2011

Тезисы международной конференции

Рудный потенциал щелочного, кимберлитового

 и карбонатитового магматизма

Abstracts of International conference

Ore potential of alkaline, kimberlite

and carbonatite magmatism

Geochemistry rare-metal of the syenites of Korsun-Novomirgorod pluton

Bezsmolova N.V.^*

N.P. Semenenko Institute of Geology and Mineralogy and Ore Formation NAS of Ukraine, Kyiv, Ukraine

bezsmolovan@meta.ua

Rare-metal fayalit-hedenbergite syenites of Velika Vyskovska massif (a southern part of Korsun–Novomyrgorod pluton, Ukraine) belong to highly differentiated varieties. They are characterized by strongly enriched by iron femic minerals (fayalite, hedenbergite, hastingsite) and also by high content of such incompatible elements as Zr, TR, Y, partly Nb. These syenites are similar to the analogous rocks of South Kalchyk and Yastrubetsky massifs  with which two large rare-earth deposits of rich Zr and TR ores (Azov and Yastrubetsky) are genetically connected. By rich of ores and content of  yttrium which makes about 0,10 % they are  similar  to the Katugin deposit (the Aladan Shield). However the Azov deposit differs from Katugin in higher content of  Zr and of the rare-earths essentially in Ce-content.

Syenites of Velika Vyska massif are one of find differentites of  Korsun – Novomyrgorod pluton.  Intensive high enrichment in iron of femic minerals and as well as considerable concentration of such incompatible elements as Zr, TR, Y, Nb and low content of  Sr and Ba, indicate of residual character of melt from which these rocks have been formed. Crystallizion differentiation with intensive fiedspar fractionation (as it is characteristic for anorthosite-rapakivigranitic plutons) have resulted mineral structure and geochemical specificity of syenites. Formation process of syenites occurs at high temperatures (1200-1300 °C) and reduced conditions what is confirmed by investigation of melt inclusions in zircon. In our opinion unusual or unique features of the syenites and partially gabbroids of South Kalchyk massif are caused by abyssal conditions of their crystallization (by reduced oxygen fugacity) and by Fenner or similar to it trend of fraction ation crystallization. A proof for that is presence of fayalite, absence of primary magnetitite in rocks and also low content of hematite minal  in ilmenite.

Rare-metal fayalit-hedenbergit syenites of Velika Vyska massif prove the  idea these syenites are genetically and spatially related to anorthosite-rapakivigranitic pluton.

These syenites are perspective for discovering rare-metal deposits such as Azov and Yastrubetsky.