Provenance analysis of stone artefact assemblages using petrography and pXRF at Murujuga (the Dampier Archipelago), Western Australia

Murujuga (also known as the Dampier Archipelago) is located on the northwestern coast of Western Australia. It is recognised on Australia's National Heritage List for hosting extensive assemblages of significant rock art (engravings/petroglyphs), knapped stone artefacts and stone arrangements. Understanding the interactions between the natural landscape and people's deep-time cultural attachment is a focal point for much research on this coastal landscape. To better understand the provenance distribution of stone artefacts in archaeological assemblages, we investigated the viability via in situ geochemical analysis by characterising artefact rock types in the field. The regional geology at Murujuga is very complex, and different rock types can appear similar, making correct identification difficult. A petrographic analysis was undertaken on bedrock samples near archaeological sites to define the rock's composition and textural characteristics. A Niton pXRF device was then used to define geochemical characteristics. A principal component analysis was performed to highlight the usefulness of Zr and Ti as key discriminators for distinguishing between local rock types. We then analysed in situ stone artefact assemblages using pXRF at sites on Rosemary Island, Dolphin Island, North Gidley Island, and at Nganjarli (Deep Gorge) on the Burrup Peninsula. Our results show that stone artefacts from most sites were sourced from local outcrops, except at Nganjarli, where > 50 % were characterised as non-local. These results indicate that pXRF is a viable technique for in situ analysis of artefact assemblages at Murujuga, increasing our understanding of landscape attachment and human mobility in this tool-stone-rich environment.