Tin isotope characterization of bronze artifacts of the central Balkans

Isotopic analysis has proved to be an effective approach to determine the provenance of copper ore sources for the production of bronze artifacts. More recently, methods for Sn isotopic analysis of bronze have been developed. However, the viability of tin isotopes as a means to define groupings that may be attributed to varying ore sources, production methods, or recycling is still in question. In part, this is due to the numerically and/or geographically limited nature of published datasets. This study reports on the Sn isotopic composition of 52 artifacts from the later Bronze Age (1500-1100 BCE) from Serbia and western Romania. The majority of samples cluster between 0.4 and 0.8 per mil for δ124Sn, and 0.2 and 0.4 per mil for δ120Sn (relative to NIST SRM 3161A), and this isotopic grouping of bronze artifacts occurs across Serbia. However, groupings of isotopically heavier and lighter artifacts are evident, and each corresponds to a more limited geographic range. Artifacts associated with higher δSn values are limited to the Vojvodina region of northern Serbia, whereas a cluster of bronzes with lower Sn-isotopic signatures are constrained to the Banat along the Serbia-Romania border, and Transylvania. One low-value outlier corresponds to an uncontextualized find near Kruševac at the southern extent of the study area. Geographic correlation of the low-value cluster with known tin mineralization in Transylvania, and the moderate-value cluster with placer tin deposits of western Serbia, suggests that these distinct bronze Sn-isotopic signatures might reflect exploitation of different tin ores. The small cluster of high Sn-isotopic values from bronzes from the Vojvodina region might reflect bronze recycling in this area that lies furthest from both known tin ore sources.