Northeastern Belgium Research Articles

Facies variability of the Lower Miocene Houthalen Member in the southern Genk municipality (northeastern Belgium)

Facies variability of the Lower Miocene Houthalen Member in the southern Genk municipality (northeastern Belgium)

Exploring the Holocene rise, disturbance and decline of pine forests in the river valleys of northeastern Belgium using pollen and botanical macroremains

The Holocene evolution of vegetation and environment in the Kleine Nete valley in the coversand region of northeastern Belgium is studied through sedimentological, palynological and macrobotanical analysis of a radiocarbon dated peat sequence. Peat formation started at the beginning of the Holocene in mesotrophic fen conditions. After a period of fast peat growth, the accumulation slowed down and the peat surface became dry in the Middle Holocene.The palynological results are compared with other pollen data from the region, in order to establish a regional pollen biozonation for the Early and Middle Holocene in the Nete Basin. This shows that pine has long been a characteristic element in the Nete Basin. Pine forest expanded immediately after the 11.4 cold event, which is earlier than in the western Scheldt Basin. Pine and birch grew along the valley, possibly also within the peatland. Peaks of microcharcoal, herbs and/or coarse sediment in the peat reflect temporary local forest disturbances in the Early Holocene. Some may reflect small-scale controlled fires induced by hunter-gatherers, although a natural cause seems much more plausible given the dominance of fire-associated pines and increased drought. Pine remained important throughout the Early Holocene. This long-lasting predominance of pine in the Nete Basin, compared to elsewhere in the Scheldt Basin, is likely related to the poor sandy subsoil in the region, which hinders more nutrient-demanding broadleaf trees to overtake.

Holocene deforestation history of NE Belgium: An evaluation of pollen- and population-based approaches for reconstructing land cover

Several methods to reconstruct past land cover are available which can be roughly divided into approaches based on pollen data and approaches based on (estimates of) historical human population. In this study, the REVEALS model and non-metric multidimensional scaling (NMDS) are applied to pollen sequences obtained from multiple alluvial floodplains located in the sandy and loamy regions of northeastern Belgium, thereby obtaining the first regional (semi-)quantitative estimates of Holocene landscape openness for this area. These estimates are subsequently compared to the two most widely-used scenarios for anthropogenic land cover change (ALCC): KK10 and HYDE.In contrast with the two population-based ALCC scenarios, the pollen-based reconstructions are well in agreement and indicate considerable variability in past land cover, not only between the two regions but even between the individual catchments. This agreement implies that NMDS could serve as an alternative approach to provide insight in large amounts of pollen data in case not all required model parameters are available to run the REVEALS model. Moreover, NMDS can provide a better understanding of which taxa are related to a particular type of landscape. Taking into account such insights in the interpretation of the REVEALS model output might help to pinpoint the onset of significant human impact on the landscape more precisely. Given that alluvial sites often experienced early anthropogenic impact, including pollen data obtained from alluvial sites could not only improve the spatial coverage and accuracy of current pollen-based land cover reconstructions but could also improve our understanding of human transformation of the landscape, which can in turn contribute to an improvement of the ALCC scenarios.

A new age model and chemostratigraphic framework for the Maastrichtian type area (southeastern Netherlands, northeastern Belgium)

A new age model and chemostratigraphic framework for the Maastrichtian type area (southeastern Netherlands, northeastern Belgium)

Reconstructing the depositional history of Pleistocene fluvial deposits based on grain size, elemental geochemistry and in-situ 10Be data

