Midcrust deformation regime variations across the Neoproterozoic Araçuaí hot orogen (SE Brazil): Insights from structural and magnetic fabric analyses

Angelo, Tiago Valim; Egydio‐Silva, Marcos; Temporim, Filipe Altoé; Seraine, Marina

doi:10.1016/j.jsg.2020.104007

Cited by 4 publications

(6 citation statements)

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“…Heating of samples from these intrusions causes an increase in susceptibility at ~480°C and a subsequent decrease at ~580°C (Supplementary Figure S2). In all cases, constricted magnetic hysteresis and first‐order reversal curves indicate low‐coercivity multi‐domain magnetite is the main carrier of the magnetic fabric (Supplementary Figure S3; Angelo et al, 2020; Cavalcante et al, 2013; Temporim et al, 2020). This fact is also supported by the values of Mrs/Ms and Hcr/Hc, which are typical of multidomain magnetite (Supplementary Figure S3).…”

Section: Sampling and Resultsmentioning

confidence: 92%

“…Stereoplots for AMS fabric are displayed for each studied pluton. Magnetic data sources: Vargem Grande, this study; Xavier (2017); Angelo et al (2020); Barra do São Francisco, Cavalcante et al (2013); Caladão, this study, Mondou et al (2012); Xavier (2017); Angelo et al (2020); Conceição de Muqui: This study; Santa Angélica: Temporim et al (2020).…”

Section: Geological Settingmentioning

confidence: 99%

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Vertical deformation partitioning across a collapsing large and hot orogen

et al. 2022

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Featuring 3 000-km-long large and hot orogen, the Mantiqueira Province provides a rare opportunity to study the process of gravitational collapse at mid to deep crustal levels. Distinct but contemporary (~500 Ma) post-collisional intrusions show structures and anisotropy of magnetic susceptibility (AMS) fabrics related to their emplacements, recording different flow patterns. In southern deep-seated intrusions, ellipsoidal-shaped roots with gabbroic-to-hybrid cores surrounded by granitic rocks show concentric patterns of AMS fabrics that cut across the NE-trending regional foliation. In contrast, northern intrusions, exposed as the upper sections of batholith-size bodies of coarse-grained granite emplaced at the shallow to mid-crust, show general NS-trending magnetic fabrics roughly parallel to strike of the orogen and the regional foliation of host rocks. These contrasting magnetic patterns from shallow to deeper crust suggest vertical magma migration from the overthickened orogenic core to be emplaced across its thinner stretched flanks during the gravitational collapse of the orogenic edifice.

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Section: Sampling and Resultsmentioning

confidence: 92%

Section: Geological Settingmentioning

confidence: 99%

Vertical deformation partitioning across a collapsing large and hot orogen

et al. 2022

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“…The fabric geometry observed in the Central domain rocks, where steeply-dipping/plunging planar and linear fabrics occur (e.g., Mondou et al, 2012;Angelo et al, 2020), strongly supports magma emplacement, i.e., efficient magma migration from its source, likely from the deep root of the orogenic belt. Such a magma emplacement would be, at least in part, synchronous with the anatexis of the middle/lower crust represented by the CCD and Nova Venécia complex (Fig.…”

Section: Regional Implicationsmentioning

confidence: 83%

“…Several studies conducted over the last three decades have produced a large body of structural, geochronological, geochemical and petrological data that provides important constraints on the tectonic setting and orogenic processes of the hot Araçuaí belt (e.g. Trompette et al, 1993;Vauchez et al, 1994Vauchez et al, , 2007Vauchez et al, , 2019Trompette, 1997;Pedrosa-Soares et al, 2001;Martins et al, 2004;Alkmim et al, 2006;Petitgirard et al, 2009;Mondou et al, 2012;Cavalcante et al, 2013Cavalcante et al, , 2014Cavalcante et al, , 2018Richter et al, 2016;Melo et al, 2017a, b;Angelo et al, 2020). However, key questions, especially those related to the geodynamic implications of the formation of a large migmatitic-anatectic area with evidence of being partially molten for a long time period (e.g., Cavalcante et al, 2018;Vauchez et al, 2019), have not received due attention.…”

