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2.2.3. Couvin Formation – CVN (revised April 2012, V. Dumoulin and S. Blockmans)

Authors: Gosselet, 1860; Bultynck & Godefroid, 1974; Bultynck, 1991c.
 
Description; In the type area the formation consists chiefly of biostromal beds and it is subdivided into two members, the Foulerie Member and the overlaying Abîme Member.
The lower part of the Foulerie Mbr is made up of bedded dark bluish crinoidal limestones with laminar and domical stromatoporoids and rugose corals; thin calcareous shale intercalations occur near the base. The middle part consists of dark bluish argillaceous limestone beds with occasionally thin calcareous nodular shales; the macrofauna consists of solitary rugose and tabulate corals, brachiopods gastropods and trilobites. Crinoidal limestone beds, frequently dolomitised, with domical stromatoporoids and branched tabulate corals make up the upper part. In the Abîme Member biostromal beds with globular stromatoporoids, branched tabulate corals and phaceloid colonial rugose corals alternate with micritic limestones mostly barren of megafauna.
 
Stratotype: The Foulerie Mbr and the lower part of the Abîme Mbr are exposed along the west banks of the Eau Noire river at Couvin (La Foulerie); the upper part of the Abîme Mbr is exposed in the cliff above the "Trou de l'Abîme" cavern downtown on the east side of the Eau Noire river.
 
Area: Southern flank of the Dinant Synclinorium between Macon to the west and Dion east of the Meuse river.
 
Thickness: Estimated at about 380m between Couvin and Nismes (Foulerie Mbr 220m thick and Abîme Mbr about 160m thick). More eastward the thickness gradually decreases, the lower part being replaced by the Jemelle Formation. The Couvin Formation disappears to the west of Wellin at the locality Les Maurlières.
 
Age: Lower to middle Eifelian, partitus and costatus conodont Zones (Bultynck & Godefroid, 1974; Bultynck et al., 2000).