METAMICT STATE OF ZIRCON FROM YASTRUBETSKYI ORE OCCURRENCE AND AZOVSKE Zr-REE DEPOSIT (UKRAINIAN SHIELD) BY X-RAY ANALYSIS DATA
Keywords:
zircon, metamict state, X-ray diffractometry, electron-probe microanalysis, admixture elements, syenites, Yastrubetskyi ore occurrence of zircon, Azovske Zr-REE deposit, Ukrainian Shield.Abstract
We performed complex research of metamict state and isomorphic admixture elements of zircon from biotite, hastingsite-ferroedenite-biotite and biotite-hastingsite syenites of Yastrubets-kyi ore occurrence main layered series by means of X-ray diffractometry and electron-probe microanalysis. By the degree of crystalline fc and conditions of formation investigated grains of zircon can be divided into two groups. The first one is represented by partially metamict, heterogeneous grains with fc = 30–50 %, which contain the altered sites and, presumably, have been formed at the final stage of ore occurrence formation. The second group is represented by weakly metamict homogeneous grains of magmatic zircon with fc = 42–60 % and Th/U-ratio 0.74–1.17. Investigation of zircon from the Azovske Zr-REE deposit showed that only a small amount of grains is in the semi-metamict state, the value of fc is very low – up to 22–33 %. The pecu-liarity of the grains is their microheterogeneity, which is due to the presence of quartz micro-inclusions in them. Most likely, quartz is contained in microcracks or nanopores and has a secondary origin.
References
Азовское редкоземельное месторождение Приазовского мегаблока Украинского щита (геология, минералогия, геохимия, генезис, руды, комплексные критерии поисков, проблемы эксплуатации) / под ред. А. Н. Пономаренко, А. В. Анциферова. – Донецк : Ноулидж, 2012. – 374 c.
Дипірамідальні макрокристали циркону із лужних порід Приазов’я / В. М. Квасниця, О. А. Вишневський, І. В. Квасниця, І. В. Гурненко // Мінерал. журн. – 2016. – Т. 38, № 3. – С. 9–23.
Кривдик С. Г. Петрология щелочных пород Украинского щита / С. Г. Кривдик, В. И. Ткачук. – Киев : Наук. думка, 1990. – 408 с.
Новые данные о геохимии циркона и возрасте (U-Pb, SHRIMP II) Ястребецкого Zr-REE-Y месторождения (Украинский щит) / Е. В. Левашова, С. Г. Скублов, Ю. Б. Марин и др. // Геохимия. – 2015. – № 6. – С. 568–576.
Ewing R. C. Radiation effects in zircon / R. C. Ewing, W. J. Weber, L. R. Corrales // Zircon. Reviews in Mineralogy and Geochemistry : eds. J. M. Hanchar, P. W. O. Hos-kin. – Washington : The Mineralogical Society of America, 2003. – Vol. 53. – P. 387–425.
Geisler T. Reequilibration of zircon in aqueous fluids and melts / T. Geisler, U. Schaltegger, F. Tomaschek // Elements. – 2007. – Vol. 3, N 1. – P. 43–50.
Kinetics of thermal recovery and recrystallization of partially metamict zircon: a Raman spectroscopic study / T. Geisler, R. T. Pidgeon, W. Van Bronswijk, R. Pleysier // European Journal of Mineralogy. – 2001. – Vol. 13. – P. 1163–1176.
Metamictisation of natural zircon: accumulation versus thermal annealing of radioactivity-induced damage / L. Nasdala, M. Wenzel, G. Vavra et al. // Contrib. Mineral. Petrol. – 2001. – Vol. 141. – P. 25–144.
Wojdyr M. Fityk: a general-purpose peak fitting program / M. Wojdyr // J. Appl. Cryst. – 2010. – Vol. 43. – P. 1126–1128.
