Causes of intraplate seismicity in central Brazil from travel time seismic tomography

Rocha, Marcelo Peres; Azevedo, Paulo Araújo de; Marotta, Giuliano Sant’Anna; Schimmel, Martin; Fuck, Reinhardt A.

doi:10.1016/j.tecto.2016.05.005

Cited by 25 publications

(12 citation statements)

References 46 publications

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“…While anomalies S2 and S3 remain apparent in the present study, they are notably less slow than previously imaged. Anomalies F1, F2, and F3, appearing in prior studies with slightly different shapes, but similar amplitudes, were interpreted as cratonic blocks beneath the São Francisco Basin (F1; Rocha et al, ), the Paraná Basin (F2; Rocha et al, ), and Amazonia (F3; Rocha et al, ). Anomaly F4, while observable in a prior study (Pesicek et al, ), appears further north and constrained to a narrower depth range in the present study.…”

Section: Resultsmentioning

confidence: 82%

Detailed Structure of the Subducted Nazca Slab into the Lower Mantle Derived From Continent‐Scale Teleseismic P Wave Tomography

et al. 2020

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Nazca subduction beneath South America is one of our best modern examples of long‐lived ocean‐continent subduction on the planet, serving as a foundation for our understanding of subduction processes. Within that framework, persistent heterogeneities at a range of scales in both the South America and Nazca plates is difficult to reconcile without detailed knowledge of the subducted Nazca slab structure. Here we use teleseismic travel time residuals from >1,000 broadband and short‐period seismic stations across South America in a single tomographic inversion to produce the highest‐resolution contiguous P wave tomography model of the subducting slab and surrounding mantle beneath South America to date. Our model reveals a continuous trench‐parallel fast seismic velocity anomaly across the majority of South America that is consistent with the subducting Nazca slab. The imaged anomaly indicates a number of robust features of the subducted slab, including variable slab dip, extensive lower mantle penetration, slab stagnation in the lower mantle, and variable slab amplitude, that are incorporated into a new, comprehensive model of the geometry of the Nazca slab surface to ~1,100 km depth. Lower mantle slab penetration along the entire margin suggests that lower mantle slab anchoring is insufficient to explain along strike upper plate variability while slab stagnation in the lower mantle indicates that the 1,000 km discontinuity is dominant beneath South America.

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Section: Resultsmentioning

confidence: 82%

Detailed Structure of the Subducted Nazca Slab into the Lower Mantle Derived From Continent‐Scale Teleseismic P Wave Tomography

et al. 2020

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“…The strongest low‐velocity anomaly is observed under the Pantanal Basin, which seems to be part of the low‐velocity belt in Central Brazil bordering the Amazonian Craton (Azevedo et al, ; Rocha et al, , ). This low‐velocity zone has been interpreted as a thin lithospheric belt (Assumpção, An, et al, ; Azevedo et al, ; Rocha et al, ) roughly parallel to the Transbrasiliano Lineament in Central Brazil. The Pantanal low velocities may reach 500‐km depth (Figure a), but depth resolution is poor with our present network.…”

Section: Resultsmentioning

confidence: 99%

Teleseismic P Wave Tomography Beneath the Pantanal, Paraná, and Chaco‐Paraná Basins, SE South America: Delimiting Lithospheric Blocks of the SW Gondwana Assemblage

