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Establishment of a high-resolution chronostratigraphic framework for a Late Pleniglacial to Late Glacial alluvial-aeolian complex: the upper Senne (NW Germany)

Julia Roskosch1, Sumiko Tsukamoto2, Janine Meinsen1, Manfred Frechen2, Jutta Winsemann1
1 Institut für Geologie, Leibniz Universität Hannover
2 Leibniz-Institut für Angewandte Geowissenschaften (LIAG)

V 1.5 in Fortschritte der Quartärstratigraphie

17.09.2012, 11:10-11:30, H8

The up to 30 m thick Pleistocene sedimentary succession of the Senne has been deposited on the southwestern slope of the Teutoburger Wald Mountains. In the past, the origin and age of these deposits have been controversially attributed either to a glaciofluvial Saalian or to a periglacial Weichselian formation. Re-examination of outcrop and borehole data indicates that the lower Senne consists of late Saalian (Drenthe) meltwater sediments and till, which are unconformably overlain by Late Pleniglacial to Late Glacial alluvial fan and aeolian sandsheet deposits (Meinsen et al., in review, Roskosch et al., in press). The Upper Pleistocene deposits of the Senne are exposed in two open pits near Oerlinghausen and Augustdorf.

To establish a high-resolution chronostratigraphic framework for the upper Senne deposits, luminescence dating techniques were performed on 12 samples from the Oerlinghausen and Augustdorf pits using coarse-grain potassium-rich feldspar and quartz minerals (Roskosch et al., in press). For feldspar measurements, an elevated temperature (290°C) post-IR infrared stimulated luminescence protocol was used (Thiel et al., 2011). Feldspar age calculation was based upon mean equivalent dose values. Quartz measurements were conducted using a conventional single regenerative dose protocol (Murray and Wintle, 2000). For quartz age determination, both central age model (CAM) and 3-parameter minimum age model (MAM-3) were applied (Roskosch et al. in press.)

Feldspar ages indicate a Late Pleistocene deposition of the upper Senne (Oerlinghausen pit: ~35 to 17 ka; Augustdorf pit: ~27 to 17 ka). Quartz CAM results point to a slightly younger Pleniglacial to Late Glacial age (Oerlinghausen pit: 30 to 13 ka; Augustdorf pit: 25 to 20 ka), quartz MAM-3 data indicates a deposition during the Late Pleniglacial to Late Glacial and even Holocene (Oerlinghausen pit: 21 to 7 ka; Augustdorf pit: 21 to 18 ka). Due to the fact that quartz MAM-3 ages seem to derive from aliquots with poor measurement precision, CAM ages seem to be more reliable and interpretations are based upon quartz CAM data in our study.

The increasing discrepancy in age of the lowermost alluvial fan deposits indicates an insufficient and therefore non-optimal bleaching enviroment, as may be expected for depositional settings, which are periodically affected by high-energy floods. In contrast, the overlying aeolian sandsheet deposits seem to have been well-bleached, since feldspar and both quartz CAM and MAM-3 ages are consistent with each other. Due to the fact that quartz bleaches more rapidly than feldspar (Godfrey-Smith et al., 1988), this agreement is only likely to occur within well-bleached sediments.

 

References

 

 

Godfrey-Smith D. I., Huntley, D. J., Chen, W.-H., 1988. Optical dating studies of quartz and feldspar sediment extracts. Quat. Sci. Rev. 7, 373–380.

Meinsen, J., Winsemann, J., Roskosch, J., Brandes, C., Frechen, M., in review. Climate control on the evolution of Upper Pleistocene alluvial fan and aeolian sandsheet systems: the Senne (NW Germany).

Murray, A.S., Wintle, A.G., 2000. Luminescence dating of quartz using an improved single-aliquot regenerative-dose protocol. Radiat. Meas. 32, 57-73.

Roskosch, J., Tsukamoto, S., Meinsen, J., Frechen, M., Winsemann, J., in press. Luminescence dating of an Upper Pleistocene alluvial fan and aeolian sandsheet complex: The Senne in the Münsterland Embayment, NW Germany. Quat. Geochronol. doi: 10.1016/j.quageo.2012.02.012.

Thiel, C., Buylaert, J.-P., Murray, A.S., Terhorst, B., Hofer, I., Tsukamoto, S., Frechen, M., 2011. Luminescence dating of the Stratzing loess profile (Austria) – Testing the potential of an elevated temperature post-IR IRSL protocol. Quat. Int. 234 (1-2), 23-31. doi:10.1016/j./quaint.2010.05.018.



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Letzte Änderung 26.07.2012