Apatite as an Indicator of Pge Mineralization Formation as Exemplified by Anorthosites of the Kievey Deposit, Fedorova-Pana Layered Complex, Kola Peninsula

This paper presents petrography, EDS, LA-ICP-MS, and Raman spectroscopy data characterizing mineral associations and composition of apatite group minerals from anorthosites of the Kievey deposit, North PGE Reef, Fedorova-Pana Complex, Russia. The mineralized coarse-grained anorthosite belongs to the most common rock type of the main ore body and hosts irregular interstitial sulfide dissemination of 5–7 vol. %. Apatite in the anorthosite forms a) euhedral grains included in the marginal parts of cumulus plagioclase laths, and b) xenomorphic grains associated with intercumulus minerals. The composition of apatite evolves along a narrow trend from fluorapatite to hydroxylapatite. The F content in apatite reaches 2.21 wt. %; the maximum Sr and REE concentration is 257 and 5623 ppm respectively, while the average ratio of La/YbN=11.78, Sr/Sr*=0.01, and Eu/Eu*=0.06. Compared to classic PGE reefs in layered intrusions such as Bushveld in South Africa and Stillwater in the United States, the mineralized anorthosite is distinguished by apatite with an unusual low chlorine concentration of only 0.46 wt. %. One of suggested reason of this difference is percolating nature of sulfide liquid which has not been enriched in PGE in situ.