Search publications of the members of the Royal Belgian institute of natural Sciences
-
Statistical imaging of the deformation over Belgium using multiple geodetic techniques.
- One of the challenges of geodesy is to characterize at the sub-millimeter level the vertical deformation of the ground in response to tectonic, anthropogenic, and climatic forcing. Reaching this level of accuracy is crucial to understand the deformation mechanisms acting in Belgium and it contributes to the mitigation of geo-hazards and the operational management of the territory. To address this challenge, the LASUGEO project, aiming at identifying ground deformation caused by groundwater exploitation, makes use of the observations of three independent geodetic techniques, namely: Global Navigation Satellite System (GNSS), Permanent Scatterers Interferometry Synthetic Aperture Radar (PS-InSAR), and repeated Absolute Gravity measurements (AG). Because GNSS, PS-InSAR, and AG provide independent measurements with different spatial and temporal resolutions, they are highly complementary. However, considering that each technique also comes with its own reference frames, accuracy, and source of biases, the optimal combination of these observations requires an appropriate statistical methodology. To estimate the deformation over Belgium, we performed a joint analysis of the GNSS position time series provided by the Nevada Geodetic Laboratory (Blewitt et al., 2018), the PS-InSAR time series processed at Geological Survey of Belgium (Declercq et al., 2021), and the AG measurement carried out by the Royal Observatory of Belgium (Van Camp et al., 2011). Our statistical analysis is divided in three steps: (1) trajectory modelling of each geodetic time series, that is, the model of the predictable motion (e.g., linear trend, periodic deformation, and instrumental discontinuities), (2) surface reconstruction of the subsidence/uplift rates from each technique, and (3) the comparison of the result of the different techniques. For each step, attention is paid to the realistic estimation of the model uncertainties, by accounting for the influence of the time correlated stochastic variability in the geodetic time series (Williams et al. 2003). We propose to describe the algorithms used and results obtained from the trajectory modelling and surface reconstruction of the subsidence/uplift rates. We show that, by combining a large number of observation, we are able to image vertical deformation at the 1.0 mm/yr level over Belgium (see Figure 1 for the GNSS imaging). We also discuss differences between GNSS, AG and PS-InSAR that could highlight the need to calibrate PS-InSAR relative estimates with GNSS and AG geocentric velocities.
-
Silurian solid bitumen from Huy: evidences for a petroleum system in Belgium
- The discovery of a bitumen bed within the Silurian Bonne Esperance Formation near the city of Huy (Belgium) is the first clear evidence for a petroleum system in Belgium. The studied section near the city of Huy (Belgium) is part of a larger structural unit called the Condroz inlier. This structural unit is a wedge of Ordovician to Silurian aged marine sediments which was thrusted up along the Midi detachment fault during the Hercynian orogeny and forming the Ardennes Massif (Adams & Vandenberghe, 1999). To understand the geological processes involved in the formation of the bitumen bed, the Bonne Esperance Formation was logged and 82 samples were collected for XRF chemostratigraphy, five samples were collected (Figure 1, pictures 1-5) for biostratigraphic purposes and one sample was taken from the bitumen itself. ICP-MS, TOC, Rock-Eval pyrolysis and Gamma-ray measurements are underway to quantify the source rock potential of the Bonne Esperance Formation. Preliminary XRF measurements already show that especially the lower part of the Bonne Esperance Formation is enriched in elements linked to anoxic conditions/enrichment of organic material, which indicates that the Bonne Esperance Formation itself is the likely candidate source rock for the bitumen. The sample from the bed which includes the bitumen has already been tested to confirm the nature of the bitumen material. The sample was crushed and heated in a vial and the released hydrocarbons were then ignited with a flame (Figure 1, picture 6C). The First occurrence of the graptolites of the Family Monograptidae was used to pinpoint the location of the Ordovician-Silurian boundary (Akidograptus Ascensus zone at sample 4) (Maletz, 2017). Given the current results and the ongoing analyses a picture emerges of the Silurian of the Condroz inlier as being Belgium’s first and to date only petroleum system.
-
Preliminary activities aimed to cluster EU cities by a geological point of view: The Urban Geo Footprint tool.
