Luminescence dating of ice‐marginal deposits in northern Germany: evidence for repeated glaciations during the Middle Pleistocene (MIS 12 to MIS 6)

Abstract

The exact number, extent and chronology of the Middle Pleistocene Elsterian and Saalian glaciations in northern Central Europe are still controversial. This study presents new luminescence data from Middle Pleistocene ice‐marginal deposits in northern Germany, giving evidence for repeated glaciations during the Middle Pleistocene (MIS 12 to MIS 6). The study area is located in the Leine valley south of the North German Lowlands. The data set includes digital elevation models, high‐resolution shear wave seismic profiles, outcrop and borehole data integrated into a 3D subsurface model to reconstruct the bedrock relief surface. For numerical age determination, we performed luminescence dating on 12 ice‐marginal and two fluvial samples. Luminescence ages of ice‐marginal deposits point to at least two ice advances during MIS 12 and MIS 10 with ages ranging from 461±34 to 421±25 ka and from 376±27 to 337±21 ka. The bedrock relief model and different generations of striations indicate that the older ice advance came from the north and the younger one from the northeast. During rapid ice‐margin retreat, subglacial overdeepenings were filled with glaciolacustrine deposits, partly rich in re‐worked Tertiary lignite and amber. During MIS 8 and MIS 6, the study area may have been affected by two ice advances. Luminescence ages of glaciolacustrine delta deposits point to a deposition during MIS 8 or early MIS 6, and late MIS 6 (250±20 to 161±10 ka). The maximum extent of both the Elsterian (MIS 12 and MIS 10) and Saalian glaciations (MIS 8? and MIS 6) approximately reached the same position in the Leine valley and was probably controlled by the formation of deep proglacial lakes in front of the ice sheets, preventing a further southward advance.

Luminescence Dating of Fluvial Deposits from the Weser Valley, Germany

“…We followed the approach by Roskosch et al (2015) who stated that the middle part of the decay curve of the pulsed IR 50 signal is characterised by a more stable, thus less fading-dependent luminescence signal when compared to other (parts of the) signals. The results of the additionally applied fading test of sample NG5 using the pulsed IR 50 , pIRIR 225 and pIRIR 290 signals suggests that the pulsed IR 50 signal is more stable than the pIRIR 225 and pIRIR 290 signal (Table 4), confirming the use of the pulsed IR 50 signal.…”

“…Comparison of both pulsed IR 50 and pIRIR 290 results showed that pIRIR 290 D e values were generally higher by about 100-150 Gy than the pulsed IR 50 ones (see Fig. 3B in Roskosch et al, 2015). Jain et al (2015) compared the residual dose obtained from a modern beach sample using continuous wave (CW) IR 50 , pulsed IR 50 , pIRIR 225 and pIRIR 290 signals and a much larger residual dose of ~10 Gy was obtained from the pIRIR 290 signal than all the other signals (less than 2 Gy).…”

“…The initial part of the decay curve (0-20 s) was actually reported to give considerably higher fading rates (up to 4.42 ± 0.46%), whereas the middle part was found to show only negligible anomalous fading (see Roskosch et al, 2015).…”

“…Sampling and preparation was performed as described in Roskosch et al (2015). For luminescence measurements, both monomineralic coarse-grained (150-200 µm) potassium-rich feldspar minerals and polymineralic finegrained (4-11 µm) minerals were used ( Table 1).…”

“…The net feldspar luminescence signal was then calculated from the middle part of the decay curve (21-60 s) after subtracting a late background of the last 50 s (see Roskosch et al, 2015). The initial part of the decay curve (0-20 s) was actually reported to give considerably higher fading rates (up to 4.42 ± 0.46%), whereas the middle part was found to show only negligible anomalous fading (see Roskosch et al, 2015).…”