Defining ‘local signature’ in terms of Sr isotope composition using a tenth- to twelfth-century Anglo-Saxon population living on a Jurassic clay-carbonate terrain, Rutland, UK

Abstract

Abstract The Sr isotope ratios and Sr concentration in tooth enamel from a rural tenth-twelfth century Anglo-Saxon population living on a Jurassic clay-carbonate terrain in eastern England gives the following mean values: 87 Sr/ 86 Sr=0.7098±0.0018 (2σ, n =22) and Sr concentrations = 74±62 p.p.m. (2σ). The isotope data are taken to be representative of Anglo-Saxon biosphere values in the area of study. The Sr isotope composition of soil leachates, plant material, riverwaters and animal tooth enamel associated with the burial site were all analysed to see which gave the best approximation to these local Anglo-Saxon values, the aim being to define the best method of predicting the local Sr signature of areas for archaeological purposes. The Sr isotope composition of acetic acid soil leachates were dominated by the carbonate soil component and gave 0.7085±0.0020 water leachates gave 0.7090±0.0014 and plant material gave 0.7092±0.0018 (all at 2σ, n =12). All of these materials were less radiogenic that those of the Anglo-Saxon population. Riverwater gave the same result as the plants at 0.7092±0.0012 (2σ, n =3). The Anglo-Saxon animal tooth enamel gave the best match with a value of 0.7099±0.0017 (2σ, n =13). Analysis of variance (ANOVA) tests show that there is a high probability (>70% probability, 2SD) that the animals and the humans sampled were from the same population with respect to Sr isotope composition. Thus animal tooth enamel proved to be the best proxy, in this study, for the local human population.