UDC 553.411.071(477)
Bondarenko Sergei M., Karly Zakhar V., Stepanyuk Leonid M., Syomka Vodymyr O., Donskoy Nikolai A., Syomka Liudmyla V.
Language: Ukrainian
Geochemistry and ore formation 2014, 34: 3-17
https://doi.org/10.15407/gof.2014.34.003
The studied 207Pb/206Pb age of monazite in aplite-pegmatoid granites of Zavallia ore occurrence is 1981,2 ± 8,4 Ma. It is determined that uranium-bearing garnet-biotite-sillimanite metasomatites are not gneisses but formed as a result of magnesianferruginous-aluminium metasomatism in cataclastic and fractured zones of aplite-pegmatoid granites and pegmatites. The metasomatites are characterized with the high values of ThO2 (16,85 %), UO2 (4,23 %), the low ones of Ce2O3 (18,83 %) and an absence of lead in monazite, presence of uraninite II with low ThO2 (1,15–1,83 %), as well as uranatennite and noncrystalline uranatennite of “young” age. An absence of radiogenic lead trace in noncrystalline uranatennite, its low grade recrystallization and presence of caolinite indicate “young” age of noncrystalline uranatennite mineralization. All these facts prove multistage and regenerative nature of TR-U-Th mineralization in granitoids of Zavallia ore occurrence.
Key words: mineralogy, geochemistry, age of formation.
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