RARE-EARTH ELEMENT DISTRIBUTION IN APATITES FROM IGNEOUS ROCKS AND RELATED POSTMAGMATIC PRODUCTS IN ORE DISTRICTS OF THE SOVIET FAR EAST

Abstract

Apatite is one of the most widespread accumulator minerals of rare-earth elements (REE) in igneous rocks. We have obtained the first data on the REE concentration and distribution in accessory apatites of igneous rocks and related postmagmatic products in some Soviet Far Eastern ore districts. REE were determined by neutron-activation method. The data indicate that accessory apatites related to mantle magmas differ from those of sialic crustal granitoids in their higher total content of REE and in the marked dominance of light REE over heavy. Large variations in the REE content of apatites from the same rock types in different ore districts probably reflect the inhomogeneous composition of the mantle or substrate from which the palingenetic granite magma was formed. For the ore districts studied, our work has revealed the identical shape of REE-distribution curves for accessory apatites of igneous rocks and related postmagmatic products, which together with other facts, therefore, indicates the paragenetic relationship of these rocks.