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3.1.6 Ombret Formation - OMB

Authors: after Martin et al., 1970.

Description: An upper sandstone-slate member of turbiditic nature in its upper part with obliquely stratified quartzitic sandstone up to several dm thick; a lower member with black shale with rare always thin micaceous sandstone intercalations (Martin et al., 1970). The upper sandstone-slate member has a similarity with the Ittre Fm in the Brabant Massif.

Stratotype: Large outcrop along the road N90, north-west of the church of Ombret-Rawsa, below the hill Tier d’Olne.

Area: Northern side of the Condroz inlier, NW of Huy.

Thickness: upper sandstone-slate member: about 300 m; lower black shale member: >50 m.

Age: Based on acritarchs and chitinozoans a definite Late Ordovician age is proposed, and probably Caradoc (Martin et al., 1970).