TY - JOUR

T1 - Mafic Magmatism of Northeastern Fennoscandia (2.06–1.86 Ga)

T2 - Geochemistry of Volcanic Rocks and Correlation with Dike Complexes

AU - Arzamastsev, A. A.

AU - Stepanova, A. V.

AU - Samsonov, A. V.

AU - Skuf’in, P. K.

AU - Salnikova, E. B.

AU - Larionov, A. N.

AU - Larionova, Yu O.

AU - Egorova, S. V.

AU - Erofeeva, K. G.

N1 - Funding Information: This work was supported by the Russian Science Foundation, project no. 16-17-10260. Publisher Copyright: © 2020, Pleiades Publishing, Ltd. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

PY - 2020/1/1

Y1 - 2020/1/1

N2 - Abstract—: The comprehensive geochemical and isotopic-geochronological study of Early Proterozoic volcanic rocks in structure of the Polmak–Pechenga–Imandra–Varzuga belt and dikes and sills of the Murmansk and Kola–Norwegian terranes is conducted. Abundant swarms of mafic dikes (2.06–1.86 Ga) are established in the northwestern frame of the belt, including swarms of metadolerites (2060 ± 6 Ma), ferropicrites and gabbronorites (1983 ± 5 Ma), and poikilophitic dolerites (1860 ± 4 Ma). The comparison of volcanic rocks of the Pechenga and Imandra–Varzuga structures shows asynchronous change in volcanism style, with a significant time lapse. The geochemical features of volcanic rocks of the Tominga Formation are typical of those of continental 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 that Neoarchean lithospheric mantle, which produced melts with low Zr/Nb ratios, was a source for primary melts of 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 material, and the related Ilmozero Formation, as well as the metadolerite dikes of the Kirkenes region, were sourced mostly from asthenosphere with separation of melt above the garnet stability depth. The formation of the volcanic rocks of the Pilguyarvi Formation is related, judging from the geochemical data, to two asthenospheric sources different in depth, which produced tholeiitic and ferropicritic melts.

AB - Abstract—: The comprehensive geochemical and isotopic-geochronological study of Early Proterozoic volcanic rocks in structure of the Polmak–Pechenga–Imandra–Varzuga belt and dikes and sills of the Murmansk and Kola–Norwegian terranes is conducted. Abundant swarms of mafic dikes (2.06–1.86 Ga) are established in the northwestern frame of the belt, including swarms of metadolerites (2060 ± 6 Ma), ferropicrites and gabbronorites (1983 ± 5 Ma), and poikilophitic dolerites (1860 ± 4 Ma). The comparison of volcanic rocks of the Pechenga and Imandra–Varzuga structures shows asynchronous change in volcanism style, with a significant time lapse. The geochemical features of volcanic rocks of the Tominga Formation are typical of those of continental 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 that Neoarchean lithospheric mantle, which produced melts with low Zr/Nb ratios, was a source for primary melts of 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 material, and the related Ilmozero Formation, as well as the metadolerite dikes of the Kirkenes region, were sourced mostly from asthenosphere with separation of melt above the garnet stability depth. The formation of the volcanic rocks of the Pilguyarvi Formation is related, judging from the geochemical data, to two asthenospheric sources different in depth, which produced tholeiitic and ferropicritic melts.

KW - dikes

KW - Imandra–Varzuga structure

KW - Kola Peninsula

KW - Pechenga structure

KW - Precambrian

KW - volcanic rocks

UR - http://www.scopus.com/inward/record.url?scp=85082629034&partnerID=8YFLogxK

U2 - 10.1134/S0869593820010025

DO - 10.1134/S0869593820010025

M3 - Article

AN - SCOPUS:85082629034

VL - 28

SP - 1

EP - 34

JO - Stratigraphy and Geological Correlation

JF - Stratigraphy and Geological Correlation

SN - 0869-5938

IS - 1

ER -