Carboniferous trilobites from Tournai

If talking about Belgian trilobites, then the area east of Tournai (Allain, Vaulx, Antoing) definitely figures among the well known and studied outcrops. Among the taxa described from this region are Piltonia (Piltonia) kuehnei, Cummingella (Cummingella) belisama belisama, Paladin (Kaskia) arduennensis, Parvidumus cernunnos and Witrtryides rosmerta.

Tournai is situated in the basin of the river Schelde/Escaut along the border with France in the Hainaut/Henegouwen province. From the geological point of view, the region is based on carboniferous limestone. It’s part of the eastern Synclinorium of Namur, belonging to the lower Carboniferous – Ivorian - period ( 359 to 345 million years). The so called “ Calcaire de Tournai” can be divided into two formations. The Tournai Formation is the lower and rather rich part; the Antoing Formation is situated above and not very fossiliferous. Both formations are divided into members. The famous trilobites come from the Allain, Providence, Pont-à-Rieu and Vaulx members of the Tournai Formation and from the lower part of the Calonne member of the Antoing Formation.
The Carrière du Milieu in Gaurain-Ramecroix

The carboniferous limestone is covered with meso-cenzoic formations and so one need to visit quarries and abandoned quarries to collect samples. During the 19th century numerous quarries were opened for building material. Today, remain several carries that exploit the black or grey limestone: the C.C.B SA, and the Carrière du Milieu at Gaurain-Ramecroix; the Carrière Lemay at Vaulx and the Carrières d’Antoing S.A. at Antoing. Unfortunately the quarry owners have recently become very restrictive and so it ‘s getting harder and harder to get access to the quarries. The abandoned quarries are not really an option. Most of them are inundated and have become rather dangerous. Access is often prohibited.

The Cimescaut SA quarry

We were able to visit the Cimescaut SA quarry in Antoing with our friends from the C.M.P.B. This is certainly not the richest quarry if you are looking for trilobites. Parts of trilobites are easy to find, but complete specimens are very hard to discover. Among our findings were an enrolled Piltonia kuehnei and a plate literally covered with pygidia of the same species. Some months later we could search in the Carrière du Milieu in Gaurain-Ramecroix. This is a huge quarry where trilobites are hard to catch.

Identifying trilobites from the “ Calcaire de Tournai” can be tricky, especially when dealing with damaged or only partial exoskeletons. The articles ‘Die Trilobiten des belgischen Kohlenkalkes’ by G. and R Hahn and C. Brauckmann in Geologica et Palaeontologica and the excellent volume by G. Daumeries ‘ Atlas de détermination des Trilobites Carbonifères de la Belgique’ can be a great help. The Daumeries book can be obtained through the ‘Cercle  Géologique du Hainaut’.

With Guy Daumeries in the Carrière du Milieu.

 

More trilobites from the Carboniferous of Tournai can be found in the album.

Tournai