Fabrics of migmatites and the relationships between partial melting and deformation in high-grade transpressional shear zones: The Espinho Branco anatexite (Borborema Province, NE Brazil)

Author(s)

Viegas, Luis Gustavo F. ^{[1, 2]} ; Archanjo, Carlos J. ^[1] ; Vauchez, Alain ^[2]

Affiliation

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

^[2] Geosci Montpellier, F-34095 Montpellier 5 - France

• Document type: Journal article
• Source: JOURNAL OF STRUCTURAL GEOLOGY; v. 48, p. 45-56, MAR 2013.
• Web of Science Citations: 10

Abstract

The Espinho Branco anatexite, located within a transcurrent, high-temperature shear zone in NE Brazil, was the subject of a comprehensive petrostructural study (Anisotropy of Magnetic Susceptibility - AMS, Anisotropy of Anhysteretic Remanence - AAR, Electron Backscatter Diffraction - EBSD) to evaluate the compatibility of different fabrics with the kinematics of melt deformation. Magnetite dominates susceptibilities larger than 1 mSI and biotite displays {[}001] lattice directions consistent with AMS k(3) axes. In contrast, migmatites with a susceptibility lower than 0.5 mSI and no visible mesoscopic foliation provide crystallographic fabrics distinct from AMS and AAR. However, AAR remains consistent with the regional strain field. These results suggest that the correlation of field, AMS and crystallographic fabrics is not always straightforward despite the relatively simple organisation of the magnetic fabric in the anatexite. We conclude that AMS recorded the final stages of the strain field in the migmatite irrespective of its complex mesoscale structures and contrasting crystallographic fabrics. (C) 2012 Elsevier Ltd. All rights reserved. (AU)

• FAPESP's process: 09/17537-1 - Deformation mechanisms and event chronology in the Patos shear zone, Borborema Province (Northeastern Brazil)
• Grantee: Luís Gustavo Ferreira Viegas
• Support type: Scholarships in Brazil - Doctorate