Provenance and stratigraphy of the oldest sediments at the western slope of the East European Craton (Volyn-Orsha Rift, SE Poland) – constraints from detrital zircon geochronology

Abstract

  The Volyn-Orsha Rift (VOR) extends NE-SW, from the interior of the East European Craton (EEC) to its western margin. The basin is filled the oldest non-metamorphosed deposits in the craton, mainly with continental reddish to variegated sandstone of the Paliessie Group. It contains no stratigraphic indexes, therefore, its age remains ambiguous. Detrital zircon ages (SHRIMP) were investigated for sandstone from the lowermost part of the Polish Polesie formation in Kaplonosy IG 1 borehole to constrain the timing of its deposition and detritus provenance. Two dominant populations have been identified: yielding 207Pb/206Pb ages of ~1850–1750 Myr, interpreted as derived from denudation of the late Svecofennian proximal basement of the northern flank of the basin, and in a range of 1560–1450 Myr, typical of anorogenic within-plate granitoid batholiths, widespread in the Fennoscandia in the direct vicinity of the NW margin of the VOR. The remaining zircons (ages ~1290–1050 Myr) are interpreted as derived from the common Sveconorwegian-Grenville orogenic belt, in the Neoproterozoic riming the EEC from the west. The youngest six detrital zircons with 207Pb/206Pb age in the range of ~1082–1048 Myr, provide a new constraint on the possible deposition time. The true depositional age of this unit is probably younger (at least ~100 Myr) interpreted here as Neoproterozoic, due to an intracratonic position of VOR basin within the assembled Rodinia.