Technological and stylistic characteristics of Chupicuaro ceramic wares (Formative Mesoamerica)

International audienceLittle is known about the social, cultural and economical relationships between Central Mexico and Western Regions during the Middle and the Late Formative Periods (600 BCE – 250 CE). The Chupicuaro culture is known as one of the most dynamic Formative traditions in Western Mesoamerica, notably through its well-polished ceramics combining complex shapes, shimmering colours and diversified iconographic motifs. The forcefulness of the Chupícuaro pottery tradition seems to have influenced the ceramic productions of the Basin of Mexico, or to have been the source of local imitations and reinterpretations.The CHUPICERAM project (2021-2024), financially supported by the French National Research Agency, aims to clarify the nature and intensity of these relationships, focusing on ceramic materials from Chupicuaro culture and from Cuicuilco culture – a cultural core of the Basin of Mexico. The project follows a comparative and interdisciplinary approach, bringing together Mexican and French scientific teams. By cross-referencing the analytical results, we attempt to establish stylistic, technical and compositional groupings that will make it possible to formulate hypotheses on the manufacturing processes and sources of supply of raw materials in the diachrony and for both Chupicuaro and Cuicuilco cultures.In a first phase, we focus on ceramic sherds from different archaeological sites and different periods of the Chupicuaro culture (Chupicuaro and Mixtlan Periods). From the corpus of about 200 sherds, archaeological groups have been established on the basis of the patterns and colours of the decorations and of the shapes of the sherds. We used non-invasive analytical methods for the characterisation of the decorations and the ceramic pastes (hyperspectral imaging, µ-Raman, p-XRF…). In parallel, polished cross-sections were prepared from a reduced number of sherds for morphological and quantitative compositional analyses under SEM-EDX. All the ceramic pastes are identified as non-calcareous (CaO < 2.5 wt%). Our first results show compositional differences in the diachrony (Chupicuaro sherds versus Mixtlan sherds) of these ceramic pastes, both for major elements (Na, Al) and trace elements (Rb, Zr). Regarding the decorations, whatever the period, they consist of a mixture of clay and iron oxides for the reds, and of clay, iron oxides and manganese oxides for the black/café ones. The clayey beige decorations are rich in calcium, while the white ones resemble the ceramic pastes in term of composition. Those results will be the focus of the present communication. They will be soon complemented by mineralogical data using petrographical and XRD analyses. In addition, a comparative analysis with geological samples from nearby sites and also with ceramic replicas fired from these samples is planned for provenance studies