THERMOLUMINESCENCE DATING OF AEOLIAN SANDS FROM POLYCYCLIC SOIL PROFILES IN THE SOUTHERN NETHERLANDS

An aeolian cover sand section with excellent C-14 control on Bolling peat and other sections with C-14 dates on humic acid extracts from Holocene polycyclic soil profiles in the southern Netherlands have been TL dated using K-feldspar separates. The C-14 dates indicated two periods of Weichselian cover sand deposition and three periods of Holocene drift sand accumulation (Bronze age, Medieval time and Post-Medieval time) alternating with periods in which the landscape was stabilized. As conventional TL methods proved unsatisfactory, a new approach has been applied to establish the equivalent dose (ED) of the samples, using the formula ED = D/(1-f). D is the dose value determined for a specific bleaching time and f is the fraction of the radiation-induced TL-signal that remains after this bleaching time, as determined by additional laboratory measurements on irradiated material. In spite of the new approach to determine the ED, the TL ages of the Weichselian cover sands are underestimated, as has been noted before on similar material. However, the TL ages of the Holocene drift sand samples indicate that TL can be used to distinguish these aeolian sands when soil profiles are lacking. An example of this is provided.