Cretaceous-tertiary boundary event - Evidence for a short time scale

The origin of the 'As, Sb, Zn anomaly' in Cretaceous-Tertiary boundary sites is investigated using data on 11 K-T boundary sites for which comprehensive trace element analyses were available. It was found that the proportions As/Ir, Sb/Ir, and Zn/Ir were remarkably constant over about 100-fold range in concentration. The correlation persisted in sublayers of boundary clay and extended to soot from burned land biomass, indicating that all the components, despite their diverse origin, became associated in a single global component prior to deposition. Data relating the amounts of As, Sb, and Zn and the amounts of marine and land biomass to the steady-state global inventory suggest a catastrophic, rather than a gradualist scenario.