LA-ICP-MS analysis of Clovis period projectile points from the Gault Site

Abstract

A key tenet of Clovis period hunter–gatherer mobility is the utilization of large ranges based on the appearance of exotic raw materials, particularly chert, in Clovis assemblages. The identification of the sources of chert in Clovis period assemblages is problematic as it has relied on macroscopic properties.Macroscopic characteristics of chert can be highly variable in a single outcrop, occur across very large areas, and have correlates in unrelated and far removed contexts. An instrumental geochemical approach was utilized that potentially offers advances in the capacity to link chert artifacts to their sources. Trace element data was recovered from 33 Clovis period projectile points from the Gault Site (41BL323) using Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS). This data was compared to trace element data recovered from 224 primary geologic samples of chert from multiple primary sources across the Edwards Plateau in Texas. The Clovis points were compared to the geologic sources using canonical discriminant analysis to establish group membership at three spatial scales: macro-regional (greater than 500 km), regional (between 30 and 500 km), and local (between 1 and 30 km). It was found at the macro-regional scale that 21 of the 33 Clovis points were to be geochemically similar to Edwards Plateau sources. At the regional scale, 15 of the 21 identified Edwards Plateau Clovis points could be attributed to a particular source. Lastly, only two Clovis points could be identified to particular sources at the local scale.