Optically stimulated luminescence dating method
The recent development of charge transfer techniques for potassium feldspar (e.g. A common approach in OSL dating is to use SAR protocols on quartz aliquots with the protocols customized for a specific sample, a study site or area (Fig. The SAR approach is predicated on a number of assumptions.post IR290) that use elevated preheats (~290˚C) to transfer electrons from stable deeper to shallower traps for ease of measurement has extended dating possibilities to 10 timescales for well solar reset grains (Duller and Wintle, 2012). 3: (a) Determination of equivalent dose (in grays) using the single aliquot regenerative (SAR) protocols, where the natural luminescence emission is Ln/Tn and the regenerative dose is Lx/Tx; sensitivity changes are corrected by the administration of a small text dose (e.g. First, that the fast component of luminescence emissions, light released within the first 4 seconds, is the dominant signal, usually 30 aliquots of quartz or feldspar grains (Fig. Each aliquot often contains 10’s to 100’s of quartz grains; the total number dependent on grain size (e.g. Statistical analyses of equivalent dose distributions are critical to render accurate OSL ages with specific age models (Galbraith and Roberts, 2012).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 exposure of quartz and feldspar grains to sunlight for 60 seconds effectively diminishes the time-stored OSL signal to a low definable level.
95% reduction in OSL within 4 seconds of exposure to light from blue diodes Optically stimulated luminescence (OSL) dating or optical dating provides a measure of time since sediment grains were deposited and shielded from further light or heat exposure, which often effectively resets the luminescence signal (Fig.1).
This technique, as thermoluminescence, was originally developed in the 1950s and 1960s to date fired archaeological materials, like ceramics (Aitken, 1985).
However, some quartz grains yield considerable emissions with infrared excitation and may host feldspathic or other mineral inclusions; such grains should be analyzed as feldspar grains.
Sediment grains act as long-term radiation dosimeters when shielded from further light exposure with the luminescence signal a measure of radiation exposure during the burial period.
Similar protocols have been also developed for quartz that has been particularly useful for dating Pleistocene loess deposits (e.g. A common metric used is an overdispersion percentage of a D values within 2σ errors, though rarely, if ever is a naught value calculated with equivalent dose data.