As a result of the “new geological map of Wallonia” program undertaken by the Walloon Government since 1990, all the maps at 1/25 000 scale covering the outcrop areas of the Brabant Massif have been ...finalised. During the long period of mapping (1993-2017) our understanding of the stratigraphy and tectonics of the Brabant Massif has evolved significantly and this led to several inconsistencies between different maps. We present here an overarching geological map of the outcrop areas of the Brabant Massif, resulting from the merging of these 21 maps, updated according to the most recent findings and insights. The resulting map, at a scale of ~1/200 000, shows a coherent image of the outcrop areas of the Brabant Massif. This map better illustrates the geological history and structural architecture of the Brabant Massif compared to previous maps (e.g. Fourmarier, 1921; Legrand, 1968) and allows for a better understanding of the geology of the Brabant Massif. Also, it fully complements the subcrop map of the Brabant Massif of Piessens et al. (2005, in prep.).
Detailed analyses of folds and cleavage/fold relationships within the Lower Palaeozoic Brabant massif have resulted in the recognition of pre-cleavage folds, three types of syn-cleavage folds, and ...two broad types of post-cleavage folds. These detailed analyses, and their integration with data from other sources, have led to major advances in our understanding of the Brabant Massif. The distribution of the different fold types yields significant insight into the small- and large-scale influence of pre-existing sedimentological, lithological and deformation features on the final deformation geometry. Changes in lithology and sedimentology result in different types of syn-cleavage folds, slump folds and local competent magmatic bodies control the position and to some extent also the orientation of syn-cleavage folds and on a larger scale also early basin-bounding features exert a major control on later deformation geometries. Moreover, combined with other data, the analysis of folds and cleavage/fold relationships provides valuable information on the large-scale architecture of the Brabant Massif, and on the evolutionary history of the Brabant Basin, from initial basin development to the final stages of basin inversion and gravitational collapse, and this both in time and in space. As illustrated herein, a thorough inventory of numerous detailed analyses of folds and cleavage/fold relationships is an absolute necessity for an understanding of the structural architecture, evolutionary history and tectonic significance of fold belts and slate belts. KEYWORDS: cleavage, cleavage/fold relationship, kink band, Palaeozoic, slump fold
Theoretically, within a given pelitic rock in which the main paramagnetic carriers are white mica and chlorite and in which, judging from the AMS parameters, AMS is controlled by the paramagnetic ...carriers, the results of X-ray pole figure goniometry should show a qualitative relationship with AMS. This idea is tested on single-phase deformed, low-grade pelites of the Lower Palaeozoic Brabant Massif (Belgium), representing the southeastern part of the Anglo–Brabant Deformation Belt. For the vast majority of the samples investigated, the different LF-AMS parameters suggest a paramagnetic control on LF-AMS. Different parameters of LF-AMS measured at 77 K (low-
T LF-AMS) and a comparison of these with the LF-AMS parameters indicate that LF-AMS is controlled virtually entirely by paramagnetic carriers. High-field torque magnetometry (HF-AMS) indicates further that AMS is controlled entirely by paramagnetic carriers for the vast majority of the samples. Two apparent discrepancies are observed, however. These are 1) a frequent mismatch between the LF-AMS fabric on the one hand and the (paramagnetic) fabric indicated by low-
T LF-AMS and HF-AMS on the other hand, and 2) a rather common mismatch between the preferred orientation of chlorite and white mica suggested by X-ray pole figure goniometry on the one hand and the LF-AMS fabric, low-
T LF-AMS fabric and HF-AMS paramagnetic fabric on the other hand. These apparent discrepancies may partly be attributed to the composite nature of both the LF-AMS fabric and the paramagnetic susceptibility fabric. The presence of different populations of paramagnetic carriers, possibly in combination with minor traces of ferromagnetic (s.l.) carriers which are not picked up by the methods applied, may explain some of the mismatches observed and are compatible with the basin evolution history of the Brabant Massif. In addition, it is possible that the low temperatures (low-
T LF-AMS) and high fields (HF-AMS) are capable of enhancing one of the paramagnetic phases, thus leading to discrepancies between methods that define the mineral and the magnetic fabrics.
The results of this study show that, even when the LF-AMS data suggest that the LF-AMS of a given pelitic rock in which phyllosilicates form the main paramagnetic carriers, is controlled entirely by paramagnetic carriers, alternative methods, such as phyllosilicate X-ray pole figure goniometry, will not necessarily reflect the paramagnetic carrier orientation. Although a number of cases have successfully correlated LF-AMS with mineral fabric and occasionally even strain, this study serves as an example for how methods to define mineral and magnetic fabrics can be sensitive in detecting different paramagnetic phases.