Constraining depositional phases in braided river deposits can be challenging if only based on sedimentology or geochronology. In this paper, we explored how different data sources can provide complementary information on the depositional history of Pleistocene fluvial deposits. The study was realized on the Zutendaal gravels that outcrop in Northeastern Belgium. In an 8 m high exposure of gravel sheets, we collected bulk samples that were processed for grain size, elemental geochemistry and cosmogenic radionuclides. After dry sieving, we derived the D10, D50, D90, gravel and sand content. From the elemental geochemistry of the bulk samples, we calculated the Ti/Zr and Cr/Zr ratios as proxies for provenance, the Al2O3/SiO2 and Ba/Sr ratios for hydrolysis, and the MnO, Fe2O3 concentrations and the Fe2O3+MnOAl2O3 ratio for oxidation. The 10Be concentration-depth profiles are informative to identify phases of landscape stability characterized by depositional hiatuses. To verify the existence of any aberrant variation in 10Be concentration associated to provenance, the in-situ 10Be concentrations were contrasted with provenance and weathering indices. Differences in grain size, elemental geochemistry and in-situ 10Be between sedimentary units were evaluated based on Mann-Whitney tests, while Spearman correlation tests informed us on the co-variation between data sources. The outcrop in the Zutendaal gravels contains three depositional units with significant differences in grain size and chemical weathering extent, and representing distinct 10Be accumulation phases. The absence of correlation between provenance and oxidation proxies indicates that weathering is essentially intraformational or post-depositional. Sedimentary hiatuses were identified based on fining upward sequences and 10Be concentration-depth profiles, whereby local deviation in 10Be concentration at the top of the fining upward sequence provided information on the duration of the hiatus. The case study illustrates how co-variations in weathering, provenance, granulometry indices and 10Be concentration are informative for the depositional history of fluvial sediments, and landscape stability during the Pleistocene.

Spatiotemporal Prediction and Mapping of Heavy Metals at Regional Scale Using Regression Methods and Landsat 7

Soil contamination by heavy metals is of particular concern, due to the direct negative impact on crop yield, food quality and human health. Although the conventional approach to monitor heavy metals relies on field sampling and lab analysis, the proliferation in the use of portable spectrometers has reduced the cost and time of investigation. However, discrepancies in spectral data from different spectrometers increase the modeling time and undermine the model accuracy for spatial mapping. This study, therefore, took advantage of the readily accessible Landsat 7 data to predict and map the spatiotemporal distribution of ten heavy metals (i.e., Sb, Pb, Ni, Mn, Hg, Cu, Cr, Co, Cd and As) over a 640 km2 area in Belgium. The Land Use/Cover Area Frame Survey (LUCAS) database of a region in north-eastern Belgium was used to retrieve variation in heavy metals concentrations over time and space, using the Landsat 7 imagery for four single dates in 2009, 2013, 2016 and 2020. Three regression methods, namely, partial least squares regression (PLSR), random forest (RF) and support vector machine (SVM) were used to model and predict the heavy metal concentrations for 2009. By comparing these models unbiasedly, the best model was selected for predicting and mapping the heavy metal distributions for 2013, 2016 and 2020. RF turned out to be the optimal model for 2009 with a coefficient of determination of prediction (R2P) and residual prediction deviation of prediction (RPDP) ranging from 0.62 to 0.92, and 1.23 to 2.79, respectively. The measured heavy metal distributions along the river floodplains, at the highlands and in the lowlands, were generally high, compared to their RF spatiotemporal predictions, which decreased over time. Increasing moisture contents in the floodplains adjacent to the river channels and the lowlands were the primary contributors to the reduction in the satellite reflectance spectra. However, topsoil erosion from rainfall, snowmelt as well as wind into the lowlands could have influenced the reduction in heavy metal spatiotemporal predicted values over time in the highlands. The spatiotemporal prediction maps produced for the heavy metals for the four different years revealed a good spatial similarity and consistency with the measured maps for 2009, which indicates their stability over the years.

Electron spin resonance (ESR), optically stimulated luminescence (OSL) and terrestrial cosmogenic radionuclide (TCN) dating of quartz from a Plio-Pleistocene sandy formation in the Campine area, NE Belgium

The chronostratigraphy of the typical quartz-rich white sands that are intensively quarried in the Campine area, northeastern Belgium, is poorly constrained. In the absence of biostratigraphical data, the age of the deposits, traditionally assigned to the Mol Formation, is thought to be late Pliocene based on sequence stratigraphical correlations (ca. 2.6–3.6 Ma). In an attempt to verify this age, we used a multi-dating method approach on two carefully selected samples in a palaeoseismological trench where the sediment was found to be vertically displaced by the Rauw fault. Three dating methods were used: electron spin resonance (ESR) dating, optically stimulated luminescence (OSL) dating and cosmogenic radionuclide (CRN) dating. In all three cases quartz was found to be a suitable dating material in terms of material properties. However, the ESR dating results based on Ti, Ti–Li and Al centres show strong internal inconsistencies, which can be explained by incomplete bleaching. As such, the youngest ESR ages obtained (ca. 5 Ma) are regarded as an absolute maximum age. In contrast, the OSL ages of ca. 1.5 Ma seem to underestimate the sequence stratigraphical age. The surface exposure CRN dating method using Bayesian inversion suggests that a palaeosurface developed around 1.55 ± 0.80 Ma, and eroded at a rate of ca. 15 m/Ma. Erosion probably accelerated after ca. 0.5–1 Ma and posterior to the last major movement along the Rauw fault.

