Establishing the standardised growth curves of Late Pleistocene fossil teeth for electron spin resonance dating

Abstract

BackgroundGamma source irradiation is the most commonly used way at present for the equivalent dose (DE) determination of fossil samples in electron spin resonance (ESR) dating. However, it is facility-limited and time-consuming in many cases.PurposeThis study aims to establish the standardised growth curves (SGCs) of fossil enamel samples for determining the DE by ESR without gamma irradiation.MethodsFirst of all, we analyzed 20 tooth samples from the Late Pleistocene sites, and they exhibited similar dose response characteristics. Then, based on our preliminary work, we attempted to establish the SGCs of these Late Pleistocene fossil teeth using three different methods: (1) a simple method (fitting the natural dose points of fossil samples from Middle to Upper Pleistocene sites with exponential functions), (2) an average method (fitting the dose points with averaged ESR signal intensities), and (3) a representative sample method (establishing a SGC by using a representative sample). Finally, dose values obtained by each method were compared with those determined by the additive dose method (ADM).ResultsThe results of DE determined by the simple and average methods are close, with a deviation of less than 32% from the ADM results. The dose values obtained by SGC using the representative sample method generally agree with those of the ADM, with a deviation within 26%, which is the smallest among the three methods.ConclusionAlthough the uncertainties of the dose values obtained for the SGCs are not very close to those obtained using the ADM, it indicates the potential to quickly determine a more reasonable Dmax for irradiation, identify the possible intrusion of fossil samples, and analyze small or precious fossil samples.

Keywords

• electron spin resonance dating
• equivalent dose
• standardised growth curves
• fossil
• late pleistocene