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Vol. 29 (2026 year), No. 1, DOI: 10.21443/1560-9278-2026-29-1

Kalinin A. A., Khachatryan M. G., Savchenko Ye. E.
Rare earth elements and yttrium minerals in altered granite-porphyry and hosting high-alumina schists in the Pellapahk Cu-Mo occurrence (Kolmozero-Voronya Belt)

Rare Earth Elements (REE) and yttrium phosphates monazite-(Ce) and xenotime-(Y), fluorine carbonates synchysite-(Ce) and parisite-(Ce), silicate allanite-(Ce) have been studied in the metamorphic rocks in the area of the Pellapahk Cu-Mo porphyry occurrence in the north-western part of the Kolmozero-Voronya greenstone belt. Monazite-(Ce) and xenotime-(Y) form regular dissemination of fine grains in interstitions in rock-forming silicates and quartz in high-alumina gneisses and schists of the Porosozero series. In the altered granite-porphyry with Cu-Mo mineralization, REE minerals form zonal grains with monazite or xenotime in the core, surrounded by apatite-(F), then by fluorine carbonates synchysite-(Ce) and parisite-(Ce), and by silicates allanite-(Ce) and epidote in the outer parts. Besides, monazite-(Ce) and xenotime-(Y) have been found in inclusions in pyrite metacrystals. In the high-alumina schists, monazite and xenotime are of metamorphic genesis, they are formed due to re-distribution of REE and Y from isomorphic impurities in silicates to proper minerals. In the altered granite-porphyry, monazite and xenotime are supposed to be of magmatic genesis, but altered later during hydrothermal processes and partly or fully substituted by apatite, REE carbonates and silicates. Two schemes of heterovalent isomorphic substitutions are defined in monazites. Combination of "cheralite" and "huttonite" types of substitution (3LREE³⁺ + P ⁵⁺ ↔ Ca²⁺ + 2Th⁴⁺ + Si⁴⁺) prevails in monazites from the high-alumina schists, and "huttonite" type (REE³⁺ + P⁵⁺ ↔ Th²⁺ + Si²⁺) is more typical for monazites in altered granite-porphyry. Monazites of metamorphic genesis in high-alumina schists differ from primary magmatic in lower content of total REE and higher thorium impurity.

(in Russian, стр.13, fig. 6, tables. 3, ref 17, AdobePDF, AdobePDF 0 Kb)