Obsidian Subsource Identification in the Sierra de Pachuca and Otumba Volcanic Regions, Central Mexico, by ICP‐MS and DBSCAN Statistical Analysis

O tumba and S ierra de P achuca obsidian deposits in C entral M exico have been important sources of raw material since pre‐ H ispanic times. Numerous archaeological investigations have suggested that the economical and political expansion of major M esoamerican societies were linked to the control of obsidian sources and distribution of quarried material. S ierra de P achuca contains several obsidian flows and numerous quarries throughout the region that were preferentially exploited by different cultures. The O tumba V olcanic C omplex has four important obsidian domes, but three of them have not been studied in detail. A geochemical characterization of subsources from the S ierra de P achuca and O tumba V olcanic C omplex is an important step toward future sourcing of obsidian artifacts that would help provide insight into spheres of influence and trade by past cultures in C entral M exico. Having this purpose in mind, inductively coupled plasma mass spectrometry ( ICP ‐ MS ) was used to analyze obsidian samples collected from five separated locations at S ierra de P achuca and four at O tumba, followed by statistical analysis (density‐based spatial clustering of applications with noise, DBSCAN ). We were able to distinguish three chemically distinctive subsources in S ierra de P achuca and three in O tumba. This study illustrates the importance of accurate characterization of obsidian raw material when attempting to define subsource usage.