Preferable use of red-thermoluminescence (RTL)-dating for quartz extracts from archaeologically burnt pottery - comparison of RTL and BTL (blue-TL) measurements using single-aliquot regenerative-dose (SAR) method

Abstract

Red- (RTL) and blue-thermoluminescence (BTL) dating procedures for quartz aliquots were applied to nine Jomon pottery pieces, which were manufactured and used 3,500-6,000 years ago. Quartz grain extracts from each piece were measured with respects of both RTL and BTL using a new automated luminescence measuring system that included a small X-ray irradiator and a single-aliquot regenerative-dose (SAR) protocol. Equivalent doses from RTL were evaluated to be higher than BTL-doses in most cases. This is due to contamination of feldspar grains and/or to light-bleaching effects. In a few cases, BTL-quartz constituents have not been detected. The TL-age results, obtained using the equivalent doses and annual doses, indicated that the RTL-ages are closer to the predicted archeological ages, giving more reliable results than the BTL-ages. Conclusively, the RTL-dating was recommended for the quartz extracts from the archaeologically burnt materials in the present experiments, probably because of the high impurity contents in the quartz grains. Although the existing BTL-dating could be already applied to the pure quartz grains without much content of impurities, the check of TL-properties, including RTL or BTL, should be considered prior to the practical TL-dating for burnt quartz fractions.