Unravelling the Quaternary river incision in the western Rhenish Massif: Cosmogenic nuclide dating (10Be & 26Al) of fluvial terraces in the lower Moselle valley (Germany)

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Understanding the chronology of Pleistocene river incision in the uplifted Rhenish Massif is of particular importance to unravel the regional tectonic behavior. However, the incision history of major rivers is poorly constrained to date. While many of the previous studies dealt with the reconstruction of terrace profiles in the Rhine and Moselle valleys, very few of them provided reliable age estimates, in particular for middle and early Pleistocene terrace levels. These middle and early Pleistocene terraces, though representing key levels in the morpho- and tectogenetic evolution of the valleys, suffer from a lack of reliable absolute dating. In the framework of this project, we intend to use terrestrial cosmogenic nuclides (10Be, 26Al) to date the upper terrace flight of the lower Moselle valley between Trier and Koblenz. Two distinct sampling/dating approaches, the depth profile technique and the isochron method, will be applied on different terrace levels in order to gain insight into the river incision pulses that governed the progressive entrenchment of the Moselle valley. Moreover, different remnants pertaining to the same terrace group will be sampled at distinct places along this reach of the valley to account for potential spatial variations of incision rates. Thus, the final aim of this research is to enlarge the dataset required to gain insights into the spatio-temporal characteristics of the mechanisms by which river incision responded to combined tectonic forcing (i.e. regional rock uplift) and climatic forcing (i.e. Pleistocene glacial/interglacial cycles).