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5.2. Samme Formation – SAM

 

Authors: Doremus & Hennebert, 1995a, 1995b.

Description: The formation includes 3 members: the Bois de la Rocq Mbr, the Feluy Mbr and the Mévergnies Mbr, reading from base to top.

- Bois de la Rocq Mbr - BDR(Doremus & Hennebert, 1995a, 1995b). Sandy and dolomitic micaceous rocks, with some calcareous or dolomitic levels. The member overlies the Famennian shales of the Franc-Warêt Fm. In the stratotype area, it consists of dolomitic sandstones, including calcareous or dolomitic layers and thin shaly interbeds. In the Tournai borehole, conglomerates, red and green sandstones and shales form the lower part, and dolomitic sandstones the upper part.

- Feluy Mbr – FEL(Paproth et al., 1983; Doremus & Hennebert, 1995a, 1995b).This member is dominantly calcareous, but it includes various lithologies, such as sandy, argillaceous or dolomitic limestones, and breccia.

- Mévergnies Mbr - MEV(Paproth et al., 1983; Doremus & Hennebert, 1995a, 1995b). The member, which lies between the Feluy Mbr and the Pont d'Arcole Fm, displays various lithologies, mainly siliciclastic. In the stratotype, it consists of thick-bedded and lenticular, light-coloured, dolomitic sandstones, sometimes micaceous, with thin blue shale intercalations in the lower part. Macrofossils are rare.

Stratotype: The Samme Fm was defined in the Samme Valley, between Feluy and La Rocq castle. The members are located as follows. Bois de la Rocq Mbr: old quarry “du Bois de la Rocq" at Feluy, on the right bank of the River Samme, in the southern part of the Bois de la Rocq. Feluy Mbr: old quarry "Exploitation des Prés" at Feluy, on the right bank of the R. Samme. Mévergnies Mbr: old quarry "Duchâteau" at Mévergnies.

Area: Western HSA. Bois de la Rocq and Feluy Mbrs: at least from Tournai to Seneffe. Mévergnies Mbr: at least from Tournai to Soignies; it does not exist in the Samme Valley but is known further westward.

Thickness: Bois de la Rocq Mbr: about 44 m in the type area; about 29 m in the Tournai borehole. Feluy Mbr: about 22 m in the type area, but it is thicker in the Leuze and Tournai boreholes, with 43 and 52 m respectively. Mévergnies Mbr: about 8 m in the type area, but thicker in the Leuze and Tournai boreholes, with 18 and 22 m repectively.

Age: Bois de la Rocq Mbr: late Famennian (Strunian) to early Hastarian (Groessens et al., 1982; Streel, 1969). Feluy Mbr: earliest Hastarian (Cf1? Foraminifer Zone; Cc1? Conodont Zone; Palynological Zone VI = zone TE in Streel, 1977). Mévergnies Mbr: early Hastarian.