Contributions of LA-ICP-MS to Obsidian Sourcing in the Pacific

Abstract

This chapter examines results from the application of LA-ICP-MS to the identification of sources of obsidian artifacts from the Western Pacific. More than 700 analyses of obsidian samples collected at the Australian National University over the past years provide an accurate geochemical dataset for major obsidian source regions in the Western Pacific unambiguously discriminating sources and sub-sources. This dataset is employed to analyze social interaction in the 3000-year timeframe of human occupation of the western Pacific as reflected by variations in lithic raw material sources. Albeit not non-destructive, the minimal sample size necessary, and the precision and accuracy of analysis for a wide range of major, minor, trace and rare earth elements enables LA-ICP-MS to not only geochemically fingerprint archaeological artifacts to known source locations, but also to provide information about general geological contexts from which these objects derived. These additional data have been successfully employed in the past to identify locations of high probability for undetected obsidian outcrops.