in order to investigate deformation history preserved in the calcite twins in the hinterland of zagros, several samples have been collected from calcschists of the paleozoic sargaz complex in the faryab area, se iran. these samples are related to f1-recumbent folding and thrust shear zones. the twin width is about 1 and 3.8 µm (thin-twin regime); the twin strain amounts 5 and 10%; twin intensit...

in order to investigate deformation history preserved in the calcite twins in the hinterland of zagros, several samples have been collected from calcschists of the paleozoic sargaz complex in the faryab area, se iran. these samples are related to f1-recumbent folding and thrust shear zones. the twin width is about 1 and 3.8 µm (thin-twin regime); the twin strain amounts 5 and 10%; twin intensit...

In order to investigate deformation history preserved in the calcite twins in the hinterland of Zagros, several samples have been collected from calcschists of the Paleozoic Sargaz complex in the Faryab area, SE Iran. These samples are related to F1-recumbent folding and thrust shear zones. The twin width is about 1 and 3.8 µm (thin-twin regime); the twin strain amounts 5 and 10%; twin intensit...

A theoretical model for the plastic deformation of calcite, based on symmetry arguments and dislocation theory, is presented. Flow mechanisms suggested by the model conflict with those previously determined by Turner. Predictions from the model include translation gliding on e., ri, f and mI parallel to <110 ( i = 1,2,3; j = 1,2,3,4 ), and twin gliding on r (+) and (-) senses; s = 2.065, 0.630 ...

We employ classical molecular dynamics to calculate elastic properties and to model the nucleation and propagation of deformation twins in calcite, both as a pure crystal and with magnesium and aspartate inclusions. The twinning is induced by applying uniaxial strain to the crystal and relaxing all stress components except the uniaxial component. A detailed analysis of the atomistic processes r...

Continuum phase field theory is applied to study elastic twinning in calcite and sapphire single crystals subjected to indentation loading by wedge-shaped indenters. An order parameter is associated with the magnitude of stress-free twinning shear. Geometrically linear and nonlinear theories are implemented and compared, the latter incorporating neo-Hookean elasticity. Equilibrium configuration...

Deformation twinning at the tip of a straight crack or notch is analyzed using a phase-field method that seeks equilibrium twin morphologies via direct minimization of a free energy functional. For isotropic solids, the tendency to twin under mode I or mode II loading is found to depend weakly on Poisson’s ratio and elastic nonlinearity and strongly on surface energy and twinning shear (i.e. ei...