Investigating the provenance of iron bars from Les Saintes‐Maries‐de‐la‐Mer Roman shipwrecks (south‐east France) with iron isotopes

Abstract

AbstractFe isotopes were used to determine the origin of iron bars from Les Saintes‐Maries‐de‐la‐Mer Roman shipwrecks, which was a major archaeological finding at the end of the 20th century in France. Their Fe isotope composition was measured by multi collector‐inductively coupled plasma‐mass spectrometry (MC‐ICP‐MS) after chemical Fe purification. The results allowed us to suggest provenances that were compared with those based on trace element analyses of slag inclusions. For most of the bars, we validate the provenance hypotheses previously proposed. Two bar groups originate from the Montagne Noire metallurgical district (south‐west France), whereas a third group comes from another source, not clearly identified so far. In this context of Roman iron production, we argue for a non‐spatially segmented production, where bars were manufactured close to smelting sites. Combined trace element and Fe isotope analyses on the same objects provide crucial information about the nature of their ore source. The elemental heterogeneity, positive Eu anomaly and Fe isotopic homogeneity of several bars were inherited from gossan‐type ores, whereas the negative Eu anomaly and variable Fe isotopes signature of others most likely correspond to sedimentary iron ores. This study demonstrates that combined trace element and Fe isotopes analyses in a well‐defined archaeological context is a promising approach for provenance studies of iron metals of archaeological interest.