Nodules in a haystack. Tracing lithic raw material sources through satellite remote sensing in the Atacama desert

Sourcing of high-quality toolstone is considered a paramount task in the study of lithic procurement among hunter-gatherers due to the key role that it played in their technological and social organization. Provenance research of artifacts made of high-quality cryptocristalline silicates (e.g. chert, chalcedony, flint, and jasper) faces the challenges of large spatial scale and the physical and chemical variation inherent between and within siliceous rocks deposits. This imposes the need for thorough geological sampling strategies to achieve representative results. Focusing on a case study of the southern Atacama Desert (northern Chile), we present and test the results of a strategy for the characterization of chert primary and/or secondary deposits through systematic field sampling and VNIR and FTIR reflectance spectroscopy. Canonical discriminant analysis of the samples spectra showed 100% accuracy of the base model in assigning the samples to their respective source area. This result shows: 1) the effectiveness of the sampling strategy to cover the cumulative variability of chert deposits belonging to different geological formations and also from the same parent geological formation; and 2) the ability of VNIR and FTIR reflectance spectroscopy as an analytical technique to differentiate between types of siliceous rocks with high geological and geographical resolution.