R.T. van Balen

Sediment budget and tectonic evolution of the Meuse catchment in the Ardennes and the Roer Valley Rift System

The Meuse river system is located in the northeastern part of the Paris Basin, the Ardennes, and the Roer Valley Rift System (RVRS). The Meuse river system developed during the uplift of the Ardennes since the Eocene and it was affected by renewed rifting of the RVRS starting in the Late Oligocene. In response to the uplift of the Ardennes, the river system incised and a terrace sequence developed during the Plio-Pleistocene. The sediments generated by erosion in the catchment were transported into the RVRS and further to the north, into the Zuiderzee Basin and the North Sea Basin. Using a digital terrain model, the amount of eroded rock volume versus time for the Meuse catchment has been computed using the Paleogene and older planation surfaces and the fluvial terraces. Comparison of the amount of eroded material with the volume of sediment preserved in the RVRS for the early Middle Pleistocene shows that about 17.5% of the sediment volume transported into the RVRS remained there, the rest being transported further into the Zuiderzee Basin and the North Sea Basin. The Quaternary tectonic uplift of the Ardennes inferred from the incision history of the Meuse river system is characterized by a long-term uplift, on which a Middle Pleistocene acceleration is superimposed. The accelerated uplift is contemporaneous with an uplift event in the RVRS and in the neighbouring Eifel area, and with the onset of the youngest phase of volcanism in the Eifel area. The areal distribution of this uplift is characterized by a dome shape centered around the Eifel area.

The Cenozoic evolution of the Roer Valley Rift System integrated at a European scale

The Roer Valley Rift System (RVRS) is located between the West European rift and the North Sea rift system. During the Cenozoic, the RVRS was characterized by several periods of subsidence and inversion, which are linked to the evolution of the adjacent rift systems. Combination of subsidence analysis and results from the analysis of thickness distributions and fault systems allows the determination of the Cenozoic evolution and quantification of the subsidence. During the Early Paleocene, the RVRS was inverted (Laramide phase). The backstripping method shows that the RVRS was subsequently mainly affected by two periods of subsidence, during the Late Paleocene and the Oligocene–Quaternary time intervals, separated by an inversion phase during the Late Eocene. During the Oligocene and Miocene periods, the thickness of the sediments and the distribution of the active faults reveal a radical rotation of the direction of extension by about 70–80j (counter clockwise). Integration of these results at a European scale indicates that the Late Paleocene subsidence was related to the evolution of the North Sea basins, whereas the Oligocene–Quaternary subsidence is connected to the West European rift evolution. The distribution of the inverted provinces also shows that the Early Paleocene inversion (Laramide phase) has affected the whole European crust, whereas the Late Eocene inversion was restricted to the southern North Sea basins and the Channel area. Finally, comparison of these deformations in the European crust with the evolution of the Alpine chain suggests that the formation of the Alps has controlled the evolution of the European crust since the beginning of the Cenozoic.

Contrasting neogene denudation histories of different structural regions in the transantarctic mountains rift flank constrained by cosmogenic isotope measurements

Separate regions within the Transantarctic Mountains, the uplifted flank of the West Antarctic rift system, appear to have distinct Neogene histories of glaciation and valley downcutting. Incision of deep glacial outlet valleys occurred at different times throughout central and northern Victoria Land. This is corroborated by measurements of cosmogenic nuclides 21Ne, robe and 26Al of glacial erosion surfaces and high-elevated moraines. 21Ne ages of two summit plateaus, at elevations of 1650 m in central Victoria Land and ~ 2800 m in northern Victoria Land, range from 3.84 to 11.2 Ma, respectively. The latter date indicates that these glacial erosion surfaces are the oldest known exposure dated surfaces on Earth. Glacial erosion terraces, remnants of early phases of valley downcutting, have 21Ne ages of 1.27 and 6.45 Ma for central and northern Victoria Land, respectively. Therefore, deglaciation of summit plateaus, valley downcutting and topographic uplift occurred during the Mid-Miocene in northern Victoria Land and not earlier than the Mid-Pliocene in central Victoria Land. In northern Victoria Land, ice flow directions changed markedly from the time a regional ice sheet occupied the level of the highest summits to the present condition with summits rising up to 800 above the valley glaciers. In central Victoria Land, the oldest documented ice flow direction occupying the summit erosion surface prior to incision was SW-NE, draining the East Antarctic Ice Sheet along an outlet glacier at least 10 times as wide as the present E-W-flowing David Glacier. This great variation in denudation histories probably results from differential tectonic uplift of various regions within the presently active rift flank. Three tectonic processes contribute to Late Neogene uplift: (1) ongoing extension in adjacent Ross Sea rift basins; (2) regional dextral transtension following SE-trending Precambrian and Palaeozoic structural trends which offsets the ~ N-S-trending grain of the rift and reactivates earlier faults; and (3) isostatic response to valley downcutting and related denudation

