Systematic sampling of quartzites in sourcing analysis: intra-outcrop variability at Naibor Soit, Tanzania (part I)

Abstract

Despite the common exploitation of quartzites as raw materials during the African Stone Age, petrographic and geochemical characterization studies have been rarely undertaken. The Naibor Soit outcrop at Oldupai Gorge (Tanzania), considered the main source for quartzite procurement in the area, probably represents the exception to this analytical scarcity. Previous studies have determined variability among quartzites and the existence of singular mineral assemblages and geochemical compositions. In this study, we present the first systematic survey and EDXRF characterization of 86 samples from the two inselbergs that conform Naibor Soit. Samples are classified into nine macroscopic varieties and are mineralogically composed of quartz, muscovite, occasional hematite, rutile, magnetite, anhydrite, and fuchsite. Geochemical analyses, which include previously published data, confirm the existence of inter-/intra-outcrop variability and suggest compositional similarities among some areas of both inselbergs. Our study contributes compositional data and elevated predictive values for future archeological sourcing studies at Oldupai. Our results emphasize the necessity of systematic surveying and sampling to fully understand raw material variability and the factors that may have influenced their selection and exploitation.