Abstract
The metasedimentary basin-fill successions of the Central Lapland belt, Peräpohja belt, and Kuusamo belt form an important part of the northern Fennoscandia Shield. They each record ca. 600 Ma (2.5–1.9 Ga) of sedimentation history and tectonic evolution, providing important information about past depositional conditions and tectonic settings. Detrital zircon geochronology shows that Archean age populations between 3.00 and 2.70 Ga have provenances from the surrounding basement complexes of granitoid/TTG rocks, whereas the Paleoproterozoic age populations (≤2.25–1.86 Ga) can be linked to the surrounding granitoids in northern Finland and Sweden. Zircon morphology studies indicate that basin sedimentation and/or provenance area(s) were likely influenced by eolian processes ca. 2.3–2.1 (or possible earlier). Major and trace element geochemistry indicates minor to moderate weathering trends, closely resembling Archean-Proterozoic sandstones and shales. Provenance signatures of tectonic settings vary from rift to arc and collisional. We propose five basin evolution stages for the Central Lapland belt, Peräpohja belt, and Kuusamo belt: a rifting stage from 2.5 to 2.1 Ga including (i) initial rifting/early syn-rift, (ii) syn-rift, and (iii) syn-rift to early post-rift; (iv) a passive margin (post-rift) stage from 2.1 to 1.94–1.92 Ga; and (v) a foreland basin system 1.94–1.92 to 1.88 Ga. The rifting stage includes bimodal subaerial to subaqueous volcanism with continental to marine sedimentation, and the initial accumulation of carbonate and evaporate successions, indicating later local tectonic stability and restricted hydrological circulation. The early development of an epeiric sea setting was followed by a passive margin stage and the development of aulacogens, controlled by cyclic sea-level fluctuations superimposed on long-term thermal subsidence. This stage was characterized by the accumulation of hemipelagic deposits together with gravity-driven sandstone deposits and associated subaqueous volcanism. The foreland basin system comprises an initial compressional stage with the development of forebulge and foredeep depozones and magmatic arc collision. This was followed by the main compressional stage, where basin inversion resulted in a foreland fold-thrust belt. The foreland basin system includes syn- and post-orogenic deposystems and a transition from underfilled marine sedimentation to overfilled non-marine deposits.
Published Version
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