Strain distribution across a partially molten middle crust: Insights from the AMS mapping of the Carlos Chagas Anatexite, Aracuai belt (East Brazil)

Autor(es)

Cavalcante, Geane C. G. ^{[1, 2, 3]} ; Egydio-Silva, Marcos ^[1] ; Vauchez, Alain ^{[2, 3]} ; Camps, Pierre ^{[2, 3]} ; Oliveira, Euridice ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Geociencias, BR-05508080 Sao Paulo - Brazil

^[2] Univ Montpellier 2, Geosci Montpellier, F-34095 Montpellier 05 - France

^[3] CNRS, F-34095 Montpellier 05 - France

• Tipo de documento: Artigo de Revisão
• Fonte: JOURNAL OF STRUCTURAL GEOLOGY; v. 55, p. 79-100, OCT 2013.
• Citações Web of Science: 10

Resumo

The easternmost part of the Neoproterozoic Aracuai belt comprises an anatectic domain that involves anatexites (the Carlos Chagas unit), leucogranites and migmatitic granulites that display a well-developed fabric. Microstructural observations support that the deformation occurred in the magmatic to submagmatic state. Structural mapping integrating field and anisotropy of magnetic susceptibility (AMS) revealed a complex, 3D structure. The northern domain displays gently dipping foliations bearing a NW-trending lineation, southward, the lineation trend progressively rotates to EW then SW and the foliation is gently folded. The eastern domain displays E W and NE SW trending foliations with moderate to steeply dips bearing a dominantly NS trending lineation. Magnetic mineralogy investigation suggests biotite as the main carrier of the magnetic susceptibility in the anatexites and ferromagnetic minerals in the granulites. Crystallographic preferred orientation (CPO) measurements using the electron backscatter diffraction (EBSD) technique suggest that the magnetic fabric comes from the crystalline anisotropy of biotite and feldspar grains, especially. The delineation of several structural domains with contrasted flow fabric suggests a 3D flow field involving westward thrusting orthogonal to the belt, northwestward orogen-oblique escape tectonics and NS orogen-parallel flow. This complex deformation pattern may be due to interplay of collision-driven and gravity-driven deformations. (C) 2013 Elsevier Ltd. All rights reserved. (AU)

• Processo FAPESP: 10/03537-7 - Estudo sismo-tectônico do leucogranito carlos chagas e unidades adjacentes na faixa araçuaí (leste do brasil).
• Beneficiário: Geane Carolina Gonçalves Cavalcante
• Modalidade de apoio: Bolsas no Brasil - Doutorado