Detrital Zircon Geochronology of the Volyn-Orsha Sedimentary Basin in Western Ukraine: Implications for the Meso-Neoproterozoic History of Baltica and Possible Link to Amazonia and the Grenvillian—Sveconorwegian—Sunsas Orogenic Belts

We used LA-ICP-MS U-Pb data for detrital zircon to constrain the Maximum Depositional
Age (MDA) and provenance of clastic sedimentary rocks of the Volyn-Orsha sedimentary basin,
which filled an elongated (~625 250 km) depression in SW Baltica and attained ~900 m in thickness.
Eighty-six zircons out of one hundred and three yielded concordant dates, with most of them (86%)
falling in the time interval between 1655 3 and 1044 16 Ma and clustering in two peaks at ca.
1630 and 1230 Ma. The remaining zircons yielded dates older than 1800 Ma. The MDA is defined by a
tight group of three zircons with a weightedmean age of 1079 8Ma. This age corresponds to the time
of a ~90 clockwise rotation of Baltica and the formation of the Grenvillian—Sveconorwegian—Sunsas
orogenic belts. Subsidence was facilitated by the presence of eclogites derived from subducted oceanic
crust. The sediments of the Orsha sub-basin in the northeastern part of the basin were derived from the
local crystalline basement, whereas the sediments in the Volyn sub-basin, extending to the margin of
Baltica, were transported from the orogen between Laurentia, Baltica and Amazonia.