3.12 Mont-Saint-Martin Formation - MSN

Authors: Dumont, 1842; Boulvain et al. (2001).

Description: Argillaceous sandstone ("Supraliasic Sandstone"), followed by ferruginous marl including several iron oolite beds, and ending with sandy marl. Locally, coquina beds.

Type area: Bois de Musson, to the west of Mont-Saint-Martin.

Area and thickness: The formation crops out in the extreme south of Belgian Lorraine. It presents a thickness of approximately 40 m in the eastern area but is strongly reduced towards the west.

Age: Mont-Saint-Martin Formation is dated from Upper Toarcian to Lower Bajocian Grammoceras thouarcense Zone to Hyperlioceras discites Zone (Maubeuge, 1947, 1972).