The effect of rift shoulder erosion on stratal patterns at passive margins: Implications for sequence stratigraphy

Abstract Numerical modelling indicates that the erosion of uplifted rift flanks at passive margins has a profound effect on offshore stratigraphic patterns. Flexural uplift, due to isostatic rebound in response to erosion, extends far into the basin and causes uplift of the shelf. As a result, the contemporaneously deposited sedimentary wedge displays a characteristic offlap pattern. When the rift shoulder is largely eroded, onlap-promoting mechanisms related to cooling of the lithosphere enable sediments to onlap onto the basin margin. The initial offlapping and subsequent onlapping strata form one complete second-order depositional sequence comprising a shelf-margin-, transgressive-and highstand-systems tract. The modelling inferences are in broad agreement with stratal patterns and basin geometries observed on the U.S. east coast, the southeastern Brazilian and southeastern Australian passive margins and the Transantarctic Mountains-Ross Sea Shelf system. The initial offlaps caused by erosion of rift shoulders have important implications for the deriviation of eustatic signals from coastal onlap patterns.

Neotectonics of the Roer Valley Rift System, the Netherlands

Abstract The Roer Valley Rift System (RVRS) is located in the southern part of the Netherlands and adjacent parts of Gemany and Belgium. The last rifting episode of the RVRS started in the Late Oligocene and is still ongoing. The present-day seismic activity in the rift system is part of that last rifting episode. In this paper, the Quaternary tectonics of the RVRS are studied using the detailed stratigraphic record. Subsidence analyses show that three periods of subsidence can be discriminated during the Quaternary. A phase of rapid subsidence took place from the beginning of the Quaternary to the Upper Tiglian (∼1800 ka). This was followed by a phase of slow subsidence lasting until the Late Quaternary (∼500 ka). An acceleration in subsidence at the end of the Quaternary occurred in the central and northern parts of the RVRS (i.e. the Roer Valley Graben and the Peel Horst) during the last 500 ka. During the Quaternary, the most active fault zones in the RVRS are the Peel Boundary Fault zone and the Feldbiss Fault zone. Average displacements along these fault zones vary between 5 and 80 mm/ka. Periods of high and low displacement rates along faults can be discriminated. The magnitude of the subsidence rate in the central part of the RVRS, which in theory is caused by a combination of processes like faulting, cooling of the lithosphere and isostasy, is within the range of the rate of displacement along the major fault zones of the RVRS, which implies that the subsidence of the RVRS is to a large extent controlled by faulting. Along the wide and staggered Feldbiss Fault zone, the location of the largest displacement rate shifts during the Quaternary, whereas the Peel Boundary Fault zone, which is narrow and has a straight structure, is more stable in this respect. The present-day fault displacement rates inferred by geodetic measurements are two orders of magnitude larger than the rates inferred from the geological record. Such a large difference can be explained by a high variability of fault movements on a short time-scale due to fault–stress interactions. The stratigraphic record has preserved average displacement rates. Flexural analyses shows that the pattern of geodetically determined displacements is in accordance with the fault spacing in the fault zone. The NW–SE directed fault system active during the Quaternary and the Tertiary is inherited from the late stage of the Variscan orogeny. This fault system was also dominantly active during the Mesozoic and Early Cenozoic evolution of the RVRS. Lineament analysis of the topography indicates that apart from the dominant NW–SE-oriented faults, N–S and NE–SW directed faults are also prominent. These faults originate from the Caledonian tectonic phases. They have, however, no large displacements during the Mesozoic and Cenozoic. The fact that Paleozoic fault systems are reactivated during Quaternary and Tertiary indicates that these faults are fundamental weakness zones.

Numerical analysis of how sedimentation and redistribution of surficial sediments affects salt diapirism

