Electron Spin Resonance (ESR) And Thermoluminescence (TL) Studies of Stalagmitic Floors of the Caune de L'Arago at Tautavel (France)

摘要

The geological radiation dose to the stalagmites of various stratigraphic levels of the Caune de L'Arago at Tautavel has been measured by Thermoluminescence (TL) and Electron Spin Resonance (ESR). In all samples the TL natural spectrum presents a well developed 280 deg C peak and a subordinate 350 deg C peak, while the ESR line spectrum may present the h sub 1 , h sub 2 and h sub 3 radiative lines of Yokoyama et al. or only h sub 2 . All TL peaks and ESR lines do increase with the laboratory applied radiation ( beta or gamma ) doses. The activated h sub 2 line is visibly unstable in laboratory conditions as well as apparently the h sub 3 line in one sample. Within the experimental precision, the geological doses determined from the 280 deg C peak and h sub 3 line on one band and the 350 deg C peak and h exp 1 line (after thermal treatment of the later, see Yokoyama et al.) on the other band are identical. When the 280C natural peak is visibly affected by natural fading as shown by the plateau test, so is h sub 3 , and the geological doses of the 280 deg C-h sub 3 peaks are lowered by the same factor as compared to those of the 350 deg C-h sub 1 peaks. Annealing experiments show that the relationships between the TL and ESR peaks may be difficult to analyse in some samples due to the possible occurrence of non radiative components in some ESR lines. Such components appear clearly at temperatures above approx. 180-200 deg C and might possibly be present below. This may have important implications for the selection of samples to be dated by ESR. (Atomindex citation 16:078953)