Sourcing geochemically identical obsidian: multiscalar magnetic variations in the Gutansar volcanic complex and implications for Palaeolithic research in Armenia

In obsidian-rich Armenia, one of the most archaeologically significant obsidian resources is the Gutansar volcanic complex (GVC). Numerous Palaeolithic sites across Armenia consist of little more than deposits of obsidian tools and debris, and within the Hrazdan Gorge, the vast majority of artifacts is crafted from GVC obsidian. For example, about 93% of the lithic assemblages from the Lower Palaeolithic site of Nor Geghi 1 and the Middle Palaeolithic site of Lusakert Cave 1 are GVC obsidian. Although erupted from multiple volcanic centers, GVC obsidians are geochemically identical and cover an area more than 70 km2. For studies seeking to reconstruct movements of Palaeolithic hunter-gatherers throughout the local landscape, the expansive GVC is problematic: geochemically identical obsidians dominate the foraging territories of sites within and near the complex. Here we explore the potential of obsidian magnetic properties to reveal hitherto unobservable patterns in GVC obsidian utilization with the ultimate goal of elucidating Palaeolithic behavioral patterns. Our results show that magnetic properties vary over multiple scales within the GVC, allowing obsidian sourcing to become multiscalar. These measurements are rapid, inexpensive, and entirely nondestructive for small artifacts. Measuring a few basic magnetic properties enables us to distinguish geochemically identical obsidians from three eruptive centers and potentially to attribute artifacts to specific quarrying sites, recognize changes in provisioning strategy, and estimate a minimum number of cores represented by a lithic scatter.