Character of Zircon Distribution on Amphibole Miaskite of the Ilmenogorsk Massif (Southern Urals)

摘要

Mineralogical, geochemical, and age peculiarities of zircons from gneissose leucocratic miaskites of the central part of the Ilmenogorsk massif have been studied [1,2]. The ages of miaskite crystallization (434+15/-10 Ma) and metamorphism (239+40/-45 Ma) were established by the classic U-Pb method for four morphologically different crystal types (prismatic with different elongation, pseudo-octahedral, and anhedral, variable by structure, color, and transparency). Evidence of zircon recrystallization and "refinement" was registered; also pneumatolytic-hydrothermal formation of pseudo-octahedral crystals at the expense of late-mag-matic crystals was established.