- This century is the “century of the cities”, where rapid urbanization and greater global connection present unprecedented urban challenges and concentrates risk in urban areas making them increasingly vulnerable (Coaffee & Lee, 2016). The need arises for urban planning must be asked to fully incorporate an understanding of the sub-surface into the deliberation/decision-making process (Howard, 1997). The Urban Geo Footprint (UGF) is classification tool being developed by a sub-group of the Urban Geology Expert Group of EuroGeoSurvey (UGEG) and it is based on a multidisciplinary effort in which different skills and expertise come into play. The main objective of this project is to set up a classification method to identify the main geological and anthropic features that influence city's resilience related to its geological setting. A tool is being developed in order to clustering cities according to their geological and climatic features and to understand why target urban contexts have different issues (e.g. climate change, floods), and thus to assess the cities’ geo-resilience. The UGF will help cities to understand what ‘economic’ and ‘social well-being’ benefits (i.e. in terms of ‘geological resilience’) could derive from urban planning associated with subsoil knowledge. The salient features required for this tool are: - It must be user-friendly and easy to use by scientists and non-scientists - It must be available at European level (and maybe, once is tested in Europe, it could be extended worldwide). The following main 5 drivers are defined in the tool: Geology, Climate, Geohazards, Geomorphology, Subsoil anthropic pressure. The assessment method of UGF tool will consist in testing it with data of different EU pilot-cities. The work in progress is developing a complex worksheet (which can be defined as the «UGF framework») with several quantitative parameters related to the 5 drivers mentioned above. All these parameters are going to be indexed (using scores) and weighted based on two levels of investigation: “basic” and “advanced”. The final result for each city is a general UGF score that will be the combination of all the drivers specific scores. Each tested city will be classified also by the weight of each driver in the calculation. Other objectives of the project are: - Contributing to develop a method for the comparison of data from different cities and update all existing database. - Improving the European collaboration and, therefore, the exchange of ideas on good practices to increase cities’ resilience. - Improving citizens' awareness of both the resources and the threats associated with geology.
-
Organic Matter Composition of Biomineral flocs and Its Influence on Suspended Particulate Matter Dynamics Along a Nearshore to Offshore Transect
- The seasonal variation in concentration of transparent exopolymer particles (TEPs), particulate organic carbon (POC) and particulate organic nitrogen (PON) were investigated together with floc size and the concentration of suspended particulate matter (SPM) along the cross-shore gradient, from the high turbid nearshore toward the low-turbid offshore waters in the Southern Bight of the North Sea. Our data demonstrate that biophysical flocculation cannot be explained by these heterogeneous parameters, but requires a distinction between a more reactive labile (“fresh”) and a less reactive refractory (“mineral-associated”) fraction. Based on all data, we separated the labile and mineral-associated POC, PON, and TEP using a semi-empirical model approach. The model's estimates of fresh and mineral-associated organic matter (OM) show that great parts of the POC, PON, and TEP are associated with suspended minerals, which are present in the water column throughout the year, whereas the occurrence of fresh TEP, POC, and PON is restricted to spring and summer months. In spite of a constantly high abundance of total TEP throughout the entire year, it is its fresh fraction that promotes the formation of larger and faster sinking biomineral flocs, thereby contributing to reducing the SPM concentration in the water column over spring and summer. Our results show that the different components of the SPM, such as minerals, extracellular OM and living organisms, form an integrated dynamic system with direct interactions and feedback controls.
-
Flocculation with heterogeneous composition in water environments: A review
- Flocculation is a key process for controlling the fate and transport of suspended particulate matter (SPM) in water environments and has received considerable attention in the field of water science (e.g., oceanography, limnology, and hydrology), remaining an active area of research. The research on flocculation has been conducted to elucidate the SPM dynamics and to diagnose various environmental issues. The flocculation, sedimentation, and transportation of SPM are closely linked to the compositional and structural properties of flocs. In fact, flocs are highly heterogeneous in terms of composition. However, the lack of comprehensive research on floc composition and structure has led to misconceptions regarding the temporal and spatial dynamics of SPM. This review summarizes the current understanding of the heterogeneous composition of flocs (e.g., minerals, organic matter, metals, microplastic, engineered nanoparticles) and its effect on their structure and on their fate and transport within aquatic environments. Furthermore, the effects of human activities (e.g., pollutant discharge, construction) on floc composition are discussed.
-
Tracking the source of lead of medieval glazed pottery of the Meuse valley (Belgium) through lead isotope analyses.
- Abstract Lead isotope analyses (by MC-ICP-MS) have been performed on lead-glazed pottery artefacts from several production and consumption sites in the Meuse basin (Belgium) spanning a long-time period from the 9th to the 16th century AD. Comparison of the lead isotope data of the glazes from three mosan workshops with those of galenas from Palaeozoic (Variscan) Pb-Zn deposits from both Belgium and Western Germany points to a common Pb source that we identify as the regional Pb deposits hosted in Dinantian limestones of the Ardenno-Rhenish Massif, more specifically in the Namur and Verviers synclines in Belgium and in the Aachen-Stolberg mining district in Germany. The overall similarity of isotopic compositions between the medieval artefacts and the Variscan galenas implies that the mosan medieval potters used accessible local Pb-Zn ores mined between Namur and Huy. On the consumption sites of Dinant, the slightly different isotopic compositions of some potteries suggest that other regional Pb sources were used to produce the glazes. A comparison with Roman lead objects discovered in north-western Europe (Northern Gaul) shows the very good correspondence of the Pb isotopic compositions with those of the Medieval artefacts which indicates a very long continuity of regional lead supply and consequently of lead ore mining. Keywords: Lead-glazed pottery; Middle Age; Lead isotope analysis; Lead ores; Sourcing; Mosan valley; Belgium
-
Complementarity of LA-ICP-MS and petrography in the analysis of Neolithic pottery from the Scheldt River valley, Belgium.
