2.2.3 Châtelet Formation

Authors: Renier, 1912, 1928; Stainier, 1932; Delmer, 1963; Delcambre & Pingot, 2000.

Description: The Châtelet Formation consists of non-marine partly silty shales, sandstones, thin coal seams (30 to 75 cm) or rootlet beds (paralic facies). It is still poor in coal but mineable seams occur in all coal basins. Two widespread goniatite-bearing marine horizons, at the base of thick cyclothemes and overlying beach barrier sandstone units, characterise this unit.

The following members have been distinguished (names and definition according to latest revision in Paproth et al., 1983), from bottom to top:

- Ransart Member (base: Ransart = Fraxhisse = Sarnsbank marine band; boundary Namurian - Westphalian), formerly known as ‘Sous-zone d’Oupeye’;

- Floriffoux Member (base: Floriffoux = Bouxharmont = Finefrau Nebenbank marine band), formerly known as ‘Sous-zone de Beyne’.

The Châtelet Formation is conformably overlying the Andenne Formation; its base coincides with the Ransart (=Sarnsbank) Marine Band. It is conformably succeeded by the Charleroi Formation.

Stratotype: Charleroi coal basin (Stainier, 1932).

Area: As for the Belgian Coal Measures Group.

Thickness: 200 m (Hainaut), 300 m (Liège), 500 m (Campine).

Age: Early Upper Bashkirian, Lower Westphalian A according to traditional subdivision.

Remark: The “Assise de Châtelet” as defined by Renier is equivalent to the “Assise de Beringen” as defined by Delmer.