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Anomalous Radiocarbon Ages Found in Campanian Ignimbrite Deposit of the Mediterranean Deep-Sea Core CT85-5

Irka Hajdas, Carla Taricco, Georges Bonani, Jürg Beer, Stefano M Bernasconi, Lukas Wacker


A detailed radiocarbon chronology has been 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 set of reversed 14C ages for sediments deposited during the eruption of the Campanian Ignimbrite (~40 ka cal BP). The anomalous young 14C ages coincide with elevated concentrations of 10Be measured in the same core. Although reversals in 14C ages have been previously found in other records at 40 ka cal BP, such extreme changes have not been observed elsewhere. The enhancement in 14C concentration in CT85-5 sediments associated with the Campanian Ignimbrite is equivalent to an apparent age ~15 ka younger than the age for the sediments deposited shortly before the eruption. 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.

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