Luminescence as a tool to reconstruct sediment transport pathways in a tidal inlet

Abstract

Luminescence dating methods are widely used to date coastal sediments, while luminescence tracing methods are a novel application to reconstruct coastal sediment pathways. Both methods rely on subaqueous resetting (bleaching) of luminescence signals by light. Differences in bleaching between grains and/or luminescence signals encode information on the light exposure history of individual grains and therefore yield information on past sediment transport. Here we assess the potential of multi-signal single-grain feldspar luminescence to inform about sediment pathways at Ameland tidal inlet in the Dutch Wadden Sea. We also tested whether nourished and native sands can be distinguished based on their luminescence signals.Single-grain infrared stimulated luminescence (IRSL50) and post-IR IRSL (pIRIR) were measured from samples collected from modern sea-floor deposits across the inlet. Equivalent dose (D_e) distributions were assessed using the Central Age Model (CAM), and bootstrapped versions of the Minimum Age Model (bMAM) and Maximum Age Model (bMAX) were applied to the IRSL50 D_e distributions. Spatial trends in CAM and bMAX-De reveal highest inherited doses at the tip of Ameland in the Borndiep channel, decreasing along transport pathways around the ebb-tidal delta. These patterns indicate erosion of Pleistocene sediments in the Borndiep channel and progressive bleaching of luminescence signals upon transport. Low D_e values in shallow areas reflect repeated reworking of Holocene sands within the active layer. Nourished and native sediments show indistinguishable luminescence characteristics for our dataset due to their shared Holocene origin.