Geochemical Variability of Obsidian in Western New Mexico with Laboratory- Based pXRF (thesis)

Abstract

Mule Creek and Mt. Taylor, located in southwestern and western New Mexico respectively, are obsidian source regions for archaeological lithic artifacts. Trace element concentrations can be used to distinguish obsidian from different regions and from different sites within regions, permitting archaeologists to identify the original source of obsidian artifacts. Within each region, source obsidian was sampled at six sites to compare its geochemical variability at three geographical scales. The chemical composition of 491 obsidian samples was analyzed using portable x-ray fluorescence. Multivariate statistical methods were used to show that obsidian varies at the broadest geographical scale (between regions) and at the intermediate geographical scale (between sites within regions) but not at the finest geographical scale (within sites). Thus, although obsidian artifacts can be sourced confidently to regions and sites, they cannot be sourced to different areas of a site using geochemical methods.