- Abstract This paper presents the results of laser ablation – inductively coupled plasma – mass spectrometry (LA-ICP-MS) analysis of the clay fraction in 70 Late Mesolithic and Early/Middle Neolithic pottery sherds from the Scheldt basin and 10 sampled sediments. The elemental concentration results were visualized using multivariate chemometric techniques and compared to the results of petrographic analysis of the same ceramics in order to investigate the complementarity of both approaches. In addition, the results for the pottery and sediments were compared for clay sourcing purposes. Overall, the elemental analysis was able to confirm part of the observations from the petrographic analysis. However, a large part of the ceramics clustering was driven by heterogeneity in the elemental composition that does not stem from differences in the clay source used. Furthermore, no conclusions could be drawn on the use of the sampled sediments for pottery production. Therefore, it is concluded that LA-ICP-MS analysis of the clay fraction in pottery can complement petrography, but petrographic analysis remains indispensable for clay sourcing of pottery from northern Belgium. Keywords: ceramic petrography, LA-ICP-MS, t-SNE, elemental analysis, Neolithic pottery, Belgium
-
Pavements et placages, l’ornementation du balnéaire privé de Warcq (Ardennes, France).
- Introduction: Une fouille préventive s’est déroulée aux lieux-dits « Simonelle » et « Sous le Chemin de Tournes » de la commune de Warcq. Cette commune se situe à trois kilomètres au nord-ouest de Charleville-Mézières, à la confluence de la Meuse, du ruisseau de This et de la Sormonne. Les opérations de terrain ont permis de mettre au jour les vestiges d’une partie d’une petite villa gallo-romaine constituée d’une cave, d’une cour ainsi que d’un balnéaire . Son occupation, qui s’étend du 1er au 4e siècle de notre ère, est caractérisée par de nombreux réaménagements pouvant être rassemblés en quatre grandes phases distinctes (fig. 1). Le secteur thermal est construit vers 130-150 de notre ère (phase 2) et forme l’aile occidentale de la villa. Vraisemblablement contraints par le bâti existant, les bâtisseurs ont opté pour un plan longitudinal où seule la natatio est en saillie. Il en découle un alignement des pièces et plus particulièrement celui du caldarium et du tepidarium dans celui du praefurnium. Sur près de deux siècles, cette partie de la villa a été soumise à des modifications architecturales dont l’agrandissement du frigidarium aux dépends de la cave (phase 3, fin 2e – début 3e siècle), puis l’ajout d’un apodyterium (phase 4, milieu 3e siècle ?). Dans son dernier état, l’ensemble thermal mesure environ 18 m de long pour 5 m de large offrant aux baigneurs un itinéraire rétrograde. L’accès se fait par le vestiaire dont aucun décor n’a été observé. Le secteur froid est une salle, presque carrée (3,40 m x 2,90 m). Elle comporte un bassin à immersion (natatio) à l’ouest et une banquette plaquée contre le mur oriental. On passe ensuite par le tepidarium, une salle rectangulaire (3,30 m x 1,90 m). Le parcours se poursuit par le caldarium. Cette pièce, aux mêmes dimensions que la précédente, est pourvue en sus d’une petite alcôve de 1,20 m de long sur 0,90 m de large dans laquelle est logé un bassin. Une seconde baignoire est flanquée contre le mur occidental (fig. 1). Ce balnéaire se distingue par l’utilisation de la pierre pour son apparat décoratif. Elle est employée aussi bien pour les pavements que pour les parois. Ce type de pratique reste méconnu et peu fréquent dans le sud de la Gaule belgique. L’ornementation des thermes sera abordée au travers de l’étude de ces décors et, dans un second temps, par la caractérisation et la provenance des roches utilisées. Il convient de mentionner que ces roches se distinguent des pierres de construction qui sont en calcaire gréseux coquillier de couleur jaune pâle à beige, attribuées à la Pierre de Romery, d’extraction locale. Ce matériau affleure à quelques kilomètres de Warcq. Ce travail résulte d’une collaboration entre archéologue, géologue, restauratrices et spécialiste des pavements, et fait suite à une intervention de dépose des pavements et des revêtements muraux mis au jour lors de la fouille.
-
Chimpanzees surviving in a fragmented high-altitude forest landscape of the Congolese Albertine Rift
-
Natuur- en landschapslezen
-
Neurogenomic Profiling Reveals Distinct Gene Expression Profiles between Brain Parts that are Consistent in Ophthalmotilapia Cichlids
-
Verstedelijking en biodiversiteit door een ecologische en evolutionaire bril
-
Verstedelijking verandert faunagemeenschappen
-
Parasitisme en symbiose wat verandert er in de stad
-
Preliminary Inventory of Bats (Mammalia, Chiroptera) in three protectd Areas of the Democratic Republic of Congo
-
Preliminary Inventory of Squirrels (Sciuridae, Rodentia) of Kisangani Region in the Democratic Republic of the Congo
-
Craniodental ecomorphology of the large Jurassic ichthyosaurian Temnodontosaurus
-
The first record of the genus Trichogomphus Burmeister from Nepal, and a checklist of Nepalese Dynastinae (Insecta: Coleoptera: Scarabaeidae)
-
Editorial. Two urgent topics: climate change and biodiversity loss
-
A masculinizing supergene underlies an exaggerated male reproductive morph in a spider
