Luminescence dating of Middle and Late Pleistocene ice-marginal and alluvial depositional systems in northern Germany

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Luminescence Dating of Fluvial Deposits from the Weser Valley, Germany

Luminescence dating was applied on coarse-grained monomineralic potassium-rich feld-spar and polymineralic fine-grained minerals of five samples derived from fluvial deposits of the Riv-er Weser in northwestern Germany. We used a pulsed infrared stimulated luminescence (IRSL) single aliquot regenerative (SAR) dose protocol with an IR stimulation at 50°C for 400 s (50 μs on-time and 200 μs off-time). In order to obtain a stable luminescence signal, only off-time IRSL signal was rec-orded. Performance tests gave solid results. Anomalous fading was intended to be reduced by using the pulsed IRSL signal measured at 50°C (IR50), but fading correction was in most cases necessary due to moderate fading rates. Fading uncorrected and corrected pulsed IR50 ages revealed two major fluvial aggradation phases during the Late Pleistocene, namely during marine isotope stage (MIS) 5d (100 ± 5 ka) and from late MIS 5b to MIS 4 (77 ± 6 ka to 68 ± 5 ka). The obtained luminescence ages are consistent with previous 230Th/U dating results from underlying interglacial deposits of the same pit, which are correlated with MIS 7c to early MIS 6

Luminescence Dating of Fluvial Deposits from the Weser Valley, Germany

Luminescence dating was applied on coarse-grained monomineralic potassium-rich feld-spar and polymineralic fine-grained minerals of five samples derived from fluvial deposits of the Riv-er Weser in northwestern Germany. We used a pulsed infrared stimulated luminescence (IRSL) single aliquot regenerative (SAR) dose protocol with an IR stimulation at 50°C for 400 s (50 μs on-time and 200 μs off-time). In order to obtain a stable luminescence signal, only off-time IRSL signal was rec-orded. Performance tests gave solid results. Anomalous fading was intended to be reduced by using the pulsed IRSL signal measured at 50°C (IR50), but fading correction was in most cases necessary due to moderate fading rates. Fading uncorrected and corrected pulsed IR50 ages revealed two major fluvial aggradation phases during the Late Pleistocene, namely during marine isotope stage (MIS) 5d (100 ± 5 ka) and from late MIS 5b to MIS 4 (77 ± 6 ka to 68 ± 5 ka). The obtained luminescence ages are consistent with previous 230Th/U dating results from underlying interglacial deposits of the same pit, which are correlated with MIS 7c to early MIS 6

The TsuSedMod inversion model applied to the deposits of the 2004 Sumatra and 2006 Java tsunami and implications for estimating flow parameters of palaeo-tsunami

Flow depth and speed are crucial but sensitive parameters describing a tsunami's overland flow. Both parameters can be measured in post-tsunami field surveys for recent events, but are difficult to infer for ancient ones. TsuSedMod, an inverse model produced by Jaffe and Gelfenbaum (2007), can be applied to estimate both the minimum flow depth and speed by using the thickness and grain size distribution of a tsunami deposit. For given estimates of flow speeds or flow depths, the application of this code can help to evaluate the magnitude of a tsunami. In this study, we compare flow depths and flow speeds calculated with TsuSedMod to field data obtained in the aftermath of the 2004 Sumatra and 2006 Java tsunami. This study shows that the model gives a reasonable estimation of local tsunami flow depths and speeds for the analyzed tsunami runup sections. These data give information on the tsunami's onshore flow characteristics, such as the number of waves and flow deceleration due to obstacles. Sediment layers from different locations within the runup section can be correlated and assigned to the same wave. The testing of TsuSedMod on recent examples shows it to be a valuable tool for calculating flow depths and speeds of ancient tsunami. Together with the dating of respective tsunami deposits, information on magnitude and frequency of events along a particular coastline can be gained