A plane kinematic model of progressive deformation in a polycrystalline aggregate

Etchecopar, A.

doi:10.1016/0040-1951(77)90092-0

Cited by 279 publications

(65 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This is not a necessary result; in some materials at some temperatures, the strain in individual grains may be nearly independent of orientation, or the strain may be such as to minimize differences in deformation between adjacent grains, or some intermediate behavior (e.g. Etchecopar, 1977;Lister and others, 1978). Strain proportional to resolved shear stress would be most likely at relatively high temperatures and low stresses, as in ice.…”

Section: Results -Fabric Formationmentioning

confidence: 99%

Flow-law hypotheses for ice-sheet modeling

1992

View full text Add to dashboard Cite

ABSTRACT. Ice-flow modeling requires a flow law relating strain rates to stresses in situ, but a flow law cannot be measured directly in ice sheets. Microscopic processes such as dislocation glide and boundary diffusion control both the flow law for ice and the development of physical properties such as grain-size and c-axis fabric. These microscopic processes can be inferred from observations of the physical properties, and the flow law can then be estimated from the microscopic processes.A review of available literature shows that this approach can be imperfectly successful. Interior regions of large ice sheets probably have depth-varying flow-law "constants", with the stress exponent, n, for power-law creep less than 3 in upper regions and equal to 3 only in deep ice; n probably equals 3 through most of the thickness of ice shelves and ice streams.

show abstract

Section: Results -Fabric Formationmentioning

confidence: 99%

Flow-law hypotheses for ice-sheet modeling

1992

View full text Add to dashboard Cite

show abstract

“…In the last two decades, LPO evolution in deforming olivine polycrystals has been simulated using purely kinematic [Etchecopar, 1977;Etchecopar and Vasseur, 1987;Ribe, 1989 [Zhang et al, 1994]. All these polycrystal plasticity models are based on the assumption that crystal reorientation and LPO development are controlled by intracrystalline slip on a few crystallographic planes.…”

Section: Modeling Lpo Development In Polycrystalsmentioning

confidence: 99%

“…Dynamic recrystallization has been taken into account in a few models [Etchecopar, 1977;Etchecopar and Vasseur, 1987; Jessel, 1988; Wenk et al, 1997]. All these models predict a similar LPO for simple shear deformation: a single maxima pattern in which the main slip system parallels the macroscopic shear.…”

Section: Modeling Lpo Development In Polycrystalsmentioning

confidence: 99%

Viscoplastic self‐consistent and equilibrium‐based modeling of olivine lattice preferred orientations: Implications for the upper mantle seismic anisotropy

Tommasi¹,

Mainprice²,

Canova³

et al. 2000

J. Geophys. Res.

333

323

View full text Add to dashboard Cite

Abstract. Anisotropy of upper mantle physical properties results from lattice preferred orientation (LPO) of upper mantle minerals, in particular olivine. We use an anisotropic viscoplastic selfconsistent (VPSC) and an equilibrium-based model to simulate the development of olivine LPO and, hence, of seismic anisotropy during deformation. Comparison of model predictions with olivine LPO of naturally and experimentally deformed peridotites shows that the best fit is obtained for VPSC models with relaxed strain compatibility. Slight differences between modeled and measured LPO may be ascribed to activation of dynamic recrystallization during experimental and natural deformation. In simple shear, for instance, experimental results suggest that dynamic recrystallization results in further reorientation of the LPO leading to parallelism between the main (010)[ 100] slip system and the macroscopic shear. Thus modeled simple shear LPOs are slightly misoriented relative to LPOs measured in natural and experimentally sheared peridotires. This misorientation is higher for equilibrium-based models. Yet seismic properties calculated using LPO simulated using either anisotropic VPSC or equilibrium-based models are similar to those of naturally deformed peridotRes; errors in the prediction of the polarization direction of the fast S wave and of the fast propagation direction for P waves are usually < 15 ø. Moreover, overestimation of LPO intensities in equilibrium-based and VPSC simulations at high strains does not affect seismic anisotropy estimates, because these latter are weakly dependent on the LPO intensity once a distinct LPO pattern has been developed. Thus both methods yield good predictions of development of upper mantle seismic anisotropy in response to plastic flow. Two notes of caution have nevertheless to be observed in using these results: (1) the dilution effect of other upper mantle mineral phases, in particular enstatite, has to be taken into account in quantitative predictions of upper mantle seismic anisotropy, and (2) LPO patterns from a few naturally deformed peridotRes cannot be reproduced in simulations. These abnormal LPOs represent a small percent of the measured natural LPOs, but the present sampling may not be representative of their abundance in the Earth's upper mantle.

show abstract

“…The grid points are organized into rigid triangular elements, the size of these rigid elements being as small as possible to best fit the fold geometry. These triangular elements are successively laid flat column by column and best fitted by a least squares method [Etchecopar, 1977]. Each triangular element is fitted into the triangular hole defined by its neighbors.…”

Section: Methodsmentioning

confidence: 99%

Recent crustal deformation in southern California deduced from the restoration of folded and faulted strata

Gratier¹,

Hopps²,

Sorlien³

et al. 1999

J. Geophys. Res.

View full text Add to dashboard Cite

and displacement field within a deformed area. When, as is the case in southern California, sediment deposits occur in a tectonically active region, the deformed strata can be used as strain gauges of the progressive deformation. If the present geometry of a reference deformed layer is well known and if this layer may be restored to its initial state (assumed to be horizontal), comparison between present (deformed) state and restored (undeformed) state allows one to estimate the finite deformation (e.g., horizontal shortening of folded and faulted blocks) and the associated total finite horizontal displacement (e.g., displacement of points with respect to a reference line). Uncertainty may appear if the sedimentary deposits are not perfectly horizontal before the deformation; however, because of the large values of the deformation in the Transverse Ranges, this uncertainty is very low. As with geodetic data, the displacement field is estimated by reference to an arbitrary fixed line. MethodTwo types of method may be used to estimate heterogeneous deformation. The first one is to partition the whole deformed area into homogeneous domains, then to restore and best fit all these domains in order to reconstitute the initial 4887

show abstract

A plane kinematic model of progressive deformation in a polycrystalline aggregate

Cited by 279 publications

References 2 publications

Flow-law hypotheses for ice-sheet modeling

Flow-law hypotheses for ice-sheet modeling

Viscoplastic self‐consistent and equilibrium‐based modeling of olivine lattice preferred orientations: Implications for the upper mantle seismic anisotropy

Recent crustal deformation in southern California deduced from the restoration of folded and faulted strata

Contact Info

Product

Resources

About