Comparing Apple and Pear Phenology and Model Performance: What Seven Decades of Observations Reveal

Based on observations for the beginning of the flowering stage of Malus domestica (apple) and Pyrus communis (pear) for the 1950–2018 period, phenological trends in north-eastern Belgium were investigated in function of temperatures during dormancy. Moreover, two different phenological models were adapted and evaluated. Median flowering dates of apple were on average 9.5 days earlier following warm dormancy periods, and 11.5 days for pear, but the relationship between bloom date and temperature was found not to be linear, suggesting delayed fulfilment of dormancy requirements due to increased temperatures during the chilling period. After warm chilling periods, an average delay of 5.0 and 10.6 days in the occurrence date of dormancy break was predicted by the phenological models while the PLSR reveals mixed signals regarding the beginning of flowering. Our results suggest overlapping chilling and forcing processes in a transition phase. Regarding the beginning of flowering, a dynamic chill model coupled to a growing degree days estimation yielded significantly lower prediction errors (on average 5.0 days) than a continuous chill-forcing model (6.0 days), at 99% confidence level. Model performance was sensitive to the applied parametrization method and limitations for the application of both models outside the past temperature ranges became apparent.

Roveacrinida (Crinoidea, Articulata) from the upper Maastrichtian Peedee Formation (upper Cretaceous) of North Carolina, USA – The last pelagic microcrinoids

Microcrinoids belonging to the Order Roveacrinida are described from the Late Maastrichtian Peedee Formation of North Carolina. Five species are present; Applinocrinus texanus Peck, 1973, Lucernacrinus multispinosus Gale, sp. nov., Birgenelocrinus degraafi Jagt, 1999, B. jagti Gale, sp. nov. and Peedeecrinus sadorfi Gale, gen. et sp. nov. Two of these species (A. texanus, B. degraafi) and close relatives of two others (Lucernacrinus, Birgenelocrinus jagti) are known from the upper Maastrichtian (upper Maastricht Formation) of the Netherlands and northeastern Belgium, indicating that the Roveacrinida were flourishing and widespread up to the end of the Cretaceous. It is concluded that Paleogene and Neogene records of Roveacrinidae represent contamination of samples by Cretaceous (Turonian) material.

Circles, Cycles and Ancestral Connotations. The Long-term History and Perception of Late Prehistoric Barrows and Urnfields in Flanders (Belgium)

The perception of and interaction with ancient relics in past societies has been intensively debated in the archaeology of north-western Europe. This paper aims to make a contribution to this debate by reconstructing the long-term history of late prehistoric barrows and urnfields in Flanders (Belgium). The period between the Late Bronze Age and High Middle Ages (c. 1100 calbc–ad1300) is centred on. Contrary to Germany, Scandinavia and especially Britain, data from the Low Countries (Belgium and the Netherlands) have so far barely played a role in wider international and theoretical discussions on the role of the past in the past. Previous studies on reuse practices in the Low Countries mainly focused on the Meuse-Demer-Scheldt region of the southern Netherlands and north-eastern Belgium, which partly overlaps Flanders. These studies are combined and summarised. Their main outcomes are tested by means of a detailed inventory of reused late prehistoric cemeteries in Flanders. This study differs methodologically from most others in that it both offers an evidence-based overview of regional diachronic trends (documented at 62 barrow cemeteries and 13 urnfields) and discusses the developments at six sites yielding high resolution data. The observed reuse practices and site biographies appear to be remarkably dynamic and more diverse than previously suggested.

What was the transport mode of large boulders in the Campine Plateau and the lower Meuse valley during the mid-Pleistocene?

