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

Melnik, A; Skublov, S.; Rubatto, Daniela; Müller, D.; Li, Xian-Hua; Li, Qiuli; Berezin, A. V.; Herwartz, Daniel; Machevariani, M. (2021). Garnet and zircon geochronology of the Paleoproterozoic Kuru-Vaara eclogites, northern Belomorian Province, Fennoscandian Shield. Precambrian research, 353, p. 106014. Elsevier 10.1016/j.precamres.2020.106014

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The Belomorian Province of the Fennoscandian Shield exposes numerous Precambrian eclogites, which makes it significant for the study of early tectonic processes. The age of these eclogites has been discussed for more than 15 years and regarded as either Archean or Paleoproterozoic. In the Kuru-Vaara quarry within the northern Belomorian Province, the eclogitic assemblage is preserved in concordant mafic boudins in felsic gneisses and a partially eclogitized gabbro-norite dike cutting discordantly through the gneiss fabric. Both eclogite types pre-serve zircon cores with a magmatic geochemical signature that yield protolith ages of ca. 2.88 Ga for a mafic boudin and ca. 2.44 Ga for the eclogitized gabbro-norite. Ca. 1.9 Ga zircon rims and grains from the eclogites show low Th/U ratio and HREE depletion, reflecting the growth of metamorphic zircon in equilibrium with garnet. In the eclogite boudin, the Archean zircon cores yield δ18O =5.1–5.9‰ typical of mantle melts; the oxygen isotope composition of garnet (δ18O =4.0–5.0‰) is in equilibrium with that of the 1.9 Ga zircon (δ18O =4.5–5.4‰). Garnet Lu-Hf geochronology coupled with U-Pb zircon geochronology constrains prograde meta-morphism for the Kuru-Vaara eclogites at 1.92–1.89 Ga. Mineral inclusions of garnet, zoisite, plagioclase, kyanite, amphibole, quartz, and low-Na clinopyroxene in ca. 1.9 Ga zircon from the eclogite boudin imply epidote–amphibolite/amphibolite facies conditions for the prograde metamorphism. All data point to a Paleo-proterozoic age of the eclogite facies metamorphism

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences
08 Faculty of Science > Institute of Geological Sciences > Isotope Geology

UniBE Contributor:

Rubatto, Daniela

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

0301-9268

Publisher:

Elsevier

Funders:

[4] Swiss National Science Foundation

Projects:

Projects 200021 not found.

Language:

English

Submitter:

Daniela Rubatto

Date Deposited:

14 Jan 2021 11:02

Last Modified:

17 Jan 2021 02:54

Publisher DOI:

10.1016/j.precamres.2020.106014

BORIS DOI:

10.48350/149541

URI:

https://boris.unibe.ch/id/eprint/149541

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