Three scoria blocks from Māori occupation sites, New Zealand: Their petrography, mineralogy, geochemistry and attribution to a source locality in eastern Polynesia

Abstract

AbstractWe document the petrography, mineralogy, major, minor, trace elements, and isotopic signatures of three shaped scoria blocks found within or associated with Māori occupation sites in southern New Zealand. Both mineralogy and geochemistry show that these scoria blocks have close affinities to alkaline lavas characteristic of intraplate, volcanic oceanic islands. Comparisons are made with broadly similar young alkaline associations on the mainland and off‐shore islands of New Zealand and it is shown that all three blocks are exotic. A number of young, east Pacific Islands are investigated and it is demonstrated that the closest comparison is with lavas from the Society Islands, French Polynesia. Geochemically it is difficult to identify which island in that group was the source but, predicated on the youthful appearance of these scoria blocks; it is suggested that the most likely location is the volcanically young island of Mehetia. This island is the location of a recent Strombolian pyroclastic event and scoria is a common rock associate of that island. These scoria blocks are the first pre‐European artefacts with secure archaeological contexts found in New Zealand, whose origins can reliably be traced to their source island group in the eastern Pacific.