Challenges involved in obtaining luminescence ages for long records of aridity: Examples from the Arabian Peninsula

In the last 35 years luminescence dating has provided a large database of ages for the deposition of dunes in desert environments. Over 380 ages have been generated for dunes from the Arabian Peninsula and demonstrate episodic dune deposition in the late Quaternary, but give a less clear pattern prior to ∼50 ka. Interpreting databases of luminescence ages faces two issues. First, the precision of luminescence ages in the last 50 ka is between 5 and 10%, but for older ages the uncertainties may be much larger as luminescence signals reach saturation. Second, different luminescence signals from quartz and from feldspar have been used over the last 35 years as the method has developed and expanded. These different signals have different saturation limits and different rates at which they are reset by exposure to daylight at deposition. Approaches which focus on the most light sensitive signals (e.g. quartz OSL) are better suited to dating recent events, while those which show growth of the luminescence signal over the largest dose range (e.g. the thermally transferred OSL (TT-OSL) signal from quartz and the post-infrared infrared stimulated luminescence (pIR-IRSL) from feldspars) have the potential to date much older events.