Models of crustal thickness for South America from seismic refraction, receiver functions and surface wave tomography

Assumpção, Marcelo; Feng, Min; Tassara, Andrés Ollero; Julià, Jordi

doi:10.1016/j.tecto.2012.11.014

Cited by 154 publications

(209 citation statements)

References 67 publications

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“…From 1990's to 2000's efforts gradually focused to more specific elements in the crust (Hasui et al 1993, Malagutti Filho et al 1996, França & Assumpção 2004, Slavec et al 2004, returning to regional scale works by seismology and potential field methods in the 2010's (Assumpção et al 2013a, 2013b, Chulick et al 2013, Marangoni & Mantovani 2013, van der Meijde et al 2013, 2015. Lesquer et al (1981) presents first the interpretations over Southern São Francisco Craton geometry, observing a NW-SE Neoproterozoic structural imprint on gravity data over its Archean grain, suggesting the existence of a WNW-ESE trending suture zone (Alfenas granulitic belt).…”

Section: Geophysical Frameworkmentioning

confidence: 99%

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Geophysical perspective on the structural interference zone along the Neoproterozoic Brasília and Ribeira fold belts in West Gondwana

Motta

Morales²,

Filho³

2017

Braz. J. Geol.

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ABSTRACT:The Brasília and Ribeira fold belts have been established in south-southwestern São Francisco Craton during the Brasiliano-Pan African orogeny (0.9-0.5 Ga -Tonian to Cambrian), and played an important role in West Gondwana continent assembly. The region is given by a complex regional fold and thrust belt superposed by shearing during the orogeny late times, with superposing stress fields forming a structural interference zone. These thrust sheets encompasses assemblies from lower-to upper--crust from different major tectonic blocks (Paranapanema, São Francisco), and newly created metamorphic rocks. Re-evaluation of ground gravity datasets in a geologically constrained approach including seismology (CRUST1 model) and magnetic data (EMAG2 model) unveiled details on the deep-crust settings, and the overall geometry of the structural interference zone. The Simple Bouguer Anomaly map shows heterogeneous density distribution in the area, highlighting the presence of high-density, high metamorphic grade rocks along the Alterosa suture zone in the Socorro-Guaxupé Nappe, lying amid a series of metasedimentary thrust scales in a regional nappe system with important verticalization along regional shear zones. Forward gravity modeling favors interpretations of structural interference up North into Guaxupé Nappe. Comparison to geotectonic models shows similarities with modern accretionary belts, renewing the discussion. KEYWORDS: modeling; gravity; magnetics; thrust tectonics; shear zones. RESUMO: Os cinturões de dobramento Brasília e Ribeira foram estabelecidos na porção sul-sudoeste do Cráton São Francisco durante a orogenia

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Section: Geophysical Frameworkmentioning

confidence: 99%

“…Several crustal thickness and mantle structure models are available proving consistent, besides differing input datasets, constraining parameters, physical property nature, sample density and data distribution (Assumpção et al 2013b, van der Meijde et al 2015.…”

Section: Geophysical Frameworkmentioning

confidence: 99%

Geophysical perspective on the structural interference zone along the Neoproterozoic Brasília and Ribeira fold belts in West Gondwana

Motta

Morales²,

Filho³

2017

Braz. J. Geol.

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“…Nevertheless, several paleogeographical reconstructions of Gondwana [Alkmim et al, 2001;Trindade et al, 2006;Rapela et al, 2007;Tohver et al, 2012] have assumed the existence of large ocean basins around the southern margin of the Amazon craton, though they disagree on whether the final amalgamation occurred in the Neoproterozoic or Cambrian time. Several geophysical studies on the continental lithosphere of the South American plate, using techniques such as seismic tomography, crustal thickness estimates from receiver functions, and gravity interpretation, have been recently published [e.g., Feng et al, 2007;Lloyd et al, 2010;Assumpção et al, 2013;Chulick et al, 2013;van der Meijde et al, 2013]. However, the resolution of these studies prevents determining the precise location of the concealed ancient plate boundaries, which could contribute to reconstructing West Gondwana formation and evolution.…”

