), related to the continental basement adjacent to the coastal zone of Pernambuco marginal basin, over which was formed the hydrographic basin of the Una River. The study was based in the integration of morphometric parameters of the Una River channel modeled with satellite radar imagery, geological data, and 2D multichannel shallow seismic data acquired over the river channel in the proximities of Barreiros and Palmares cities. Morphometric analysis comprised the calculation of the length-gradient index along the longitudinal profile of the Una River. Geological data were collected from basement outcrops near the cities of Barreiros and Palmares. Barreiras Formation outcrops located in the coastal basin, nea...

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Deep crustal framework of the Borborema Province, NE Brazil, derived from gravity and magnetic data

Cited by 73 publications

References 119 publications

Zippered Shear Zone Model for Interacting Shear Zones in the Borborema Province, Brazil, as Constrained by U‐Pb Dating

Zippered Shear Zone Model for Interacting Shear Zones in the Borborema Province, Brazil, as Constrained by U‐Pb Dating

New U-Pb (SHRIMP) and first Hf isotope constraints on the Tonian (1000-920 Ma) Cariris Velhos event, Borborema Province, NE Brazil

Quaternary Tectonic Reactivation in the Southern Domain of Borborema Province, NE Brazil: Integration of Morphometric, Geological and Geophysical Data From the Una River Drainage Basin

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