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

ISSN 2307-2091 (Print) 

ISSN 2500-2414 (Online)


P. S. Kozlov / News of the Ural State Mining University. 2021. Issue 1(61), pp. 25-32


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

: polymetamorphic complexes, Al2SiO5 polymorphs, blastomylonites, dislocation metamorphism, Mayakon,
North Yenisei Ridge.



1. Kozlov P. S., Lepezin G. G. 1995, Petrology, petrochemistry and metamorphism of the Transangarian rocks of the Yenisei Ridge. Geologiya i
geofizika [Geology and Geophysics], vol. 36, no. 5, pp. 3–22. (In Russ.)
2. Likhanov I. I., Polyansky O. P., Kozlov P. S., Reverdatto V. V., Vershinin A. E., Krebs M., Memmi I. 2000, Replacement of andalusite by kyanite
with increasing pressure and low geothermal gradient in metapelites of the Yenisei Ridge. Doklady AN [Doklady Earth Sciences], vol. 375, no. 4,
pp. 509–513. (In Russ.)
3. Kerrick D. M. 1990, The Al2SiO5 polymorphs. Mineralogical Society of America. Reviews in Mineralogy, vol. 22, 406 p.
4. Likhanov I. I., Reverdatto V. V., 2014, Р–Т–t evolution of metamorphism in the Transangarian Yenisei ridge: petrological and geodynamic
consequences moderate pressures. Geologiya i geofizika [Geology and Geophysics], vol. 55, no. 3, pp. 85–16. (In Russ.)
5. Likhanov I. I., Polyansky O. P., Reverdatto V. V., Kozlov P. S., Vershinin A. E., Krebs M., Memmi I. 2001, Metamorphic evolution of high-alumina
metapelites near the Panimba overthrust (Yenisei ridge): mineral associations, РТ-conditions and tectonic model. Geologiya i geofizika [Geology
and Geophysics], vol. 42, no. 8, pp. 1205–1220. (In Russ.)
6. Whitney D. L., Evans B. W. 2010, Abbreviations for names of rocks-forming minerals. American Mineralogist, vol. 95, no. 1, pp. 185–187.
7. Bel’kov I. V. 1963, Kianitovyye slantsy svity Keyv (geologicheskoye stroyeniye, kristallicheskiye slantsy i kianitovyye rudy) [Kyanite shales of
the Keiv Formation (geological structure, crystalline shales and kyanite ores)]. Moscow, 136 p.
8. Likhanov I. I., Kozlov P. S., Polyansky O. P., Popov N. V., Reverdatto V. V., Travin A. V., Vershinin A. E. 2007, Neoproterozoic age of collisional
metamorphism in the Transangara region of the Yenisei Ridge (based on 40Ar/39Ar data). Doklady AN [Doklady Earth Sciences], vol. 413, no. 6,
pp. 234–237. (In Russ.) https://doi.org/10.1134/S1028334X07020225
9. Likhanov I. I., 2020, Metamorphic indicators of geodynamic settings of collision, extension and shear zones of the Earth’s crust. Petrologiya
[Petrology], vol. 28, no. 1, pp. 4–22. (In Russ.) https://doi.org/10.31857/S0869590320010045
10. Nozhkin A. D., Turkina O. M., Bobrov V. A. 2003, Radioactive and rare earth elements in metapelites as indicators of the composition and
evolution of the Precambrian-continental crust of the Southwestern margin of the Siberian Craton. Doklady AN [Doklady Earth Sciences], vol. 390,
no. 6, pp. 813–817. (In Russ.)
11. Reverdatto V. V., Likhanov I. I., Polyanskiy O. P. 2017, Priroda i modeli metamorfizma [Nature and models of metamorphism], 331 p.
12. Likhanov I. I., Reverdatto V. V., Kozlov P. S., Popov N. V. 2006, Collisional metamorphism of Precambrian complexes in the Transangara
Yenisei Ridge. Petrologiya [Petrology], vol. 16, no. 2, pp. 148–173. (In Russ.)
13. Likhanov I. I., Reverdatto V. V., Kozlov P. S., Vershinin A. E. 2011, The Teysky polymetamorphic complex in the Transangarian Yenisei Ridge
is an example of combined zoning of facies series of low and moderate pressures. Doklady AN [Doklady Earth Sciences], vol. 436, no. 4, pp.
509–514. (In Russ.)
14. Likhanov I. I., Reverdatto V. V., Kozlov P. S., 2011, Collisional metamorphic complexes of the Yenisei Ridge: evolutionary features, age Ridges,
and exhumation rate. Geologiya i geofizika [Geology and Geophysics], vol. 52, no. 10, pp. 1593–1611. (In Russ.)
15. Likhanov I. I., Nozhkin A. D., Reverdatto V. V., Kozlov P. S., Popov N. V. 2014, Grenville-age tectonic events and evolution of the Yenisei Ridge,
western margin of the Siberian craton. Geotektonika [Geotectonics], no. 5, p. 32–53. (In Russ.)
16. Sobolev V. S. 1972, Fatsii regional’nogo metamorfizma umerennykh davleniy [Facies of regional metamorphism of moderate pressures],
Moscow, 288 p.
17. Sobolev V. S. 1974, Fatsii regional’nogo metamorfizma vysokikh davleniy [Facies of regional high-pressure metamorphism], Moscow, 328 p.

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