Chemical relative dating of skeletons of the Iron Age cemetery of Tabriz on the basis of fluorine, uranium, and nitrogen content

Abstract

Relative dating of archaeological bones by the measurement of fluorine, uranium, and/or nitrogen content is a well-established method, where the content of these elements in the bone structure must be determined. This research aims to study the human skeletal samples of Iron Age site of Blue Mosque in Tabriz, IRAN, on the basis of FUN relative dating method. In this way, the amount of fluorine in the selected samples was measured by UV–Vis spectrophotometry method, while the amount of uranium and nitrogen was determined by ICP-MS, and CHNS and Kjeldahl techniques, respectively. Totally, four bone samples of the skeleton from the cemetery were selected to be relatively dated. The results showed that sample no. 81.9 is the first one buried. Although the nitrogen content of this sample was the same as that of sample no. 80.6, but due to its higher concentration of fluorine and uranium compared to the other samples, it was likely the oldest sample studied at this work. While sample no. 80.6 had the lowest nitrogen content, but due to its lower levels of fluorine and uranium, it could be considered as the youngest,. Also, comparing the relative age of the two samples, no. 81.7 and no. 81.8, it can be concluded that sample no. 81.8 has spent more time under the soil. The results of this study clearly showed the necessity of applying all the three types of relative chemical dating methods (fluorine, uranium, and nitrogen dating) alongside, which is known as the FUN dating method.