Paleogeografie van de Maas

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Middle to Late Pleistocene faulting history of the Heerlerheide fault, Roer Valley Rift System, influenced by glacio-isostasy and mining-induced displacement

Faults of the Roer Valley Rift System (RVRS) are characterized by seismicity, scarps and displaced fluvial terraces, showing that they are active. The Heerlerheide fault is part of the southern boundary fault system of the RVRS, the Feldbiss fault zone (FFZ). During the late 19th and first half of the 20th century coal was mined in the subsurface south of the FFZ. As a result, general subsidence, sinkholes, and fault scarplets appeared on the surface. One of the induced fault scarps coincides with the location of the Heerlerheide fault, indicating that the upper part of the fault was reactivated by the mining. A trench was opened across the fault to study the mining-induced fault reactivation as well as the tectonic fault displacement history. The Heerlerheide fault offsets a 340 ka Meuse river terrace overlain by loess and loess-like deposits of Eemian to Late Pleniglacial age, including the Rocourt soil, the Eben/Patina discordance and the Nagelbeek soil complex. At least three tectonic faulting events were reconstructed, which are most likely surface rupturing earthquakes. However, the two oldest displacements could represent multiple faulting events. The age of the youngest event is well constrained between 17 and 15 ka. The duration of the time interval between the penultimate and youngest events is at least 8 ky (the inter-event time is an important parameter for assessing seismic hazard). The vertical coseismic displacement of the youngest event was around ∼0.25 m; the estimated moment magnitude is around 6.2. This event is more or less synchronous with the age of events found in other fault trench studies of the FFZ. The timing is roughly contemporaneous with surface rupturing earthquakes along the northern boundary fault zone of the RVRS, the Peel Boundary fault zone (PBFZ), and a phase of volcanism in the nearby Eifel area, suggesting a common mechanism. The timing also corresponds to the start of the glacio-isostatic forebulge collapse, which has been invoked before to explain earthquake events in the RVRS, and in northern Germany and Denmark. Previous studies provided evidence for a Holocene surface rupturing earthquake with an offset of about 1 m at the Geleen fault in the Meuse valley on Belgian territory, taking place between 2.5 ± 0.3 and 3.1 ± 0.3 ka. The Geleen and Feldbiss faults on Dutch territory experienced faulting during the Late Glacial – Holocene. The incision and deposition history of a brook crossing these faults suggests an age around 7.5 ka for this event. However, in contrast, our results for the Heerlerheide fault show no evidence for Late Glacial – Holocene tectonic fault activity. We also observed 0.34 m of vertical displacement of the base of the plough layer, which corresponds to the amount to what was observed at the surface during the mining in 1936, indicating that no fault motions have occurred afterwards, despite re-flooding of the mines and consequent surface rebound. However, the fact that the fault was reactivated by subsurface mining shows that it is a weakness zone in the subsurface, and therefore fault reactivation might occur due to still ongoing rebound. In contrast to the tectonic fault displacement, the mining-induced offset was accompanied by downslope movement of the upper part of the hanging wall, resulting in splaying of the fault tip and crack formation

A Late Glacial surface rupturing earthquake at the Peel Boundary fault zone, Roer Valley Rift System, the Netherlands

Paleoseismological trenching studies constrain recurrence times and magnitudes of faulting events and earthquakes on active faults. In a trench along the central part of the Peel Boundary fault zone (PBFZ), southeastern Netherlands, evidence was found for such a large faulting event that occurred around 14 ka. The event caused a fault scarp in unconsolidated sediments of ∼1 m height. A colluvial wedge was formed next to the scarp. A second faulting event offsets this colluvial wedge by 0.2–0.1 m. This event can be tentatively dated at ∼13 ka. During or immediately after the second event, a large clastic dyke intruded along the fault plane. The dyke is not faulted, but its emplacement did cause some minor thrust faulting around the injection. The sudden character of the main faulting event, the brittle deformation style of loam layers, the lack of growth faulting in the colluvial wedge, the clastic dykes and the flame structures demonstrate that the main faulting event was a surface rupturing earthquake. Based on the scarp height, the estimated moment magnitude is about 6.8 ± 0.3. Similar observations in a previous trench site suggest that the length of the surface rupture was at least 32 km. The earthquake took place during the Weichselian (Würmian) Late Glacial. This timing corresponds to the start of the glacio-isostatic forebulge collapse in the Netherlands. Glacio-isostatic movements have been invoked before to explain earthquake events in the Roer Valley Rift System in which the PBFZ is situated, and in northern Germany and Denmark. If these earthquakes can indeed be attributed to a collapsing forebulge, their ages should show a decrease in the direction of ice-sheet retreat. This might indeed be the case, as the ages decrease from 14 ka and 13 ka in this trench via 13–16 ka at the Osning Thrust Zone, NW Germany, to 12–14 ka in northern Denmark.</p

Spatial and temporal variations in river terrace formation, preservation and morphology in the Lower Meuse Valley, the Netherlands

The Lower Meuse Valley crosses the Roer Valley Rift System and provides an outstanding example of well-preserved late glacial and Holocene river terraces. The formation, preservation, and morphology of these terraces vary due to reach-specific conditions, a phenomenon that has been underappreciated in past studies. A detailed palaeogeographic reconstruction of the terrace series over the full length of the Lower Meuse Valley has been performed. This reconstruction provides improved insight into successive morphological responses to combined climatic and tectonic external forcing, as expressed and preserved in different ways along the river. New field data and data obtained from past studies were integrated using a digital mapping method in GIS. Results show that late glacial river terraces with diverse fluvial styles are best preserved in the Lower Meuse Valley downstream sub-reaches (traversing the Venlo Block and Peel Block), while Holocene terrace remnants are well-developed and preserved in the upstream sub-reaches (traversing the Campine Block and Roer Valley Graben). This reach-to-reach spatial variance in river terrace preservation and morphology can be ascribed to tectonically driven variations in river gradient and subsurface lithology, and to river-driven throughput of sediment supply

Patterns in river channel sinuosity of the Meuse, Roer and Rhine rivers in the Lower Rhine Embayment rift-system, are they tectonically forced?

