Revisiting elastic anisotropy of biotite gneiss from the Outokumpu scientific drill hole based on new texture measurements and texture-based velocity calculations

Wenk, Hans‐Rudolf; Vasin, R. N.; Kern, H.; Matthies, S.; Vogel, Sven C.; Ivankina, T. I.

doi:10.1016/j.tecto.2012.06.023

Cited by 44 publications

(41 citation statements)

References 59 publications

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“…We used the MAUD software for the texture evaluation (Lutterotti et al, 1997;Wenk et al, 2010), for the discussion of practical limitations refer to Wenk et al (2012) and Keppler et al (2014). Since RTA requires knowledge of the mineral structures present in the sample, mineral assemblages and chemical compositions were determined by means of microprobe analysis on a JEOL JXA 8200 Electron microprobe.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

Crystallographic preferred orientations of exhumed subduction channel rocks from the Eclogite Zone of the Tauern Window (Eastern Alps, Austria), and implications on rock elastic anisotropies at great depths

et al. 2015

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Section: Accepted M Manuscriptmentioning

confidence: 99%

Crystallographic preferred orientations of exhumed subduction channel rocks from the Eclogite Zone of the Tauern Window (Eastern Alps, Austria), and implications on rock elastic anisotropies at great depths

et al. 2015

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“…Their elastic properties are highly anisotropic (e.g., Aleksandrov and Ryzhova, 1961;Vaughan and Guggenheim, 1986;Militzer et al, 2011). Also, they are usually characterized by strong preferred crystallographic and morphologic orientations (e.g., Wenk et al, 2008Wenk et al, , 2010Wenk et al, , 2012. Thus, they contribute greatly to elastic anisotropy of rocks in the Earth's crust.…”

Section: Introductionmentioning

confidence: 99%

“…The shape orientations distributions (in the form of shape ODFs or SODFs) describe ellipsoidal particle shapes relative to sample coordinates. Recently, such a self-consistent method has been applied to calculate bulk elastic properties of biotite gneiss (Wenk et al, 2012) and shale (Vasin et al, 2013), based on their microstructural characteristics, including preferred orientations and grain shapes. Quite unexpectedly, it has been found that anisotropic grain shape of sheet silicates increases elastic anisotropy of rocks containing small amounts of platelet-shaped grains (gneiss with ∼20% of biotite) and reduces elastic anisotropy of rocks with large amounts of platelet-shaped grains (shale with ∼70% of sheet silicates).…”

Section: Introductionmentioning

confidence: 99%

The influence of grain shape and volume fraction of sheet silicates on elastic properties of aggregates: Biotite platelets in an isotropic matrix

et al. 2014

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Elastic anisotropy of sheet-silicate-rich rocks such as shales and slates strongly depends on the orientation distribution of platelet-shaped minerals, as well as shape and orientation of pores. Bulk elastic anisotropy of the rock results in the anisotropy with respect to the propagation of elastic waves, and consequently, the fastest P-waves can travel with velocities exceeding the slowest velocities by a factor of two or even greater. An important factor is the sheet-silicate's grain shapes. We approached a model system of biotite platelets in an isotropic matrix with different methods: A mean-field self-consistent method that considered ellipsoidal particles in an effective anisotropic matrix, and a full-field method based on fast Fourier transforms that considered the microstructure, the topology of the polycrystal, and local interactions. Both methods provided numerically very close results. Using these results, we predicted that the aggregate with more oblate grain shape (thinner platelets) was elastically more anisotropic than the material with grains of less oblate shape, but only for small volume fractions of oriented platelets. For large fractions of platelets, the opposite was true. This switchover in the elastic anisotropy depended on texture strength, platelet shape, and elastic properties of the isotropic matrix.

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“…It is clear that the difference between actual anisotropy and XYZ anisotropy (orientation of the cores for ultrasonic measurements in the sample reference system) is due to the effect of texture (e.g. Wenk et al, 2012). The selection of the averaging scheme (Voigt, Reuss, Hill, Geometric Mean) has some effect.…”

Section: (29%)mentioning

confidence: 99%

Texture and elastic anisotropy of a mylonitic anorthosite from the Morin Shear Zone (Quebec, Canada)

Barreiro

Wenk

Vogel

2015

Journal of Structural Geology

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a b s t r a c tA sample of anorthosite from the granulite facies Morin Shear Zone (Quebec, Canada) was investigated for crystal preferred orientation and elastic anisotropy. Time-of-flight neutron diffraction data obtained with the HIPPO diffractometer at LANSCE were analyzed with the Rietveld method to obtain orientation distribution functions of the principal phases (plagioclase, clinopyroxene and orthopyroxene). Texture and microstructures are compatible with the plastic deformation of the aggregate under high-T conditions. All mineral phases depict a significant preferred orientation that could be related to the general top-to-the north shearing history of the Morin Shear Zone. Texture patterns suggest that (010)[001] in plagioclase and (110)[001] in clinopyroxene are likely dominant slip systems. Using preferred orientation data P-and S-waves velocities and elastic anisotropy were calculated and compared with previous studies to explore elastic properties of rocks with different pyroxene-plagioclase mixtures. P-wave velocity, S-wave splitting and anisotropy increase with clinopyroxene content. Seismic anisotropy is linked to the texture symmetry which can lead to large deviations between actual anisotropy and that measured along Cartesian XYZ sample directions (lineation/foliation reference frame). This is significant for the prediction and interpretation of seismic data, particularly for monoclinic or triclinic texture symmetries.

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Revisiting elastic anisotropy of biotite gneiss from the Outokumpu scientific drill hole based on new texture measurements and texture-based velocity calculations

Cited by 44 publications

References 59 publications

Crystallographic preferred orientations of exhumed subduction channel rocks from the Eclogite Zone of the Tauern Window (Eastern Alps, Austria), and implications on rock elastic anisotropies at great depths

Crystallographic preferred orientations of exhumed subduction channel rocks from the Eclogite Zone of the Tauern Window (Eastern Alps, Austria), and implications on rock elastic anisotropies at great depths

The influence of grain shape and volume fraction of sheet silicates on elastic properties of aggregates: Biotite platelets in an isotropic matrix

Texture and elastic anisotropy of a mylonitic anorthosite from the Morin Shear Zone (Quebec, Canada)

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