RAPAKIVI OF THE BERDYAUSH MASSIF, SOUTHERN URALS - PETROLOGY AND REE DISTRIBUTION

The intrusive complex of the Berdyaush rapakivi massif consists of a c omagmatic rock series ranging from syenodiorite and quartz syenite to granite. The numerical model proposed for the magmatic differentiation of this series is the first to take into account the REE distribution in the rocks and minerals. It is demonstrated that the REE distributi on correlates with the silicity and alkali-calc ratios of the rocks an d is compatible with the theoretical model for fractional crystallizat ion. Based on this reasoning, it is concluded that the rapakivi series comprises genetically related rocks, which are the differentiates of a common parental magma. The major-element characteristics and chondri te-normalized REE patterns standard types of the Berdyaush rapakivi gr anites are analogous to those of reference Proterozoic rapakivi series .