LUMINESCENCE DATING OF AEOLIAN SEDIMENTS: CURRENT STATE-OF-THE-ART AND FUTURE DIRECTIONS

Luminescence dating of sediments began in earnest with the thermoluminescence (TL) dating of aeolian sediments, including sand dunes and loess. The primary reason for researchers applying this technique to these contexts was the expectation of significant daylight exposure times for grains prior to burial at deposition. Many hours of daylight exposure is required to reduce trapped charge populations responsible for TL signals to a stable “residual” level. The success of this approach in terms of internal stratigraphic consistency and agreement with independent age control in the rare circumstances where this was available such as at archaeological sites, broadly sustains this expectation. Optical dating using the optically stimulated luminescence (OSL) signal of quartz and the infra-red stimulated luminescence (IRSL) signal of feldspar was developed later; these techniques were specifically focused at isolating only the most light sensitive components of the trapped charge populations. The single aliquot regenerative-dose (SAR) OSL protocol for quartz developed around 15 years ago revolutionized luminescence dating, providing a widely applicable and reliable method to date sediments. Furthermore, this approach provides indications of incomplete signal zeroing at deposition or post-depositional mixing, allowing problem samples to be rejected or circumvented. Much effort has been put into determining dune construction chronologies for the major sand seas using this approach, and major advances have been made in understanding the development of dunes and dunefields, and the timing of periods of dune formation in many regions. However, not every location is well suited to this approach, and even in locations where results are forthcoming, problems can exist for some samples. Single grain OSL measurements of quartz grains, and more recently post-IR IRSL age determination of single grains of K-feldspar, can provide more reliable age determinations, besides offering information concerning the processes operating during grain transport and deposition, and post-depositional mixing. The limits of robust interpretation of luminescence age estimates, and the problems that approaches currently under development may help address, will be examined, including applications to other planets.