Geochemical fingerprinting of Holocene tephras in the Willaumez Isthmus District of West New Britain, Papua New Guinea

Abstract

Electron microprobe analyses were conducted on volcanic glasses extracted from Holocene tephra marker beds on the Willaumez isthmus in West New Britain, Papua New Guinea. These tephra beds are pivotal in the dating of a wide range of human artefacts and manuports found in the intervening buried soils, extending back over the last 40,000 years. Three major groups can be easily separated: W-K1 and 2; W-K3 and 4; and the Dakataua tephra. Of the remaining post-W-K4 tephras, most show slightly higher FeO and CaO and lower SiO2 contents than the W-K3 and 4 group, although there is some overlap. The combination of these geochemical data sets with the known stratigraphy and radiocarbon dates has helped resolve tephra correlation where these ashes become thin and less visually diagnostic or where pumice has been resorted and redeposited by the Kulu-Dulagi River.