et al. 2019

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We present velocity anomalies for the upper mantle beneath the Pantanal, Paraná, and Chaco-Paraná basins, using teleseismic P-wave tomography. Three hundred thirty-nine stations were used to record 4,989 events for P and PKIKP phases, during the years 1992-2017. A new temporary deployment with 34 stations improved the coverage in that region. A high-velocity anomaly beneath the Paraná Basin was interpreted as a cratonic basement. Its northern portion is consistent with the cratonic block presented by Cordani et al. (1984), and the southern portion is consistent with that presented by Mantovani et al. (2005, https://doi.org/10.1016/s1342-937x(05)71137-0). Low velocities are consistent with the limits of the Rio de la Plata craton, proposed by Rapela et al. (2011, https://doi.org/10.1016/j.gr.2011.05.001). A low-velocity anomaly under the Pantanal Basin correlates with the seismicity, suggesting lithospheric thinning. This result is not consistent with an extension of the Rio Apa Block beneath the Pantanal Basin. We observed high velocities separating the Pantanal and South-Paraguay seismic zones. The Western Paraná Suture (as proposed by Dragone et al., 2017, https://doi.org/10.1016/j.precamres.2017.01.029) shows no correlation with the seismic tomography anomalies. The thick lithosphere in the central part of the Paraná Basin is consistent with deviation of mantle flow, as suggested by SKS fast polarization (Melo & Assumpção, 2018, https://doi.org/10.1093/gji/ggy288). Synthetic tests show low resolution of the model for structures smaller than 200 x 200 km in the southwest portion of the study area but good resolution for large structures. the Transbrasiliano Lineament (TBL; Figure 1): The Amazonian Domain, including mainly the Amazonian Craton and related to the supercontinent of Laurentia, and the Extra-Amazonian (or Brasiliano) Domain, related to the supercontinent of West Gondwana. The Brasiliano Domain was formed by several paleocontinental fragments, where the largest are the São Francisco and Rio de La Plata (RDLP) cratons and the Paranapanema Block.The understanding of the tectonic evolution of the SAP requires a study of how these various paleocontinental fragments are related and how this mosaic of fragments reached its present state. This is more important for the Extra-Amazonian Domain, where these fragments are smaller than for the main representative of the Amazonian Domain, the Amazonian Craton. Defining the limits and geometry of these fragments at depth using seismic tomography is one way to understand the processes that allowed the formation of the SAP, especially when those limits are covered by sedimentary basins, hindering direct geological observations. Several geological and geophysical studies have been conducted to better understand the layout and geometry of the various cratonic nuclei of the SAP. Cordani et al. (1984), based on regional geology and radiometric dating from deep boreholes, suggested the first limits of the cratonic block related to the Paraná Basin basement. Mantovani et ...

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“…In the same area, several studies show that the direction of the maximum horizontal stress trends E-W (Assumpcao, 1992;Barros et al, 2009;Chimpliganond et al, 2010;Coblentz & Richardson, 1996;Ferreira et al, 1998;Neto et al, 2013). Further onshore, a similar compressional E-W trend is observed in the Parana, Pantana and Chaco basins (Milani & Zalán, 1998;Rocha et al, 2016;Ussami et al, 1999).…”

Section: Length Scales Of Deformation During Passive Margin Inversionsupporting

confidence: 63%

Rheological and kinematic conditions for forced subduction initiation at continental passive margins

Auzemery¹

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Antoine Auzemery -Rheological and kinematic conditions for forced subduction initiation at continental passive margins 1 Rheological and kinematic conditions for forced subduction initiation at continental passive margins Reologische en kinematische vereisten voor initiatie van geforceerde subductie op continentale passieve marges (met een samenvatting in het Nederlands) Conditions rhéologiques et cinématiques pour l'initiation de la subduction forcée aux marges passives continentales (avec un résumé en français) Proefschrift ter verkrijging van de graad van doctor aan de Universiteit Utrecht op gezag van de rector magnificus, prof.dr. H.R.B.M. Kummeling, ingevolge het besluit van het college voor promoties in het openbaar te verdedigen op vrijdag 3 september 2021 des middags te 2.

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Causes of intraplate seismicity in central Brazil from travel time seismic tomography

Cited by 25 publications

References 46 publications

Detailed Structure of the Subducted Nazca Slab into the Lower Mantle Derived From Continent‐Scale Teleseismic P Wave Tomography

Detailed Structure of the Subducted Nazca Slab into the Lower Mantle Derived From Continent‐Scale Teleseismic P Wave Tomography

Teleseismic P Wave Tomography Beneath the Pantanal, Paraná, and Chaco‐Paraná Basins, SE South America: Delimiting Lithospheric Blocks of the SW Gondwana Assemblage

Rheological and kinematic conditions for forced subduction initiation at continental passive margins

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