The oldest crust in the Ukrainian Shield - Eoarchaean U-Pb ages and Hf-Nd constraints from enderbites and metasediments

Claesson, Stefan,1950-Naturhistoriska riksmuseet,Enheten för geovetenskap (författare)

The oldest crust in the Ukrainian Shield occurs in the Podolian and Azov domains which both include Eoarchaeanarchaean components. U-Pb age data for Dniestr-Bug enderbites, Podolian Domain, indicate these are ca. 3.75 Ga old, and Lu-Hf isotope date indicate extraction from chondritic to mildly isotopically depleted sources with εHf up to ca. +2. Nd model ages support their Eoarchaeanarchaean age, while model ages for Dniestr-Bug metasedimentary gneisses indicate that these also include younger crustal material. Most of the Hf-age data for metasedimentary zircon from the Soroki greenstone belt, Azov Domain, reflects Eoarchaeanarchaean primary crustal sources with chondritic to mildly depleted Hf isotope signatures at 3.75 Ga. A minor portion is derived from Mesoarchaeanarchaean crust with a depleted εHf signature of ca. +4 at 3.1 Ga. U-Pb zircon ages from Fedorivka greenstone belt metasediments are consistent with the Soroki age data, but also include a 2.7‒2.9 Ga component. Nd whole rock model ages provide support for a younger crustal component in the latter. Both domains have been subject to Neoarchaeanarchaean, ca. 2.8 Ga, and Palaeoproterozoic, ca. 2.0 Ga metamorphism. The spatial distribution indicates that the Podolian and Azov domains have evolved independently of each other before the amalgamation of the Ukrainian Shield.

Bibikova, ElenaVernadsky Institute of Geochemistry and Analytical Chemistry RAS, Kosygin St 19, 119991 Moscow, Russia (författare)
Shumlyanskyy, LeonidM. P. Semenenko Institute of Geochemistry, Mineralogy and Ore Formation, Palladina Ave. 34, 03142 Kyiv, Ukraine (författare)
Dhuime, BrunoDepartment of Earth and Environmental Sciences, University of St Andrews, North Streeet, St Andrews KYI6 9AL, UK (författare)
Hawkesworth, C. H.Department of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol BS8, 1RJ, UK (författare)
Naturhistoriska riksmuseetEnheten för geovetenskap (creator_code:org_t)

Ingår i:Continent Formation Through TimeLondon : The Geological Society Publishing House

Av författaren/redakt...: Claesson, Stefan ...; Bibikova, Elena; Shumlyanskyy, Le ...; Dhuime, Bruno; Hawkesworth, C. ...

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