Paleoenvironment across the Cretaceous-Tertiary transition in eastern Bulgaria

TitlePaleoenvironment across the Cretaceous-Tertiary transition in eastern Bulgaria
Publication TypeBook Chapter
Year of Publication2002
AuthorsAdatte, T, Keller, G, Burns, S, Stoykova, KH, Ivanov, MI, Vangelov, D, Kramar, U, Stüben, D
Book TitleCatastrophic Events and Mass Extinctions: Impacts and Beyond: Boulder, Colorado
PublisherGeological Society of America Special Paper 356

The Cretaceous-Tertiary (K-T) transition in eastern Bulgaria (Bjala) was analyzed in terms of lithology, mineralogy, stable isotopes, trace elements, and planktic foraminifera. The sequence represents a boreal-Tethyan transitional setting, spans from the last 300 k.y. of the Maastrichtian (zone CF1) through the early Danian (zones P0-Plc), and contains several short hiatuses. It differs from low-latitude Tethyan sequences primarily by lower diversity assemblages, pre-K-T faunal changes, a reduced K-T δ13C shift, and the presence of two clay layers with platinum group element anomalies. The first clay layer marks the K-T boundary impact event, as indicated by an iridium anomaly (6.1 ppb), the mass extinction of tropical and subtropical planktic foraminifera, and cooling. The second clay layer is stratigraphically within the upper Parvularugoglobigerina eugubina (Pla) zone and contains a small Ir enrichment (0.22 ppb), a major Pd enrichment (1.34 ppb), and anomalies in Ru (0.30 ppb) and Rh (0.13 ppb) that suggest a volcanic source.  PDF