Search for impact ejecta at the Paleocene–Eocene boundary

Abstract Almost 10 years have passed since microtektites and microkrystites were reported for the Paleocene–Eocene (P–E) boundary in drill cores and outcrop in New Jersey and in ODP Hole 1051B in the western North Atlantic. The glassy spherules were interpreted to reflect an impact trigger for the Paleocene–Eocene Thermal Maximum (PETM). Since then, many detailed studies of sediment strata across the P–E boundary worldwide have been performed, but so far, no additional reports of impact spherules have been published. Negative results usually are not published, but here we report a lack of success in finding such spherules at the P–E boundary in ODP Hole 1051B. We searched 90 g of sediment from the same interval in the same core from which 56 impact spherules >63 μm were previously reported from 35 g of sediment, but did not find microtektites or microkrystites. We also did not find impact spherules in a detailed search of 2.3 kg of sediment from the P–E boundary in the Zumaia section (Spain), where the boundary is marked by a minor iridium anomaly. In addition, we did not find such spherules in P–E boundary sediment from sections in Europe and the Middle East nor in drill cores from the southern Atlantic. We urge the research community to report further both negative and positive results on this issue in order to elucidate the envisioned P–E boundary impact event.