Мінеральні ресурси України (Dec 2019)
Distribution of rare earth elements in Ruska Poliana granites and accessory fluorites
Abstract
Fluorite is one of the main concentrators of rare earth elements (REE) in the granites of the Ruska Polіana massif of the Korsun-Novomyrhorod pluton of the Ukrainian Shield. Despite its distribution in the granites of the massif, the geochemical features of the fluorites have not yet been investigated. The aim of this work was to determine the content of REE in the fluorites, the granites and to study the distribution of REE in the fluorites and granites containing this mineral. The content of REE in 4 samples of the granites and 4 monofraction the fluorites from these granites (well № 8568) was determined by the ICP MS method on the Element-2 device at M. P. Semenenko Institute of Geochemistry, Mineralogy and Ore Formation of the NAS of Ukraine (Kyiv). The well № 8568 was drilled in the southeastern part of the Ruska Polіana granite massif of the Korsun-Novomyrhorod pluton of the Ukrainian Shield (Ruska Polіana Village). In this part, the researchers revealed granites with rare metal mineralization. The investigated granites of well are represented by 3 types: the gray-pink fine-medium-grained granites (type I) (156,1–158,0 m), the gray-pink porphyriform granites (type II) (174,6–176,5 m), the gray medium-coarse-grained granites (type III) (225,0–227,0 m) and the pink-gray medium- coarse granites (type III) (239,6–242,0 m). According to the results of the ICP MS analysis, the highest content of lanthanides (26933 ppm) and yttrium (11 705 ppm) was observed in fluorites from the gray-pink fine-medium granites of the upper part of the well. But the gray-pink fine-medium granites have the lowest total lanthanide content (218 ppm). The lowest levels of lanthanides (692 ppm) and yttrium (831 ppm) were determined in the fluorites of the pink-gray medium-coarse grained granites of the deepest part of the well. The pink-gray medium-coarse granites are characterized by high lanthanide content (797 ppm). The fluorites from Ruska Poliana of the gray-pink fine-medium grained granites can be compared with the fluorite from Perga granite by the total content of lanthanides. Among the rock-bearing minerals in biotites from the Ruska Poliana granites of different depths of the well, there is a high content of REE, almost at the level of the granites themselves. Such a high level indicates the presence of inclusions of accessory minerals enriched with REE in the biotites, especially fluorites.
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