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Eoarchean rock association in the Dniester-Bouh Domain of the Ukrainian Shield: A suite of LILE-depleted enderbites and mafic granulites

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cris.lastimport.scopus2024-02-12T19:43:36Z
dc.abstract.enWe present the results of a study of an Eoarchean rock assemblage in the Dniester-Bouh Domain of the Ukrainian Shield. This comprises granulite-facies granitoids intercalated with mafic and ultramafic granulites. Zircon U-Pb geochronology indicates enderbite crystallisation at 3786 ± 32 Ma, followed by a subsequent event at ca. 3500 Ma. Several events can be tentatively identified that affected these rocks between ca. 3000 and 2700 Ma. The last zircon growth event took place in response to granulite facies metamorphism and included two separate episodes at ca. 2000 and ca. 1900 Ma. The oldest two zircon populations in enderbites have εHf values around 0, indicating their crystallisation from a protolith with a short crustal residence time. Zircons that crystallised during the 3000–2700 Ma event(s) vary in Hf isotope systematics from εHf ~ 1 at ca. 3000 Ma to εHf ~ −14 at c. 2700 Ma. Paleoproterozoic zircons reveal even more significant variations in εHf value from +6 to –22. Such variations are indicative of juvenile input and mixing with old non-radiogenic Hf. All Eoarchean rocks are depleted in incompatible trace elements and have negative Ta-Nb, P, and Ti anomalies. Compared to the typical TTG associations, enderbites record depletion in felsic components (SiO2, Na2O, K2O, Rb, Th), and enrichment in mafic ones (TiO2, MgO, CaO, V), allowing them to be defined as “mafic” or “depleted” TTG. Geochemical data indicate that mafic and ultramafic rocks of the Dniester-Bouh Domain formed by shallow high-degree melting of the mantle, with the absence of garnet in their source, and the presence of residual Ti-bearing minerals and/or amphibole. In contrast, enderbites were formed from a mixed garnet-bearing amphibolite – eclogite source, i.e. melting over a range of pressures/depths. Our preferred model for the formation of the Eoarchean rock association involves the shallow melting of mantle and formation of basalts and accompanying ultramafic cumulates at a spreading centre, with subsequent underthrusting of one segment of oceanic crust beneath the other, and partial melting of hydrated metamorphosed (eclogitized) mafic rocks in the underthrust plate, leading to the formation of the TTG melts.
dc.affiliationUniwersytet Warszawski
dc.contributor.authorClaesson, Stefan
dc.contributor.authorWilde, Simon A.
dc.contributor.authorBillström, Kjell
dc.contributor.authorNemchin, Alexander A.
dc.contributor.authorShumlyanskyy, Leonid
dc.contributor.authorBagiński, Bogusław
dc.date.accessioned2024-01-24T22:49:31Z
dc.date.available2024-01-24T22:49:31Z
dc.date.issued2021
dc.description.financePublikacja bezkosztowa
dc.description.volume352
dc.identifier.doi10.1016/J.PRECAMRES.2020.106001
dc.identifier.issn0301-9268
dc.identifier.urihttps://repozytorium.uw.edu.pl//handle/item/106315
dc.identifier.weblinkhttps://api.elsevier.com/content/article/PII:S0301926820305908?httpAccept=text/xml
dc.languageeng
dc.pbn.affiliationearth and related environmental sciences
dc.relation.ispartofPrecambrian Research
dc.relation.pages106001
dc.rightsClosedAccess
dc.sciencecloudnosend
dc.subject.enEoarchean
dc.subject.enTTG
dc.subject.enEnderbite
dc.subject.enUkrainian Shield
dc.subject.enU-Pb dating
dc.subject.enHf isotopes
dc.titleEoarchean rock association in the Dniester-Bouh Domain of the Ukrainian Shield: A suite of LILE-depleted enderbites and mafic granulites
dc.typeJournalArticle
dspace.entity.typePublication