Correlation of neoproterozoic volcanism in the southeastern White Sea region and western Urals: New age data on the Solozero basalts (Onega Graben)

The isotopic dating of the volcanic rocks localized in rift (aulacogen) systems makes a valuable contribution towards solving geochronological problems of the Late Precambrian riftogenic rocks of the East European Platform (EEP). The efficiency of this approach is demonstrated by results of study of the volcanic rocks from the eastern margin of the EEP. These volcanic rocks belong to Late RipheanVendian sequences that compose the large KvarkushKamennogorsk anticlinorium on the western slope of the Middle Urals representing the inverted Late Cambrian riftogenic trough. The Upper Vendian and Upper RipheanLower Vendian volcanosedimentary rocks of this structure are very similar in composition and structure to the Late Cambrian volcanosedimentary rocks of the southeastern White Sea region in the northern EEP. However, the available isotopic-geochronological data allow reliable correlation of only Upper Vendian rocks of these regions: UPb zircon datings of ashes from the Upper Vendian Sylvitsa Group on the western Urals yield 557 10 Ma (SHRIMP), while zircons from ash intercalations in the Upper Vendian Ust-Pinega Formation of the White Sea region define ages of 558 1 and 555.3 0.3 Ma. The correlation of the Upper RipheanLower Vendian rocks of the eastern and northern EEP is significantly complicated by the varying degrees of their isotopic-geochronological study.