DEPENDENCE OF LUMINESCENCE CHARACTERISTICS OF IRRADIATED QUARTZ WITH THE THERMAL TREATMENT AND CONSEQUENCES FOR TL DATING.

The dependence of luminescence properties of archaeological quartz pebbles with their thermal history is investigated and consequences for TL-dating are examined; the archaeological samples studied were collected from Solutrean layers at Laugerie Haute West rock shelter (Dordogne, France). This study is supported by a simulation experiment carried out on a natural quartz, using a combined approach by Cathodoluminescence (CL), Thermoluminescence (FL) and Electron Paramagnetic Resonance (EPR) techniques. The quartz grains used were given a high beta dose, then independent aliquots were annealed in air at a temperature varying from 3 00°C to 900°C. It has been observed that the TL growth with dose, after annealing and re-irradiation, evolved from a linear behaviour to a marked supralinear one according to annealing temperature linked respectively with a partial or a total thermal drainage of charges in deep traps. Consequently, during the TL-dating process of materials anciently heated at low temperature in the past (between 3 00°C and 500°C approximately), a special care has to be taken by adopting an annealing treatment that approaches the filling state of trapped charges that the samples had after the archaeological zeroing. This necessary new requirement strengthens accuracy and reliability of TL-dates obtained at Laugerie Haute. [ABSTRACT FROM AUTHOR]