Radiocarbon dating of charcoal from tropical sequences: results from the Niah Great Cave, Sarawak, and their broader implications

Subsamples of charcoal from a number of different excavation contexts at the early modern human (Homo sapiens) site of Niah Great Cave (Malaysia) were accelerator mass spectrometry (AMS) 14 C dated. Samples were prepared using one of a number of different methods: untreated (control); acid-base-acid (ABA); and acid.-base-wet oxidation with stepped combustion (ABOX-SC) after Bird et al. 0 999). The results show that for material younger than similar to 25 ka BP there is little difference between the two chemical pretreatment methods and the control. For charcoal beyond similar to 25 ka BP, however, there are differences Of LIP to 4000 a, with ABOX-SC ages being consistently older. This is argued to be a more effective pretreatment method for decontaminating charcoal Samples prior to radiocarbon dating. For radiocarbon dating charcoals greater than similar to 25 ka BP, the ABOX-SC pretreatment and combustion approach appears to be the most rigorous method for developing a robust chronological framework for tropical sequences and should be more widely applied in contexts where the material being dated is likely to be ancient. The new chronology developed for Niah Cave based on this technique suggests that the earliest human evidence dates back to at least 45 ka BP and may extend significantly earlier than this based on the recent discovery of lithics 50cm below the earliest dated charcoal. Copyright (C) 2008 John Wiley & Sons, Ltd.