Development of a robust C-14 chronology for Lynch's Crater (North Queensland, Australia) using different pretreatment strategies

Lynch's Crater in northeastern Australia provides a long, continuous record of environmental change within the Late Quaternary. Here, we present newly determined radiocarbon ages, using acid-base-acid stepped combustion (ABA- SC) and acid-base-wet oxidation stepped combustion (ABOX-SC) pretreatment s trategies. The new results largely confirm the original untreated radiocarb on results for the uppermost 9 in of sediments, (ca. 35 ka BP). Below this depth, results from both pretreatment methods are in stratigraphic agreemen t and extend the dating of the record from 38 ka BP to about 48 ka BP. alth ough an apparent increased sedimentation rate below 12 rn is questionable. The scarcity of "charcoal" in several of the samples raises questions regar ding the application of ABOX-SC to lake or swamp sediments, with evidence f or contributions from younger, chemically resistant bacterial carbon along with fine "charcoal" in some samples, However, the extent to which this phe nomenon is significant to the final age estimate appears to be sample speci fic, and is probably dependent upon the length of the wet oxidation step in the pretreatment.