The boundary between the middle Eocene Brussel sand and the Lede sand formations in the Zaventem-Nederokkerzeel area (northeast of Brussels, Belgium)

In the Zaventem airport railway cutting, to the north-east of Brussels, the upper part of the Brussel Sand Formation consists of two major units, both attributable to calcareous nannofossil zone NP14a. The lower predomi­nantly sandy unit ZB1 (including subunits A, B and C, belonging to NP14al) is built up of sparsely glauconitic, relatively coarse tidal current deposits with nodule levels cemented by carbonate and silica, of which one shows slump­ing structures and is interpreted as a seismite. The uppermost unit ZB2 (also labelled D, belonging to NP14a2), com­posed of alternating thin fine sandstone bands and silty marls, represents the fill of a large channel. In the Berg-Nederokkerzeel sandpit the carbonate-rich Brussel Sand Formation is finer grained and more homogeneous. Here, the basal sand (unit A) is attributable to NP14a3 and consequently, younger than the section exposed at Zaventem. It is incised at its the top by a rather narrow erosive gully, filled in with well-sorted fine sand rich in washed-in molluscs (unit B), some of which seem to point to a brackish influence. The extreme top is made up of half a meter of sand with abundant Callianassa burrows and echinid fragments (unit C). From the nannofossil data it appears that, east of Brus­sels, at least two generations of tidal channel systems seem to have occurred within the Brussel Sand Formation, followed by a partial emersion at the end of the filling of the uppermost channel (Nederokkerzeel B). This was suc­ceeded by a relative sea-level rise, as shown by unit C and the remains of a completely eroded fully marine deposit, reworked in the base of the overlying Lede Sand Formation. The lowest relative sea level, with at least partial emer­gence of the Brussels area, occurred during middle to late Biochron NP14b. In both outcrops the Lede Sand Formation displays its characteristic pale grey relatively fine-grained homogeneous nature with a stone layer near its base. It can be concluded that, at the beginning of the "Lede transgression", an erosion of older deposits, containing already lifhified stone layers, occurred. This was, apparently, at least locally, caused by storms, which could redistribute, imbricate and turn over the stones, explaining their bio-perforation on both sides. Afterwards the stones have been above water for a relatively long time, enough to allow the dissolution of the perforating organisms and consequently an important oxidation of their surfaces. These stones have subsequently been colonised by a new marine fauna. Part of the shark teeth and calcareous nannofossil assemblages found in the coarse base of the Lede Sand is definitely older than the taxa normally found in the Lede Sand Formation. These fossils are the remains of a sediment package, believed to represent the formerly "Laekenian" stage

Stable oxygen isotope record of the Eocene-Oligocene transition in the southern North Sea Basin: positioning the Oi-1 event

Preliminary stable oxygen isotope data are presented from the southern North Sea Basin successions, ranging from the Lutetian to Rupelian. Analyses were performed on fish otoliths, nuculid bivalves and benthic foraminifera and are presented as bulk delta(18)O values relative to a well established regional sequence stratigraphic framework. The most significant positive shift in delta(18)O values clearly falls at the top of the regionally recognised Bassevelde 3 sequence, which base corresponds to the Eocene-Oligocene GSSP boundary. The here documented delta(18)O shift is closely associated with the base of the traditional Rupelian unit-stratotype and is tentatively correlated to the globally recognised Oi-1 event

Ernest Van den Broeck medallist lecture 2016. Tectonic and climatic signals in the Oligocene sediments of the Southern North-Sea Basin

