Age Limits for the Zaonega Formation of the Ludicovian Superhorizon and the Shunga Event in the Onega Basin: New U–Pb Zircon Data for the Konchezero Sill

New U–Pb data for zircon from the Konchezero sill reliably determine the age of the Suisari Formation of the Ludicovian and the limit of the maximum age of the volcanogenic–sedimentary Zaonega Formation with isotope-light carbon and the Shunga isotope event.