Luminescence properties and dating of glacial to periglacial sediments from northern Switzerland

Abstract

Abstract. Luminescence dating has become a pillar of the understanding of Pleistocene glacial advances in the northern foreland of the Swiss Alps. However, both quartz and feldspar from the region are equally challenging as dosimeters with anomalous fading and partial bleaching being some of the obstacles to overcome for the establishment of decisive chronologies. In this study, luminescence properties of coarse- and fine-grained quartz, feldspar, and polymineral fractions of eight samples from a palaeovalley, Rinikerfeld in northern Switzerland, are systematically assessed. Standard performance tests are conducted on all four fractions. Deconvolution of luminescence signals of the quartz fractions is implemented and shows the dominance of stable fast components. Reader-specific low preheat temperatures are investigated on the infrared stimulated luminescence (IRSL) signal of feldspar. Thermal stability of this signal is found for low preheats, and thermal quenching could be excluded for higher preheats. However, anomalous fading is observed in the feldspar and polymineral IRSL signals and two correction approaches are applied. For one approach, fading corrected coarse-grained feldspar ages are consistent with those derived from quartz. In general, coarse-grained quartz and feldspar, as well as the fine-grained polymineral fraction of one sample, are in chrono-stratigraphic agreement and present negligible evidence for partial bleaching. However, ages derived from fine-grained quartz are found to underestimate those of the coarse-grained quartz fractions. Hence, the impact of alpha efficiency and water content on the dose rate and thus the ages are assessed. A finite explanation for the observed discrepancies remains lacking, but this systematic investigation of different luminescence signals allows for the establishment of a chronology for the palaeovalley fill dating back to at least Marine Isotope Stage 6 (MIS 6).

Age of the Most Extensive Glaciation in the Alps

“…Therefore, we suggest that the first overdeepened valley formed not later than approximately 500 ka. Recently, several drill cores were obtained from overdeepened valleys in the Swiss northern Alpine Foreland to comprehensively analyze the infill and to reconstruct the glaciation history [83][84][85][86][87]. Sediments from the base of the investigated overdeepened valley fills were dated to approximately 180 ka [83][84][85][86][87].…”

“…Recently, several drill cores were obtained from overdeepened valleys in the Swiss northern Alpine Foreland to comprehensively analyze the infill and to reconstruct the glaciation history [83][84][85][86][87]. Sediments from the base of the investigated overdeepened valley fills were dated to approximately 180 ka [83][84][85][86][87]. Some of these also represent an older sedimentary infill [74].…”

“…According to these findings, the beginning of the overdeepening has been assigned to a glacial advance at 260 ka or older [83]. In the Lower Aare Valley, the presence of different sediment units implies that during 160 ka to 180 ka, the area was dominated by a periglacial setting; the lowermost sands covering a glacial diamicton are older than 180 ka [87]. The presence of glaciolacustrine sediments, dated by applying OSL, indicate that glacial lakes dominated the Wehn Valley and the Lower Glatt Valley between ca.…”

Rinikerfeld Palaeolake (Northern Switzerland) – a sedimentary archive of landscape and climate change during the penultimate glacial cycle

“…For the lower part of the QRIN profile (including base of LFA 4b), only minimum ages corresponding to MIS 6 can be determined (Fig. 3; Mueller et al, 2020). Samples taken from LFA 4c and LFA 4d gave luminescence ages of 159±8 ka to 194±10 ka and 186±10 ka, for the polymineral and quartz fractions, respectively (Table S5).…”

“…In addition, deposits related to older glaciations can often be challenging to date (e.g. Lian and Roberts, 2006; Mueller et al , 2020), and therefore to correctly classify and interpret. Some of the most valuable scientific archives of the Pleistocene consist of the deposits of ancient lakes that served as sediment sinks, and these archives may allow for detailed environmental reconstructions through sedimentological, geochemical and palynological studies.…”