Modelling the impact of regional uplift and local tectonics on fluvial terrace preservation.
Viveen, W. ; Schoorl, J.M. ; Veldkamp, A. ; Balen, R.T. van - \ 2014
Geomorphology 210 (2014). - ISSN 0169-555X - p. 119 - 135.
mino river terraces - sea-ice correlation - climatic variability - multiproxy analysis - external controls - drainage-basin - level change - maas record - margin - evolution
A terrace formation model (TERRACE) combined with a longitudinal river profile model (FLUVER) was used to simulate fluvial terrace formation and preservation in the northwest Iberian lower Miño River basin under the influence of three tectonic conditions; namely regional vertical uplift, local basin subsidence, and localised differential uplift. The simulation results were compared against mapped terrace altitudes and deposit thicknesses. The best results were achieved by combining all three tectonic factors, indicating that specific terrace formation is a complex interplay of regional and local tectonics. The best fit regional uplift rate of 0.10 m ka- 1 over the past 600 ka is higher than the 0.08 m ka- 1 previously estimated for a section farther to the west, which can be attributed to an increase in tectonic uplift from the NW Iberian Atlantic margin toward the east. Local relative subsidence causes sediment accumulation in the local basin and less sedimentation in the fluvial terraces on the surrounding uplifting blocks. Different uplift rates on both sides of the valley caused preservation of unpaired terraces, which are fill terraces on one side of the valley and strath terraces on the other side. Usually, the formation of fill or strath terraces is considered to be only climate-dependent. Our results indicate that local tectonics can be important in the terrace formation and preservation. This suggests that terrace correlations in other river systems, based on deposit thicknesses only, might be over-simplified.
Reconstructing late quaternary fluvial process controls in the upper aller valley (north Germany) by means of numerical modeling
Veldkamp, A. ; Berg, M. van den; Dijke, J.J. van; Berg van Saparoea, R.M. van den - \ 2002
Netherlands journal of geosciences 81 (2002)3-4. - ISSN 0016-7746 - p. 375 - 388.
geomorfologie - kwartaire afzettingen - tektoniek - terrassen - dalen - simulatiemodellen - geologische sedimentatie - duitsland - rivieren - geomorphology - rivers - geological sedimentation - quaternary deposits - tectonics - terraces - valleys - simulation models - germany - terrace stratigraphy - maas record - europe - uplift - system
The morpho-genetic evolution of the upper Aller valley (Weser basin, North Germany) was reconstructed using geological and geomorphologic data integrated within a numerical process model framework (FLUVER-2). The current relief was shaped by Pre-Elsterian fluvial processes, Elsterian and Saalian ice sheets, followed by Weichselian fluvial processes. Structural analysis based on subsurface data and morphological interpretations were used to reconstruct uplift/subsidence rates. A detailed analysis led to the hypothesis that we are dealing with either a NNW-SSE or a WSW-ENE oriented compression leading to uplift in the upper Aller valley. It is also hypothesised that the NNW-SSE compression might have caused strike-slip deformation leading to differential block movement and tilt.Two different uplift rate scenarios were reconstructed and used as a variable parameter in numerical modelling scenarios simulating the Late Quaternary longitudinal dynamics of the Aller. Each different scenario was run for 150.000 years and calibrated to the actual setting. The resulting model settings were consequently evaluated for their plausibility and validity. Subsequently, regional semi-3D simulations of valley development were made to test the two tectonic stress hypotheses. Differential tectonic uplift and regional tilt seems to have played an important role in shaping the current valley morphology in the upper Aller. Unfortunately, due to the uncertainties involved, we were unable to discriminate between the two postulated tectonic stress scenarios.