he comprehensive geochemical and isotopic-geochronological study of Early Proterozoic volcanicrocks in structure of the Polmak–Pechenga–Imandra–Varzuga belt and dikes and sills of the Murmansk andKola–Norwegian terranes is conducted. Abundant swarms of mafic dikes (2.06–1.86 Ga) are established in thenorthwestern frame of the belt, including swarms of metadolerites (2060 ± 6 Ma), ferropicrites and gab-bronorites (1983 ± 5 Ma), and poikilophitic dolerites (1860 ± 4 Ma). The comparison of volcanic rocks of thePechenga and Imandra–Varzuga structures shows asynchronous change in volcanism style, with a significanttime lapse. The geochemical features of volcanic rocks of the Tominga Formation are typical of those of conti-nental magmatism and can hardly be correlated with those of the Pilguyarvi Formation. According to isotopic-geochronological data, depleted mantle melts in the Pechenga and Imandra–Varzuga zones intruded at 2010–1970 and 1970–1980 Ma, respectively. The analysis of the conditions of formation of volcanic series shows thatNeoarchean lithospheric mantle, which produced melts with low Zr/Nb ratios, was a source for primary meltsof the Kuetsjarvi Formation of the Pechenga structure and their homologs of the Imandra–Varzuga structure.In contrast, the volcanic rocks of the Kolasjoki Formation, which were weakly contaminated with crustal mate-rial, and the related Ilmozero Formation, as well as the metadolerite dikes of the Kirkenes region, were sourcedmostly from asthenosphere with separation of melt above the garnet stability depth. The formation of the volca-nic rocks of the Pilguyarvi Formation is related, judging from the geochemical data, to two asthenosphericsources different in depth, which produced tholeiitic and ferropicritic melts.
|Translated title of the contribution||Базитовый магматизм северо-восточной части Фенноскандии в конце палеопротерозоя 2.06 – 1.86 млрд лет: геохимия вулканитов и корреляция с дайковыми комплексами|
|Journal||Stratigraphy and Geological Correlation|
|Publication status||Published - 22 Jan 2020|
Arzamastsev, A. A., Stepanova, A. V., Samsonov, A. V., Skufin, P. K., Salnikova, E. B., Larionov, A. N., Larionova , Y. O., Egorova, S. V., & Erofeeva, K. G. (2020). Mafic magmatism of the northeastern Fennoscandia at the end of Paleoprotero-zoic 2.06 – 1.86 billion years: Geochemistry of volcanic rocks and correlation with dike complexes. Stratigraphy and Geological Correlation, 28(1), 1-34.