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Aim & approach
The aim of this research is to
reconstruct the fluvial development of the Niers-Rhine (Germany) during the Late Weichselian (ca. 16-12 ka BP) in order to better understand fluvial response to climate change. Very well-preserved point bar series and meander cut-offs are directly found at the present-day surface. This makes it an excellent research location to test different dating methods and to compare results.
Multiple dating strategy
We used a combination of dating methods to investigate their
applicability and to obtain insight in the chronology of the site. Point bar
deposits and clastic channel infills were optically dated. Organic channel infills were biostratigraphically analysed and correlated with radiocarbon-dated sequences in the direct vicinity.
Presence of Laacher See Tephra (12.9 ka) provides additional chronologic control.
PEETERS J.1, 2, WALLINGA J.1, HOEK, W.Z.2 AND KASSE C.3
1 Netherlands Centre for Luminescence dating, Delft University of Technology, The Netherlands.
2 Utrecht University, Faculty of Geosciences, The Netherlands. J.Peeters@students.uu.nl 3 Vrije Universiteit, Faculty of Earth and Life Sciences, The Netherlands.
Late Weichselian fluvial evolution of the Niers-Rhine: a multiple dating strategy
Niers-Rhine valley research locations.
0 5 10 15 20 25 30
0 10 20 30 40 50 60 70 80 90 100 0
2 4 6 8 10
Frequency (#)
Equivalent dose (Gy)
Sample 4305069 accepted aliquots rejected aliquots Median = 19.37 Gy
Mean = 19.24 Gy
Aliquot (#)
Schematic cross-section of Niers-Rhine valley. Radiocarbon ages are cal ka BP with 2σ range limits (INTCAL04).
0 5 10 15 20 25 30
0 10 20 30 40 50 60 70 80 90 100 0
2 4 6 8 10
Frequency (#)
Equivalent dose (Gy)
Sample 4305070 accepted aliquots rejected aliquots Median = 27.38 Gy
Mean = 28.18 Gy
Aliquot (#)
Conclusions
Synthesis of the Late Weichselian to Early Holocene fluvial evolution
OSL ages of point bar sediments are in general agreement with radiocarbon and biostratigraphical results from channel infills.
The multiple dating strategy has shown that OSL can be a powerful tool in dating sandy fluvial systems, although
single-grain dating may be necessary to improve the ages of heterogeneously bleached sediments.
Correlation methods can provide valuable additional time- control.
Optical dating
A Single-Aliquot-Regenerative-dose (SAR) procedure is applied to sand-sized quartz. The use of the post-IR blue OSL signal was necessary to eliminate contributions from contaminating feldspar grains, even after the second HF treatment of the sediment.
To avoid bias in results due to the presence of grains for which the quartz OSL signal was not completely reset upon deposition, single- aliquot equivalent doses, separated more than 2 SD from the sample mean, were iteratively removed from the distribution. This lead to the removal of one or more data points for 90% of the samples.
“well-bleached” “poorly-bleached”
14.5
± 0.7
14.3 ± 0.6
14.4 ± 0.6
14.3 ± 0.7
15.1 ± 0.7
12.2 ± 0.7
14.1
± 0.6
14.0 ± 0.8
13.6 ± 0.7
15.2 ± 0.6
12.3 ± 0.5
13.3 ± 0.7
16.1 ± 0.9
15.1 ± 0.8
NE
± 13.1 ± 12.7
11.3 (11.2-11.5) 11.6 (11.3-11.8) 13.6 (13.4-13.8)
OSL
Radiocarbon Biostratigraphy
Tephrochronology Dating-/correlation method:
°
± 12.9
SW
± 12.7 ± 11.6 ± 13.9
Point bar migration direction
Transition level Meander level Meander level Meander level Meander level Transition level Peat
Medium/coarse sand Very fine/fine sand Loamy clay
Lithology
[III]
[I] [II] [IV] [V] [VI]
River pattern
Rhine/Meuse River pattern Niers-Rhine
Underfit local streams Abandonment Continued meandering (threshold not crossed)
Meandering phase (landscape stability)
Transition phase (delayed response) Braided phase Early Preboreal
Younger Dryas
Allerød
Older Dryas Bølling
Late Pleniglacial Stratigraphy
11.9
12.9
13.7 14.0
14.5 cal ka BP (INTCAL04)