Abstract Two-dimensional finite-element models are used to study how sedimentation and redistribution of sediments on the upper surface affects the development of subsurface salt diapirs. A rising diapir creates a bulge flanked by topographic lows in a generally accumulating sedimentary pile. We find that the rate at which this topography is flattened by erosion and redeposition controls the style of diapirism. This is because the redistribution of material from topographic highs to flanking lows is equivalent to changing the effective forces acting on the salt. Redistributing a potential topography modulates diapiric growth rate. The main effects of including surficial sediment redistribution in numerical models of diapirism are: 1. (1) diapirs grow 10–100 times faster; 2. (2) diapirs may rise above their level of neutral buoyancy and extrude; 3. (3) diapirs assume “finger” or “stock” like shapes rather than “mushroom” or balloon-on-string shapes; 4. (4) layers in the surrounding sediments remain nearly horizontal and only steepen sharply near the diapir. In effect, the rate of redistribution of surficial overburden strongly controls the mode of diapirism. Sediment redistribution (referred to as erosion for brevity) is modeled using a one dimensional diffusion equation. We show the results of two different erosion rates: infinitely slow (no erosion) and extremely fast (which redistributes surficial sediments but does not remove them from the system). We show that the shapes of model diapirs rising beneath surfaces subjected to rapid erosion simulate salt diapirs in the Gulf of Mexico. Columnar diapirs indicate rapid deposition on the shelf and plug-like diapirs slow sedimentation on the abyssal plane. Diapirs rising beneath surfaces with negligible erosion have the “mushroom” shapes interpreted for salt diapirs in central Iran.

Process-based modelling of fluvial system response to rapid climate change I: model formulation and generic applications.

A comprehensive model strategy is presented which enables the prediction of catchment hydrology and the dynamics of sediment transport within the alluvial river systems draining these catchments. The model is driven by AGCM-based weather predictions, generalised by using a stochastic weather generator, and by palaeo-climate and palaeo-environment reconstructions. The model consists of a lumped hydrological rainfall-runoff model, calibrated against modern daily discharge data and the AGCM control experiment, combined with simple modules for hillslope erosion, river channel geometry, sediment transport and fluvial planform type. We apply the model to a conceptualised climatic cycle, and investigate the response to brief climatic events. Model predictions are discussed and compared to reconstructed river behaviour.

Process-based modelling of fluvial system response to rapid climate change II. Application to the River Maas (The Netherlands) during the Last Glacial-Interglacial Transition

A comprehensive process-based numerical model of catchment hydrology and alluvial channel dynamics is applied to the evolution of the river Maas during the Last Glacial-Interglacial Transition. Palaeo-climatological reconstructions based on a number of climatic and environmental proxies are combined with atmospheric circulation model predictions to yield continuous time series for temperature, precipitation and vegetation cover for the period of 14-9 C-14 kyr BP. These climatic data are used as input for the numerical model. Predictions are made for discharge statistics, hillslope erosion potential, river channel sediment transport, channel pattern and incision potential. These predictions are compared with reconstructed fluvial dynamics of the Maas during this time period. We find that the major fluvial morphodynamical events can be explained by our model as a result of climate change induced affects. However, relatively high precipitation amounts during GS-1 must be applied in order to correctly predict floodplain wide incision during this period. We further show by means of a number of sensitivity analyses that the uncertainty in the adopted climate reconstructions do not have a large impact on modelled morphodynamics

Modelling the hydrocarbon generation and migration in the West Netherlands Basin, the Netherlands

The hydrocarbon systems of the Mesozoic, inverted West Netherlands Basin have been analyzed using 2-D forward modelling. Three source rocks are considered in the modelling: Lower Jurassic oil-prone shales, Westphalian gas-prone coal deposits, and Lower Namurian oil-prone shales. The Lower Namurian hydrocarbon system of the basin is discussed for the first time. According to the modelling results of the Early Jurassic oil system, the oil accumulations were filled just after the main inversion event. Their predicted locations are in agreement with exploration results. Modelling results of the Westphalian gas system, however, show smaller and larger sized accumulations at unexplored locations. The gas reservoirs were filled during the Late Jurassic-Early Cretaceous rifting phase. Results of modelling of the Lower Namurian oil system indicate that gas formed by secondary cracking of the oils can have mixed with the Westphalian coal-derived gas. Such a mixing is inferred from geochemical analyses. The existence of a Lower Namurian hydrocarbon system in the West Netherlands Basin implies that hydrocarbons are possibly trapped in the Westphalian and Namurian successions. These potential traps in the basin have not yet been explored.

Late Quaternary activity of the Feldbiss Fault Zone, Roer Valley Rift System, the Netherlands, based on displaced fluvial terrace fragments

The Meuse River crosses the Feldbiss Fault Zone, one of the main border fault zones of the Roer Valley Graben in the southern part of the Netherlands. Uplift of the area south of the Feldbiss Fault Zone forced the Meuse River to incise and, as a result, a flight of terraces was formed. Faults of the Feldbiss Fault Zone have displaced the Middle and Late Pleistocene terrace deposits. In this study, an extensive geomorphological survey was carried out to locate the faults of the Feldbiss Fault Zone and to determine the displacement history of terrace deposits. The Feldbiss Fault Zone is characterized by an average displacement rate of 0.041 -0.047 mm a