The radiocarbon ages of different organic components in the mires of Eastern Australia

Abstract

Radiocarbon (14C) dating is widely used to determine the age of organic material in palaeoenvironmental research. Here we compare 14C dates (n=17) resulting from macro-charcoal (>250 μm), short-lived plant macrofossils and pollen-rich residues isolated from two mire environments in eastern Australia. In most samples we found that short-lived plant macrofossils were the youngest organic component, the charcoal samples most often fell into the middle and the pollen-rich residues consistently returned older dates than the other samples. Although pollen-rich residues have been widely used for 14C dating in Australasia we suggest some caution in their use, perhaps because in our fire-prone environments these samples often also contain fine charcoal and other oxidative resistant organic matter that is older than the surrounding sediment matrix. The macro-charcoal samples also often returned older calibrated ages compared to short-lived plant macrofossils from the same depth, although this difference was relatively small (<245 years). Our results demonstrate that 14C dating of short-lived plant macrofossils are likely to yield more accurate chronologies and we advocate their routine use in palaeoenvironmental research when they are available. © 2018 by the Arizona Board of Regents on behalf of the University of Arizona.