Accurate Dating of Organic Deposits by AMS ¹⁴C Measurement of Macrofossils

We made a comparative study of AMS 14 C ages of organic deposits (minerotrophic peats and gyttjas) and macrofossils in order to evaluate the magnitude of a number of sources of error that may be present in bulk sediment samples. The consistency of 14 C ages found for coexisting macrofossils suggests that they are unlikely to record disturbances. Some of our gyttja samples yielded an age 0.2–0.6 ka 14 C years too old due to hardwater effect. We also found an aging effect in several bulk samples with a high admixture of siliciclastic material; this is attributed to fluvial input of reworked, older organic debris. Rejuvenation of bulk material as a result of root contamination occurs mainly in samples overlain by slowly accumulated deposits, and particularly in samples affected by (sub)recent roots.