Optically stimulated luminescence dating laboratory church of god dating daan
We call this measurement our “equivalent dose”, because it is equivalent to the dose that the sample received in nature.
The equivalent dose value is measured in the SI unit “grays” (Gy). Depositional pathway tracing in glacial catchments using the OSL of coarse-grained quartz and K-feldspar.
Hollie Wynne (Aberystwyth University) stirs OSL samples being treated with acid in the preparation lab of the Aberystwyth Luminescence Research Laboratory. We make an approximation of the number of trapped electrons by measuring the light that they emit following stimulation by light (hence the name of the technique, “Optically stimulated luminescence”).
The way that we do this is through sampling sand from the landforms in opaque plastic tubes and taking the sample back to a luminescence laboratory where only red light conditions are used. Optically stimulated luminescence dating of glaciofluvial sediments on the Canterbury Plains, South Island, New Zealand.
We analyse the quartz or feldspar minerals in sand deposits.
When these quartz or feldspar minerals are exposed to the ionising radiation emitted by the radioactive isotopes in zircons, electrons within the crystals migrate and become trapped in their crystal structure.
If we assume that the radiation dose rate of the sediment has remained constant over time, then if we measure that dose rate, we can calculate the sample age. | Calculating Age | Challenges for OSL | Case studies of OSL dating in glacial environments | References | Comments | Another way of dating glacial landforms is optically stimulated luminescence dating (OSL). The OSL signal is reset by exposure to sunlight, so the signal is reset to zero while the sand is being transported (such as in a glacial meltwater stream). Luminescence dating can be applied to the age range from present to approximately 500,000 years, thus spanning critical time-scales for human development and quaternary landscape formation.
Precision varies from ±3-10% of age for heated materials and ±5-20 % for sediments.
Following an initial zeroing event, for example heating of ceramics and burnt stones, or optical bleaching of certain classes of sediments, the system acquires an increasing luminescence signal in response to exposure to background sources of ionising radiation.