Detrital zircon U-Pb and Hf constraints on provenance and timing of deposition of the Mesoproterozoic to Cambrian sedimentary cover of the East European Craton, Belarus
Published on Sep 1, 2019in Precambrian Research4.427
· DOI :10.1016/J.PRECAMRES.2019.105352
Abstract The sedimentary cover of the East European Craton (EEC) is unique because of its low degree of diagenetic alteration that allows preservation of the original “source to sink” relationships. The present study provides U-Pb and Hf zircon data for the entire Proterozoic sedimentary section of the EEC based on samples from five boreholes in Belarus within the Volyn-Orsha Basin, one of the most important sedimentary basins of the craton. Twenty-one samples of mudstones and sandstones were selected for detrital zircon U-Pb geochronology, supplemented by the Hf isotope analyses of zircons from 6 samples representing different U-Pb age spectra and bulk rock XRD mineralogy of all mudstone samples collected from the studied boreholes. Five clastic successions in the Volyn-Orsha Basin are characterized by different sources of detrital material: (1) The Mesoproterozoic Pinsk Suite with a narrow population of c. 2.0 Ga zircons, (2) The Orsha Suite with a broad 1.3–3.2 Ga zircon age distribution, (3) Glacial sediments of the Vilchitsy Series with an age spectra similar to the Orsha Suite, except for a c. 1.0 and 1.2 Ga cluster, (4) The Volyn and Valdai Series, including lowermost Cambrian, with a narrow trimodal population of 0.5, 1.5, and 1.8 Ga zircons, and (5) lower Cambrian (?) sediments with a diffused zircon age spectrum, including a 500–700 Ma cluster. Maximum depositional ages were constrained for the Vilchitsy Series at 977 ± 6 Ma and for the Volyn Series at 579–545 ± 4 Ma. Combined Hf zircon data indicate four episodes of new continental crust generation at 3.3, 2.8, 2.1–2.3 and 1.8 Ga, suggestive of source terrains within the crust of the present-day EEC. These sources experienced subsequent reworking of crust at c. 1.8 Ga and 550–600 Ma. Only a lower Cambrian sample lacks any trend or clustering within the Hf data probably due to mixing of zircons from exotic and local sources. Paleogeographic models explaining these provenance signals in terms of intracratonic erosion and sediment transport are presented.