The Visean strata of the Heibaart borehole (DzH1, Campine-Brabant Basin, northern Belgium) can be divided into four lithological units. Biostratigraphical data indicate that the first unit was formed during the Late Moliniacian (foraminifer subzone Cf4d), the second during the Livian (Cf5), the third and the fourth during the Early Warnantian (subzones Cf6a-ß and Cf6? respectively).The Upper Moliniacian bioclastic packstones and grainstones were deposited in a shallow open marine environment in which water turbulence and circulation rates were high enough to prevent a considerable accumulation of mud.Due to a deepening of the sedimentation environment in the Heibaart area, the limestones of the Livian were deposited at depths below significant wave activity. In contrast, the lithoclastic limestones at the top of the Livian were formed in an environment with an important wave and/or current activity.The lower part of the Lower Warnantian (Cf6a-ß) strata represents deposits at or just below normal wave base. Current or wave activities are probably responsible for the grains-supported texture and the reworked fragments.A rise of the sea-level at the base of the upper part of the Early Warnantian caused a deepening of the sedimentation environment. An algal-cryptalgal buildup developed in the Heibaart area. The lower part of the buildup consists of non-laminated cryptalgal bodies (thrombolites) which are not restricted to the intertidal zone. However, in the upper part laminated stromatolites occur which are characteristic for a very shallow subtidal and intertidal zone. This shallowing upward sequence resulted from a drop of the sea-level at the end of the Early Warnantian or/and from the growth of the buildup.