Evaluation of ESR residual dose in quartz modern samples, an investigation into environmental dependence - Archive ouverte HAL Accéder directement au contenu
Communication Dans Un Congrès Année : 2014

Evaluation of ESR residual dose in quartz modern samples, an investigation into environmental dependence

Résumé

Luminescence and ESR dating methods of quartz sediment are based on the natural resetting of the signal by light exposure (optical bleaching). When the bleaching is incomplete, a residual dose (DeR) is added to the post-depositional dose accumulated since the deposit and hence the age is overestimated. Insufficient bleaching is usually linked to the environment and conditions of transport/deposition of the quartz grains affecting the light exposure duration. Indeed, each transportation mode – fluvial, marine or aeolian – is associated to specific conditions of light exposure, depending mainly to the location of grains in the transport agent during the transport phase, the opacity of the transport environment and the velocity of the transport. The present study attempts to discriminate the modes of transport/deposition providing a satisfying reset of the ESR signals of quartz grains. For this purpose, we investigated bleaching rates and ESR residual doses of aluminum centers from “present-day” aeolian, fluvial and marine sediments sampled in various sedimentary environments. The bleaching efficiency evaluation in these different environments may help for a better understanding of the resetting phenomenon for quartz signals which represents presently the main difficulty for ESR dating. The results show that the residual doses are small enough to allow an ESR dating of the main part of the sediment transported in almost all the context examined in this study. The smallest residual doses are obtained from quartz grains within the range of 100–200 μm and transported in clear water. Some limits for the application of optically bleached quartz ESR dating appears nevertheless, mainly when the residual dose and the dose accumulated after the deposit are quite similar, i.e. for Upper Pleistocene samples.
Fichier non déposé

Dates et versions

hal-01729922 , version 1 (12-03-2018)

Identifiants

Citer

Pierre Voinchet, Shin Toyoda, Christophe Falguères, Marion Hernandez, Hélène Tissoux, et al.. Evaluation of ESR residual dose in quartz modern samples, an investigation into environmental dependence. 14th Luminescence and Electron Spin Resonance Dating, Jul 2014, Montréal, Canada. ⟨10.1016/j.quageo.2015.02.017⟩. ⟨hal-01729922⟩
145 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More