Paleoenvironment across the Cretaceous-Tertiary transition in eastern Bulgaria

Thierry Adatte, Gerta Keller, S. Burns, K. H. Stoykova, M. I. Ivanov, D. Vangelov, Utz Kramar, Doris Stüben

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28 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)231-251
Number of pages21
JournalSpecial Paper of the Geological Society of America
StatePublished - Jan 1 2002

All Science Journal Classification (ASJC) codes

  • Geology


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