Modelling evolution of anisotropy in fabric and texture of polar ice

Faria, Sérgio H.; Ktitarev, Dimitri; Hutter, Kolumban

doi:10.3189/172756402781817040

Cited by 15 publications

(12 citation statements)

References 57 publications

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“…Even those very few models which account for polygonization (e.g. Montagnat and Duval, 2000; Faria and others, 2002) often do so in a somewhat artificial manner, by considering a sudden split of one grain into two. This artificial modeling of polygonization as a discontinuous process is partially justified by the usual observation of polygonization by interference analysis in thin sections.…”

Section: Bent Slip Bandsmentioning

confidence: 99%

Preferred slip-band orientations and bending observed in the Dome Concordia (East Antarctica) ice core

Faria

Kipfstuhl

2004

Ann. Glaciol.

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Fabric analysis of the upper 1300 m of the Dome C (East Antarctica) ice core reveals a slight clustering tendency of c axes towards the vertical, which gradually enhances with depth from an initially isotropic orientational distribution of c axes at the free surface. Such a strain-induced anisotropy is compatible with the expected macroscale stress state in a dome, i.e. dominated by vertical compression. Yet, when one analyzes the orientational distribution of the visible gliding layers of individual crystallites (slip bands), the evidence is quite contrasting. Direct observation of slip bands in samples from the Dome C ice core taken from different depths (204–1291 m) indicates a higher slip activity in nearly horizontal planes, in such a manner that >60% of the detected slip bands have an inclination of <30˚ with respect to the horizontal. Furthermore, the observed slip activity is not symmetric, i.e. the number of slip bands discerned at 20˚, say, is usually not comparable with the number found at 160˚. Such features are not consistent with the predicted slip activity induced by compression and/or extension. In this work, we present evidence for this unexpected orientational distribution of slip bands and discuss some of the possible causes. Natural and artificial agents are investigated, together with their respective consequences for ice-sheet modeling and ice-core processing. Additionally, we show the occurrence of bent slip bands in certain crystallites. Such a bending represents an early stage of polygonization, and highlights the strong inhomogeneity of deformation at the crystal level. Moreover, it indicates that polygonization might be mathematically interpreted as a continuous process of rotation, characterized by the divergence of c axes from a common direction.

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Section: Bent Slip Bandsmentioning

confidence: 99%

Preferred slip-band orientations and bending observed in the Dome Concordia (East Antarctica) ice core

Faria

Kipfstuhl

2004

Ann. Glaciol.

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“…Moreover, at the present stage of the research a clear theoretical understanding of the mechanisms of recrystallization processes is lacking. One needs to improve the conceptional part of the simulation model, which is the subject of our further research (a variaton of the present model is considered by Faria et al [2002]).…”

Section: Simulations Of Grip Ice Core Datamentioning

confidence: 99%

Cellular automaton model for recrystallization, fabric, and texture development in polar ice

2002

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[1] A model for simulations of the ice microstructure evolution during its deformation is presented. Several competing processes are considered which lead to the development of anisotropic crystal c axes orientation distribution. Existing theories of the plastic deformation and recrystallization dynamics are combined in a discrete algorithm based on the cellular automata approach. We simulate the evolution of the fabric and texture, that is, orientations and sizes of single crystals of polycrystalline ice which experiences uniaxial compression, the loading condition close to that at the summit of the Greenland Ice Sheet. The results of our simulations are in a good qualitative agreement with the data obtained from the Greenland Ice Core Project ice core drilled at this location.

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“…Some micro-processes, such as lattice dislocation, intra-grain sliding, and diffusion creep with respect to the temperature of ice since its formation can be used to deduce inversely the paleo-air-temperature, ice-flow control laws, c-axis fabrics, and grain sizes. For this reason, constructing the relationship between the evolution of microstructure and fabric and climate change [6][7][8][9][10][11][12][13] is meaningful work, even though it is challenging and complex. Ice microstructure challenging and complex.…”

Section: Introductionmentioning

confidence: 99%

Ice Microstructure and Fabric of Guliya Ice Cap in Tibetan Plateau, and Comparisons with Vostok3G-1, EPICA DML, and North GRIP

Kipfstuhl

Huang

2017

Crystals

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This work is the first in the general natural ice literature to compare microstructures and fabrics of continent-type mountain ice in mid-low latitudes with polar ice in order to find out how they evolved based on similar fabric patterns of their vertically girdles. Microstructures and fabrics along the Guliya ice core on the Tibetan Plateau, China, were measured at a depth interval of approximately 10 m. The grain sizes increase unevenly with depth. The fabric patterns vary from the isotropic fabric, to broad single maximum, to vertical girdle, to single-maximum, and finally to multiple-maximum fabric. The grain growth rate of the Guliya core is faster than that of the Vostok3G-1, the EPICA DML, and the North GRIP. The vertical girdle fabric of the Guliya core forms at a high temperature and low strain rate. The strong single maximum fabric of the Guliya core appears in the mid-low part of the core with vertical uniaxial compression or simple shear. The thermal kinemics caused by the temperature can play a vital role in different stress cases to cast the similar or same fabric patterns. Normal grain growth, polygonization/rotation recrystallization, and migration recrystallization play roles different importance at different depths.

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Modelling evolution of anisotropy in fabric and texture of polar ice

Cited by 15 publications

References 57 publications

Preferred slip-band orientations and bending observed in the Dome Concordia (East Antarctica) ice core

Preferred slip-band orientations and bending observed in the Dome Concordia (East Antarctica) ice core

Cellular automaton model for recrystallization, fabric, and texture development in polar ice

Ice Microstructure and Fabric of Guliya Ice Cap in Tibetan Plateau, and Comparisons with Vostok3G-1, EPICA DML, and North GRIP

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