The Campine Plateau in northeastern Belgium, a remnant of an alluvial fan deposited by the Meuse River during the mid-Pleistocene, is characterised by the presence of boulders with maximum dimensions of up to 2m, embedded in a gravel matrix. These boulders originated in the Ardennes region and are generally assumed to have been transported by ice-rafting processes. This paper investigates for the first time quantitatively the possibility of purely hydraulic transport of the boulders, taking into account channel and flow characteristics in the boulder provenance area during the mid-Pleistocene. Empirical transport relations that describe incipient motion thresholds in nonuniform river beds as a function of the relative grain size, or the ratio between the grain size of interest and the median grain size of the channel bed, are applied in order to calculate critical water depths for transport of boulders of various sizes. Results indicate that hydraulic transport of boulders with intermediate diameters <1m could have occurred within limited reaches of the palaeoriver, more specifically in the palaeo-Amblève tributary; whereas the small slope gradient of the palaeo-Meuse most probably inhibited boulder movement by hydraulic forces only. Although calculations of the ice volume required to lift a boulder to the water surface and comparison of the ice floe's dimensions with palaeochannel morphology do suggest that ice rafting is theoretically possible, several alternative, more probable transport mechanisms for the larger boulders of the Campine Plateau are proposed, requiring much smaller critical ice volumes and water depths than ice-rafting processes or purely hydraulic transport. These hypotheses include decreased bed friction and effective boulder density caused by a limited ice layer attached to the river bed and the boulder, hence lowering hydraulic transport thresholds, as well as the formation of ice jams and dams inducing catastrophic flooding and mechanical impacts by ice floes upon failure.

Der Buntsandstein in den Niederlanden und Nordost-Belgien

Der Buntsandstein in den Niederlanden und Nordost-Belgien

Multi-scale aquifer characterization and groundwater flow model parameterization using direct push technologies

Direct push (DP) technologies are typically used for cost-effective geotechnical characterization of unconsolidated soils and sediments. In more recent developments, DP technologies have been used for efficient hydraulic conductivity (K) characterization along vertical profiles with sampling resolutions of up to a few centimetres. Until date, however, only a limited number of studies document high-resolution in situ DP data for three-dimensional conceptual hydrogeological model development and groundwater flow model parameterization. This study demonstrates how DP technologies improve building of a conceptual hydrogeological model. We further evaluate the degree to which the DP-derived hydrogeological parameter K, measured across different spatial scales, improves performance of a regional groundwater flow model. The study area covers an area of ~60 km2 with two overlying, mainly unconsolidated sand aquifers separated by a 5–7 m thick highly heterogeneous clay layer (in north-eastern Belgium). The hydrostratigraphy was obtained from an analysis of cored boreholes and about 265 cone penetration tests (CPTs). The hydrogeological parameter K was derived from a combined analysis of core and CPT data and also from hydraulic direct push tests. A total of 50 three-dimensional realizations of K were generated using a non-stationary multivariate geostatistical approach. To preserve the measured K values in the stochastic realizations, the groundwater model K realizations were conditioned on the borehole and direct push data. Optimization was performed to select the best performing model parameterization out of the 50 realizations. This model outperformed a previously developed reference model with homogeneous K fields for all hydrogeological layers. Comparison of particle tracking simulations, based either on the optimal heterogeneous or reference homogeneous groundwater model flow fields, demonstrate the impact DP-derived subsurface heterogeneity in K can have on groundwater flow and solute transport. We demonstrated that DP technologies, especially when calibrated with site-specific data, provide high-resolution 3D subsurface data for building more reliable conceptual models and increasing groundwater flow model performance.

Long-term evolution of the surface environment of the Campine area, northeastern Belgium: first assessment

Abstract In this paper we describe the characteristics of the surface environment of the Boom Clay in the Campine area (outcrop and subcrop zone), which is regarded as a potential host formation for disposal of radioactive waste. A good description and understanding of the relationship between surface variables – the geomorphology, hydrography, vegetation, soils, land use and hydrology – is needed to evaluate the past evolution and assess the future evolution of the surface environment. Changing climatic conditions (glacials and interglacials), global sea-level variations and tectonic movements (uplift and subsidence) may cause the surface environment to change profoundly over long timescales. Starting from the present status, the palaeogeographical and palaeohydrological evolution of the Campine area is described in the framework of the Quaternary geological history of the area. Finally, a first assessment of possible future conditions of the surface environment is given, based on the integration of the palaeorecord and several published modelling studies.

