The problem of long-term fading of absorbed palaeodose on ESR-dating of quaternary mollusc shells

Due to relatively low thermal stability of radiation-induced centres in biogenic carbonate of subfossil molluscs (mean life τ = 3.7 x 10 5y at 100C, g = 2.0012) correct dating of the latter by means of ESR-spectroscopy without considering natural relaxation of absorbed palaeodose may prove rather problematic. The long-term fading of palaeodose complicates correlation between absorbed natural radiation energy, and the value of the laboratory effect observed restricts the upper dating limit and may result in considerably younger ages on dating of the most ancient Quaternary samples. The present paper deals with the connection between the absorbed palaeodose value and the age of the sample, its dosimetric properties, as well as with the effect of different factors on the upper dating limit. Mathematical models of the palaeodose accumulation in nature are discussed. The author suggests palaeodosimetric equations for calculating the age of shells and some other materials. The equations may be applied both to ESR-and TL-dating. (author)