One type of these regions commonly features en echelon folds.
One type of these regions commonly features en echelon folds. Theta, delta, phi and sigmaporphyroclasts, which have an eye-like or bowtie-like pattern, form in these regions, and, like S-C fabrics,mica fish, and sheath folds, can be used to identify its sense. The angle between foliation and the marginsof these regions can be plotted against the aspect ratio of the strain ellipse. A two-dimensional kinematicspectrum of these regions has four end members: compaction, dilation, simple, and pure; a mix of simpleand pure is known as subsimple. An indicator of these regions is the presence of strongly-banded rocksknown as mylonites. For 10 points, identify these tabular zones of localized high strain, of which faults arean example in the brittle regime.
One type of these regions commonly features en echelon folds.
shear zones [or thrust zones; or mylonite zones until "mylonite" is read; prompt on faults]