Anisotropy and Texture development in mylonitic felsic granulites of the Sobrado Unit (NW Iberia)
- J.M. Benítez-Pérez 1
- J. Gómez-Barreiro 1
- J.R. Martínez Catalán 1
- H-R. Wenk 2
- S.C. Vogel 3
- Bachir Ouladdiaf 4
- L. Mancini 5
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1
Universidad de Salamanca
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2
University of California System
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- 3 Los Alamos Neutron Science Center
- 4 Institut Laue-Langevin, Neutron for Science
- 5 Sincrotrone Trieste S.C.p.A.
ISSN: 1576-5172
Année de publication: 2016
Titre de la publication: IX CONGRESO GEOLÓGICO DE ESPAÑA
Número: 16
Pages: 479-482
Type: Article
D'autres publications dans: Geotemas (Madrid)
Résumé
Quantitative fabric analyses of mylonitic felsic granulites from the Sobrado unit (Upper allochthon, Órdenes Complex, NW Iberia) have been done with HIPPO, a Time-Of-Flight (TOF) neutron diffractometer (LANSCE center; Los Alamos National Lab) and D1B, a pulsed neutron diffractometer (ILL center, Institut Laue-Langevin). Shape analyses of selected phases were done with X–ray computed microtomography at ELETTRA (SYRMEP beamline). The Sobrado unit represents and excellent example of laminated mid/lower crust. The unit is a tectonic stack of highly deformed slices of metabasites, paragneisses and ultramafic rocks with metamorphism ranging from amphibolite facies on top, to eclogites facies at the bottom. Contrasted rheological behavior suggests that felsic lithologies accommodated most of the flow during the exhumation. We explore the crystallographic preferred orientation or texture to constraint the deformation mechanisms and determine their contribution to the elastic anisotropy of the aggregate. Microstructure and texture evolution suggests that deformation evolved from granulite to amphibolite facies along a N-S flow, driven by dislocation creep partially assisted by grain boundary sliding and diffusion. The kinematic and mechanical implications are discussed in terms of the regional geology.