Sedimentatie-cyclothemen in de kalkstenen uit het Boven-Krijt van Zuid-Limburg

A description has been given of the sedimentation-cyclothems in the limestones from the Upper-Cretacious, Maestrichtien, of South-Limburg (the Netherlands). These cyclothems consist of a basal conglomerate of varying composition with sometimes fossil grit or pebbles and on top of it a layer of calcarous sand (calcarenite). Bioturbations, hardgrounds and flintnodules can be characteristic for this calcarous sandlayer (fig. 1). From the base to the top of the cyclothem an increase takes place of the amount of CaCO3. At the base the CaCO3 content is 60-95% and at the top 95-99%. There is also a difference in grainsize. The lower part of the calcarenite is more fine grained than the higher part. The origin of these cyclothems is attributed to synsedimentary tectonical block-faulting.