TL ANALYSIS OF LOESS SAMPLES FROM ACHENHEIM

We have investigated four loess samples from Achenheim. Sample J2a and L1 were collected above and below a horizon with a supposed age of 30 ka. Sample O1 was collected below the last integlacial soil and T1 below the next interglacial soil. For the determination of EDs, the additive dose and regeneration techniques were applied using different filters. The additive dose technique was complicated by the observation that the dose-response could not be described by a single saturation function. We have applied two saturation functions and used only the values below the intercept dose for ED determination. Nearly all calculated ages are younger than expected. Given the uncertainties, there is not a significant difference between results obtained by the additive dose and the regeneration methods. The use of the BG12 and UG11 filters seem to give slightly lower results than the 5-58 filter. We have calculated mean lives for the TL signals of samples L1, O2 and T1 assuming the youngest possible estimates (30, 130 and 240 ka). Our measurements imply that the thermal stability of the recorded signals is somewhere in the 100-200 ka region for the 5-58 filter and around 100 ka for the other filters. Due to the uncertainty of the geological age estimates, these values are more likely upper limits of the thermal stability.