The 'Maagdentoren' of Zichem (Belgium) : damage assessment of ferruginous sandstone by X-ray tomography

The ferruginous sandstone of the gothic “Maagdentoren” is suffering from a specific biological deterioration process triggered by perforating activities of mason bees. The damage due to these perforations causes extensive loss of material, so that a durable conservation of such degraded stone blocs becomes questionable. In order to evaluate the conservation possibilities of stone blocs damaged by perforating mason bees, an investigation of the internal structure by means of X-ray tomography was carried out. This investigation revealed that the cumulative effect of the digging work by multiple generations of mason bees may result in networks of perforations. Bioturbated sandstones were found to be most suitable for attack by mason bees because of morphological and geometrical compatibility between the original layered burrowings by marine organisms and those by the mason bees. As a conclusion the conservation is not recommended of sandstone blocs for which the load bearing capacity is endangered by the branched and layered perforations

Damage assessment of ferruginous sandstone by X-ray tomography : the 'Virgin Tower' of Zichem (Belgium)

The ferruginous sandstone of the Gothic “Virgin Tower” is suffering from a specific biological deterioration process triggered by perforating activities of mason bees. The damage due to these perforations causes extensive loss of material, so that a durable conservation of such degraded stone blocks becomes questionable. In order to evaluate the conservation possibilities of stone blocks damaged by perforating mason bees, an investigation of the internal structure by means of X-ray tomography was carried out. This investigation revealed that the cumulative effect of the digging work by multiple generations of mason bees may result in networks of perforations. Bioturbated sandstones were found to be most suitable for attack by mason bees because of morphological and geometrical compatibility between the original layered burrowings by marine organisms and those by the mason bees. As a conclusion, the conservation is not recommended of sandstone blocks for which the load bearing capacity is endangered by the branched and layered perforations

Post Mining Ground Deformations Transition Related to Coal Mines Closure in the Campine Coal Basin, Belgium, Evidenced by Three Decades of MT-InSAR Data

peer reviewedSpatio-temporal ground-movement measurements and mappings have been carried out in the Campine coalfield in Belgian Limburg since the closure of the mines to document post-mining effects. MT-InSAR measurements are compared to groundwater head changes in the overburden and to height data from the closest GNSS stations. Radar interferometry is used to estimate the extension and the velocity of ground movements. In particular, the MT-InSAR technique has been applied to SAR acquisitions of the satellites ERS-1/2 (1991–2005), ENVISAT (2003–2010), COSMO-SkyMed (2011–2014), and Sentinel-1A (2014–2022). The images were processed and used to highlight a switch from subsidence to uplift conditions in the western part of the coal basin, while the eastern part had already been affected by a rebound since the beginning of the ERS-1/2 acquisitions. Following the closure of the last active colliery of Zolder in 1992 and the subsequent cease of mine-water pumping, a recharge of mine-water aquifers occurred in the western part of the basin. This process provoked the change from subsidence to uplift conditions that was recorded during the ENVISAT period. In the center of the coal-mining area, measured uplift velocities reached a maximum of 18 mm/year during the ENVISAT period, while they subsided at -12 mm/year during the ERS-1/2 period. Mean velocities in the western and eastern parts of the coalfield area have decreased since the last MT-InSAR measurements were performed using Sentinel-1A, while the Zolder coal mine continues to rise at a faster-than-average rate of a maximum of 16 mm/year. The eastern part of the coalfield is still uplifting, while its rate has been reduced from 18 mm/year (ERS-1/2) to 9 mm/year (Sentinel-1A) since the beginning of the radar–satellite observations. Time-series data from the two GNSS stations present in the study area were used for a local comparison with the evolution of ground movements observed by MT-InSAR. Two leveling campaigns (2000, 2013) were also used to make comparisons with the MT-InSAR data. The station’s measurements and the leveling data were in line with the MT-InSAR data. Overall, major ground movements are obviously limited to an extension of the actual underground-mining works and rapidly diminish outside of them

The Kasterlee Formation and its relation with the Diest and Mol Formations in the Belgian Campine

