Optically Stimulated Luminescence (OSL) dating is a dating method for Quaternary sediments and archaeological materials.
Heat can also reset the OSL signal, so in the case of archaeological material (pottery, bricks, ceramics, hearth stones), the event that is dated is the last time the material was heated above 300°C, e.g. OSL dating is usually performed on sand-sized grains of quartz (c.200 μm), although feldspar can also be used.
The lower age limit is around 30 years, the upper limit around 100-300 thousand years, depending on the sediment.
With the assistance of Fugro UK we have developed a method for converting the measured water content to a time-averaged water content for each sample.
The limiting factor in the age range for luminescence dating is the 'saturation' of the signal at large dose rates (i.e. Accurate age determination therefore becomes increasingly difficult for older samples and there is a loss in dating precision (an increase in statistical uncertainty).
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.
The basic cost is £550/sample plus reporting time based on your requirements.
A residue of pure quartz is extracted by chemical digestion in hydrochloric acid, hydrogen peroxide and fluorosilicic acid, in a process which may take several weeks.
The luminescence of each sample is measured using industry-standard Luminescence Readers (manufactured by Risoe National Laboratories, Denmark) which incorporate 90Sr beta-sources, and 470nm LED optical stimulation.
New advances in OSL methods may push this limit towards ½ million years in the near future. The luminescence dating laboratory at Wits is the only one of its kind in southern Africa.
We have a range of specialist facilities, including We provide luminescence ages on a collaborative basis (co-authorship on publications using lab results), with a fee of R4600 VAT per sample. We would like to give advice on sampling strategies before fieldwork is attempted.
The report will contain OSL results calibrated for sample water content and salinity.