Luminescence dating of glacially sourced deposits from northern Switzerland: Comparing multigrain aliquots and single grains of quartz and feldspar

Abstract

A complex picture of the Pleistocene glaciation history of northern Switzerland has been identified over the last three decades. To gain further insights into the long-term landscape evolution, numerical dating is required. In the absence of alternative dating techniques, luminescence dating is the key method for establishing chronological constraints of past glaciations. However, this is presented with complex challenges, especially in regard to the resetting of the luminescence signal prior to deposition, the components contributing to the signal as well as the signal intensity and stability. In this study, the luminescence properties of glacially sourced deposits from northern Switzerland are assessed using single aliquot (SA) and single grain (SG) measurements of feldspar (F) and quartz (Q). While no obvious connection between bleaching and distal or proximal deposition in relation to the proposed ice margin is observed, most samples seem to reveal a partially bleached signature in F SG De measurements. This appears to be masked in the respective F SA measurements even though only few grains emit luminescence signals. In addition, comparisons between fading corrected infrared stimulated luminescence (IR) and post-infrared infrared stimulated luminescence (pIR) De values appear to be unreliable indicators of bleaching, even though these signals bleach at different rates. Hence, it is recommended to conduct both IR and pIR investigations in combination with Q measurements on a SG level. The dating potential of the investigated deposits remains rather limited, yet, in the sedimentologic context the presented results reveal that several glacial advances occurred prior to the Last Interglacial in the study area.