The Oligocene sediments formed between the Pyrenean and Savian tectonic pulses. The earliest Oligocene was characterized by a widespread shallow water transgression. Global cooling coincided with the subsequent retreat of the sea which is also the time of the Grande Coupure faunal turnover. Renewed stepwise transgression resulted in the deposition of the Boom Clay during the Rupelian. High-frequency cyclic changes in water depth of the Boom Clay are driven by waxing and waning of ice masses while lower-frequency cycles can be tectonic signals. By the end of the Rupelian, differential vertical tectonics resulted in considerable erosion west of the Campine subsidence area and in shallower water depth in the eastern part of the southern coastal area. Subsidence of the Lower-Rhine graben resumed at the start of the Chattian. The sea could only briefly transgress over the area outside the graben but in the graben thick Chattian sediments are preserved. Outside the graben, erosion continued to dominate during the Chattian and the Aquitanian. This long period above sea level is due to a combination of the Savian tectonic uplift pulse and a global low sea level

Re-assessment of the new geological map of Belgium: earliest Oligocene dinoflagellate cyst-based ages in the Leuven area (sheet 24 Aarschot)

The dinoflagellate cyst (dinocyst) assemblages of two samples from a temporary outcrop in the vicinity of Haacht (Leuven) have been analysed. The co-occurrence of Areosphaeridium diktyoplokum, Cerebrocysta bartonensis, Glaphyrocysta semitecta, Rombodinium perforatum and Thalassiphora reticulata allows correlation with the North Sea Oligocene-1 zone. As a consequence, the considered unit has a latest Eocene to earliest Oligocene age, equivalent to the age of the marine Tongrian. Comparison of the studied area with the recent 1:50 000 geological map (sheet 24 Aarschot) shows that the current lithostratigraphic interpretation of the analysed section, i.e. the Middle Eocene Maldegem Formation, can no longer be uphold

Genetics of Chronic Lymphocytic Leukemia: Practical Aspects and Prognostic Significance

status: publishe

Stratigraphic architecture of the Upper Cretaceous and Cenozoic along the southern border of the North Sea Basin in Belgium

The Late Cretaceous and Cenozoic sedimentary record in the Campine Basin along the southern border of the North Sea Basin is analysed in terms of sequence stratigraphy. All available biostratigraphic, and in some cases, magnetostratigraphic data are used to constrain the sequence chronostratigraphy. The relative geographic extent of the strata is used as an indication of the relative sea level.Tectonic and eustatic components could be distinguished in several cases using regional geological information. Generally, sequences consist of transgressive and highstand systems tracts only and have flat, abrasiontype lower boundaries. Lowstand deposits are only identified as infill of erosional space, which generally implies marked tectonic uplift. Several eustatic and tectonic events can be correlated with similar events known elsewhere in the North Sea Basin. The time intervals spanned by the different sequences vary considerably, pointing out different control mechanisms

Calibration of the modified Bartlett-Lewis model using global optimization techniques and alternative objective functions

The calibration of stochastic point process rainfall models, such as of the Bartlett-Lewis type, suffers from the presence of multiple local minima which local search algorithms usually fail to avoid. To meet this shortcoming, four relatively new global optimization methods are presented and tested for their ability to calibrate the Modified Bartlett-Lewis Model. The list of tested methods consists of: the Downhill Simplex Method, Simplex-Simulated Annealing, Particle Swarm Optimization and Shuffled Complex Evolution. The parameters of these algorithms are first optimized to ensure optimal performance, after which they are used for calibration of the Modified Bartlett-Lewis model. Furthermore, this paper addresses the choice of weights in the objective function. Three alternative weighing methods are compared to determine whether or not simulation results (obtained after calibration with the best optimization method) are influenced by the choice of weights

Copula-based downscaling of spatial rainfall: a proof of concept

Fine-scale rainfall data is important for many hydrological applications. However, often the only data available is at a coarse scale. To bridge this gap in resolution, stochastic disaggregation methods can be used. Such methods generally assume that the distribution of the field is stationary, i.e. the distribution for the entire (fine-scale) field is the same as the distribution of a smaller region within the field. This assumption is generally incorrect and we provide a proof of concept of a method to estimate the distribution of a smaller region. In this method, a copula is used to construct a bivariate distribution describing the relation between the scales. This distribution is then used to estimate the distribution of the fine-scale rainfall within a single coarse-scale pixel, by conditioning on the coarse-scale rainfall depth