Optically stimulated luminescence dating of fluvial deposits
In the past 15 years there have been significant advances in luminescence dating with the advent of single aliquot and grain analysis, and associated protocols with blue/green diodes that can effectively compensated for laboratory induced sensitivity changes (Murray and Wintle, 2003; Wintle and Murray, 2006; Duller, 2012) and render accurate ages for the past ca. Most recently, the development of protocols for inducing the thermal-transfer of deeply trapped electrons has extended potentially OSL dating to the 106 year timescale for well solar-reset quartz and potassium feldspar grains from eolian and littoral environments (Duller and Wintle, 2012).
The OSL signal of potassium feldspar is usually more resista nt to solar resetting than most quartz.
This residual level is the point from which the geological OSL signal accumulates post burial.
Many types of sediment receive prolonged ( 1 hr) light exposure with transport and deposition, particularly in eolian, littoral and sublittoral sedimentary environments.
The purity of the quartz extract is primal for effective dating because a small amount contamination (1%) by potassium feldspar and other minerals can dominate the luminescence emissions.
Multiple soaks in HF may be needed to obtain a pure quartz separate.