Texture analysis of a muscovite-bearing quartzite: a comparison of some currently used techniques Klaus Ullemeyer a, * , Gu Ènter Braun b , Michael Dahms c , Jo Èrn H. Kruhl d , Niels é. Olesen e , Siegfried Siegesmund a a Institut fu Èr Geologie und Dynamik der Lithospha Ère, Goldschmidtstr. 3, 37077 Go Èttingen, Germany b Institut fu Èr Geowissenschaften, Olshausenstr. 40-60, 24118 Kiel, Germany c GKSS Forschungszentrum, Max-Planckstr. 12, 21502 Geesthacht, Germany d Institut fu Èr Geologie, Geotechnik und Baubetrieb, Arcisstr. 21, 80290 Mu Ènchen, Germany e Department of Earth Sciences, C.F. Mùllers Alle, 8000 A Ê arhus C, Denmark Received 14 December 1999; accepted 28 June 2000 Abstract Four well-established techniques were applied to determine the mineral textures of a muscovite-bearing quartzite: (1) directional measure- ments on an optical U-stage; (2) X-ray; (3) neutron; and (4) electron diffraction (EBSD). Techniques (1) and (4) are of the `single grain' type and techniques (2) and (3) of the `statistical' or `volume' type. Experimental pole density diagrams were compared by means of the construction of pole ®gure differences (`difference pole ®gures'), which led to the observation that EBSD- and U-stage derived pole ®gures agree well, even in detail. In contrast, pole ®gures derived from X-ray and neutron diffraction are clearly different from pole ®gures derived from the single grain techniques, visible as pronounced preferred orientation in the difference pole ®gures. Speci®c properties of the applied techniques may be responsible for the observed differences, such as (1) missing proportionality to the grain volume in the single grain methods, (2) the accessible sample volume, (3) erroneous data correction, or (4) statistical errors. Also the method of data treatment, which is basically different for the single grain and statistical methods, should be considered when pole ®gures are evaluated. Apart from purely economical constraints and availibility of equipment, the decision on the most suitable method for a texture determination should be based on the scienti®c goals and speci®c properties of particular techniques. Texture measurements of the statistical type are well suited for determination of bulk textures of rocks (e.g. as required for the calculation of anisotropic physical properties of rocks), whereas single grain measurements are advantageous for the investigation of local textures and texture forming mechanisms. q 2000 Elsevier Science Ltd. All rights reserved. 1. Introduction The lattice preferred orientation, or texture, of rock forming minerals is related to the deformation history of the rock and to its physical properties. Texture investi- gations are routinely performed with the following three main goals. 1. Deconvolution of the deformation history of rocks on the basis of the symmetry of the mineral textures, which commonly re¯ects the symmetry of deformation, has been the subject of many studies, with a focus on quartz (e.g. Bouchez and Pecher, 1981; Schmid and Casey, 1986; Law, 1990), carbonates (e.g. Erskine et al., 1993; Leiss, 1996), phyllosilicates (e.g. Oertel, 1985; O'Brien et al., 1987), and olivine (e.g. Wedel et al., 1992; Van der Wal and Vissers, 1996). 2. The modelling of physical anisotropies of rocks. Since all minerals are anisotropic with regard to physical proper- ties such as the elastic, thermal and magnetic properties, the anisotropy of bulk rock also depends upon the texture (refer to Siegesmund, 1996 for a review). For example, the elastic properties of rocks are related to the rock fabric and therefore can support the geological interpre- tation of geophysical anisotropies in the earth's crust (e.g. Rabbel et al., 1998) and upper mantle (Weiss et al., 1999). Texture determinations can also be of impor- tance to the Society: the mechanical weathering of marble building stones is partly controlled by the aniso- tropic intrinsic rock properties (e.g. Siegesmund et al., 2000). 3. The understanding of the texture-forming processes in rocks. Lattice preferred orientations result from various Journal of Structural Geology 22 (2000) 1541±1557 0191-8141/00/$ - see front matter q 2000 Elsevier Science Ltd. All rights reserved. PII: S0191-8141(00)00103-6 www.elsevier.nl/locate/jstrugeo * Corresponding author. Fax: 149-551-399700. E-mail address: kulleme@gwdg.de (K. Ullemeyer).