Optically stimulated luminescence dating of fluvial deposits a review 100 real free cam 2 cam

Après une présentation des principes physiques généraux, les procédures mises en œuvre aussi bien sur le terrain qu’en laboratoire sont abordées, à partir de l’exemple des analyses réalisées sur des alluvions sableuses issues d’une basse terrasse de la Moselle.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.

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).

They lead to the emission of electrons which are subsequently trapped in crystalline lattice defects.

Ainsi, l’article souligne l’importance de la méthode pour les recherches en géomorphologie, notamment dans le cadre du développement de la géomorphologie quantitative.

Absolute dating methods have been developed over the last five decades (Jull and Scott, 2007).

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.

This results in the release of trapped electrons (“bleaching”) and the emission of the luminescence signal.

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.

2, the luminescence signal obtained by stimulation corresponds with a decay curve which shows the progressive emptying of the electrons from the traps.

They are now largely used to date not only palaeontological or organic remains, but also minerals that characterise detrital clastic sedimentary material.

The most common methods applied to minerals are cosmogenic radionuclides, electron spin resonance (ESR) and luminescence techniques.

Hence it underlines the increasing importance of the method to geomorphological research, especially by contributing to the development of quantitative geomorphology.

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