Archaean Kuru-Vaara eclogites in the northern Belomorian Province, Fennoscandian Shield: crustal architecture, timing, and tectonic implications

Abstract

This paper addresses the relationships between relic amphibole-eclogite facies (AE) eclogites and their host units, Archaean amphibolites, enveloped by Archaean tonalite–trondhjemite–granodiorite (TTG) gneisses, in the Kuru-Vaara study area in the northern Belomorian Province. According to observational constraints, the crystallization of the relic peak omphacite + Mg-garnet ± kyanite assemblage and the subsequent replacement of omphacite by clinopyroxene–plagioclase symplectite occurred before the earliest deformational, metamorphic, and migmatization events that are recorded in the amphibolites. The amphibolites and their TTG hosts have a shared deformational and metamorphic history that is composed of the Archaean and Palaeoproterozoic periods. This history favours the conclusion that the AE metamorphism recorded in the relic eclogites within the amphibolites occurred during the Mesoarchaean to Neoarchaean periods. The deformation and metamorphism of the amphibolite facies of the second period resulted from the Lapland–Kola collisional orogeny at 1.91–1.93 Ga, which led to eclogite–high-pressure granulite (E–HPG) facies conditions in the lowermost portions of the over-thickened crust in Belomorian Province (the southwestern foreland of the Lapland–Kola collisional orogen). The Palaeoproterozoic E–HPG overprint was reported from the Palaeoproterozoic Gridino mafic dikes. Although the ages of the oldest low Th/U zircons are close to the time of the Lapland–Kola collision, the low Th/U 1.9–1.8 Ga zircons reflect a zircon response to regional fluid infiltration in the eclogites during slow exhumation following the Lapland–Kola orogeny and do not record any metamorphic event. Contrary to the Palaeoproterozoic E–HPG overprint, the areal occurrence of the 2.7–2.8 Ga AE eclogites with mid-ocean ridge basalt-like chemistry and their paragenetic link with the TTG gneisses suggest a tectonic regime that involves subduction. This research favours concepts suggesting that the modern-style plate tectonics has operated in some places, at least since the late Mesoarchaean.

Keywords:

• plate tectonics
• eclogite
• deformational history
• Archaean
• Palaeoproterozoic
• Belomorian Province
• Fennoscandian Shield

View correction statement:

Victor Balagansky, Andrey Shchipansky, Alexander I. Slabunov, Il’ya Gorbunov, Sergey Mudruk, Mikhail Sidorov, Pavel Azimov, Svetlana Egorova, Alexandera Stepanova, and Anatoly Voloshin, 2014, Archaean Kuru-Vaara eclogites in the northern Belomorian Province, Fennoscandian Shield: crustal architecture, timing, and tectonic implications: International Geology Review, v. 57, p. 1543–1565. doi:10.1080/00206814.2014.958578

Acknowledgements

We appreciate I.I. Yakovenko, head of the former Kovdor-Slyuda Joint-Stock Company, S.N. Khalliulova, head of the Kuru-Vaara enterprise, and the Kuru-Vaara staff (especially L.O. Guseinova, N.P. Suleimanova and T.V. Yas’kina) for permission to conduct fieldwork in the quarry and for help with the logistics of this study. We thank S.L. Presnyakov for his assistance in isotope dating and E.A. Selivanova for her help in identifying minerals using the X-ray refraction technique. Furthermore, we thank T.N. Bazhanov, G.A. Bezhev, L.A. Cherednik, T.V. Kartushinskaya, and M.Yu. Raud for their help with the fieldwork and treatment of the materials. M. Brown is greatly appreciated for a discussion of the Belomorian eclogites during the meeting and the geological excursion ‘Precambrian High-Grade Mobile Beltsʼ (June 2014, Petrozavodsk–Gridino–Chupa–Kuru-Vaara–Salma, Russia). M. Väisänen and one anonymous reviewer are thanked for their constructive criticisms and notes that have resulted in significant improvements of the manuscript. We are thankful to V. Singh and R.J. Stern for their editorial support.

Additional information

Funding

This research was supported by RFBR under grants [12-05-00597], [12-05-01080], [13-05-91162], and [14-05-31137-mol-a], and by the Department of Earth Sciences at the Russian Academy of Sciences (program ONZ-6).