Slate – A new record for crystal preferred orientation

ABSTRACTWe have mapped the full crystallographic orientation of sea ice using electron backscatter diffraction (EBSD). This is the first time EBSD has been used to study sea ice. Platelet ice is a feature of sea ice near ice shelves. Ice crystals accumulate as an unconsolidated sub-ice platelet layer beneath the columnar ice (CI), where they are subsumed by the advancing sea–ice interface to form incorporated platelet ice (PI). As is well known, in CI the crystal preferred orientation comprises dominantly horizontal c-axes, while PI has c-axes varying between horizontal and vertical. For the first time, this study shows the a-axes of CI and PI are not random. Misorientation analysis has been used to illuminate the possible drivers of these alignments. In CI the misorientation angle distribution from random pairs and neighbour pairs of grains are indistinguishable, indicating the distributions are a consequence of crystal preferred orientation. Geometric selection during growth will develop the a-axis alignment in CI if ice growth in water is fastest parallel to the a-axis, as has previously been hypothesised. In contrast, in PI random-pair and neighbour-pair misorientation distributions are significantly different, suggesting mechanical rotation of crystals at grain boundaries as the most likely explanation.

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Deformation patterns in a high-viscosity lava flow inferred from the crystal preferred orientation and imbrication structures: an example from Salina (Aeolian Islands, southern Tyrrhenian Sea, Italy)

Bulletin of Volcanology ◽

10.1007/s004450050112 ◽

1996 ◽

Vol 57 (7) ◽

pp. 555-562

Author(s):

Guido Ventura ◽

Rosanna De Rosa ◽

Elena Colletta ◽

Roberto Mazzuoli

Keyword(s):

Lava Flow ◽

High Viscosity ◽

Preferred Orientation ◽

Tyrrhenian Sea ◽

Aeolian Islands ◽

Crystal Preferred Orientation ◽

Southern Tyrrhenian Sea ◽

Deformation Patterns

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Quantitative texture analysis by neutron diffraction in deformed crystalline aggregates: Contín Shear Zone, Morais Complex, N Portugal.

10.5194/egusphere-egu2020-6714 ◽

2020 ◽

Author(s):

Manuela Durán Oreja ◽

Jeremie Malecki ◽

Juan Gómez Barreiro

Keyword(s):

Neutron Diffraction ◽

Shear Zone ◽

Seismic Anisotropy ◽

Preferred Orientation ◽

Distribution Functions ◽

P Wave ◽

Orientation Data ◽

Crystal Preferred Orientation ◽

Two Samples

<p>Two samples of mylonitic-ultramylonitic ortogneisses collected along the Cont&#237;n shear zone were investigated for crystal preferred orientation and seismic anisotropy. Neutron diffraction data obtained at the D1B beamline at ILL (Institute Laue-Langevin, Grenoble) were analyzed with the Rietveld method as implemented in the code MAUD, to obtain the orientation distribution functions (ODF) of the principal phases (quartz, K-feldspar, plagioclase, phlogopite, muscovite and riebeckite). Texture and microstructure are compatible with the plastic deformation of the aggregates under medium to low-temperature conditions. Kinematic analysis supports a top-to-the SE sense of shear, suggesting a thrust character. Using preferred orientation data and single crystal elastic tensors, P and S-waves velocities and elastic anisotropy have been calculated. We have explored the role of several factors controlling the elastic properties of rocks, particularly the role of strain state and mineral changes in a shear zone. Those factors have a direct impact on the medium impedance and consequently on the interphase reflectivity. P-wave velocities, S-wave splitting and anisotropy increase with muscovite content. Seismic anisotropy is linked with the texture symmetry, which can result in 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. (Research support CGL2016-78560-P)</p>

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Seismic signatures of a hydrated mantle wedge from antigorite crystal-preferred orientation (CPO)

Earth and Planetary Science Letters ◽

10.1016/j.epsl.2013.06.003 ◽

2013 ◽

Vol 375 ◽

pp. 395-407 ◽

Cited By ~ 25

Author(s):

