207Pb/206Pb ages and Hf isotope composition of zircons from sedimentary rocks of the Ukrainian shield: Crustal growth of the south-western part of East European craton from Archaean to Neoproterozoic

摘要

The results of simultaneous LA-ICP-MS measurements of Pb/Pb and Hf isotope ratios are reported for zircons separated from five Ukrainian shield sedimentary rocks: (1) c. 3.0 Ga quartzite of the Bug Series; (2) c. 2.0 Ga quartzite of the Topilnya Series; (3) c. 1.75 Ga quartzite of the Ovruch Series; (4) c. 1.2-1.0 Ga sandstone of the Polissya Series; and (5) c. 0.6 Ga conglomerate of the Volyn Series. The age-Hf isotope (εHfT) data indicate four main crustal growth events at 3.75, 3.20-3.15, 2.2-2.0, and 1.5 Ga in the south-western part of the East European craton (EEC). An additional rather minor event could have place at 2.5-2.4 Ga. The oldest event is represented by enderbites of the Bug domain in the south-western part of the Ukrainian shield. The second crust-forming event occurred at c. 3.20-3.15 Ga and it is documented by detrital zircons separated from the Bug Series quartzite and metasediments of the Soroki greenstone belt, Azov domain. A small number of zircons with positive εHfT values reveal some input of the juvenile material into the crust at 2.5-2.4 Ga, whereas the 2.2-2.0 Ga event is dominated by zircons with positive εHfT values. The youngest event is represented by numerous zircons that crystallized at c. 1.5 Ga. The possible sources of these zircons are the rock complexes of the south-western part of the Fennoscandian shield.