The occurrences of high-pressure tectonites localized in the tectonic suture zone of the Cis-Yenisei regional shear zone (CYRSZ) separated the cratonic and oceanic island-arc terranes were distinguished for the first time at the western margin of the Siberian Craton. Tectonites are characterized by high pressures (up to 15 kbar), which exceed significantly the background P–T parameters of regional metamorphism. The generation of tectonic overpressure is induced by rapid deformations along ductile shear zones, which is consistent with the numerical simulation results and thermodynamic calculations. These data confirm the important role of tectonic stress as an effective thermodynamic factor of metamorphic transformations in suture zones of the lithospheric crust.