A landscape evolution model deciphering the influence of large-scale uplift patterns on the Central European drainage system

Despite its complexity, the Neogene/Quaternary evolution of Central Europe’s drainage system is well constrained by a diverse set of empirical data (e.g., provenance, geochronology, biostratigraphy). However, the underlying causes of major changes in drainage patterns remain debated. For example, it is still unclear which factors and mechanisms (e.g., large-scale uplift patterns) led to flow reversals of the major eastern tributaries of the Rhine since the Miocene. Commonly, it is stated that the reorganizations of rivers were caused by the opening of the Upper Rhine Graben driven by an extensional tectonic regime since the Eocene and the associated lowering of the base level. Recent studies often attribute relief changes due to the late phases of Alpine tectonics and the last uplift of the Alb, although the reason and dimensions usually remains unclear. We hypothesize that the uplift pattern of Miocene folding of the lithosphere, as described in tectonically oriented journals, could be the reason for the river reversals. We also assume that the reversals were probably not caused by river beheading alone, but mainly by river capture.

To test our hypothesis, we use our newly developed landscape evolution model TTLEM-3D in addition to analysis of many regional studies. The model can be used with a pure detachment-limited as well as with a shared-stream power model and uses one or more layers. The results of a first sensitive analysis, which involves a simplified simulation of the main tectonic forcing since the Cretaceous, indicate that the assumed uplift pattern of the lithospheric folding could have led to a flow reversal. From the rate of change of the catchment size, it can be estimated that river capture, rather than river beheading, could be the main drainage rearrangement mechanism here. In addition, the timing and the hypothesized pattern of uplift and lowering of the lithosphere are in good agreement with the reversal of the Main and Neckar rivers observed in regional studies.

The findings suggest that a baseline drop alone is insufficient and that additional uplift impulses are required. Our simplified numerical model supports the idea of folding of the lithosphere but does not rule out other tectonic and geological processes. The overlapping of different mechanisms makes deciphering this area difficult. We try to combine geomorphological observations with tectonic studies. This study challenges established theories and attempts to contribute to a better understanding of the geomorphological history of Central Europe. It seeks to unravel the complex interactions between tectonic, landscape and fluvial dynamic processes.