Osl age dating
In addition, the inherent residual level is influenced by the susceptibility of the luminescence signal of a specific mineral to solar resetting.The OSL signal of potassium feldspar is usually more resista nt to solar resetting than most quartz.Purity of the separate is accessed through microscopic inspection and point counting of grain mineralogy.Spectral purity of quartz is often determined by excitation by infrared light from a diode array with subsequent light emissions associated presumably with feldspar contaminants.Often mineral grains that are fresh from a bedrock sources have significantly lower luminescence emissions per radiation dose in comparison to grains that have cycled repeatedly. (b) The luminescence for grains is zeroed by exposure to sunlight with erosion and transport.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).
A subpopulation of stored electrons with trap depths of ~1.3 to 3 e V is a subsequent source for time-diagnostic luminescence emissions.
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.
OSL dating is predicated on measurements of a specific mineral and particle size, usually quartz or potassium feldspar.
Mineral separations are performed by standard techniques using heavy liquids and hydrofluoric acid (HF) to digest non-quartz minerals and etch the outer 10 to 20 µm of quartz grains which are affected alpha radiation.