Basalt compositional variability on Rapu Nui and its implications in artifact sourcing and prehistoric resource use

Many classes of prehistoric artifacts on Rapa Nui are composed of basalt, a ubiquitous volcanic rock that is one of the few available lithic resources on this remote volcanic island. Basalt artifacts include adzes, bifaces, fishhooks, and large architectural blocks. Sources of basalt are found across Rapa Nui that result from distinct volcanic flows. Laser-ablation time-of-flight ICP-MS provides a means of measuring elemental concentrations and thus characterizes the composition of basalt flows. Through the comparison of source and artifact composition, locations from which the raw materials for prehistoric basalt artifacts were collected can be distinguished. My analyses generate compositional descriptions of artifact material across the prehistoric landscape of Rapa Nui. The results presented here demonstrate that patterns of prehistoric artifact composition are explained by differential utilization of locationally-specific basalt flows that are not a function of simple distance. This conclusion suggests that for certain artifact classes the composition of specific basalt flows was a factor in their procurement and utilization.