Although it is generally accepted that buckle folds will not develop in a perfectly planar layer without the presence of some irregularity or perturbation at which the folds initiate, there are very ...few cases in which individual natural folds can be linked to specific irregularities. Within the Lower Ordovician Abbaye de Villers Formation, Anglo-Brabant Deformation Belt, metre-scale tectonic folds occur, of which the position and, to a certain extent, the geometry appear to be controlled by slump folds and related features. The metre-scale tectonic folds, interpreted as parasitic structures on the limb of a large-scale host fold, occur only within a stratigraphic level affected by slumping. In this level, tectonic antiforms tend to form superimposed on antiformal slump folds and on zones of abrupt, slump-related thickness increase, and tectonic synforms on synformal slump folds and on zones of abrupt thickness decrease. The rather irregular 3D geometry of sedimentary sequences suggests that many more similar cases should exist in which folds can be linked to specific irregularities. However, possibly it is also this abundance of irregularities in sedimentary sequences, in combination with fold and outcrop scale, that makes it difficult to attribute a particular fold to a particular perturbation.
The empirical power law relation (PR) between resonance frequency (
f
0
), obtained from H/V spectral ratio analysis of ambient noise, and sediment thickness (h), obtained from boreholes, is ...frequently used in microzonation studies to predict bedrock depth. In this study, we demonstrate (i) how to optimally construct a PR by including the error on the picked
f
0
in the regression, and (ii) how to evaluate a regression quality by identifying the under- or overestimation of the sediment thickness prediction. We apply this methodology on
f
0
data derived from 74 ambient noise recordings acquired above boreholes that reach the Brabant Massif bedrock below Brussels (Belgium). Separating the
f
0
data into different subset based on the cover geology does not significantly improve the bedrock depth prediction because the cover geology in Brussels has common base layers. In Brussels, the PR relation
h
= 88.631.
f
0
−1.683
is the best candidate to convert
f
0
to depth, with a prediction error of 10%. The Brussels PR was subsequently applied on a local survey (404 measurements; 25 km
2
) in southern Brussels with the aim to study Brussels’ Brabant Massif bedrock paleorelief. By linking the obtained paleorelief, Bouguer gravity data and aeromagnetic data, a NNW-SSE oriented, 20 m-high subsurface ridge could be identified. This ridge stands out because of differential erosion between less-resistant and hard quartzitic rock formations of the Brabant Massif. This subsurface ridge deflects the local radiation of seismic energy resulting in an anomaly in the otherwise regional consistent azimuthal dependency of the resonance frequency. We conclude that adding a polarisation analysis to a microzonation survey analysis allows detecting anomalous features in the paleorelief.
Aims To describe the IQED, a quality‐assurance system started in 2001 in Belgian hospital‐based multidisciplinary diabetes centres, and its effects on the quality of care.
Methods The study was ...conducted through four data collections (in 2001, 2002, 2004 and 2006). Approximately 120 diabetes centres provided data on a systematic random sample of 10% of their adult diabetic patients on at least two daily insulin injections. Data on patient characteristics, glycaemic control, cardiovascular risk, diabetes complications, follow‐up procedures and treatment were obtained. Local quality promotion was encouraged by returning comprehensive feedback (benchmarks) and during information meetings.
Results Nearly all diabetes centres (98–100%) participated. The pooled sample consisted of 9194 (32%) Type 1 and 19 828 (68%) Type 2 diabetes patients, with mean diabetes duration of 17 years and 14 years, prevalence of microvascular complications of 23% and 38% and prevalence of macrovascular complications of 9% and 26%, respectively. At the start, the quality of care was good in terms of risk‐factor testing rates and moderate in terms of patients meeting goals for risk‐factor management. At least 50% of the centres initiated quality‐promoting initiatives. After 5 years, significant improvements were seen in risk‐factor testing rates, apart from renal screening. Improvements in intermediate outcomes were less obvious, apart from an increase in patients reaching the targets for blood pressure and LDL cholesterol.
Conclusions It is feasible to implement a continuous quality‐improvement project on a nationwide scale, with improvements particularly in process indicators.
We aimed to investigate care processes and outcomes among children and adolescents with type 1 diabetes treated in hospital-based multidisciplinary paediatric diabetes centres. Our retrospective ...cross-sectional study among 12 Belgian centres included data from 974 patients with type 1 diabetes, aged 0–18 years. Questionnaires were used to collect data on demographic and clinical characteristics, as well as process of care completion and outcomes of care in 2008. Most patients lived with both biological or adoption parents (77 %) and had at least one parent of Belgian origin (78 %). Nearly all patients (≥95 %) underwent determination of HbA
1c
and BMI. Screening for retinopathy (55 %) and microalbuminuria (73 %) was less frequent, but rates increased with age and diabetes duration. Median HbA
1c
was 61 mmol/mol (7.7 %) interquartile range 54–68 mmol/mol (7.1–8.4 %) and increased with age and insulin dose. HbA
1c
was higher among patients on insulin pump therapy. Median HbA
1c
significantly differed between centres from 56 mmol/mol (7.3 %) to 66 mmol/mol (8.2 %). Incidence of severe hypoglycaemia was 30 per 100 patient-years. Admissions for ketoacidosis had a rate of 3.2 per 100 patient-years. Patients not living with both biological or adoption parents had higher HbA
1c
and more admissions for ketoacidosis. Parents' country of origin was not associated with processes and outcomes of care.