Section: Introductionmentioning

confidence: 99%

Paraguay‐Araguaia Belt Conductivity Anomaly: A fundamental tectonic boundary in South American Platform imaged by electromagnetic induction surveys

Bologna

Padilha

Pádua

et al. 2014

Geochem Geophys Geosyst

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[1] We discovered and mapped a 1200 km-long zone of enhanced electrical conductivity through a large array of magnetometers, over a narrow corridor parallel to the Paraguay and Araguaia belts which surround the Amazon craton. The anomaly has been further studied using magnetotelluric measurements made along a 300 km profile crossing the Paraguay belt; modeling shows the anomaly at this location as a very strong 100 km-wide upper-crust to mid-crust conductor, located under a region where surficial rocks show an increase in deformation and metamorphism within the belt. From the high conductivity of the anomalous structure, its observed geometry and surface rock exposures, the most likely interpretation of its source is graphitized biogenic material in metasediments, now deeply underthrust in a Neoproterozoic or Early Cambrian suture zone. This result strongly supports the hypothesis that the collision between the Amazon plate and the western Paran a block has probably closed an ocean in the Paraguay belt region, contrary to former propositions of an ensialic evolution for this belt. Although the precise age of this ocean closure have been a matter of debate, our finding significantly constrains the tectonic setting of West Gondwana amalgamation involving the Amazon plate and its surrounding blocks.

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“…In the current paper, this Moho depth estimation (Riccardo Barzaghi, personal communication, April 20, 2012) is compared with other models based on both seismic and gravity observations, under the North Patagonian Massif (NPM). Said massif is an Argentinean plateau that stands out 500 to 700 m higher in altitude than the surrounding topography and was created by a sudden uplift without noticeable internal deformation (Aragón et al (2011b) Upper mantle geodynamic constrains beneath the north patagonian massif, Argentina). The features described led us to analyze the crustal thickness in the area.…”

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confidence: 99%

Mohorovicic Discontinuity Depth Analysis Beneath North Patagonian Massif

Dacal

Tocho

Aragón

2015

International Association of Geodesy Symposia

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The Mohorovicic discontinuity (Moho) is the surface that limits the Earth's crust and mantle. It is of paramount importance in understanding and investigating the dynamics of the Earth's interior. The GEMMA project (GOCE Exploitation for Moho Modeling and Applications), funded by the European Space Agency and Politecnico di Milano, has provided a high resolution map of the Moho surface (GEMMA Model), based on the inversion of homogeneous, well-distributed gravimetric data measured by the SteadyState Ocean Circulation Explorer (GOCE), which ensures a global coverage using gravity field. In the current paper, this Moho depth estimation (Riccardo Barzaghi, personal communication, April 20, 2012) is compared with other models based on both seismic and gravity observations, under the North Patagonian Massif (NPM). Said massif is an Argentinean plateau that stands out 500 to 700 m higher in altitude than the surrounding topography and was created by a sudden uplift without noticeable internal deformation (Aragón et al. (2011b) Upper mantle geodynamic constrains beneath the north patagonian massif, Argentina). The features described led us to analyze the crustal thickness in the area. The work describes different Moho models available in the area under study and their comparison with the GEMMA Model. The aim is to validate this well distributed, homogeneous data model in this area with sparse seismic data and check its usefulness to get more information about the Moho. According to comparisons with the different models, the crustal thickness in the study area varies between 36 and 46 km. The good agreement between the GEMMA Model and some of the other Moho models may account for the use of such model to study this little known area.

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Models of crustal thickness for South America from seismic refraction, receiver functions and surface wave tomography

Cited by 154 publications

References 67 publications

Geophysical perspective on the structural interference zone along the Neoproterozoic Brasília and Ribeira fold belts in West Gondwana

Geophysical perspective on the structural interference zone along the Neoproterozoic Brasília and Ribeira fold belts in West Gondwana

Paraguay‐Araguaia Belt Conductivity Anomaly: A fundamental tectonic boundary in South American Platform imaged by electromagnetic induction surveys

Mohorovicic Discontinuity Depth Analysis Beneath North Patagonian Massif

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