ESR AND MASS-SPECTROMETRIC URANIUM-SERIES DATING STUDIES OF A MAMMOTHTOOTH FROM STANTON HARCOURT, OXFORDSHIRE, ENGLAND

The age of the Channel Deposits at Stanton Harcourt, Oxfordshire, Engl and, has been a topic of debate with important implications for Britis h Pleistocene stratigraphy. Recent excavations led by K. Scott reveal ample evidence for ancient environmental conditions characteristic of an interglacial. However, the question remains on the assignment of it s age. At present it is thought to represent an interglacial correspon ding to either marine OI Stage 7 or 5e. In an attempt to constrain the chronology of the site, and to assess the techniques' reliability, we have made electron spin resonance (ESR) measurements on enamel and ma ss-spectrometric U-series measurements on both enamel and dentine from a mammoth tooth buried in the Channel Deposits at Stanton Harcourt. F our dentine samples gave U-series dates between 65.4+/-0.4 and 146.5+/ -1.0 ka and two enamel samples between these dentine layers were dated to 53.3+/-0.2 and 61.1+/-0.6 ka. The corresponding ESR age estimates for the enamel samples are 59+/-6 and 62+/-4 ka (early U-uptake, EU) a nd 95+/-11 and 98+/-7 ka (linear U-uptake, LU). The recent U-uptake (R U) dates are 245+/-38 and 238+/-31 ka, but in light of the U-series da ta we would not expect these to represent realistic age estimates. Sim ilar ESR results were obtained from two other adjacent enamel samples. The effect of the large size of the mammoth tooth on the external gam ma dose, and the internal gamma contribution from the high U content o f the dentine, are considered. While the recent uptake ESR dates appea r to coincide with OI Stage 7, all the early and linear uptake ESR and mass-spectrometric U-series dates are younger than the expected age e stimation based on recent geological interpretation and amino acid rac emisation measurements (>200 ka) and optical dating studies (200-450 k a). Possible causes of the unexpected dating results are discussed. We conclude that our mass-spectrometric U-series and EU and LU ESR measu rements represent minimum age estimates for the tooth analysed. Our re sults seem to suggest that the tooth and hence the Channel Deposits ar e at least 147 ka in age, i.e. predating the last interglacial. (C) 19 97 Elsevier Science Ltd.