Timing of fluvial sedimentation in the Upper Rhine Graben since the Middle Pleistocene: constraints from quartz and feldspar luminescence dating

Abstract

The Heidelberg Basin (HDB) hosts one of the thickest Quaternary sediment successions in central Europe. To establish a reliable Middle and Upper Pleistocene chronology for a recently drilled core from the depocentre of the Heidelberg Basin, we applied multiple luminescence dating approaches, including quartz optically stimulated luminescence (OSL), two feldspar post‐IR IRSL protocols using second IR stimulation temperatures of 225 °C (pIRIR225) and 290 °C (pIRIR290), and two fading correction models. Relatively high anomalous fading was observed for both the pIRIR225 and pIRIR290 signals, with mean fading rates of 2.13±0.27 and 2.08±0.49%/decade, respectively. Poor dose recovery behaviour of the pIRIR290 signal suggests that the pIRIR290 ages are not reliable. The comparison of two fading correction methods for the K‐feldspar ages indicates that the correction method proposed by Kars et al. (2008) Radiation Measurements 43, 786, yields reliable ages, whereas the dose‐rate correction method proposed by Lamothe et al. (2003) Radiation Measurements 37, 493, does not. A chronology for the HDB is established using the quartz ages and reliable fading corrected feldspar pIRIR225 ages. Our chronology shows that the sediments in the upper Mannheim Formation were deposited during Marine Isotope Stage (MIS) 4 (c. 70 ka), constrained by two quartz ages in the upper 20 m of the core. Four fading corrected pIRIR225 ages of c. 400 ka show that the upper Ludwigshafen Formation was deposited during MIS 12–11, correlated with the Elsterian‐Holsteinian stage. Two ages of 491±76 and 487±79 ka indicate that the Middle and Upper Ludwigshafen Formation were probably deposited during the Cromerian Complex. This luminescence chronology is consistent with palynological results. It also indicates that the IR‐RF ages reported earlier are probably underestimated due to anomalous fading.