Приразломные тектониты енисейского кряжа. статья 1: геолого-структурные, минералогические и геохронологические свидетельства полиметаморфизма

Abstract

Metapelites and metabasites subjected to intensive deformations with recrystallization of the substrate and the formation of tectonites have been studied within the Yenisei regional shear zone of the Yenisei Ridge. Overprinting of the later mineral assemblages on the early during subsequent tectonic events as a result of different geodynamic processes is clearly recorded by the geological and structural features of rheology of deforming rocks, reaction microtextures, chemical zoning in minerals, and isotop-ic dating. These indicators provide evidence for the polymetamorphic history of rocks and suggest distinct tectonic processes. Such rock behavior between superimposed metamorphic events could be generated with intense shear deformation in an inhomogeneous environment, suggesting a tectonic control over the late stage of metamorphism in the suture zones of the earth's crust and possibility for the existence of tectonic overpressure. In order for the present suggestions to be considered more reasonably, further robust geothermobarometric evidence is required in support of overpressure, including P-T estimates for intensely deformed tectonites compared to the background values of the earlier metamorphic events, measured from the less deformed rocks. The obtained data are the basis for the sub¬sequent reconstruction of the tectono-thermal evolution of the region and its interpretation within the framework of known tectonic models.