The challenge of AMS dating SE Asian archaeology: new methodological improvements
Katerina Douka (University of Oxford)
Thibaut Deviese (Oxford University)
Paper short abstract:
Reliable chronologies are crucial for understanding cultural change and prehistory. Radiocarbon dating is challenging in SE Asia owing to often poor preservation of dateable materials. We describe improved methods to overcome this.
Paper long abstract:
Radiocarbon dating is challenging in SE Asia. The dating of bone from archaeological sites in particular is very difficult because of the low preservation of the remaining protein. Collagen diagenesis is very closely linked with the thermal history of the bone, the site pH, the level of microbial and bacterial activity and the presence of water. High values for these parameters mean that collagen survival is compromised and where it survives, it does so in very low proportions. To overcome these difficulties we have worked on several methods of improving the routine dating of bone and related biominerals from SE Asian sites.
We have applied and tested improved methods for screening remaining collagen by measuring bulk bone % nitrogen values. This allows us to only focus our efforts in the laboratory on extracting collagen from bones that contain a level of nitrogen that is above ~0.6% weight. Since the nitrogen is only found in the bone protein it is a correlate for collagen. We use ultrafiltration of the bone collagen to improve the purification of the sample prior to AMS dating. In cases where the % nitrogen falls below 0.6% we have developed a method of extracting single amino acids from poorly preserved bones that allows a purified amino acid fraction to be isolated using an HPLC for dating. Finally, we have tested and applied methods for dating tooth enamel carbon from subtropical environments. We will describe these methods and some of the results from specific sites.
Chronology building for prehistoric SE Asia