The Lapland-Kola orogen: Palaeoproterozoic collision and accretion of the northern Fennoscandian lithosphere

Abstract

A tectonic model is proposed for the Palaeoproterozoic Lapland-Kola orogen (LKO) in the northern Fennoscandian Shield. Although long regarded as an Archaean craton, integrated geological, geochemical and geophysical observations show that the Lapland-Kola orogen is a Palaeoproterozoic collisional belt containing both Archaean terranes and an important component of juvenile Palaeoproterozoic crust. Rifting, from 2.5 to 2.1 Ga, began under the influence of a mantle plume (> 1000 km diameter), related to the break-up of the Kenorland supercontinent. Two linear suture zones within the orogeriic core mark the sites of continental separation, ocean formation and closure. One of these is identified as a belt of 1.98-1.91 Ga juvenile crust of both arc magmatic and sedimentary origin, marked by the Lapland Granulite, Umba and Tersk terranes. Palaeomagnetic data and ancient sedimentary detritus within these terranes suggest limited oceanic separation. Collision of juvenile terranes with the surrounding Archaean took place mainly between 1.93 and 1.91 Ga, resulting in a Himalayan-scale mountain belt, manifest by a thick-skinned region of high-Pgranulite-facies metamorphism, including the classical Lapland Granulite Belt and a broad zone of compressional deformation extending southwards into the Belomorian Mobile Belt. Protracted cooling and exhumation, possibly related to the buttressing effect of surrounding lithosphere, culminated in the intrusion of 1.80-1.77 Ga post-tectonic granites.

Paleomagnetism of the Amazonian Craton and its role in paleocontinents

“…4, the Karelia position was constrained by the 1984 Ma Pudozhgora Intrusion pole (Lubnina et al 2016), and Kola Craton is tentatively positioned close to Karelia. According to Daly et al (2006), after the formation of the Archean Kernoland supercontinent (Pesonen et al 2003), a Wilson cycle was developed between Kola and Karelia after the break-up of this supercontinent at ca. 2500 Ma.…”

Amalgamation of the North China Craton: Key issues and discussion

“…1) has shown that: Both belts were formed by the superposition of two Precambrian orogenies. The earth crust of the Belomorian belt was produced during the Mesoarchaean to Neoarchaean Belomorian collisional orogeny [Slabunov, 2008;Slabunov et al, 2006] and then was reworked during the Palaeoproterozoic Lapland-Kola collisional orogeny [Daly at al., 2006;Balagansky et al, 2014]. The earth crust of the Trans-North China orogen was formed during a Neoarchean accretionary orogeny and then was reworked during a Paleoproterozoic collisional orogeny [Zhao et al, 2012;Guo et al, 2012Guo et al, , 2005.…”

New high-resolution aeromagnetic and radiometric surveys in Finnmark and North Troms: linking anomaly patterns to bedrock geology and structure

“…2) with its magmatic arctype granodiorites, diorites and gabbros that have yielded Neoarchaean zircon ages in the east/northeast and Palaeoproterozoic ages in the west/southwest (Meriläinen, 1976;Lehtinen et al, 2005;Daly et al, 2006). Subordinate metasupracrustal rocks have also been reported in this terrane.…”

“…In general, there is a basic two-fold division into the Caledonides sensu stricto and a mid-crustal continental lithospheric basement comprising autochthonous crystalline com plexes that range in age from Neoarchaean to Late Palaeo proterozoic and form the northern margin of the Fennoscandian Shield ( Fig. 1; Gaál et al, 1989;Daly et al, 2006). These older Precambrian rocks occur mainly in eastern Finnmark and western Troms, and some are either affected locally by Caledonian deformation or incorporated as thrust slices in the Caledonian nappes (Fig.…”

“…West of the PPP is the Inari Terrane (IT) (Fig. 2) comprising mainly migmatitic orthogneisses, and this in turn is succeeded by the Palaeoproterozoic granulite-facies rocks of the Lapland Granulite Belt (LGB) (Koslov et al, 1995;Daly et al, 2006). The southwestern border of the LGB is a shallowly NE-dipping thrust zone with spectacular blastomylonites, subjacent to which is the highly strained, mélange-like Tanaelv Belt (TB) (Fig.…”