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'eir', 'e Ord', 'T', '23 August 2010', 'Accepted 6 September 2010', 'Central Portugal between Serra da Estrela and Castro Daire massifs, was studied for this work. Despite a good geological mapping and documented geochemistry and petrography for these granites, the relationship between the emplacement of these granites and regional tectonics has so far remained unexplored. Microstructural studies focused on the Ossa Morena Zone and the South Portuguese Zone. Later, Farias et al. (1987) included the allochthonous and parautochthonous units of the CIZ in a separate zone called the Galicia Tr?s-os-Montes Zone. According to this classification, the studied area is located within the autochthonous terrains of the CIZ (Fig. 1). The Variscan orogeny was a major event in the tectonic evolution of Western Europe resulting from the Laurussiae-Gondwana collision through the late Devonian and most of the Carboniferous (Ribeiro et al., 1990; Mart?nez Catal?n et al., 2009). Its magmatic contents lists available. Journal of Structural Geology, Journal of Structural Geology 32 (2010) 1450-1465. E-mail address: hsantov@fc.up.pt (H. Sant’Ovaia). In the absence of direct geochronological evidence, correlating the deformations and the mode of emplacement of granite bodies with regional tectonic events is a challenge because granitic rocks do not always display deformation fabrics at a mesoscopic scale. Anisotropy of magnetic susceptibility (AMS) studies may be used to characterize and measure weak anisotropic fabrics (foliations and lineations), either magmatic or solid-state ones, which are essential to describe the different deformations for a granite, to identify the constraints leading to the granite intrusion, and finally to link these features to the regional tectonics. A large area (c. 5000 km²) of Variscan granitic outcrops in Central Portugal was studied for their magmatic and solid-state fabrics by means of the Anisotropy of Magnetic Susceptibility (AMS) technique. Article history: Received 17 December 2009; Received in revised form 6 September 2010. The late-D3 Variscan granites, which represent the most important volume of granites of Central Portugal (Serra da Estrela and Castr?o Daire areas), were studied. Helena Sant’Ovaia et al., Universidade do Porto, Faculdade de Ciências, Departamento de Geociências Ambiente; Philippe Olivier, Universit? de Toulouse, UPS (OMP), CNRS, IRD, LMTG, 14 Avenue Edouard Belin, F-31400; Narciso Ferr?a, LNEG, Unidade de Geologia e Cartogra?a Geol?gica, Rua da Amieira, 4466-956 S. Mamede; Fernando Noronha, Infesta, Portugal; Denis Leblanc, Universit? de Toulouse, UPS (OMP), CNRS, IRD, LMTG, 14 Avenue Edouard Belin, F-31400. The Variscan granites from the CIZ have been explained by an obduction-collision orogenic model with left lateral-transpression (Dias and Ribeiro, 1994). In the northwestern part of the Iberian Peninsula, three main phases of ductile deformation (D1, D2 and D3) have been described (Ribeiro, 1974; Noronha et al., 1979; Ribeiro et al., 1983). They are characterized by the generation of subvertical D1 folds with a steep slaty cleavage and, particularly in the allochthonous terrains of the Galicia Tr?s-os-Montes Zone, D2 recumbent folds with axial plane crenulation cleavage or schistosity associated to large thrust units or sub-horizontal extensional shear zones. Late stage D3 ductile deformation produced vertical folds with sub-horizontal axes and subvertical strike-slip shear zones, both right and left lateral. In central Portugal, especially in the studied area, the CIZ is characterized by a domain of D3 vertical folds deforming D1 sub-horizontal structures. However, earlier D1 fabrics overprinted by an extensional event prior to D3 are described in the Spanish part of the CIZ (Diez Balda et al., 1990; 1995; Escuder Viruete, 1998). A post-D3 brittle phase is characterized by a set of conjugate strike-slip faults (NNW-SSE dextral and NNE-SSW sinistral) late structures, whose geometry is often strongly influenced by pre-existent discontinuities (Ribeiro, 1974; Arthaud and Matte, 1975; Pereira et al., 1993). Based on geological, petrographic and geochemical studies, the Portuguese Variscan granites were divided into two main groups: dominant biotite granites (biotite >> muscovite) and two-mica (muscovite > biotite) granites. Considering their relation with the D3 deformation phase, syn-D3, late-D3 and late-post-D3 granites were defined (Ferreira et al., 1987). The CIZ zone is characterized by huge volumes of granitic rocks that represent about 60-70% of the outcropping rocks. Syn-D3 granites are represented by two-mica peraluminous granites, granodiorites and biotite granites. Late and post-D3 granites are represented by biotite and two-mica granites, and also by gabbros, diorites, quartz-monzodiorites and granodiorites (Azevedo and Valle Aguado, 2006). Isotopic ages for some granitoids in the Portuguese sector of the CIZ are recently published. These data are as follows: - granitoids which have been interpreted as syn-D3 by most authors because of their strong deformation fabrics are dated in the 314-307 Ma time-span (e.g., U-Pb on zircon and...) Ключевые слова: daire pluton, shear zone, quartz, univ, bouchez, uepb, grain, castro daire, tectonophysics, servios geolgicos, da, europe, mart?nez, central, variscan granite, vigneresse, geology, large area, ma, facies, emplacement, geol, nicolas, direction, journal structural, grain size, shallow, drawing, covilh?, submagmatic, characterized, ams, shallow plunge, shear, manteigas granite, strike-slip fault, schermerhorn ferreira, doe, serra, magmatic, castro, granitic pluton, gonzalez lodeiro, mus, schermerhorn, steep, valle aguado, stretching, orientation, located, studied area, intrusion, journal, study, seia, ovaia, dominantly ne-sw-, regional tectonics, biotite, magnetic susceptibility, studied granite, feature, pluton, susceptibility, wa, structure, monazite, solid-state fabric, thepb, valle, iberian peninsula, london, stage, zone, ovaia journal, dip, two-mica, region, tectonic, foliation, relationship, age, granite, martnez garcia, emplaced, guarda, truc tur, martnez cataln, structural study, estrela, galicia, trancoso, frequency histogram, geological, tectonic evolution, constraint, escala, studied, alonso, earth, main direction, strike-slip, sinistral, iberian massif, granite emplacement, paterson, mangualde, magnetic lineation, garc?a, country rock, explicativa, si, neiva, display microstructures, submagmatic microstructures, zircon, stretching lineation, area, structural geology, pluton emplacement, daire, estrela castro, iberian, fault, trancoso area, pereira, model, ciz, sousa, huge volume, doi, sub-vertical foliation, lineation, large, map, site, madrid, azevedo, zona, magnetic foliation, aguado, granitic rock, rochette, portugal, lineation orientation, serra da estrela, steep foliation, estrela pluton, regional, fabric, anisotropy, tectonics, orientation stereonets, lab, time-span, late, quartz grain, microstructures, saint blanquat, main, ferreira, independently, interpreted, phase, journal structural geology, data, guarda area, rock, magnetic anisotropy, concentrically distributed, histogram, characterization, variscan, ribeiro, distributed, portuguese sector, sant, porto, magma pressure, granitic, teixeira, magma, heller, display, deformation, granitoids, solid-state, lithos, structural, boorder, magnetic, noronha, central portugal