The use of Ti centers for estimating burial doses of single quartz grains:: A case study from an aeolian deposit ∼2 Ma old

Several single quartz grains from an aeolian deposit (Beerse Member, N. Belgium, similar to 2 Ma old) are investigated using Q-band electron spin resonance (ESR) spectroscopy. Palaeodose estimates based on Ti centers are presented both for grains containing a mixture of Ti-Li and Ti-H centers (group 1), and grains containing only the Li compensated type of Ti centers (group 2). The results are obtained using the regenerative dose method after thermal zeroing. The separate Ti-Li and Ti-H palaeodoses from group I show severe over- and underestimates of the expected burial dose, respectively. In contrast, palaeodoses based on the total Ti defect concentration are in fair agreement with the expected dose, as are the Ti-Li palaeodoses from grains of group 2. As to the origin of this, several possible mechanisms are proposed, but none appears adequate to provide a satisfactory explanation. Nevertheless, this study shows that reasonable palaeodose estimates can be obtained if they are based on the use of either all Ti absorption lines or only the Ti-Li ones, depending on which centers are present in the quartz grains. These results may provide an important step forward in the development of a solid ESR dating protocol for sedimentary deposits up to 2 Ma old. (c) 2005 Elsevier Ltd. All rights reserved.