RARE-EARTH ELEMENTS IN THE MINERALS OF TH E GREISEN DEPOSITS - EVIDENCE OF MINERALIZATION DEPTH

The distribution of rare-earth elements in fluorite, apatite, and plag ioclase from greisen-type beryllium and fluorite deposits that were fo rmed at different depths was studied. The minerals from the deeper sea ted group of deposits (Malyshevskoe beryllium-emerald and Boevskoe ber yllium-fluorite deposits) show an excess of Eu, and the minerals from the shallower group (Uzun-Tashty magnetite-danalite-chrysoberyl-type d eposit and Solnechnoe, Sargardon, and Voznesenskoe fluorite-beryllium deposits) show a deficit;of Eu. It was also established that, irrespec tive of the mineralization depth, at the magmatic stage the total REE content, the light/heavy REE ratio, and Yb/La ratio progressively incr eased from the early to the late phases, whereas at the postmagmatic s tage these parameters decreased through the sequential stages. In usin g the above regularities of REE distribution in minerals to make genet ic inferences and exploration decisions, one should take into account the variations in REE distribution in minerals at different mineral-fo rmation stages and as a function of interaction with the wall rocks.