Paleoproterozoic alkaline magmatism of the Murmansky Neoarchean craton, Kola Peninsula
Petrovskiy M. N., Petrovskaya L. S.
Zapiski RMO (Proceedings of the Russian Mineralogical Society). 2019. V. 148. N 2. P. 1-11
The article represents results of geological, geochronological and isotope-geochemical studies of the alkaline-ultrabasic massif located in the lower reaches of the Iokanga River in the Karelian- Kola Alkaline Province. The alkaline-ultramafic massif is composed of nepheline clinopyroxenites, nepheline gabbroids, malignites, and nepheline syenites. These rocks are of Paleoproterozoic age. The age of crystallization determined for nepheline clinopyroxenites by the 40Ar/39Ar phlogopite method is 1955 ± 10.8 Ma, and Rb-Sr isochron over the entire pool of samples of the intrusive rocks corresponds to an age of 1937 Ma, at ISr = 0.70316. According to their isotope-geochemical Sm-Nd and Rb-Sr characteristics, rocks of the alkaline-ultrabasic massif in the lower reaches of the Iokanga River have the mantle origin, and the source of their melts was apparently a mantle of the BSE type.
Key words: alkaline-ultrabasic magmatism, Paleoproterozoic, Karelian-Kola Alkaline Province, nepheline clinopyroxenites, nepheline syenites, mantle