ORIGINAL ARTICLE Characterisation of obsidian subsource variability at El Pared on, Mexico A. Gabriel Vicencio 1 | Aurelio L opez Corral 2 | Alejandro Mitrani 3 | Armando Arciniega 4 | David M. Carballo 1 1 Department of Anthropology, Boston University, Boston, Massachusetts, USA 2 Instituto Nacional de Antropologia e Historia, Tlaxcala, Mexico 3 LANCIC-IF, Universidad Nacional Autonoma de Mexico, Mexico City, Mexico 4 Coordinacion Nacional de Conservacion del Patrimonio Cultural, CODICE, Mexico City, Mexico Correspondence A. Gabriel Vicencio, Department of Anthropology, Boston University, Boston, MA, USA. Email: gabrielv@bu.edu Funding information CONACyT, Grant/Award Numbers: 2014-225845, LN293904, LN299076, LN314846, LN315853; PAPIIT UNAM, Grant/Award Number: IN108521 Abstract Portable X-ray fluorescence (pXRF) geochemical anal- ysis on obsidian from five Formative period (1200 BCE to AC 100) sites from Tlaxcala, Mexico, has revealed that most of the material had similar values to those found in the closest obsidian source, named El Pared on, Puebla. Nevertheless, initial analyses did not resolve whether these materials came from the same caldera or from a specific obsidian deposit. Here we present a methodology that allows the identification of obsidian subsources. The results reveal that Tlaxcalan populations took advantage of a specific obsidian deposit called Tres Cabezas, Puebla, providing valu- able new data to identify associated regional exchange networks. KEYWORDS El Pared on source, Formative period, Mesoamerica, obsidian, pXRF analysis, subsources INTRODUCTION The contemporary Mexican state of Tlaxcala, located less than 100 km east of Mexico City, is key to understanding the cultural development of pre-Hispanic cultures from highland Mesoamerica. Middle (1200–600 BC) and Late Formative periods (600 BC–AD 100) societies from this area formed the sociopolitical and economic foundations of later settlements that appeared in the central highlands. Settlements ranged from small villages to monumental cen- ters, making this region a relevant locus to better understand early economic systems of regional polities and how their inhabitants supplied themselves with basic necessities, such as obsidian. The characterisation of obsidian sources and subsources employing geochemical methods has been a productive line of research in archaeology for understanding economic exchange net- works. These analyses have aided in the identification of commercial interactions between Received: 27 December 2022 Accepted: 31 August 2023 DOI: 10.1111/arcm.12914 © 2023 The Authors. Archaeometry © 2023 University of Oxford. Archaeometry. 2023;1–17. wileyonlinelibrary.com/journal/arcm 1