Lapland Granulite Belt–Neoarchean subduction zone in the North-Eastern Baltic shield

ABSTRACT

This paper represents a geological review of the Lapland Granulite Belt (LGB). Description of the general geological framework of the LGB complex is coupled with reviews of the geochronological data, metamorphism, mineral endowment and concludes with a discussion of the geotectonic models. It is shown that the belt was formed in the Neoarchean (2703 ± 9 Ma using the U-Pb method) and consists of two compositionally different units. The lower member with dominating amphibolites is interpreted as metamorphosed volcanics, while the upper member is mainly composed of metamorphosed sandstones. It is noted that the composition and structure of the LGB complex are broadly consistent with typical Phanerozoic island-arc complexes. An interpretation of the LGB complex as a Neoarchean island-arc system is proposed. It is consistent with existing geodynamic interpretations of the adjacent terrains and, in general, fits the global geodynamic model of the supracrustal Archean complexes in the Baltic Shield.

KEYWORDS:

• Baltic Shield
• Lapland granulites
• lithostratigraphy
• geochemistry
• metallogeny
• Arctic geology
• reconstruction

Acknowledgements

The research has been carried out in the framework of the State Orders Nos. 0226-2019-0052 and 0149-2019-0005. The authors thank Dr. M. Lindsay, Dr. А. Vrevsky, Dr. J. Verncombe, Dr. M. Often and anonymous reviewer of the journal for thorough reviews, useful comments and recommendations that have helped to improve the paper. The authors are also grateful to T. Marchuk for drawing the diagrams and T. Miroshnichenko for help with the paper translation to English. The authors also express their sincere gratitude to Dr. M. Abzalov for valuable discussions and many useful comments.

Disclosure statement

No potential conflict of interest was reported by the author(s).