The Boltysh meteorite impact crater formed in the Ukrainian Shield on the margin of the Tethys Ocean a few thousand years before the Cretaceous-Paleogene boundary and was rapidly filled by a freshwater lake. Sediments filling the lake vary from early lacustrine turbidites and silts to ~300 m of fine silts, organic carbon–rich muds, oil shales, and lamenites that record early Danian terrestrial climate signals at high temporal resolution. Combined carbon isotope and palynological data show that the fine-grained organic carbon–rich lacustrine sediments preserve a uniquely complete and detailed negative carbon isotope excursion in an expanded section of several hundred meters. The position of the carbon isotope excursion in the early Danian stage of the Paleogene period, around 200 k.y. above the Cretaceous-Paleogene boundary, leads us to correlate it to the Dan-C2 carbon isotope excursion recorded in marine sediments of the same age. The more complete Boltysh carbon isotope excursion record indicates a δ 13 C shift of around -3‰, but also a more extended recovery period, strikingly similar in pattern to the highest fidelity carbon isotope excursion records available for the Toarcian and Paleocene-Eocene hyperthermal events. Changes in floral communities through the carbon isotope excursion recorded at Boltysh reflect changing biomes caused by rapidly warming climate, followed by recovery, indicating that this early Danian hyperthermal event had a similar duration to the Toarcian and Paleocene-Eocene events.

Specimens spanning 10 m across the Cretaceous/Tertiary (K/T) boundary in Core 32 at DSDP Site 527, Walvis Ridge, were analyzed for trace elements and for evidence of shock deformation. Results from INAA/RNAA chemistry of the 45 samples suggest that multiple events are recorded at this site, including at least two enrichments of chalcophile elements possibly related to basaltic volcanism. A major event, coincident with the paleontological K/T boundary, is marked by a strong Ir anomaly and high frequency of shock deformation in quartz and feldspar. A strong secondary peak in elemental enrichment and mosaicism occurs at 1.87 m below the K/T boundary, suggesting appreciable volcanic activity about 10 5 years prior to the K/T event. Carbon and oxygen isotopes from the site also suggest that changes in climate began before the shock event at the boundary. Correlations between biostratigraphy, isotopes, and the data from this study suggest that the decline in marine productivity over an extended period of time may be the result of complex coupling of basaltic volcanism to climate change.