Anomalous radiocarbon ages found in Campanian Ignimbrite deposit of the Mediterranean deep-sea core CT85-5

A detailed radiocarbon chronology was established for the deep-sea core CT85-5 from the Tyrrhenian Sea. This chronology, which is based on the analysis of foraminifera shells, shows a sequence of reversed 14C ages for sediments deposited during the eruption of the Campanian Ignimbrite (ca. 40 ka cal BP). The anomalous ages coincide with high concentrations of 10Be measured on the same core. Although reversals in 14C ages have been previously found in other records at 40 ka cal BP, never before such extreme changes have been observed elsewhere. Here we present consistent results of repeated measurements showing no analytical problems that can explain the observed rapid changes in 14C of this particular record.