Isotope-geochemical characteristics of zircon and their meaning for reconstruction of geological history of Early Archean granulites of the Ukrainian shield
Lobach-Zhuchenko S. В., Kaulina T. V., Lokhov K. I., Egorova Yu. S., Skublov S. G., Galankina O. L., Antonov A. V.
Zapiski RMO (Proceedings of the Russian Mineralogical Society). 2016. V. 145. N 4. P. 1-19
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Language: Russian
Abstract
This paper presents results of the complex study (morphology of grains, internal texture in cathodoluminescence and back-scattered electrons, microprobe analysis of rare and rare-earths elements, Lu-Hf data) of five differently aged groups of zircons separated from a single sample of granulite of the Bug River complex at Ukrainian Shield. Obtained data show that the most ancient zircon crystals (3.74 Ga) are xenogenic and were formed from a granitic melt; zircon of the second group (3.66 Ga) was crystallized from a basic melt contaminated with acid host rock. The third group (3.59 Ga) is represented by granulite zircon formed approximately 100 Ma later than the second one. Geochemical isotope characteristics indicate its crystallization under the influence of fluid-saturated anatectic melts. Two Paleoproterozoic zircon groups (~ 2.5 and ~ 2.1 Ga) were also formed under granulite-facies conditions; their structure and composition demonstrate a significant effect of the fluid. In general, geochemical characteristics of all zircons indicate their crystallization in the continental crust environment from sources with different participation of mantle material and oxygen fugacity.
Key words: zircon, Paleoarchean, Lu-Hf system, Bug granulite complex, Ukraine.
