Main stages of the Kostomuksha greenstone belt Banded Iron Formation genesis, Karelian Craton: based on U-Th-Pb dating of zircon

We studied zircon from banded iron formations (BIFs) in the Kostomuksha greenstone belt (KGSB), Karelian Craton, for first time. Here, BIFs are associated with Mesoarchean basalt-komatiites – BIF-1 and felsic volcanics BIF-2, as well Neoarchean graywackes BIF-3. All contain accessory zircon. Analysis of its isotopic age shows presence 1-4 clusters each sample. There single grains detrital most BIFs. The commensurable or older than BIF enclosing rocks. ages zircons differ among association: 2.84 Ga BIF-1, no zincon 2.98–2.75 Most is metamorphic origin. groups 2.75–2.72 zircon, while BIF-3 also has 2.65–2.64 magmatism. Rims 1.89–1.85 BIF-3, indicative local tectono-thermal processes simultaneous formation Svecofennian Orogen, reported here