3.2.9 Moncheret Formation - MCH

Authors: Michot, 1928; Delcambre & Pingot, in press b.

Description: Dark green, silty shale with either metric dark sandstone beds, divided in lenticular layers, or centimetric to decimetric lenses of the same dark sandstone. The shale is often punctuated with patches of rusty iron oxides or of dark manganese oxide. The top of the formation is unknown because of faulting of the Midi thrust fault.

Stratotype: outcrops along the Ri d'Acoz valley, south of Bouffioulx, Charleroi.

Area: In the westernmost part of the Condroz inlier, along the Ri d'Acoz valley near Bois de Châtelet; in an area supposed to belong to the para-autochtonous northern part of the Condroz inlier.

Thickness: Poorly known, at least 50-70 m in the Ri d'Acoz.

Age: Ludlow or Pridoli, based on trilete spores (Brochotriletes sanpetrensis) together with reworked Ordovician acritarchs (Steemans, 1994 and unpublished data of 1995 in Delcambre & Pingot, in press b).

Remarks: According to the palynofacies the sedimentation environment was littoral or continental (Steemans, 1995 and unpublished data). Michot (1928) classified this unit as the Vitrival-Bruyère Fm. The recently studied palynology indicates the presence of a previously not described unit.

(B. DELCAMBRE and J.L. Pingot)