Redox bottom-water conditions in Neoproterozoic basins on eastern and north-eastern periphery of East-European Platform

Abstract

The redox bottom-water conditions in the sedimentary basins, which existed during the Late Riphean-Vendian on the east and north-east (in modern coordinates) margins of the Baltic, are investigated. It is concluded that in the context of local, fairly pronounced variations of the bottom-water redox indicators in the Late Riphean (primarily coefficient of stagnation, Mo/Mn, and to a lesser extent - V/(V + Ni)), suggesting that the accumulation of sediments in some areas which we have considered occurred on environment including disoxic or close to anoxic conditions. During the Vendian and appear at the end of the Late Riphean in the bottom waters of almost all sedimentary basins dominated oxidative conditions. The most well substantiated this conclusion for the relatively well-dated Upper Riphean-Vendian interval of the western slope of the Southern Urals, less justified it to other parts of the territory under review. New data in one way or another underscore the complex, non-linear/shift-gradual ocean oxygenation in the Late Riphean and Vendian with inversion “oxygen environments” in some of the major sedimentary basins or their parts in the Early Vendian, on the border of Vendian-Cambrian and in Cambrian itself. It seems, however, that a significant impact on this process acted not only global, but also local factors.