Biostratigraphy and ecostratigraphy of Late Cretaceous deposits in the Kunrade area (South-Limburg, SE Netherlands)

The Late Cretaceous deposits in the Kunrade area in South-Limburg (SE Netherlands) differ from the classic outcrops around Maastricht in their lithofacies and fossil content. On the basis of biostratigraphic and ecostratigraphic data from 24 sections (2 boreholes and 22 outcrops), an ecostratigraphic subdivision into five ecozones is proposed. This ecozonation is correlated with sections at Valkenburg a/d Geul (Thermae Borehole), Maastricht (Kastanjelaan Borehole), Hoepertingen and Diet-Heur

Bioklasten in het krijt uit boringen van West-en Oost-Vlaanderen

During recent years nearly 500 samples from boreholes drilled in West Flanders have been analyzed (figs 1-3). These samples appeared to contain sufficient amounts of bioclasts (1-2.4 mm) to allow a subdivision into ecozones, which formed the basis of a lithostratigraphic subdivision (fig. 4). The bioclast assemblages indicate that these boreholes are situated outside the depositional area of the Campine-Limburg basin (Maastricht-Hasselt-Antwerp). That is the reason why Arabic numerals have been used in the ecozonation, in distinction with the ecozonation of the Campine-Limburg basin (Roman numerals, fig.5). In the boreholes examined Cretaceous rests directly either on Cambro-Silurian of the Brabant Massif or on the Devono-Carboniferous of the Tournai Basin (Namur Synclinorium), north of the Bordière Fault. A limited number of samples from the Mons basin (Fig.6) appear to indicate that the West Flanders samples are more closely correspond with strata of that basin. The Nevele and Dendermonde boreholes (East Flanders) cannot directly be tied in with the ecozones. The Nevele samples may belong to ecozones 4 and 5. The Dendermonde borehole is characterized by a different bioclast assemblage and thus cannot be correlated with boreholes.Bioclast cannot be used for age determination of strata, which is why other methods are necessary. In the present case we have relied on the studies carried out by F. Robaszynski 1989 and S. Louwye 1993

Late Cretaceous sea level rise and inversion: their influence on the depositional environment between Aachen and Antwerp

Pluridisciplinary investigations on Upper Cretaceous (Santonian to Maastrichtian) in the Aachen-Antwerp area (NE Belgium, SE Netherlands and Aachen area of Federal Republic of Germany) have revealed the rather complex sedimentary history of the same. Correlations between different lithologies are based on bioclasts, foraminifera, ostracodes, belemnites and petrophysical borehole logs. Deposition was controlled by continuous sea level rise during the Santonian to late Upper Maastrichtian and by tectonic movements (inversion of subsidence since the Lower Campanian, relaxation of the inversion since the middle Upper Maastrichtian, differential warping of blocks to the south of the Rur Valley area notaby during the Upper Campanian to early Upper Maastrichtian).A major change in the fossil assemblages at the onset of the middle Upper Maastrichtian is noticed in the appearance of mediterranean elements, in a dramatic change in the quantitative composition of bioclast assemblages, and in a rather abrupt and pronounced diversification of most fossil groups. This change matches the beginning relaxation of the inversion in the Rur Valley area and it is interpreted as one of several regional, tectonically induced ecostratigraphical events