Silurian K‐bentonites of the Dnestr Basin, Podolia, Ukraine

Abstract

The Dnestr Basin of Podolia, Ukraine, is an epicratonic basin consisting of neritic carbonate and calcareous mudstone facies including a nearly complete Silurian sequence ranging from late Llandovery to late Pridolí in age. The Silurian section has served as a standard for regional and interregional studies as a consequence of its well‐documented macro‐ and microfaunal assemblages. Approximately 24 mid‐ to Late Silurian K‐bentonites are present in this succession, and their lateral persistence has aided in establishing regional correlations. The K‐bentonites range from 1 to 40 cm in thickness and occur in the Bagovitsa (late Wenlock), Malinovtsy (Ludlow) and Skala (Prídoli) Formations. Discrimination diagrams based on immobile trace elements together with rare earth element data suggest the K‐bentonites had a volcanic origin in a collision margin setting related to subduction. Thickness and stratigraphic distribution considerations are consistent with a source area in the Rheic Ocean.