LITHOLOGY AND BIOSTRATIGRAPHY OF UPPER CRETACEOUS-PALEOCENE CARBONATES IN THE MOLENBEERSEL BOREHOLE (NE BELGIUM)

The Molenbeersel well was drilled by the Belgian Geological Survey as a reconnaissance well in the Rur (= Roer) Valley Graben (NE Belgium). Paleocene and Upper Cretaceous (Upper Maastrichtian) carbonates were t raversed between 1223-1283.17m of which interval the major part was co red. A sedimentological and biostratigraphical analysis allows the rec ognition of three megasequences which correlate with thicker successio ns on the adjoining Brabant Massif, including the Maastrichtian type a rea. These megasequences testify to repeated flooding events on the in verted Rur Valley Block. Each of these is characterized by a basal con glomerate overlain by glauconite-rich deposits. In the upper two megas equences these deposits pass into pure calcareous strata. All deposits indicate shallow nearshore environments above storm wave base. Occasi onal emergence occurred as indicated by karstified horizons. Fossil as semblages belong to the boreal province with the exception of an immig ration of mediterranean organisms in the middle megasequence. This may be related to a period of tectonic relaxation of the Rur Valley Block during the Late Maastrichtian.