Regional groundwater flow modelling of the confined aquifers below the Boom Clay in NE Belgium

Abstract For more than 35 years, SCK•CEN has been investigating the possibility of high-level radioactive waste disposal in the Boom Clay in northeastern Belgium. This research, defined in the long-term management programme for high and medium long-lived waste of ONDRAF/NIRAS, includes the regional hydrogeological modelling of the aquifer systems surrounding the Boom Clay. In this paper, the most recent update of the Deep Aquifer Pumping model (DAP) is described, which is capable of quantifying the regional groundwater flow in the complex confined aquifers lying below the Boom Clay in NE Belgium. The DAP model was successfully calibrated using an automated inverse optimization algorithm and is able to reproduce satisfactorily the general trends in the observed groundwater heads. This model can be used as a tool for planning future characterization efforts and reducing the predictive model uncertainty.

Patterns and estimates of post-Rupelian burial and erosion in the Campine area, north-eastern Belgium

We have compiled a dataset containing information on patterns of burial and erosion that occurred during the last ca. 30Ma in the Campine area, north-eastern Belgium. This area coincides with the occurrence of the Rupelian Boom Clay which is considered as one of the potential host formations for radwaste disposal. Patterns and estimates of erosion and sedimentation, based on geological and geomorphological data, from several locations within the Boom Clay outcrop and subcrop zone, show increasing burial in northern and north-eastern direction over the last 30Ma. More southern areas have experienced erosion and denudation during some geological stages, usually in the order of several 10m, up to 100m at most at two discrete locations. During the Quaternary, erosion is a widespread phenomenon in the Campine area, except in the Roer Valley Graben. The obtained estimates of erosion and burial are compared and discussed in the context of the overall geodynamic evolution of north-western Europe.

Variation in cancer incidence in northeastern Belgium and southeastern Netherlands seems unrelated to cadmium emission of zinc smelters

Exposure to cadmium has been established to be carcinogenic for humans by the International Agency for Research on Cancer, but this is mainly based on studies with occupational exposures. The substantial 100 year long emission of cadmium by three zinc smelters in the Kempen area across the Dutch-Belgian border might have affected the incidence of cancer in this region. Following a study of increased risks of lung cancer due to cadmium emission (hazard ratio was 4.2 for high vs. low cadmium exposure areas in that study), we used data from the three regional population-based cancer registries, covering an area with 2.9 million inhabitants. Analyses of observed incidence were carried out for all cancers and cancer of the lung, kidney, bladder, prostate, testis, and breast separately. At the municipality level standardized incidence ratios were calculated and smoothed using a Poisson-gamma or a conditional autoregressive model. To detect clusters and to calculate an observed/expected ratio (O/E ratio) for each cluster a spatial scan statistic was applied. Significantly increased cancer incidence rates were found at a multimunicipality level for female lung cancer (O/E ratio=1.2), male and female bladder cancer (O/E ratio male=1.8, O/E ratio female=1.7), and prostate cancer (O/E ratio=1.3), none of these clusters being located specifically around the area of the zinc smelters. Therefore, the long term emission of cadmium by the zinc smelters in the Kempen area did not seem to lead to an increase in the incidence of all cancers, and lung, kidney, bladder, prostate, testicular, or breast cancer.

