Infrared radiofluorescence (IR-RF) dating of middle pleistocene fluvial archives of the Heidelberg Basin (Southwest Germany)

Abstract

Abstract:The infrared radiofluorescence (IR-RF) dating technique was applied to eight fluvial samples that were collected from two sediment cores at the Heidelberg Basin located near Viernheim and Ludwigshafen in southwest Germany. Based on the IR-RF derived ages of the samples it was possible to establish a chronological framework for the Mid-Pleistocene fluvial deposits of the Heidelberg Basin. The results allow us to distinguish between four main periods of aggradation. The lowermost sample taken from 100 m core depth lead to an IR-RF age of 643 ± 28 ka pointing to a Cromerian period of aggradation . For the Elsterian it is now possible to distinguish between two aggradation periods, one occurring during the Lower Elsterian period (OIS 15) and a second during the Upper Elsterian period (OIS 12-11). For the so called Upper interlayer (or "Oberer Zwischenhorizont" -a layer of organic-rich and finer-grained deposits), the IR-RF results point to a deposition age of around 300 ka, with samples taken directly on top and out of this layer yielding IR-RF ages of 288 ± 19 ka and 302 ± 19 ka, respectively. Hence, the measured IR-RF ages clearly point to a deposition during the Lower Saalian period (OIS 9-8) whereas earlier studies assumed a Cromerian age for the sediments of the Upper Interlayer based on pollen records and also mollusc fauna. The new IR-RF dataset indicates that significant hiatuses are present within the fluvial sediment successions. In particular the Eemian and Upper Saalian deposits are missing in this part of the northern Upper Rhine Graben, as the 300 ka deposits are directly overlain by Weichselian fluvial sediments. It is obvious that time periods of increased fluvial aggradation were interrupted by time periods of almost no aggradation or erosion which should have been mainly triggered by phases of increased and decreased subsidence of the Heidelberg Basin.

A consistent magnetic polarity stratigraphy of late Neogene to Quaternary fluvial sediments from the Heidelberg Basin (Germany): A new time frame for the Plio–Pleistocene palaeoclimatic evolution of the Rhine Basin

“…Due to partial bleaching, a minimum age model (MAM3) was applied for the fluvial samples (Lauer et al, 2010). An age of 288 ± 19 ka resulted from infrared radiofluorescence(IR-RF) dating of a sample from a depth of 39.5 m (Lauer et al, 2011). From our point of view, certain uncertainties are related to the use of two different methods and the limits of the applications.…”

“…The proposed solutions are in accordance with the established magnetostratigraphy, as set out above, and support the above assumptions. The OSL and IR-RF ages of Lauer et al (2010Lauer et al ( , 2011 are also depicted in Fig. 9a.…”

“…Nevertheless, unconformities are present in the succession of the Heidelberg Basin. An estimate of the temporal dimension of these hiatuses can be taken from the work of Lauer et al (2010Lauer et al ( , 2011 on the Viernheim core. An age of 56.2 ka ± 6.3 ka was identified at a depth of 32.7 m via optically stimulated luminescence (OSL) dating.…”

Luminescence Dating of Fluvial Deposits from the Weser Valley, Germany

“…The quartz luminescence signal is much more light-sensitive, thus faster to bleach than the feldspar luminescence signal, but feldspar minerals allow for dating comparably older (fluvial) sediments (e.g. Krbetschek et al, 2008;Lauer et al, 2011) due to the higher saturation limit of the luminescence signal. Yet, feldspar minerals may suffer from a certain signal loss over time, referred to as anomalous fading (Wintle, 1973;Aitken, 1985;Spooner, 1994).…”

“…However, luminescence dating of fluvial deposits has been successfully applied in many case studies (Lewis et al, 2001;Wallinga et al, 2001;Rittenour et al, 2005;Briant et al, 2006;Choi et al, 2007;Busschers et al, 2008;Frechen et al, 2008Frechen et al, , 2010Krbetschek et al, 2008;Lauer et al, 2010Lauer et al, , 2011. Lauer et al (2011) compared the quartz and feldspar luminescence ages from fluvial sand samples from the River Rhine intercalated with the Laacher See tephra (12.9 ka). Both quartz and feldspar ages agreed perfectly with the independent tephra age, suggesting that insufficient bleaching, if any, might not be a problem for Pleistocene samples.…”