Rare metal granites and related rocks of the Ukrainian shield

ESIPCHUK. K. Ye.; SHEREMET, Ye. M. and SVESHNIKOV, K. I., 1993. Rare metal granites and related rocks of the Ukrainian shield. Bull. Geol. Soc. Finland 65, Part II, 131-141. Two rare metal leucocratic granites, Perga and Kamennaya complexes, can be distinquished on the Ukrainian shield. The Perga complex consists of mediumand coarse grained, mainly porphyric, biotite, riebeckite and aegirine granites, granite porphyries, microclinites and albitites with rare metal mineralization (genthelvite, phenacite, tantalite, cassiterite and wolframite etc.). Granites from several stocks (up to 30 km) in the northwestern part of the shield, situated along the fracture zone, restricted the large Korosten pluton of rapakivi granites to the northwest. The age of these granites (Pb-Pb and U-Pb methods on zircon and monazite) practically coincide with the age of rapakivi granites being 1750 Ma. Within the Korosten complex of rapakivi granites we consider that zinnwaldite granites, which are characterized by fluorite and topazine mineralization, represent the final phase of pluton. These granites differ from the Perga ones by their low content of rare metals. The Kamennaya Mogila complex lies in the southeastern part of the Ukrainian shield. It consists of biotite and muscovite-biotite, mediumand coarse-grained (also porphyric, and occasionally greisining) granites with rare metal mineralization (cassiterite, columbite, molybdenite, wolframite and beryl). Granites form several stocks (5-30 km) situated 10-30 km to the west-northwest of the South-Kalchik gabbro-syenite-granite pluton. Granitoids in both of these complexes have similar isotopic ages (1800 Ma). Leucocratic subalkaline granites (the Novoyanisol type) are known within the pluton itself, occupying an intermediate position between the above mentioned in terms of mineral and geochemical composition. The gabbro-syenite-granite formation of the Nearazov region has a substantial similarity to the anorthosite-rapakivi-granite formation. In this respect the relation of each of them to rare metal granites is rather remarkable. This relation is, most probably, not only spatial, but also genetic. The typical rare metal granites are situated not in the parent plutons but at some distance from them.