Provenance of lead ores used for water pipes production in the ancient Roman Gaul (Vienne, France)

The urban fabric of Roman cities developed through the installation of water supply networks, mainly made of lead (Pb). In Gaul, the city of Vienne (France) was central to the manufacturing of Pb artifacts, including large volumes of Pb water pipes. Although Pb artifacts were often labeled with Roman-period stamps indicating the location of manufacturing, our knowledge of the provenance of extracted Pb ore and the way they were imported remains limited. In this study, Roman-period artifacts were analyzed for Pb isotope signatures to document the source of Pb ore used in Vienne's manufactories. Lead isotope signatures were then compared with new local Pb ores data and an updated Pb isotope database using a new algorithm to identify the provenance of Pb. Results indicate that Pb used for artifact manufacturing at Vienne originates mainly from a single source. Data treatment with the new algorithm identifies the Rhenish Massif and the Pennines mining regions as the primary and most probable source, but some artifacts exhibit a similar isotope composition to that of local Pb ores. The similarity of the Pb isotopic signatures of the artifacts produced in Vienne with those of Mainz pipes and lead ingots from the Rhenish massif, as well as the synchronicity of the mining periods in this region, support the Rhenish Massif as the most likely source of Pb for Vienne. Finally, we propose the Rhine and Saone Rivers as the most probable Pb ores conveyance routes to Vienne during the Roman Period.