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

https://doi.org/10.30695/zrmo/2019.1482.00

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Language: Russian 

Abstract

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 I_Sr = 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