An effective method for identifying tectonic-magmatic causes of metamorphism is the reconstruction and analysis of P–T–t paths, which can be used to develop a tectonic model of rock evolution with time. Diagnostic P-T-t paths characteristic of rocks formed in zones of active tectogenesis – under collision, extension and in shear zones of the earth’s crust – have been established. This report discusses some of the ambiguous interpretations of P-T-t paths in areas with simultaneous manifestation of different metamorphic processes.