Reviewing the puzzling intracontinental termination of the Araçuaí-West Congo orogenic belt and its implications for orogenic development

Cavalcante, Carolina; Fossen, Haakon; Almeida, Renato Paes de; Hollanda, Maria Helena Bezerra Maia de; Egydio‐Silva, Marcos

doi:10.1016/j.precamres.2018.12.025

Cited by 47 publications

(34 citation statements)

References 123 publications

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“…In their model, the orogenic system formed in response to the closure of the Macaúbas basin. This Recent studies (Fossen et al, 2017;Cavalcante et al, 2018Cavalcante et al, , 2019 These authors also find strong support in currently available P-T, geochronologic, petrographic, and structural data (Vauchez et al, 2007;Mondou et al, 2012;Meira et al, 2015;Cavalcante et al, 2013Cavalcante et al, , 2014Cavalcante et al, , 2018 to explain the Araçuaí orogen as a hot intracontinental orogen. New radiometric and thermal data show that crystallization of the anatectic core of the orogen (EAU, Carlos Chagas anatectic domain) was going on already ca.…”

Section: Ii133 Tectonic Evolution Models Of the Araçuaí Orogensupporting

confidence: 58%

“…However, the presence of this ocean between the San Francisco and Congo cratons is under debate (Cavalcante et al, 2019). The presence of marine deposits and a probable representative unit of a typical metavulcanosedimentary rock of the ocean floor found in the northern portion of the Araçuaí belt and dated to ~850 Ma are observations that support the hypothesis.…”

Section: Iii12 the Ribeira-araçuaí Orogenic Systemmentioning

confidence: 88%

“…However, even if there is evidence of the breakup of Rodinia, the fact that there is no obvious identification of oceanic crust in the northern portion of the Ribeira belt and in the southern portion of the Araçuaí belt causes the subduction hypothesis to be considered with caution. The Paramirim Aulacogen indicates that the rift was aborted in the northern portion of the San Francisco craton and this suggests that a more southern oceanic spread occurred, resulting in an extension not large enough to initiate subduction and generate a magmatic arc during the convergence between the cratons (Mondou, 2010;Cavalcante et al, 2019).…”

Section: Iii12 the Ribeira-araçuaí Orogenic Systemmentioning

confidence: 99%

“…show that this model is incompatible with the general orogenic evolution proposed in recent literature, which involves ca. 50 Ma of subduction of oceanic crust and associated arc formation, followed by collisional orogeny and crustal thickening Cavalcante et al (2019). suggest that oceanic crust was nonexistent or very limited in the Macaúbas basin.Tonalitic and granodioritic bodies emplaced ca.…”

mentioning

confidence: 97%

“…Cross -sections are based onTack et al (2001),Alkmim et al (2006),. Dotted area indicates the Carlos Chagas (Eastern Anatectic Unit) anatectic domain (Source:Cavalcante et al, 2019). The yellow box represents the location of the studied area.…”

mentioning

confidence: 99%

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Deformation regime variations across the Neoproterozoic Araçuaí hot orogen (SE Brazil): insights from structural and magnetic fabric analyses

Angelo¹

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The Neoproterozoic Araçuaí belt of East Brazil formed during the amalgamation of Western Gondwana and holds characteristics of a hot collisional belt, involving large amount of magma, partial melting of the middle crust, and slow cooling rates. This work combines structural analysis, magnetic fabric, and geochronological studies in order to access information related to the flow of rocks, deformation history, and structural patterns associated with the behavior of this orogenic setting. Microstructural observations support that deformation of the plutonic bodies occurred in the magmatic state while the host metasedimentary and basement rocks remained in the solid-state. A detailed structural mapping integrating field and anisotropy of magnetic susceptibility (AMS) revealed four domains with contrasting flow patterns. The structural patterns from W to E are characterized by: westward thrusting orthogonal to the belt (region 1), orogen-parallel tranpression induced strain partitioning (regions 2 and 3), and orogen-parallel flow and subsidiary eastward vergence magmatic flow (region 4). Anisotropy of anhysteretic remanent magnetization (AARM) and magnetic mineralogy investigations suggest that the main carriers of the AMS are biotite and/or amphibole in paramagnetic samples (host metassediments and basement unit), and multi-domain (MD) or pseudo-single domain (PSD) magnetite grains in ferromagnetic materials (hosted in plutonic bodies). U-Pb dating of zircons from granitoids in the western arc border and central arc regions (structural regions 1, 2, and 3) reveal that magmatism occurred between 615-567 Ma. Microstructural investigations in the igneous bodies suggest that deformation occurred before complete solidification. This magmatism is associated with the main tectono-metamorphic peak attained by the orogen. To the east (structural region 4), younger bodies were emplaced in a still thermally buffered environment, but after solidification of the anatectic country rock. This late magmatism (540-480 Ma) is associated with a minor tectono-metamorphic peak, and magmatic deformation affected these bodies during that time. In the context of protracted deformation under slow cooling conditions, the composite observed fabric results from the interplay of collision-driven (thrusting and transpression strain partitioning) and gravity-driven (orogen-parallel flow) deformations, induced by the East-West convergence between the São Francisco and Congo Cratons.

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