INAA of pre-contact basalt quarries on the Samoan Island of Tutuila: a preliminary baseline for an artifact-centered provenance stusy

Abstract

This project presents a material-centered instrumental neutron activation analysis (INAA) characterization of 120 geologic samples selected from four fine-grained basalt quarries on the Samoan Island of Tutuila. Previous attempts at definitive differentiation of these Tutuilan quarries have utilized x-ray fluorescence (XRF). In this study, clear differentiation of each analyzed quarry was achieved using INAA. Biplots of canonical discriminant analysis (CDA) scores for the INAA data illustrate clear separation based on the variation in chemical composition between each quarry. The samples analyzed not only define quarry separation, but also provide the ‘‘core group’’ for a preliminary baseline necessary for future artifact-centered provenance studies. Inclusion of these ‘‘core group’’ samples in the baseline was confirmed by stepwise discriminant analysis. These findings suggest the ability to determine artifact quarry of origin on the island of Tutuila, which can elucidate the importance of individual Tutuilan quarries in the production, distribution and consumption of fine-grained basalt artifacts in Polynesia.