Garnet and zircon geochronology of the Paleoproterozoic Kuru-Vaara eclogites, northern Belomorian Province, Fennoscandian Shield

The Belomorian Province of the Fennoscandian Shield exposes numerous Precambrian eclogites, which makes it significant for study early tectonic processes. age these eclogites has been discussed more than 15 years and regarded as either Archean or Paleoproterozoic. In Kuru-Vaara quarry within northern Province, eclogitic assemblage is preserved in concordant mafic boudins felsic gneisses a partially eclogitized gabbro-norite dike cutting discordantly through gneiss fabric. Both eclogite types preserve zircon cores with magmatic geochemical signature that yield protolith ages ca. 2.88 Ga boudin 2.44 gabbro-norite. Ca. 1.9 rims grains from show low Th/U ratio HREE depletion, reflecting growth metamorphic equilibrium garnet. boudin, ?18O = 5.1–5.9‰ typical mantle melts; oxygen isotope composition garnet (?18O 4.0–5.0‰) 4.5–5.4‰). Garnet Lu-Hf geochronology coupled U-Pb constrains prograde metamorphism at 1.92–1.89 Ga. Mineral inclusions garnet, zoisite, plagioclase, kyanite, amphibole, quartz, low-Na clinopyroxene imply epidote–amphibolite/amphibolite facies conditions metamorphism. All data point to Paleoproterozoic