Bioclasts form an important component of the Campanian and Maastrichtian deposits in South-Limburg and Northeastern Belgium. As such, these may be used for characterizing individual layers, such as the 'coprolith bed' and the 'bryozoan bed of Kunrade'. If this principle is applied to continuous sections, a detailed comparison of outcrops and boreholes should be possible. Therefore, a quantitative analysis has been made of two groups of bioclasts; namely those from the sieve fraction 1.0-2.4 mm and the ostracodes from the sieve fraction 0.125-1.0 mm. In this way, it is possible to construct bioclast diagrams which permit a detailed bed-by-bed correlation between different sections. Whenever possible, these correlations have been checked by the vertical distribution of foraminifera. Comparison between these ecostratigraphic bioclast correlations and the existing lithostratigraphic correlations shows some remarkable differences, notably around the boundary between the Gulpen and Maastricht Formations and around the boundary between the Vaals and Gulpen Formations. If future investigations might confirm the ecostratigraphic correlations based on bioclasts and ostracodes, one has to accept that on the one hand the Vaals and Gulpen Formations and on the other the Gulpen and Maastricht Formations are in part time equivalents. This would also mean, that the foraminifer zonation of HOFKER (1966) should be slightly modified. Since the quantitative analysis of bioclasts and ostracodes and even the recognition of some key species amongst the foraminifera are easily learned and don't require very expensive equipment, this method may be attractive even for non-professional geologists.

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Grondboor & Hamer

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Nederlandse Geologische Vereniging

P.J. Felder, M.J.M. Bless, & J.P.M.T. Meessen. (1985). Bioklasten, ostracoden en foraminiferen in het Campanien en Maastrichtien van Zuid-Limburg en Noordoost-België. Grondboor & Hamer, 39(6), 163–198.