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5.33.2 Grand-Chemin Formation - GRC

Authors: Groessens et al., 1982; Paproth et al., 1983; Conil & Delcourt, 1989; Doremus & Hennebert, 1995a, 1995b.

Description: Brown, crinoidal dolomite with brachiopods and corals (mainly syringoporids), with some variations from bottom to top. The dolomites are dark and fine-grained with chert in the lower part, but become well-bedded, medium grained, and almost devoid of chert in the upper part. Concentrations of calcite geodes typically occur at some levels. The formation overlies the Montils Fm.

Stratotype: Several small exposures along the "Grand Chemin" at Brugelette.

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

Thickness: About 150 m in the type area.

Age: Moliniacian (Groessens et al., 1982).