4.2.14. Etroeungt Formation - ETR

Authors: Gosselet, 1857; Barrois, 1913; Conil & Lys, 1980.

 

Description: The Etroeungt Fm is made up of of several dm- to several m-thick beds of green shales and siltstones interbedded with argillaceous or carbonate, micaceous sandstones, often of yellow brown color.  Interbedded nodular or lenticular beds of carbonate, often crinoidic, are also frequent.  Three lithological units may be distinguished, respectively from bottom to top : a shale dominant unit, a sandstone dominant unit and a carbonate dominant unit (the latter corresponding to the Etroeungt Limestone s.s.).

Former names: Etroeungt zone or “assise”; Etroeungt limestone; Etroeungt Limestones and Shales.

 

Stratotype: Parcq quarry, Etroeungt, near Avesnes (N of France).

 

Area: Dinant Synclinorium.

 

Thickness: 120 m at Hastière and Yves-Gomezée; 200 m at Walcourt.

 

Age: Uppermost Famennian (Strunian, Fa2d-Tn1a).  Biostratigraphical correlations between miospores and conodonts due to Maziane et al. (1999) indicate that the base of the Retispora lepitophyta-Knoxisporites literatus miospore biozone is correlated with the middle or late P. expansa conodont biozone and the base of the Retispora lepidophyta-Indotriadites explanatus microspore biozone with the early to middle Siphonodella praesulcata conodont biozone.

 

Remark: The Comblain-au-Pont Fm (formerly, Comblain-au-Pont zone or “sous-assise”) is a synonym to characterize the same formation in Belgium, when moving eastwards.