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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 d 13 C 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.

Terra Nova, 24, 477–486, 2012 Abstract The early Cenozoic, which is punctuated by several negative carbon isotope excursions (CIEs), was a time of climatic and oceanographic transition from ‘Greenhouse’ to ‘Icehouse’ conditions. The occurrence of a ∼0.5‰ CIE starting at the top of Chron C27n (TC27N) is reconfirmed with stable isotope data from Zumaia (Spain) and Bjala (Bulgaria) localities. Spectral analysis on respective carbonate/magnetic susceptibility proxy records substantiates the orbital cyclostratigraphy allowing correlation to a high‐resolution benthic foraminifera isotope record from ODP Pacific Site 1209, that indicates a coeval 2 °C transient warming. The hyperthermal event lasts ∼200 ka, contrasting with other short‐lived events from the Eocene, and displays a relatively rapid onset and a longer tailing back to pre‐event values similar to the Palaeocene–Eocene Thermal Maximum (PETM), though lower in amplitude. That a causal trigger for the TC27N event may be the onset of volcanism in the North Atlantic Igneous Province (NAIP) can be inferred from a ∼200‐m‐thick lava pile erupted during C27n/C26r polarity transition in the E Greenland margin.

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