Osl dating sediments
Optically stimulated luminescence (OSL) dating is used to determine the (robust) chronology of the phases of sediment deposition and incision in a headwater sub-basin of the Yzeron Basin, France.
Different statistical approaches to extract the mean equivalent dose from dose distributions are compared to estimate the effect of differential bleaching of the OSL signal prior to deposition.
The channel incised during this period was later partly filled with sediment.
The decline of agricultural land use from about 1915 onwards decreased sediment supply, while the increase of urbanisation from about 1950 amplified the flow energy of flooding by pluvial waters and overflows from storm basins, causing the presently ongoing incision in the area that began about AD 1975.
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.
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 trapping sites are imperfections of the lattice — impurities or defects.
It is concluded that sediment deposition was mainly forced by sediment supply from ploughing areas.