Conclusion
: Outcomes of care ranked well compared to other European countries, while complication screening rates were intermediate. The observed centre variation in HbA
1c
remained unexplained. Outcomes were associated with family structure, highlighting the continuing need for strategies to cope with this emerging challenge.
Following the dioxin crisis of 1999, several studies were conducted to assess the impact of this crisis on the dioxin body burden in the Belgian population. The Scientific Institute of Public Health ...identified a population from whom plasma samples were available and from whom, during the follow up survey, plasma samples were obtained in 2000. In total, 496 samples were collected for GC-HRMS and CALUX analyses to verify statistical assessment conclusions. This study was seen as an opportunity to validate the CALUX bioassay for biological sample analysis and to compare toxic equivalency (TEQ) values obtained by the reference GC-HRMS technique and by the screening method. This article focuses on the validation results of the CALUX bioassay for the analyses of the dioxin fractions of blood plasma. The sample preparation is based on a liquid–liquid extraction, followed by an acid silica in series with an activated carbon clean-up. A good recovery (82%) and reproducibility (coefficient of variation less than 25%) were found for this method. Based on 341 plasma samples, a significant correlation was established between the bioassay and chemical method (
R = 0.64). However, a proportional systematic error was observed when the results obtained with the CALUX bioassay were regressed with the results from the GC-HRMS analyses. The limit of quantification (LOQ) used to calculate TEQ values from the GC-HRMS determinations, the use of the relative potency values instead of the toxic equivalent factor and the potential of CALUX bioassay to measure all compounds with affinity for the
AhR may partly explain this proportional systematic error. Nevertheless, the present results suggest that the CALUX bioassay could be a promising valid screening method for human blood plasma analyses.
Within the Lower Palaeozoic Anglo-Brabant Deformation Belt, magnetic susceptibility on its own does not allow for a straightforward distinction between different lithostratigraphic units, except for ...the high-susceptibility levels of the Lower Cambrian Tubize Formation. Moreover, the variation in magnetic susceptibility within individual lithostratigraphic units is often larger than that between different units, but at the same time, this internal variation in susceptibility may show no clear relationship to features obvious in outcrop or hand specimens. Hence, the applicability of magnetic susceptibility for stratigraphic purposes in the Anglo-Brabant Deformation Belt is low. Better results are obtained using the temperature-dependent variation in terms of percentage of magnetic susceptibility within the "room temperature interval". Also the anisotropy of magnetic susceptibility allows for a better distinction between different lithostratigraphic units than does magnetic susceptibility. The best results are obtained by a comparison of thermal demagnetisation curves of magnetic remanence, used for determining ferromagnetic mineralogy. This method even allows distinguishing lithostratigraphic units in which ferromagnetic carriers do not contribute to overall magnetic susceptibility and its anisotropy. Ideally, each magnetic technique should be used for stratigraphic purposes only in combination with other magnetic techniques. Moreover, knowledge about the magnetic carriers (s.l.) facilitates this use of magnetic techniques and strongly improves the accuracy of the interpretations. KEYWORDS: AMS, composite fabric, ferromagnetic mineralogy, magnetic fabric, magnetic susceptibility.
A regional analysis of the anisotropy of magnetic susceptibility (AMS) has been performed on low-grade metamorphic, deformed homogeneous siltstone beds (HSBs) of the Plougastel Formation in the ...Central Armorican Domain together with exhaustive compositional analyses of the studied specimens. Despite sampling a single horizon, different paramagnetic minerals are controlling the AMS in the Crozon peninsula sites (white mica and chlorite) and in the inland sites of the Central Armorican Domain (white mica, chloritoid and some chlorite). Both the Crozon peninsula and inland datasets show a hockey-stick shaped pattern on a plot of the shape parameter T versus the corrected degree of anisotropy PJ, although the whole pattern is shifted to higher PJ values for the inland dataset. High-field AMS indicates that the low-field PJ and T values from two inland sites are slightly enhanced by a small ferromagnetic (sensu lato) contribution. Furthermore, variation in PJ and T values within single sites can be attributed to an effect of the observed quartz/white mica ratio, as quartz grains disrupt the petrofabric intensity. Our findings clearly demonstrate that the AMS of the HSBs in the Central Armorican Domain is strongly influenced by compositional variations and does not merely indicate tectonic strain, even in very similar tectonostratigraphic settings.
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