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ESR dating of sedimentary quartz: Possibilities and limitations of the single-grain approach |
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| Authors: | Koen Beerten Andre Stesmans |
| Institution: | aLaboratorium voor Stratigrafie, Afdeling Historische Geologie, Departement Geografie-Geologie, Katholieke Universiteit Leuven, Redingenstraat 16, 3000 Leuven, Belgium bAfdeling Halfgeleiderfysica, Departement Natuurkunde en Sterrenkunde, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, 3001 Leuven, Belgium |
| Abstract: | Usually, multiple-grain aliquots are used for electron spin resonance (ESR) dating of sediments. However, this approach excludes the ability of detecting insufficient bleaching, as would be the case when measuring several single aliquots or single grains. In this paper, we present preliminary results of single-grain ESR dating experiments on three different sedimentary deposits (fluvial, fluvio-aeolian and desert aeolian), ranging in age between  100 ka and 2 Ma. Titanium-related impurity centres (Ti–Li and Ti–H) were measured in a Q-band ESR spectrometer for estimating equivalent doses (De) of individual quartz grains (0.5–1 mm). Both additive and regenerative dose methods were used. The resulting De plots show a large scatter in De—from 100 Gy to more than 600 Gy—for the fluvial sample, probably reflecting different bleaching histories of the grains. On the contrary, a clear plateau can be observed in De for sands with a strong aeolian component. Preliminary single-grain ESR ages are in relatively good agreement with independent estimates, the best results being obtained for the desert aeolian sample (200 ka). It is concluded that ESR has a promising potential for estimating large naturally accumulated doses of well-bleached sediments. Nevertheless, the method is challenged by several experimental difficulties, such as long measurement times, excessive errors, and presumably a complex interrelationship between Ti–Li and Ti–H components. |
| Keywords: | ESR spectroscopy Q-band Single quartz grains Ti centres Pleistocene |
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