ACCESSORY RARE EARTHS-BEARING MINERALS IN PALAEOPROTEROZOIC SCHISTS OF VORONEZH CRYSTALLINE MASSIF
The paper is focused upon the accessory rare earth elements (REE) mineralization in Paleoproterozoic schists of Voronezh Crystalline Massif (VCM). REE mineralization of two Paleoproterozoic structures (Vorontsovskaya and Tim-Yastrebovskaya) is described in details. Studied rocks contain various accessory REE-minerals: phosphates (monazite-Ce, xenotime-Y, REE-apatite), fluor-carbonates (bastnasite-Ce, synchisite-Ce), silicates (allanite-Ce, britholite, huttonite, thorite, REE-bearing thorite-zircon solid solutions, REE-chlorite) and oxide (niobium-aeshenite-Y). Thus, accessory REE minerals are common in metamorphic schists even with moderate content of REE - about 150-200 g/t. These minerals are not inert during metamorphism, and take active part in progressive metamorphic reactions. REE-minerals in Paleoproterozoic schists of VCM are in reaction interrelations with each other and with rock-forming minerals.