Quartz osl dating
La place des datations OSL dans la recherche géomorphologique en France et son potentiel pour les recherches futures sont décrits à travers une présentation de la diversité des environnements sédimentaires et des problématiques pouvant être traités.Ainsi, l’article souligne l’importance de la méthode pour les recherches en géomorphologie, notamment dans le cadre du développement de la géomorphologie quantitative.It is exposed again to radiation and accumulates trapped electrons.Much later the grain is sampled in the field and stimulated in the laboratory using either visible light for quartz (OSL As shown in fig.The paper also reviews the place of OSL dating in geomorphological research in France and assesses its potential for further research, by focusing on the diversity of sedimentary environments and topics to which it can be usefully applied.Hence it underlines the increasing importance of the method to geomorphological research, especially by contributing to the development of quantitative geomorphology.Improvements of this technique led to the development, for more than twenty years, of the optical dating method [commonly referred to as Optically Stimuled Luminescence (OSL)] which is now applied to sediments from various origins (Wintle, 2008).
The radiation () comes from radionucleides which are present in the mineral and its natural environment, mainly uranium, thorium (and their decay products), potassium, and for a small proportion from cosmic particles (Aitken, 1985).
The most common methods applied to minerals are cosmogenic radionuclides, electron spin resonance (ESR) and luminescence techniques.
The latter were first applied to burned minerals from archaeological artefacts [thermoluminescence (TL) method].
The intensity of the signal is proportional to the amount of released electrons.
The wavelength of the signal is allocated to the nature of the mineral: the OSL from quartz is typically measured in ultra-violet (340-370 nm wavelength), while quartz also emits in blue (460-500 nm wavelength) and in orange-red (600-650 nm wavelength; Huntley , when the mineral is stored within the host-rock), natural radiation generates the trapping of electrons and the build-up of a latent luminescence signal; ii) when a grain is produced by mechanical erosion and transported (at the Earth’s surface, in the air, or in a river), it is exposed to sunlight.
The total amount of trapped electrons within a crystal is proportional to the total energy absorbed and retained by the crystal (or dose), hence the time it was exposed to radiation.