Strontium Isotope Analysis and the Southern Mesopotamian City: Intraurban ⁸⁷Sr/⁸⁶Sr Variation and Diagenesis at Ur (Iraq)

Two key gaps exist that constrain the ability of strontium isotope analysis to reveal the life histories of the animals and people that lived in and moved around ancient southern Mesopotamia: (1) the aridity and salinity of the Iraqi alluvium pose concerns for the preservation of biogenic strontium in bioarchaeological remains, and (2) the range of ⁸⁷Sr/⁸⁶Sr variation associated with specific locations is as yet poorly understood, complicating interpretation of bioarchaeological values. This paper reports the successful recovery of biogenic strontium isotope values in faunal bone excavated at Tell al-Muqayyar (the ancient city of Ur), establishing that bone is a material appropriate for ⁸⁷Sr/⁸⁶Sr analysis in at least some southern Mesopotamian contexts. Our data also reveal intraurban variability in soil ⁸⁷Sr/⁸⁶Sr values (0.70799–0.70821). This variation may reflect some combination of differential proximity to ancient watercourses, diachronic variation in the sediments deposited within the city, anthropogenic activity, and modern influences from the water table, for example. These results address the aforementioned gaps in strontium isotope analysis in the region. Future work is needed to clarify the roles of fluvial geology and diachronic change in establishing strontium baselines and local bioavailable strontium signals across Ur.