Stratigraphic analysis of cored and geophysically logged boreholes in the Kasterlee-Geel-Retie-Mol-Dessel area of the Belgian Campine has established the presence of two lithostratigraphic units between the classical Diest and Mol Formations, geometrically related to the type Kasterlee Sand occurring west of the Kasterlee village and the study area. A lower 'clayey Kasterlee' unit, equivalent to the lithology occurring at the top of the Beerzel and Heist-op-den-Berg hills, systematically occurs to the east of the Kasterlee village. An overlying unit has a pale colour making it lithostratigraphically comparable to Mol Sand although its fine grain size, traces of glauconite and geometrical position have traditionally led stratigraphers to consider it as a lateral variety of the type Kasterlee Sand; it has been named the 'lower Mol' or 'Kasterlee-sensu-Gulinck' unit in this study. In the present analysis, the greenish glauconitic Kasterlee Sand in its hilly stratotype area evolves eastwards into the lower 'clayey Kasterlee' unit and possibly also into an overlying 'lower Mol' or `Kasterlee-sensu-Gulinck' unit, although it is equally possible that the latter unit has an erosive contact and therefore is stratigraphically slightly younger than the type Kasterlee Sand west of the Kasterlee village. A lateral extension of this detailed stratigraphic succession into the faulted one of east Limburg is proposed

Enkele opmerkelijke personen - Quelques personnes remarquables

info:eu-repo/semantics/publishe

Grote verwezenlijkingen - Principales réalisations

info:eu-repo/semantics/publishe

Hommage à Yvan de Magnée

info:eu-repo/semantics/publishe

Levé des couches de transition du Frasnien au Famennien, sur la route Marche-en-Famenne - Liège, dans la traversée de Baillonville

info:eu-repo/semantics/publishe

Cirkelvormige depressies in de Vlakte van Bocholt

In de Vlakte van Bocholt, het landelijke en rustige gebied gelegen tussen Hamont, Bree en Kinrooi, komt een onopvallend landschapselement voor dat als natuurlijk relict uniek is voor dit gebied. Een tweehonderdtal cirkelvormige depressies met een doormeter van gemiddeld 140 m en verhoogde wallen van gemiddeld 1,50 m kon dankzij de opmaak van hellingschaduwkaarten op basis van het DHM Vlaanderen in kaart gebracht worden. Veldonderzoek uitgevoerd op de Sint-Martensheide in Bree heeft aangetoond dat ze zijn ontstaan als windkuil of deflatiekom. Die ontstaan meestal in hogere duinen waar hun vorm meer langgerokken is en de morfologie snel verandert. In gebieden met een laag zandaanbod en een hoge grondwaterstand, zoals in de Vlakte van Bocholt, worden deflatiekommen gefixeerd in een vroeg stadium. Dergelijke morfologische structuren hebben een zeer laag bewaringspotentieel in de bewoonde wereld want zij worden snel vernietigd door grondverzet bij ploegen. Het voorkomen in de Vlakte van Bocholt is dus uitzonderlijk maar ook zeer kwetsbaar, door omzetting in maïsakkers of door ontgronding. Het bevestigt de waarde van het gebied rond de Abeekvallei en Stamprooierbroek als ankerplaats en de noodzaak om een aantal representatieve plaatsen tegen aantasting te beschermen.no ISBNstatus: publishe

Connecting the Chalk Group of the Campine Basin to the dinoflagellate cyst biostratigraphy of the Campanian to Danian in borehole Meer (northern Belgium)

A palynological study of the Chalk Group (Campanian-Danian) in the Meer borehole (northern Belgium), which penetrated the thickest succession known in the Campine Basin, has revealed diverse, well-preserved organic-walled dinoflagellate cyst assemblages. The succession contains numerous chronostratigraphically significant dinocyst events, which are based mainly on the highest consistent occurrences of index species. At least 35 bioevents have enabled a subdivision into nine intervals, at stage or substage level, within the Campanian to Danian interval, as based on comparison with coeval assemblages elsewhere in northwest Europe, inclusive of stratotypes of stages and stage boundaries. Bio-events allow correlation of the section studied with the Campanian Exochosphaeridium? masureae, Areoligera coronata and Samlandia mayi zones, the Maastrichtian Pervosphaeridium tubuloaculeatum, Deflandrea galeata and Hystrichostrogylon coninckii zones, and the Danian Damassadinium californicum Zone. In addition, a correlation with other zonal schemes for the southern North Sea Basin and with conventional northwest European belemnite zones is presented. Comparisons with Boreal and Tethyan realms confirm that most bio-events may also be useful for interregional and global correlation. The Campanian-Danian dinocyst biostratigraphy of the Meer borehole is put alongside geophysical well logs and an ecozonation, in order to check the validity of lithostratigraphical correlations across the Campine Basin. This first, detailed correlation attempt shows that sensitivities to facies change associated with differences in accommodation space and sediment supply appear to be at the base of slight, yet consistent, shifts between the local lithological succession and the standard lithostratigraphical scheme of the Maastricht type area