The tectonic and fluvial setting of the Rhine-Meuse river system in the Lower Rhine Embayment rift system is exceptionally well known. The 19th century, pre-regulation river courses of three rivers are used to study a postulated sinuosity response to faulting. The fault-perpendicular Meuse River shows patterns of sinuosity changes at different spatial scales. The large-scale (>5 km) sinuosity changes are related mainly to the faulting-induced changes of the subsurface lithology, determining the bed and bank characteristics. However, at a smaller scale, some fault-related channel sinuosity anomalies are observed. The fault-parallel Roer River shows sinuosity changes related to a normal, non-tectonic longitudinal gradient change. Sinuosity patterns of the Rhine River are predominantly related to lithological differences and reduced incision rates. Sinuosity can thus be an indicator of tectonic motions, but gradient, subsurface lithology and river bank composition determine sinuosity as well. Therefore, a sinuosity change is no proof for fault activity. On the other hand, the absence of a sinuosity change does not imply inactivity of a fault at geological time-scales

Spatial and temporal variations in river terrace formation, preservation and morphology in the Lower Meuse Valley, the Netherlands

The Lower Meuse Valley crosses the Roer Valley Rift System and provides an outstanding example of well-preserved late glacial and Holocene river terraces. The formation, preservation, and morphology of these terraces vary due to reach-specific conditions, a phenomenon that has been underappreciated in past studies. A detailed palaeogeographic reconstruction of the terrace series over the full length of the Lower Meuse Valley has been performed. This reconstruction provides improved insight into successive morphological responses to combined climatic and tectonic external forcing, as expressed and preserved in different ways along the river. New field data and data obtained from past studies were integrated using a digital mapping method in GIS. Results show that late glacial river terraces with diverse fluvial styles are best preserved in the Lower Meuse Valley downstream sub-reaches (traversing the Venlo Block and Peel Block), while Holocene terrace remnants are well-developed and preserved in the upstream sub-reaches (traversing the Campine Block and Roer Valley Graben). This reach-to-reach spatial variance in river terrace preservation and morphology can be ascribed to tectonically driven variations in river gradient and subsurface lithology, and to river-driven throughput of sediment supply

Digitaal Basisbestand Paleogeografie van het Maasdal

This dataset "Digital Basemap for the Lower Meuse Valley Palaeogeography” provides a detailed reconstruction of the Lower Meuse Valley since the Weichselian Late Pleniglacial. It covers the Meuse reach between Maastricht and Nijmegen (The Netherlands). The Meuse valley provides an outstanding example of geomorphological preservation of terrace elements of different fluvial styles, produced during the Weichselian Lateglacial and Holocene. By means of compiling an Age Determination Database (Access tables) and a vector polygon geological map (ArcGIS), shapefiles were produced that give overview of the age of series of terraces and of the paleogeography of the active river bed. The setup of database and GIS is such that it unlocks the information hidden in older published sources and institutional databases (i.e. from journal papers, archaeological reports, geological survey mapping activities, university fieldworks, etc.) in a modern, quick to use but still to trace form. The digital basemap and underpinning ID database were created using the same software setup and database structure as the 2012 Rhine-Meuse Delta Digital Base Map elsewhere on this depository website [ https://doi.org/10.17026/dans-x7g-sjtw ]. In the north of the study area, where coverage overlaps, the new maps here updates the 2012 version. Production of this dataset is part of the project: “Reconstruction and Modelling of the Meuse- and Rhine River. Sinuosity Response to Faulting in the Roer Valley Rift System” funded by The Netherlands Organisation for Scientific Research (NWO; project nr. 821.01.011). The first peer-reviewed publication using the dataset is: “Spatial and temporal variations in river terrace formation, preservation and morphology. Lower Meuse Valley, the Netherlands” (Woolderink et al., exp. 2018)

Patterns in river channel sinuosity of the Meuse, Roer and Rhine rivers in the Lower Rhine Embayment rift-system, are they tectonically forced?

The tectonic and fluvial setting of the Rhine-Meuse river system in the Lower Rhine Embayment rift system is exceptionally well known. The 19th century, pre-regulation river courses of three rivers are used to study a postulated sinuosity response to faulting. The fault-perpendicular Meuse River shows patterns of sinuosity changes at different spatial scales. The large-scale (>5 km) sinuosity changes are related mainly to the faulting-induced changes of the subsurface lithology, determining the bed and bank characteristics. However, at a smaller scale, some fault-related channel sinuosity anomalies are observed. The fault-parallel Roer River shows sinuosity changes related to a normal, non-tectonic longitudinal gradient change. Sinuosity patterns of the Rhine River are predominantly related to lithological differences and reduced incision rates. Sinuosity can thus be an indicator of tectonic motions, but gradient, subsurface lithology and river bank composition determine sinuosity as well. Therefore, a sinuosity change is no proof for fault activity. On the other hand, the absence of a sinuosity change does not imply inactivity of a fault at geological time-scales