Mid-Pleistocene uplift-induced acceleration of incision in the lower Meuse valley constrained by cosmogenic burial ages

The succession of fluvial terraces situated in the lower Meuse River (Netherlands–Belgium border, NW Europe) provides a morpho-sedimentary record of regional Quaternary landscape evolution. Although these terraces have been extensively studied in the past, the mechanisms and especially the timing related to their formation remain debated. We measure cosmogenic 26Al and 10Be concentrations from quartz-bearing sediment samples of two Higher/Main terraces and calculate terrace burial ages using both the isochron-burial method and the P-PINI (Particle-Pathway Inversion of Nuclides Inventories) inversion approach. Results indicate ages of ca. 1.2 Ma for the Sint Geertruid 2 terrace and ca. 0.5 Ma for the Sint Pietersberg 3 terrace (also known as the Younger Main Terrace). We combine our results with published ages for other terrace levels to refine the lower Meuse River terrace chronology for the Early-to Middle-Pleistocene. Our proposed chronology reveals that four terraces (Sint Pietersberg 3, ‘s-Gravenvoeren, Rothem 1 and Rothem 2) were formed within a single glacial-interglacial cycle (MIS 14 – 13). Their formation and preservation are best explained by an episode of increased valley incision. Such episode is constrained by our proposed chronology and terrace elevations, revealing three distinct incision phases: (i) a phase between ca. 1.2 and 0.5 Ma with relatively low incision rates (ca. 30 – 40 m/Ma); (ii) a period between 0.5 and 0.3 Ma with high incision rates (ca. 150 – 425 m/Ma); and (iii) an interval from 0.3 to 0.01 Ma marking a return to low incision rates (ca. 30 – 40 m/Ma). We relate the accelerated incision phase to plume-induced uplift, which is also responsible for the contemporaneous increased Middle-Pleistocene volcanic activity of the Eifel
Volcanic Field that started around ca. 0.55 Ma. The plume-induced uplift acts in addition to the long term (Neogene) and continuing upheaval resulting from the
Alpine foreland deformation.