On the relationships between the Al2SiO5 polymorphs during formation of blastomylonites (North Yenisei Ridge)

Relevance. When mapping the vast areas of Precambrian polymetamorphic complexes in North Yenisei Ridge, there is a problem metamorphism interpretation and phasing geological development particular area along with thrust tectonics. The solution these issues also great importance for purposes delineation metamorphic rocks that are favorable detection high-alumina (andalusite, kyanite, sillimanite) schists. Purpose work: to substantiate itemize some prospecting, mineralogical petrological indicator criteria garnet-kyanite-staurolite blastomylonites dislocation formed by andalusite-bearing regional metamorphism. Research methodology: detailed structural-metamorphic zoning (collisional) Mayakon key sampling petrographic studies mineral parageneses. Investigation polished thin sections microprobe analysis elucidation minerals zoning, their chemical composition, calculation Р–Т paths determination absolute age blastomylonite formation based on 40Ar/39Ar dating biotite. Analysis generalization results obtained comparison other Ridge. Results. At potential area, progressive kyanite-bearing has been identified, transitional I, outer II, middle III, inner zones determined as intensifies towards Panimba fault. Based compositions garnets, biotite, plagioclase, P–T early andalusite-sillimanite type late local kyanitesillimanite were calculated. A list isotope-geochronological recognizing among substantiated itemized. Conclusions. Method polymetamorphism reconstruction Ridge shows tectonic inversion conditions took place Neoproterozoic, Tonian era (~850 Ma ago In terms occurrences, they related final stage Grenville orogeny (1.1–0.85 Ga). metapelites accompanied an increase number phases leads reduction usable space andalusite