The geochemical characterization and correlation of Late Holocene tephra layers at Ambra Crater and Kuk Swamp, Papua New Guinea

Major element geochemical analyses of volcanic glass shards from visible, macroscopic tephra layers in Papua New Guinea were used to test field-based correlations between local Late Holocene sequences. Previously, synchronization of sediment records at archaeological and palaeoecological sites across the Papua New Guinea highlands had been based largely on the physical properties and stratigraphic relationships of visible volcanic layers. The geochemical analysis of tephra-derived glass demonstrates miscorrelations and enables more robust tephrostratigraphic links to be made between a globally significant archaeological site, Kuk Swamp, and a nearby volcanic cone, Ambra Crater. The results indicate that field-based correlations of tephras can be problematic, especially given variable post-depositional changes in colour and texture of relatively thin tephra layers in different depositional environments. Additionally, the findings call into question some previous tephrochronological associations at archaeological and palaeoecological sites in the Papua New Guinea highlands, and demonstrate the necessity of grain-discrete geochemical analysis of glass shards as a basis for future tephrochronological studies in this region.