5.24 Mont-sur-Marchienne Formation - MSM

Authors: Delcambre & Pingot, 2000.

Description: Thick-bedded, pale limestone with calcite nodules, rich in corals and brachiopods (Levitusia humerosa). The limestone comprises layers rich in oncoliths and algal ribbons. The boundary with the underlying Pont-à-Nôle Fm is marked by the change of colour and the occurrence of algal limestones. The formation is overlain by the Terwagne Fm.

Stratotype: North part of the Gralex quarry at Mont-sur-Marchienne, in the Eau d’Heure valley.

Area: Mont-sur-Marchienne area (NSA). The formation, when dolomitized, passes laterally to the upper part of the Namur Group.

Thickness: At least 40 m.

Age: Moliniacian (Cf4a1/Cf4a2 Foraminifer Subzones).