LUMINESCENCE DATING OF INTERGLACIAL COASTAL MARINE ENVIRONMENTS

Pre-Holocene interglacial high sea level stands are recognized in the modern landscape by their sedimentary and paleontological facies, elevation, and less commonly by numerical dating. Luminescence dating methods (OSL) developed over the last decade offer absolute depositional ages. These are therefore more useful than the commonly used technique of aminoacid racemization, but OSL comes with much less precision than U-Th dating from corals. A unique advantage of luminescence is its almost ubiquitous applicability since the routinely used dosimeters, minerals of quartz and feldspars, can be found on most beaches. Specific methodologies were developed for both minerals, and even though a relatively large body of OSL ages has recently appeared in the literature, dating applications to sediments from former high sea level beaches and coastal dunes are still clouded by low accuracy, caused by one or several of the following: onset of saturation, multimodal age distribution from single aliquots and uncertainties about dosimetry, especially for the correct assessment of water content prevalent during the time of burial or the impact of early diagenesis for carbonate-rich sediment on the dose-rate. A major limitation arises from the near saturation of the natural luminescence level, commonly observed for sediments older than the Last Interglacial. The latter imposes severe constraints in the use of quartz as a reliable dosimeter for any environment beyond the Late Pleistocene. In the case of feldspar, if apparent ages are corrected for anomalous fading (AF), interglacial coastal sediments might be datable up to ca 500 ka. These AF-corrected ages may suffer from the uncertainty in assessing the fading rate. In which case, uncertainties in the order of several 10’s of ka could be propagated in the final ages. At this stage of research, reliable luminescence chronologies have been obtained for the last three high sea level stands. Sites from Europe, Africa and America will be discussed and compared in order to assess the contribution of luminescence to the chronology of former coastal environments.