Human impact on sediment dynamics — quantification and timing

Several methods to reconstruct past land cover are available which can be roughly divided into approaches based on pollen data and approaches based on (estimates of) historical human population. In this study, the REVEALS model and non-metric multidimensional scaling (NMDS) are applied to pollen sequences obtained from multiple alluvial floodplains located in the sandy and loamy regions of northeastern Belgium, thereby obtaining the first regional (semi-)quantitative estimates of Holocene landscape openness for this area. These estimates are subsequently compared to the two most widely-used scenarios for anthropogenic land cover change (ALCC): KK10 and HYDE.In contrast with the two population-based ALCC scenarios, the pollen-based reconstructions are well in agreement and indicate considerable variability in past land cover, not only between the two regions but even between the individual catchments. This agreement implies that NMDS could serve as an alternative approach to provide insight in large amounts of pollen data in case not all required model parameters are available to run the REVEALS model. Moreover, NMDS can provide a better understanding of which taxa are related to a particular type of landscape. Taking into account such insights in the interpretation of the REVEALS model output might help to pinpoint the onset of significant human impact on the landscape more precisely. Given that alluvial sites often experienced early anthropogenic impact, including pollen data obtained from alluvial sites could not only improve the spatial coverage and accuracy of current pollen-based land cover reconstructions but could also improve our understanding of human transformation of the landscape, which can in turn contribute to an improvement of the ALCC scenarios.

First Report of the Root-Knot Nematode Meloidogyne minor on Turfgrass in Belgium.

The root-knot nematode, Meloidogyne minor, was described during 2004 after it was found on potato roots in a field in the Netherlands and in golf courses in England, Wales, and Ireland (2). Since it is associated with yellow patch disease in turf grass and causes deformation of potato tubers (2), it is important to know whether this organism is already widespread in these and neighboring countries. In addition, it has a relatively wide host range (2,4). A small survey conducted in Belgium was comprised of 10 golf courses geographically spread over the country. In each location, 3 to 9 samples were taken (one per green) consisting of 30 to 40 cores (1.5 × 20 cm deep). Nematodes were extracted from a 200-g subsample (containing roots) from each sample using zonal centrifugation (1). All Meloidogyne spp. were mounted on semipermanent slides and identified morphologically. M. minor was discovered in 3 of 6 samples taken in April 2006 from a golf course in Hasselt (northeastern Belgium). Between 41 and 50 M. minor per 100 g of soil were found together with M. naasi (7 to 20 individuals per 100 g of soil). Occurrence of M. minor together with other Meloidogyne species has been reported in natural and cultivated sites (2,4). Moreover, spores of Pasteuria spp. were clearly visible on 42% of the observed second-stage juveniles of M. minor, but not on those of M. naasi. The infected juveniles had between 2 and 15 spores attached to their cuticles. Additional juveniles were extracted from the soil samples and used for molecular identification by real-time PCR (2), which confirmed the presence of M. minor. There were no symptoms on the grass, consisting of a mixture of Agrostis stolonifera (10%), Festuca rubra (30%), and Poa annua (60%). Grass was sown in Rhine sand and heath land compost used for the construction of the greens in Hasselt. It could be that these soil amendments were infested with M. minor or that M. minor was introduced by other means, e.g., shoes, maintenance machinery, or golf equipment. On the other hand, the detection of M. minor in this small survey indicates that the species may be prevalent in golf courses in the region. The nematode has been found in several golf courses and sport fields in the United Kingdom and the Netherlands, including a golf course at Breda (close to the Belgian border) (3). The survey will be expanded to include grasslands and dune areas, the presumed natural habitat of M. minor.

Transferability of Species Distribution Models: a Functional Habitat Approach for Two Regionally Threatened Butterflies

Numerous models for predicting species distribution have been developed for conservation purposes. Most of them make use of environmental data (e.g., climate, topography, land use) at a coarse grid resolution (often kilometres). Such approaches are useful for conservation policy issues including reserve-network selection. The efficiency of predictive models for species distribution is usually tested on the area for which they were developed. Although highly interesting from the point of view of conservation efficiency, transferability of such models to independent areas is still under debate. We tested the transferability of habitat-based predictive distribution models for two regionally threatened butterflies, the green hairstreak (Callophrys rubi) and the grayling (Hipparchia semele), within and among three nature reserves in northeastern Belgium. We built predictive models based on spatially detailed maps of area-wide distribution and density of ecological resources. We used resources directly related to ecological functions (host plants, nectar sources, shelter, microclimate) rather than environmental surrogate variables. We obtained models that performed well with few resource variables. All models were transferable--although to different degrees--among the independent areas within the same broad geographical region. We argue that habitat models based on essential functional resources could transfer better in space than models that use indirect environmental variables. Because functional variables can easily be interpreted and even be directly affected by terrain managers, these models can be useful tools to guide species-adapted reserve management.