Unravelling the Quaternary river incision in the western Rhenish Massif: Cosmogenic nuclide dating (10Be & 26Al) of fluvial terraces in the lower Moselle valley (Germany)
Palaeontology
Final Report Abstract
In the framework of this project, we used (i) electron spin resonance (ESR), (ii) terrestrial cosmogenic nuclides (TCN; 10Be and 26Al) and (iii) palaeomagnetism to date the upper terrace flight of the lower Moselle valley, with a specific emphasis on the MTC. (i) ESR measurements on quartz yielded two age clusters for the MTC, one around 0.5 Ma and the other around 1.2 Ma. Whilst the second time span is in good agreement with ESR-inferred ages of MTC deposits in the Saar valley, it highlights the need to crosscheck the reliability and robustness of these ages. As for ESR dating, we also recommend using the multiple centre approach. (ii) Unlike isochron burial dating, unaffected by postdepositional reworking or erosion processes, the depth profile technique is very sensitive to these. We therefore state that the first method is more suitable and robust than the second to date Early Pleistocene terrace deposits. The robust burial age points to a formation time around 1.2 Ma for the MMT. (iii) Palaeomagnetic measurements in the MMT and the YMT highlighted two reverse-to-normal polarity reversals. While the first one can be reliably correlated with the Jaramillo Event, the second might identify the Brunhes/Matuyama boundary. These results are in good concordance with the TCN-derived chronology. Whilst further chronological data are still required to decipher the complex interactions ruling the incision in the lower Moselle, the vast majority of our results points to an older timespan for the formation of the MTC than previously suggested (i.e. Early Pleistocene formation age). This represents the main chronostratigraphical outcome of this project. Importantly, this statement probably imposes to fundamentally revise the whole chronological framework for river incision in the Rhenish massif, especially in the middle Rhine valley.
Publications
- 2015. ESR dating of fluvial terraces in the Moselle and Meurthe valleys (France, Germany): chronostratigraphical implications and methodological issues/Datations ESR de terrasses alluviales des vallées de la Moselle et de la Meurthe (France, Allemagne): implications chronostratigraphiques et limites méthodologiques. Quaternaire 26, 13-25
Harmand, D., Voinchet, P., Cordier, S., Bahain, J., Rixhon, G.
(See online at https://doi.org/10.4000/quaternaire.7137)
