How long can the middle crust remain partially molten during orogeny?

Cavalcante, Carolina; Hollanda, Maria Helena Bezerra Maia de; Vauchez, Alain; Kawata, Marcelo

doi:10.1130/g45126.1

Cited by 42 publications

(41 citation statements)

References 23 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: 56%

“…597-593 Ma, and others in the interval of 589 and 572 Ma. The age distribution suggests a younging from NW to SE and from WNW to ESE in the Carlos Chagas batholith (Cavalcante et al, 2018).…”

Section: Ii1323 Basin Materialsmentioning

confidence: 84%

“…Richter et al, 2015). Several of SHRIMP U-Pb ages are reported for the EAU anatexites (Vauchez et al, 2007;Cavalcante et al, 2018). A number of diatexites and anatectic granites yielded ages in the range ca.…”

Section: Ii1323 Basin Materialsmentioning

confidence: 99%

“…Investigations of Cavalcante et al (2014Cavalcante et al ( , 2018 The magmatic bodies in the EAU in the studied region were described by Tuller (2000). According to his work, the predominant lithotype of the kinzigites ( Figure 14B) is a sillimanite-garnet-cordierite-biotite gneiss of fine-to medium-grained texture, frequently exhibiting compositional banding in which felsic layers are represented by a quartzofeldspathic association (and cordierite) and the mafic bands are composed of biotite (and sillimanite).…”

Section: Ii1323 Basin Materialsmentioning

confidence: 99%

“…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. 600 Ma, and that the middle crust at this point was already heated to >750 °C in a large area (Cavalcante et al, 2018). The achievement of such high temperatures and associated partial melting together with the transformation of a thinned crust to an over-thickened crust requires time (ca.…”

Section: Ii133 Tectonic Evolution Models Of the Araçuaí Orogenmentioning

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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