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Journal of Structural Geology 32 (2010) 803-817 Contents lists available at ScienceDirect Journal of Structural Geology journal homepage: www.elsevier.com/locate/jsg Evaluating quartz crystallographic preferred orientations and the role of deformation partitioning using EBSD and fabric analyser techniques Mark Peternell a,*, Pavl?na Hasalov? b, Christopher J.L. Wilson a, Sandra Piazolo c,1, Karel Schulmannd a School of Earth Sciences, The University of Melbourne, Victoria 3010, Australia b School of Geosciences, Monash University, Clayton, Victoria 3800, Australia c Department of Geological Sciences, Stockholm University, Stockholm 10691, Sweden d L’Universit? de Strasbourg, l’Institut de Physique du Globe de Strasbourg, UMR 7517, 1 Rue Blessig, Strasbourg 67084, France Article info Article history: Received 31 October 2009 Received in revised form 5 May 2010 Accepted 13 May 2010 Available online 21 May 2010 Keywords: Crystallographic preferred orientation Deformation partitioning Electron back-scattered diffraction Fabric analyser Quartz Thaya dome Abstract Quartz crystallographic preferred orientations (CPO) from three distinct orthogneisses using both the Electron Back Scatter Diffraction (EBSD) and Fabric Analyser (FA) techniques reveal a clear trend from basal and rhomb slip for high PeT conditions (670 ± 20 ×14C 9 kbar), rhomb and basal slip for medium PeT (590 ± 15 ×14C 6 kbar) and a dominance of prism slip for lower PeT conditions (<570 ×14C 4e5 kbar). The textural variations are interpreted in terms of a temperature ?eld gradient and microscale strain partitioning controlled by a weak feldspar matrix that can locally invert the expected slip system sequences. Locally quartz CPOs are different within one thin section, and in comparison to bulk orientation measurements both, EBSD and the Fabric Analyser techniques are ideal to determine such textural heterogeneities. While the EBSD is a powerful technique to determine the full CPO, measurements from similar locations inside several quartz grains from the orthogneisses and an annealed and undeformed quartzite show that the FA is an accurate tool to determine CPOs of c-axis orientations in uniaxial materials. In a CPO focussed study the FA is a cheap alternative to EBSD as the analysis of whole thin section can be accomplished in a very short time, with minimal sample preparation. With the FA it is possible to evaluate the CPOs of several samples quickly with an accuracy that allows identification of the main slip systems and their homogeneity. ? 2010 Elsevier Ltd. All rights reserved. 1. Introduction Crystallographic Preferred Orientation (CPO) measurement in deformed rocks is a common procedure introduced into classical structural analysis (e.g. Sander, 1930; Fairbairn, 1949; Turner and Weiss, 1963). A CPO analysis is crucial in order to decipher observed microstructures and or deformation mechanisms (e.g. Prior and Wheeler, 1999), model other physical anisotropies of rocks (e.g. Ji and Mainprice, 1988; Bascou et al., 2001) and to understand and quantify sedimentary, metamorphic and magmatic processes (e.g. M?rk and Moen, 2007; Romeo et al., 2007; Hasalov? et al., 2008). Quartz is one of the most common minerals in the Earth’s crust and therefore understanding its deformational behaviour is important. There are many studies of experimentally and naturally deformed quartz-rich rocks that provide some insight in understanding of quartz deformational behaviour and development of its CPO (Hobbs, 1968; Tullis, 1977; Blumenfeld et al., 1986; Schmid and Casey, 1986; Dell’Angelo and Tullis, 1989; Gleason et al., 1993; Stipp et al., 2002; Vernooij et al., 2006; Menegon et al., 2008; Stipp and Kunze, 2008). Quartz CPO is controlled by temperature, strain rate, differential stress and ?uid content (e.g. Stipp et al., 2002; Menegon et al., 2008). Therefore deformed quartz has distinctive CPOs that can be related to specific conditions of formation (e.g. Tullis, 1977; Schmid and Casey, 1986; Stipp et al., 2002). * Corresponding author. Tel.: ?61 3 8344 6910; fax: ?61 3 8344 7761. E-mail address: petm@unimelb.edu.au (M. Peternell). 1 Present address: Department of Earth and Planetary Sciences, Macquarie University, Australia. 0191-8141 $ e see front matter ?2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.jsg.2010.05.007 Ключевые слова: point, thaya orthogneiss, geometric quality, fabric, crystallographic orientation, high, basement, method-related misorientations, point comparison, unit, mmpixel resolution, schulmann, materials, pattern, kruhl, rock, thaya dome, polymineralic rock, journal structural geology, basal, c-axis orientation, cpo, peternell journal, deformation partitioning, weitersfeld, mainprice, deformation, ebsd analysis, misorientation, orthogneiss sample, hemisphere contoured, btes weitersfeld, electron, sample, thaya, orthogneiss, single, measure point, melka, quality, wheeler, structural, frequency distribution, clear trend, springer, temperature, extinction plane, science, study, quartz analysis, quartz, ebsd measurement, quartzite, data, wa, method, carbon coating, texture, geology, wenk, sequence, opening angle, transmitted light, combined geometric, die, preferred orientation, appin, prior, retardation, b?te s orthogneiss, accuracy, carbon, single crystal, uniaxial mineral, resolution, crystal impurity, geological, fynn powell, case, position, metamorphic, quartz grain, mm, rhomb, dynamic recrystallization, metamorphic condition, kunze, broad band, geophysical, heilbronner, condition, axis orientation, weitersfeld orthogneiss, sem image, journal structural, recrystallised plagioclase, der, orthogneisses, microstructural, single measurement, peternell, axis, grain boundary, coated, dome, measurement, tullis, individual grain, threshold, spatial resolution, law, spatial, slip, eds, difference, impurity, subgrain, analysis, image, ebsd method, larger number, fa, elongated aggregate, subgrain boundary, textural evolution, microstructures, sample preparation, measured point, distribution, t?psk?, c-axis pattern, polygonal texture, bohemian massif, mineral, pixel, uncoated sample, result, structural geology, lowest temperature, american, fueten, hobbs, microscopy, appin quartzite, combined threshold, c-axis, circle, boundary, analysed, btes orthogneiss, comparison, standard deviation, texture analysis, b?te s, x-ray diffraction, elsevier, geometric, quartz c-axis, metamorphic grade, technique, misorientations, quartz cpos, scatter image, adams, method-related, maximum, journal, deformed, thaya orthogneisses, tectonophysics, ebsd, orientation, controlling factor, setup, stretching lineation, ava image, stipp, carbon coated, goodchild wilson, quality threshold, feldspar, pole gures, crystallographic, prism, diffraction, preferred, total number, measured, mineral texture, retardation quality, wilson, sander, schmid, internal impurity, quartz texture, thaya sample, mineral inclusion, deformation mechanism, crystal, method-related misorientation, recrystallised, grain