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2.2.9. Terres d'Haurs Formation - THR

Authors: Pel, 1975; Preat & Tourneur, 1991c.
Description:The formation mainly consists of alternating argillaceous, crinoidal bedded or nodular limestones and mostly calcareous shales with corals, brachiopods and trilobites. Locally the base of the formation is characterized by the development of patch-reefs with stromatoporoids and rugose and tabulate corals.
Stratotype: South-eastern walls of Mont d'Haurs fortress, 1km south-east of Givet.
Area: Southern and south-eastern flank of the Dinant Synclinorium, west of the Xhoris Fault.
Thickness:Between 65 and 70m in the stratotype. Due to the more argillaceous-shaly character than the underlying Trois Fontaines Fm and the overlaying Mont d'Haurs Fm, the formation is generally not well exposed and lateral thickness changes cannot be accurately established.
Age: Early Givetian. Conodonts from the stratotype section are assigned to the timorensis Zone (= lower part of Lower varcus Zone; Bultynck, 1987).
Remarks:As for the Trois Fontaines Fm an increasing influx of terrigenous material is noticed on the south-eastern flank of the Dinant Synclinorium. In former literature the Terres d'Haurs Fm was designed as a transitional zone between the Trois Fontaines and the Mont d'Haurs Formations (Bonte & Ricour, 1949) or partially included respectively in the upper part and lower part of the two latter formations (Errera et al., 1972).