Optically stimulated luminescence dating
Exposure of mineral grains to light or heat (at least 300˚C) reduces the luminescence to a low and definable residual level.
Often this luminescence “cycle" occurs repeatedly in many depositional environments with signal acquisition of mineral grains by exposure to ionizing radiation during the burial period and signal resetting (“zeroing") with light exposure concurrent to sediment erosion and transportation. (a) Luminescence is acquired in mineral grains with exposure to ionizing radiation and trapping of electrons.
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.
OSL dating provides an estimate of the time elapsed with latest period of burial and thus, yields a depositional age (Fig. (c) With burial and exposure to ionizing radiation free electrons are stored in charge defects within grains crystal lattice.Ensuing research in the 1970s documented that marine and other sediments with a prior sunlight exposure of hours to days were suitable for thermoluminescence dating (Wintle and Huntley, 1980).Discoveries in the 1980s and 1990s that exposure of quartz and feldspar grains to a tunable light source, initially with lasers and later by light emitting diodes, yield luminescence components that are solar reset within seconds to minutes, expanded greatly the utility of the method (Huntley et al., 1985; Hütt et al., 1988; Aitken, 1998).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).