Section: Introductionmentioning

confidence: 99%

The role of Ediacaran synkinematic anatectic rocks and the late-orogenic charnockitic rocks in the development of the hot Araçuaí belt

Cavalcante

Meira

Magalhães

et al. 2021

Precambrian Research

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“…Portanto, a geometria esperada neste caso seria um plúton plano (flatfloored), pouco espesso com grande extensão horizontal. Os plútons G5 da região norte do AO podem ter experimentado esse mecanismo de colocação dadas algumas características publicadas sobre alguns deles, como grandes dimensões horizontais, dados de geotermobarometria compatíveis com a transição rúptil-dúctil da crosta (2,4 -3,5 Kbar, Serrano et al, 2018) e foliação e lineação quase horizontalizadas (Angelo et al, 2020).…”

Section: Colocação De Plútons Pós-colisionais Versus Reologia Da Crostaunclassified

Anisotropia magnética e gravimetria do Complexo Intrusivo Santa Angélica, Faixa Araçuaí

Júnior¹,

de²

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The Santa Angélica Intrusive Complex (SAIC) is located in the Araçuai Belt, in Southeast Brazil. It is a Cambrian, NE elongated plutonic complex, composed of two twin plutons (lobes Northeast and Southwest) with a bull's eye shape and a concentric fabric ("onion skin"). It was formed during the post-collisional stage of the Araçuaí Orogen (AO), an example of Neoproterozoic orogen formed during the Brasiliano cycle. In the southern portion of the AO, the post-collisional plutons intrude into a deeper crust and have an inversely zoned concentric pattern, while in the northern portion of the AO they form larger granitic/charnockitic batholiths with sub-horizontal lineations. Although the SAIC is widely recognized as free of regional deformation due to its tectonic context and dating, important solid-state structures have been reported at its borders, and along an internal shear zone. In this work, the mechanisms responsible for the generation of these features was studied in order to get a better understand of the causes of the different architectures presented by post-collisional bodies when placed at different crustal levels. We applied 2D direct modeling of gravimetric data at CISA and its country rocks, together with a complete structural analysis by means of anisotropy of magnetic susceptibility (AMS), anisotropy of remanent magnetization (ARM) and oriented microstructural data from thin sections. The gravimetric data obtained with the field survey reflect the inversely zoned distributions, with a gradation from the granitic borders to the mafic cores. Magnetic analyses indicate that multidomain magnetite controls the magnetic fabric of the SAIC's country rocks. 2D gravimetric modeling shows that in the Northeast lobe represents the pluton's roots and its thickness is much lower than that of the Southwest lobe. Using microstructural analysis and magnetic mineral fabric, three zones were identified where solid-state microstructures occur: (i) country rocks with foliation parallel to contact with SAIC, (ii) the granitic edge and (iii) the internal shear zone. In areas (i) and (ii), higher temperature solid state microstructures are overlapped by lower temperature structures, while area (iii) has only high temperature solid state structures. Two hypotheses might explain this configuration.First, the structures represent the partitioning of deformation during the pluton's cooling and follow the regional stress field also expressed in the shear zones that cur the host rocks. Alternatively, they may represent a reverse diapirism, caused by the negative buoyancy of the mafic core after crystallization.

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Midcrust deformation regime variations across the Neoproterozoic Araçuaí hot orogen (SE Brazil): Insights from structural and magnetic fabric analyses

Cited by 4 publications

References 65 publications

Vertical deformation partitioning across a collapsing large and hot orogen

Vertical deformation partitioning across a collapsing large and hot orogen

The role of Ediacaran synkinematic anatectic rocks and the late-orogenic charnockitic rocks in the development of the hot Araçuaí belt

Anisotropia magnética e gravimetria do Complexo Intrusivo Santa Angélica, Faixa Araçuaí

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