Sarah J. Brownlee ◽

Bradley R. Hacker ◽

George E. Harlow ◽

Gareth Seward

Keyword(s):

Mantle Wedge ◽

Preferred Orientation ◽

Crystal Preferred Orientation

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Plastic deformation and development of antigorite crystal preferred orientation in high-pressure serpentinites

Earth and Planetary Science Letters ◽

10.1016/j.epsl.2012.06.049 ◽

2012 ◽

Vol 349-350 ◽

pp. 75-86 ◽

Cited By ~ 39

Author(s):

José Alberto Padrón-Navarta ◽

Andréa Tommasi ◽

Carlos J. Garrido ◽

Vicente López Sánchez-Vizcaíno

Keyword(s):

Plastic Deformation ◽

High Pressure ◽

Preferred Orientation ◽

Crystal Preferred Orientation

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Crystal preferred orientation in peridotite ultramylonites deformed by grain size sensitive creep, Étang de Lers, Pyrenees, France

Journal of Structural Geology ◽

10.1016/j.jsg.2011.10.002 ◽

2011 ◽

Vol 33 (12) ◽

pp. 1776-1789 ◽

Cited By ~ 23

Author(s):

M.R. Drury ◽

H.G. Avé Lallemant ◽

G.M. Pennock ◽

L.N. Palasse

Keyword(s):

Grain Size ◽

Preferred Orientation ◽

Crystal Preferred Orientation

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Crystal preferred orientation of olivine in mantle xenoliths from Catalonia (NE Spain) Orientación cristalina preferente del olivino en xenolitos mantélicos de Cataluña (NE de España)

Trabajos de Geología ◽

10.17811/tdg.36.2016.119-138 ◽

2018 ◽

Vol 36 (36) ◽

pp. 119

Author(s):

M. Fernández-Roig ◽

G. Galán ◽

E. Mariani

Keyword(s):

Lithospheric Mantle ◽

Fiber Type ◽

Volcanic Rocks ◽

Preferred Orientation ◽

Mantle Xenoliths ◽

Fiber Types ◽

Electron Backscattered Diffraction ◽

Crystal Preferred Orientation ◽

Diffraction Patterns ◽

Península Ibérica

Abstract: Mantle xenoliths in Neogene-Quaternary alkaline volcanic rocks from the Catalan Volcanic Zone indicate that ≪anhydrous≫ spinel lherzolites, harzburgites and much subordinate olivine websterites form the lithospheric mantle of NE Iberian Peninsula. Olivine crystal preferred orientation, determined by indexation of electron-backscattered diffraction patterns, provides three types of deformation fabric: a dominant [010]-fiber type in peridotites and websterites equilibrated at high temperature, and subordinate orthorhombic and [100]-fiber types, which appear mostly in porphyroclas tic and equigranular lherzolites equilibrated at lower temperature.Keywords: Lithospheric mantle, lherzolites, harzburgites, websterites, olivine, deformation fabric.Resumen: Los xenolitos mantelitos en lavas alcalinas neógeno-cuaternarias de la Zona Volcánica de Cataluña indican que lherzolitas y harzburgitas ≪ anhidras≫ y con espinela son las rocas predominantes en el manto litosférico del NE de la Península Ibérica, con presencia también subordinada de websteritas olivínicas. Las orientaciones cristalográficas preferentes del olivino, determinadas por indexación de los espectros de difracción de electrones retrodispersados, muestran tres tipos de fábrica de deformación: una dominante, tipo axial [010], en peridotitas y websteritas equilibradas a alta temperatura, y otras subordinadas, de tipo ortorrómbico y axial [100], que aparecen en lherzolitas porfidoclásticas y equigranulares equilibradas a menor temperatura.Palabras clave: Manto litosférico, lherzolitas, harzburgitas, websterita, olivino, fábricas de deformación

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