The middle part of the Talassian Alatau ridge is composed of Upper Precambrian-Lower Paleozoic greenschists (the Usunakhmatian sheet), which were overthrust on unmetamorphosed rocks of nearly the same age (the Talassian and Kumishtagian sheets). Three phases of deformation can be recognized in the Usunakhmatian sheet, the most intensive of which was the Late Silurian-Early Devonian D₂ deformation. In the Usunakhmatian sheet, the axis of maximum extension is subhorizontal and parallel to F₂ fold axes. R_xz varies from 2.4 to 7.5 and k from 0.03 to 1.75. Flattening is widespread, but the strain of many samples is nearly plane strain. In the Talassian sheet, R_xz varies from less than 1.8. to 4.4 and k from 0 to 0.35. R_xz and k values increase near large faults. R_xz values determined by quartz and chert grains were found to be linearly related. A three-stage strain history is related to D₂ deformation. The earliest was simple shear parallel to the axial surfaces of folds. Following this, the fold and thrust system was transformed by pure shear with an orogen-parallel axis of extension. Some minor increments of strain are locally represented by pressure shadows around pyrite crystals.