Geochemical Sourcing of the 41LU6 Lithic Cache: Integrating PXRF and MANA for Enhanced Insights into Chert Provenance and Geoheritage Significance

This thesis integrates geological, archaeological, and heritage-based approaches to develop an interdisciplinary framework for chert provenance analysis grounded in the principles of geoheritage and geodiversity. While geology classifies chert by its silica mineralogy, diagenetic history, and stratigraphic context, and archaeology interprets its technological and cultural use, these perspectives often operate independently. By treating geoheritage as a synthesis between the natural and cultural dimensions of stone, this study positions chert as a material archive through which Earth’s history and human history converge. The central research question asks: can portable X-ray fluorescence (p-XRF) and Minimum Analytical Nodule Analysis (MANA) meaningfully capture geochemical variation in chert sufficient to distinguish geological sources and inform heritage interpretation? Seventeen geological datasets from chert-bearing formations across Texas, spanning the Permian through the Miocene–Pliocene, were standardized, cleaned, and evaluated using Canonical Discriminant Analysis (CDA), followed by a multi-stage element ranking protocol designed to quantify reliability and reveal diagnostic compositional patterns. The ranking system graded elements (A+–D) according to detection stability and statistical significance, providing the framework through which formation-level variation could be interpreted and the CDA results explained. The analysis demonstrated clear clustering among the Alibates, Adair–Steadman (San Angelo Formation), Edwards Plateau, and Ogallala groups. Distinct Fe and Al enrichment defined Alibates samples; elevated Ba characterized Adair–Steadman; the Ogallala group exhibited widespread elemental absences; and Edwards Plateau cherts formed a cohesive but compositionally distinct cluster. The analytical outcome establishes a reproducible methodology for constructing regional geochemical reference frameworks for chert. By combining p-XRF precision, MANA sampling control, and ranked-element interpretation, the study demonstrates how regional databanks of chert chemistry can be systematically assembled and used to classify archaeological materials within statistically defined provenance fields/sources. This framework strengthens the reliability of sourcing studies and provides a transferable model for future lithic research across geologically diverse landscapes. With this geological dataset as a foundation, the study applied CDA modeling and the ranking protocol to the 41LU6 lithic cache, revealing strong alignment with the Alibates Formation (n = 19), while a smaller subset (n = 9) displayed mixed geochemical traits—elevated Al similar to Alibates and Ba enrichment comparable to Adair–Steadman—suggesting an unresolved but compositionally adjacent source, possibly within an Edwards-type or Permian Pease River Group (San Angelo Formation) Adair–Steadman variant. Framed within the emerging paradigm of geodiversity, this research positions chert as more than a utilitarian material: it is both an epistemic and ontological record of Earth’s deep-time processes and humanity’s enduring interaction with them. By emphasizing analytical precision alongside philosophical reflection, the project advances geoheritage beyond its conventional conservation framework, proposing it instead as a dialectical space where scientific and cultural modes of knowing converge, as a bridge between scientific and cultural understandings of the landscape. The results illuminate how quantitative sourcing studies can contribute not only to archaeological interpretation but also to broader discussions about the relationship between people, materials, and the dynamic geologic environments that shape human history and planetary identity.