Improving the Reliability of 14C Dating of Snail Shells: Towards an Innovative Approach Using Conchiolin ; Fiabilisation de la datation 14C des coquilles d’escargots : vers une approche innovante par la conchyoline

International audience ; Establishing chronological frameworks in archaeological contexts can be challenging due to the absence of suitable materials for radiocarbon dating, such as charcoal, wood, or bones. In certain cases, snail shells become the only available material for dating. However, as early as the 1980s, it was demonstrated that the mineral carbon in these shells can be a mixture of plant-derived carbon from the snail's diet and geological carbon, devoid of 14C, associated with the calcium required for shell formation. This results in an apparent aging effect in radiocarbon dates obtained from the carbonate of these shells. While selecting specific species in well-defined geological and sedimentary contexts can mitigate this risk, building a chronology based on 14C dating of snail shell carbonate remains a challenge. Unlike carbonate, the organic carbon in the shell, which exclusively originates from the animal’s plant-based diet, is not subject to this aging effect. Thus, radiocarbon dating of conchiolin—the proteins that make up the organic structure of snail shells—offers a promising alternative. Although conchiolin is present in very small quantities, the use of a MICADAS (Mini Carbon Dating System), capable of measuring just a few dozen µgC, makes this alternative feasible. The main challenge lay in developing an extraction protocol capable of dissolving the carbonate while preserving the complex three-dimensional structure of the proteins, which is essential for further processing in the 14C dating workflow. This poster presents the extraction protocol developed for conchiolin, along with the first characterization results of the extracted proteins. ; La mise en place de chronologies en contexte archéologique peut être compliquée en raison de l’absence de matériels appropriés pour la datation 14C, tels que le charbon, le bois ou les ossements. Dans certains cas, les coquilles d’escargots deviennent les seuls supports disponibles pour la datation. Cependant, dès les années 1980, il a été ...