Following the natural zeroing event and subsequent burial, the natural minerals begin luminescence acquisition afresh from the ionizing radiation (alpha, beta and gamma) constantly provided by the decay of radioactive elements (U238, Th232, K40, Rb) present in the sediments and also from the cosmic rays.
For calculating the age, the radiation energy stored in the mineral (known as Paleodose) and the annual radioactivity rate (annual dose) from the surrounding sediments has to be calculated.
The ‘depth’ of the traps within which the electrons are held effectively dictates the point at which a sample will become saturated with charge and so the limit of the dating range.
The following events can be dated by luminescence technique i) The most recent sun bleaching (application in sediment dating) ii) The most recent thermal event (application in archaeology, baking by lava flows, fusion crust of meteorites) iii) Crystallization event (application in travertine's in caves) Sediment sample should be collected in steel pipe to avoid any exposure to sun light. In the lab (under sub-dued red light condition), chemical treatment, sieving and mineral extraction will be carried out.
This page was contributed by Dr Georgina King from the Aberystwyth Luminescence Research Laboratory in the Institute for Geography and Earth Sciences. OSL is used on glacial landforms that contain sand, such as sandur or sediments in glacial streams.
| 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).
Although a relatively new technique, particularly in subaqueous sediments, Strata Data have pioneered its industrial application in dating superficial seabed deposits for geohazard risk assessment.
Suitable for samples up to about 150Ka containing quartz. Ideal for young sediments with no biogenic material present or where the age of the sediments exceeds the range of 14C dating (c. Requires precise measurement of sample water content and salinity.