Sm‒Nd Age of the Kolvitsa Fe‒Ti–V Deposit, Porya Guba Clinopyroxenite–Wehrlite Complex, Kola Region

The isotopic age of rocks from the Porya Guba clinopyroxenite–wehrlite complex hosting the Kolvitsa Fe–Ti–V deposit is determined for the first time. The Sm–Nd age of the barren clinopyroxenites prevailing in the studied massif is 1858 ± 34 Ma (εNd(T) = –1.5) and is considered as the time of emplacement of the Porya Guba Complex that occurred after the peak of granulite metamorphism (1925–1915 Ma). Quenching zones found around xenoliths of granulites in clinopyroxenites indicate the emplacement of the complex into the cooled rocks of the Lapland–Kola orogen, which is consistent with the estimated time of its cooling (1880–1870 Ma, 450°, by rutile). Mineralized rocks, as inferred from active assimilation of granulite xenoliths, are formed at a late stage of development of the complex: the age of mineralized pyroxenites enriched in platinum and palladium (0.8 g/t) is 1832 ± 35 Ma (εNd(T) = –2.0), while the age of titanomagnetite ores is 1823 ± 19 Ma (εNd(T) = –2.5). Thus, the obtained isotopic data indicate that the emplacement of small ultramafic intrusions developed in the Kandalaksha–Kolvitsa granulites (Kolvitsa Melange) took place during the cooling stage of the Lapland–Kola orogen.