5.6 Vesdre Formation - VES

Authors: Boonen, 1979; Swennen et al., 1982; Paproth et al., 1983; Laloux et al., 1996a, 1996b.

Description: The lower part comprises brown to grey-brown, thick-bedded, coarse-grained dolomite, whereas the upper part has pale, thick-bedded, coarse-grained dolomite alternating with dark, thin-bedded, fine-grained dolomites. Chert and calcite, quartz or dolomite nodules are abundant locally. The calcite, quartz and dolomite nodules are interpreted as pseudomorphs after anhydrite. In the uppermost part of the formation, the Walhorn Mbr (WAL) (Paproth et al., 1983) is distinguished as a dolomitic breccia composed of dark, coarse-grained elements in a grey-brown dolomitic matrix.

Stratotype: The base of the formation is exposed in the section situated 500 m north of Dolhain station (R. Vesdre area) and the boundary with the overlying Belle-Roche Breccia can be observed in the Walhorn quarry.

Area: Eastern NSA – eastern CSA.

Thickness: About 150 m deduced from geological mapping.

Age: Late Hastarian (early Tournaisian) to Moliniacian (early Visean, Cf4a2 Foraminifer Subzone), based on foraminifera preserved in chert nodules (Laloux et al., 1996a, 1996b).