5.20 Malon-Fontaine Formation - MAF

Authors: Cornet, 1927; Groessens, 1978; Paproth et al., 1983; Doremus & Hennebert, 1995a, 1995b.

Description: Thin-bedded, fine-grained, argillaceous limestones with thin marlstone intercalations. Fossils are rare. The distinction between the Thiarmont Mbr - THI (Doremus & Hennebert, 1995a, 1995b) and the overlying Cognebeau Mbr – COG (Doremus & Hennebert, 1995a, 1995b) is based on the abundance of chert nodules and bands in the latter whereas they are absent in the former.

Stratotype: Thiarmont Mbr: old quarry “Goffart" at Thiarmont, two km SW from Lalaing castle. Cognebeau Mbr: Hainaut quarry, at Soignies, situated NW of the Cognebeau stream.

Area: Western HSA, at least from Ath to Seneffe.

Thickness: The formation is 65 m thick in the type area (Thiarmont Mbr: 33 m; Cognebeau Mbr: 32 m).

Age: Ivorian (Cc2b-d Conodont Zones, Cf2 Foraminifer Zone, Conil et al., 1991).